Thesis (MSc Food Sc)--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Maize is an important crop for both human and animal consumption. Maize kernel texture (kernel hardness) is an important quality trait for many sectors in the South African maize industry, where a harder texture is desired. Both total protein content and the main storage proteins, zein, have been associated with kernel texture. The zein profiles of South African white maize hybrids, from a breeding program, grown at three localities together with their respective inbred parent lines were evaluated to determine the difference in zein expression. For only the hybrids, total protein content, zein content and degree of hardness (kernel texture) was determined to establish possible relationships. Zein consists of four main classes, α-, β-, γ-, and δ-zein, which can further be divided into sub-classes. Zein was characterised using matrix-assisted laser desorption ionisation time-offlight mass spectrometry (MALDI-TOF MS) after optimisation of the zein extraction and matrix preparation procedures. Two matrices [2-(4-hydroxyphenylazo)benzoic acid (HABA) and α- cyano-4-hydroxy-cinammic acid (CHCA)] and three pH levels (<1.5, 1.7 and 2.9) for matrix solutions were investigated. Two solvent concentrations (50% and 70% acetonitrile (ACN) were also investigated. Parallel to this investigation, a zein extraction procedure was optimised. Zein was extracted from non-defatted (NDF) and defatted (DF) maize meal at ambient temperature and 60°C and meal with different particle size distributions. Particle size of maize meal did not influence the quality of spectra. Regardless of matrix conditions used, zein extracted at 60°C from NDF meal produced spectra with a low signal-to-noise (S/N) ratio. When only HABA was included (pH<1.5), not all γ-zein sub-classes were observed. This was also true for zein extracted at ambient temperature from NDF and DF meal. Good S/N ratios for all zein classes were obtained when zein was extracted from NDF meal at ambient temperature using a matrix solution containing both matrices in 70% ACN at pH 2.9. MALDI-TOF MS provided accurate detection and good profile resolution for zein characterisation. Spectral profiles of hybrids were a combination of their respective inbred parent lines. Zein proteins were quantified using reverse-phase high performance liquid chromatography (RP-HPLC). Total protein content was determined and kernel texture assessed using a particle size (PSI) method. Significant (P<0.01) differences were observed for total protein content and degree of hardness between certain hybrids as well as average values for localities. Correlations and principal component analysis indicated that hybrids with a higher protein and total zein content had a harder kernel texture. The β- and γ-zein contents also correlated positively with kernel hardness. However, when expressed as percentage of total zein the opposite was observed. Collectively the α-zeins and most individual α-zeins correlated positively with hardness. Scanning electron microscopy micrographs showed differences between the floury endosperm of harder and softer maize kernels; illustrating starch types (amylose and amylopectin) should also be analysed in future hardness studies. The correlations obtained were not strong (r<0.6) and the variation explained by first two principal components was low. Other maize constituents, more hardness measurements should be considered in future studies to improve this. / AFRIKAANSE OPSOMMING: Mielies is a belangrike gewas vir beide mens- en dierlike inname. Mieliepittekstuur (pithardheid) is ‘n belangrike kwaliteitseienskap vir baie sektore in die Suid Afrikaanse mielieindustrie, waar ‘n harder tekstuur verlang word. Beide totale proteïeninhoud en die hoof opbergingsproteïen, zein, is al geassosieer met pittekstuur. Die zein profiele van Suid- Afrikaanse witmielie basters, van ‘n teel program, wat by drie lokaliteite verbou is sowel as hul onderskeie ingeteelde ouerlyne is geevalueer om verskille in zein uitdrukking te bepaal. Die totale proteïeninhoud, zeininhoud en graad van hardheid is bepaal om verhoudings vas te stel. Zein bestaan uit vier hoof klasse, α-, β-, γ-, en δ-zein, wat verder onderverdeel word in subklasse. Zein is gekarakteriseer met matriks-ondersteunende laser desorpsie ionisasie tyd-vanvlug massa spektrometrie (MBLDI-TVV MS) na die zein ekstraksie en matriks voorbereidingprosedures geoptimaliseer is. Twee matrikse [2-(4-hydroksiephenylazo)benzoë suur (HABA) en α-cyano-4-hydroksie-kaneelsuur (CHCA)] en drie pH vlakke (<1.5, 1.7 and 2.9) vir matriksoplossings was ondersoek. Twee oplossingkonsentrasies [50% and 70% asetonitriel (ACN)] is ook ondersoek. Zein ekstraksie kondisies is ook geoptimiseer. Zein is geëkstraheer van nie-ontvette (NOV) en ontvette (OV) mieliemeel by omgewings temperatuur en 60°C. Die partikelgrootte van die mieliemeel het nie die kwaliteit van spektra beïnvloed nie. Ongeag watter matrikskondisies gebruik is het zein wat van NGV meel by 60°C ge-ekstraheer is, spektra met ‘n lae sein-tot-geraas (S/G) verhouding geproduseer. As die HABA alleenlik gebruik (by pH<1.5) is, is nie alle γ-zein klasse waargeneem nie. Dit was ook waar vir zein wat by omgewings temperatuur van NGV en OV mieliemeel ge-ekstraheer is. Goeie S/G verhoudings is waargeneem met zein, ge-ekstraheer van NGV mieliemeel by omringende temperatuur, met die bebruik van beide matrikse in 70% ACN by pH 2.9. (MBLDI-TVV MS) het akkurate en goeie resolusie van profiele vir zein karateriseering verksaf. Spektrale profiele van basters was ’n kombinasie van hul onderskeie ouer lyne. Zeinproteïene is met omgekeerde-fase hoë prestasie vloeistofchromatografie gekwantifiseer. Totale proteïeninhoud is bepaal en die hardheidsgraad was bepaal met ‘n partikelgroote indeks (PGI) metode. Beduidende verskille tussen proteïeninhoud en hardheidsgraad is waargeneem tussen sekere basters sowel as gemiddelde waardes by die verskeie lokalieteite. Korrelasies en hoofkomponent analise het aangedui dat basters met ‘n hoër proteïeninhoud en totale zein ‘n harder tekstuur gehad het. Die β- en γ-zeininhoud het ook positief gekorreleer met hardheid. Alhoewel, wanneer die proteïene as persentasie van totale zein uitgedruk is, is die teenoorgestelde waargeneem. Gesamentelik het α-zein asook die meeste indivduele α-zeins positief gekorreleer met hardheid. Skandeer elektron mikroskopie mikrograwe het verskille tussen die meelerige endosperm van harder en sagter pitte aangedui; meer proteïenliggame was aanwesig in die harder pitte en die stysel was digter gepak. Dus moet stysel tipes ook in ag geneem word in toekomstige hardheidsstudies. Korrelasies wat verkry is, was nie hoog (r<0.6) nie en die variasie verduidelik deur die eerste twee hoofkomponente was laag. Ander miielie samestellende dele as ook meer hardheidsmetings moet in toekomstige studies in ag geneem word om dit te verbeter.

Thesis (MSc Food Sc)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The purpose of this study was to determine whether acceptable polony can be manufactured with varying quantities of chicken mechanically recovered meat (MRM), soya flour and pork rind to a fixed protein content of 10%, irrespective of fat content and without the addition of more fat to obtain a total meat equivalent (TME) of 75%. The effect of replacing MRM with soya and rind on the chemical, physical and sensory characteristics of polony was measured. The cost of producing each treatment by using the varying ingredients was also calculated. Three levels of soya flour (0, 4 and 8%) were combined with three levels of pork rind (0, 8 and 16%) to formulate the nine treatments of polony (R0S0, R0S4, R0S8, R8S0, R8S4, R8S8, R16S0, R16S4 and R16S8, where R and S represents rind and soya, respectively). The cost of making the nine treatments varied from R4.54/kg to R2.91/kg, where the most expensive treatment was the one in which no replacement of MRM was done (R0S0) and the least expensive treatment was R16S8, where most MRM was substituted with rind (16%) and soya (8%). The chemical results showed that the protein content of the nine treatments varied between 9.7 and 10.5%. Fat and ash decreased while moisture and total collagen increased as more MRM was being replaced with increasing levels of soya, rind or combinations of them. The physical results indicated that L* and b* increased while a* decreased, resulting in treatment samples which were lighter, more yellow and less red in colour. Hardness and gumminess increased in samples singly replaced with 8% rind, 4% soya or their combination (R0S0, R0S4, R8S0 and R8S4), while they decreased in the rest of the treatments. Cohesiveness increased in all treatments with increasing levels of soya and rind except for the sample containing 16% rind and 8% soya (R16S8). The pH of treatments containing 0% soya increased with rind increase whereas those with 4% soya did not change. The lowest pH was for the sample with 16% rind and 8% soya (R16S8). Sliceability was used to determine the ease of cutting intact slices at slice thicknesses of 2 and 3 mm. The sliceability of polony treatments which exhibited good slicing characteristic ranged between 80 and 100% at both 2 mm and 3 mm slice thicknesses. Sliceability was poorest for the treatment with high levels of rind and soya (R16S8) at both 3 mm (40%) and 2 mm (0%). The water holding capacity (WHC) of all treatments improved, except for the treatments to which no rind and soya was added (R0S0) and the treatment in which MRM was replaced with 8% soya (R0S8). Sensory analyses results signified that pink colour, colour intensity, salty taste, flavours (garlic, polony and spicy) and firmness decreased while soya flavour, pasty and fatty mouthfeel increased with increasing levels of rind, soya or their combination. Coarse texture decreased as rind increased while it increased with an increase in soya levels. Only five treatments were employed for consumer analyses. The most preferred treatment was that with 0% rind and 0% soya (R0S0), while the sample with 0% rind and 8% soya (R0S8) was the least preferred. It can be concluded that the production of polony through the replacement of MRM with rind and soya flour is possible, but consumer preference results show that consumers like polony products which have low levels of soya (≤4%) and moderate levels of rind (≤8%). However, the negative effects of rind and soya in polony with high levels of soya and rind can be rectified by adding appropriate additives, as provided for by manufactured meat regulations. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om vas te stel of wisselende hoeveelhede meganies herwonne hoendervleis, sojameel en swoerd gebruik kan word om aanvaarbare polonie te vervaardig met ʼn vaste proteïeninhoud van 10%, ongeag die vetinhoud, en sonder die byvoeging van meer vet om ʼn algehele vleisekwivalent van 75% te kry. Hiervoor is die uitwerking op die chemiese, fisiese en sintuiglike kenmerke van polonie gemeet wanneer meganies herwonne vleis (“mechanically recovered meat”, oftewel “MRM”) met soja en swoerd vervang word. Voorts is die produksiekoste van elke formule op grond van verskillende bestanddele bereken. Drie vlakke sojameel (0%, 4% en 8%) is met drie vlakke swoerd (0%, 8% en 16%) gekombineer om die nege polonieformules (R0S0, R0S4, R0S8, R8S0, R8S4, R8S8, R16S0, R16S4 en R16S8) te skep, waar R die swoerd (“rind”) en S die sojameel verteenwoordig. Die vervaardigingskoste van die nege formules wissel van R4,54/kg tot R2,91/kg: Die duurste formule was dié sonder enige MRM-vervanging (R0S0), en die goedkoopste waar die meeste MRM met swoerd en soja vervang is (R16S8). Die chemiese resultate toon dat die proteïninhoud vir die nege formules tussen 9,7% en 10,5% wissel. Vet en as het afgeneem en vog en algehele kollageen het toegeneem namate al hoe meer MRM met toenemende vlakke soja, swoerd of ʼn kombinasie daarvan vervang is. Fisiese resultate toon dat L* en b* met MRM-vervanging toegeneem het, terwyl a* afgeneem het, met ligter, geler en minder rooi monsters tot gevolg. Hardheid en taaiheid het toegeneem by monsters waar MRM stuksgewys met 8% swoerd, 4% soja of ʼn kombinasie daarvan vervang is (R0S0, R0S4, R8S0 en R8S4), terwyl dit by die res van die formules afgeneem het. Saamklewing het by alle formules met hoër vlakke soja en swoerd toegeneem, buiten by die monster met 16% swoerd en 8% soja (R16S8). Die pH van formules met 0% soja het toegeneem namate die swoerd vermeerder is, terwyl dié met 4% soja onveranderd gebly het. Die laagste pH is aangeteken by die monster met 16% swoerd en 8% soja (R16S8). Snybaarheid is bepaal aan die hand van die gemak waarmee skywe van onderskeidelik 2 mm en 3 mm dik gesny kon word. Goeie snybaarheid, met ander woorde tussen 80% en 100%, is aangeteken vir polonie wat in sowel 2 mm as 3 mm diktes gesny kon word. Snybaarheid was die swakste vir die formule met hoë vlakke swoerd en soja (R16S8), vir sowel die 3 mm (40%) as die 2 mm diktes (0%). Die waterhouvermoë het by alle formules verbeter, buiten by die formule waarby geen swoerd of soja gevoeg is nie (R0S0) en die formule waar MRM met 8% soja vervang is (R0S8). Die resultate van die sintuiglike ontledings dui daarop dat die pienk kleur, kleurdiepte, sout smaak, geure (knoffel, polonie en speserye) en fermheid afgeneem het, en die sojageur, deegagtige tekstuur sowel as die tekstuur op die tong toegeneem het namate meer swoerd, soja of ʼn kombinasie daarvan bygevoeg is. Grofheid van tekstuur het afgeneem namate die swoerd verminder is, terwyl dit weer toegeneem het met ʼn toename in soja. Slegs vyf formules is vir verbruikersontledings gebruik. Die gewildste formule was dié met 0% swoerd en 0% soja (R0S0), terwyl die monster met 0% swoerd en 8% soja (R0S8) die minste byval gevind het. Daar kan dus afgelei word dat polonieproduksie deur die vervanging van MRM met swoerd en sojameel moontlik is, hoewel die proetoetsresultate toon dat verbruikers polonieprodukte met lae sojavlakke (≤4%) en matige swoerdvlakke (≤8%) verkies. Tog kan die negatiewe uitwerking van groot hoeveelhede swoerd en soja in polonie reggestel word deur toepaslike bymiddels, waarvoor die regulasies oor verwerkte vleis voorsiening maak, by te voeg.

Thesis (MScFoodSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Twenty five commercial Chenin blanc wines produced solely from bush vine vineyards and including three vintages, three styles and five production areas, were sourced for this study. Descriptive sensory analysis (DSA) and chemical analyses including GC-FID (gas chromatography fitted with a flame ionisation detector) and FTMIR (Fourier transform mid-infrared) spectroscopy were employed to establish the sensory and chemical characteristics, whereas consumer tests were conducted to determine consumer perception and liking of bush vine Chenin blanc wines. DSA (a profiling technique) was also compared to the sorting task (a classification technique) with a description assignment to evaluate the sorting task’s ability to profile wines. According to the results of DSA, the wines separated into two groups. One group associated with sensory attributes which can be considered indicative of the Fresh and Fruity Chenin blanc style. The other group associated with sensory attributes which can be considered indicative of the Rich and Ripe style of Chenin blanc. No separation between the wooded and unwooded Rich and Ripe styles was apparent. According to the results of the chemical analyses, the wines also separated into two groups. This separation seemed to be caused by vintage and the chemical changes associated with ageing as the wines from the youngest vintage (2010) was strongly associated with high levels of esters and malic acid. The older wines were situated farthest away from these attributes indicating low concentrations. When comparing the results from the sorting task and DSA, it could be seen that similar wine style groupings formed, indicating that DSA can also be regarded as an effective tool when categorising wines. The differences in the positioning of some of the wines and attributes on the DSA multivariate plots and the sorting task plots could be attributed to the difference in panels used. The sorting task was conducted using an expert panel with persons illustrating significant technical knowledge of Chenin blanc wines. Experience, exposure and technical knowledge tend to establish a common language amongst wine experts which could have caused the expert panel to perceive some wines differently when comparing the results of the latter panel to that of the trained panel. DSA was found to remain the most effective method for establishing a comprehensive sensory profile. Consumer analyses showed that regular white wine drinkers prefer the unwooded styles (Fresh and Fruity and Rich and Ripe unwooded) of Chenin blanc more than the wooded style. It was also found that consumers with a higher level of objective wine knowledge tend to associate the terms ‘bush vine’ and ‘old bush vine’ with the Rich and Ripe style of Chenin blanc, whereas consumers with a lower level of objective wine knowledge associated ‘old bush vine’ with the Fresh and Fruity style. Since all the wines used in the consumer analysis were produced from old bush vines, it is evident that consumer education on the impact of bush vine training system and vine age on wine quality is needed. Better understanding of these principles could lead to elevated product appraisals and consumer satisfaction. / AFRIKAANSE OPSOMMING: Vyf en twintig kommersiële Chenin blanc wyne, uitsluitlik van bosstok wingerde geproduseer, is bekom vir hierdie studie. Die wyne het drie style, drie oesjare en vyf produksiestreke ingesluit. Beskrywende sensoriese analise (BSA) en chemiese analises, wat GC-FID (gas chromatografie gekoppel met vlam-ioniserende deteksie) en FTMIR (Fourier-transformering mid-infrarooi) spektroskopie insluit, is uitgevoer om onderskeidelik die sensoriese en chemiese eienskappe van die wyne te bepaal. Verbruikerstoetse is ook uitgevoer om verbruikerspersepsie en -voorkeure vir bosstok Chenin blanc wyne te bepaal. BSA (‘n profilerings tegniek) was ook vergelyk met ‘n sorterings taak (‘n klassifikasie tegniek) met ‘n beskrywings opdrag, primêr om die sorterings taak se vermoë om wyne te profileer te ondersoek. Volgens die resultate van BSA, het die wyne in twee groepe verdeel. Een groep het met die sensoriese eienskappe wat op ‘n Vars-en-Vrugtige-styl dui, geassosieër. Die ander groep het met sensoriese eienskappe geassosieër wat met die Volrond-styl verband hou. Geen verdeling tussen die gehoute en ongehoute wyne binne die Volrond-styl was sigbaar nie. Volgens die resultate van die chemiese analises, het die wyne ook in twee groepe verdeel. Die verdeling blyk asof dit veroorsaak is deur oesjaar en die chemiese veranderinge wat met wynveroudering gepaard gaan. Wyne van die jongste oesjaar (2010) het ‘n sterk verband met hoë vlakke van esters en appelsuur getoon. Die ouer wyne was verder weg van hierdie eienskappe geleë, wat op laer ester en appelsuur konsentrasies dui. Wanneer die meerveranderlike resultate van die sorterings taak (met en sonder die aanduiding van sensoriese eienskappe) en dit van BSA vergelyk word, kon soortgelyke groeperings gesien word. Dit is ‘n aanduiding dat BSA ook wyne effektief kan kategoriseer. Die verskil in posisionering van sommige wyne tussen die BSA en sorterings taak resultate, kan toegeskryf word aan die verskillende panele wat gebruik is om die tegnieke uit te voer. ‘n Deskundige paneel (wynkenners) is gebruik om die sortingstaak uit te voer. Ervaring, blootstelling en tegniese kennis is geneig om te lei tot die vestiging van ‘n gemeenskaplike taal onder wynkenners. Hierdie gemeenskaplike taal kan as rede aangevoer word vir die uiteenlopende analise van sommige wyne wanneer die resultate van die deskundige paneel met dié van die opgeleide paneel (in BSA gebruik) vergelyk word. Dit is gevind dat BSA, wanneer ‘n omvattende sensoriese profiel bepaal moet word, die mees effektiefste metode bly. Verbruikerstoetse het getoon dat gereelde witwyn-verbruikers die ongehoute Chenin blanc style (Vars-en-Vrugtig en ongehoute Volrond) bo die gehoute styl verkies. Dit is ook bepaal dat verbruikers met ‘n hoër vlak van objektiewe wynkennis neig om die terme ‘bosstok’ en ‘ou bosstok’ met die Volrond-styl van Chenin blanc te assosieer, terwyl verbruikers met ‘n laer vlak van objektiewe wynkennis die term ‘ou bosstok’ met die Vars-en-Vrugtige Chenin blanc styl assosieër. Aangesien al die wyne wat in die verbruikerstoetse ingesluit is van ou bosstok wingerde geproduseer is, is dit duidelik dat verbruikeropvoeding insake die effek van die gebruik van bosstokke en ou wingerdstokke op wynkwaliteit noodsaaklik is. ‘n Beter begrip van hierdie beginsels sal lei tot verhoogde produkwaardasie, asook ‘n toename in verbruikertevredenheid.

Thesis (MScFoodSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Postharvest losses of three different vegetables (tomato - a fruit, cabbage - a leaf and carrot - a root vegetable) were investigated directly after retail purchasing and during consumer simulated storage. To conduct this study, three retail outlets (2 supermarkets and an outdoor market) were selected in Stellenbosch, South Africa. Retail prices of each vegetable were recorded from each respective Outlet. Surrounding environmental conditions (air temperature and relative humidity) at retail and during simulated consumer storage were also monitored. Vegetable postharvest losses were determined by quantifying the incidence of physical loss and changes in physico-chemical properties (colour, firmness, weight loss, ascorbic acid, total pigments, total soluble solids, titratable acid and proximate composition) over time. The percentage losses observed were then used to estimate the associated economic and environmental resource impacts of postharvest vegetable losses at the national level. Vegetable losses immediately at retail purchase were 14.56%, 21.21% and 17.93% for tomato, cabbage and carrot, respectively. The estimated combined volume lost for all three vegetables at national level was approximately 26 460 t valued at R33.70 million. Overall economic loss was highest for tomatoes and least for carrots. The magnitude of the losses observed differed for all the outlets. Vegetable losses were mostly high for the produce from the outdoor market compared to the supermarkets during storage. Throughout the whole trial, mechanical damage accounted for at least 50 to 70% of the losses while the remainder was due to decay and insect damage. Post retail storage temperature; ambient (22–25ºC) vs. cold store (0ºC and 10–12 ºC) had a significant (P<0.05) effect on the vegetable losses. This was for both quantitative and qualitative attributes. Losses for tomato and cabbage were 18.52% and 16.67% after 3 days while carrot losses were 11.83% at 7 days after having been kept in the recommended respective cold storage temperatures. Ambient storage losses were also lowest for carrots at 22.53% after 7 days, while tomato and cabbage losses stood at 24.27% and 34.34% after 3 days of storage, respectively. Vegetable firmness generally decreased while weight loss increased with storage time. Colour development increased favourably at ambient temperature for the tomato whereas for cabbage and carrot better colour retention was observed in the cold storage. Chemical changes for all three vegetables were also most pronounced at ambient temperature with significant (P<0.05) losses observed for ascorbic acid. Changes were also noted for total pigments, soluble solids and acidity, however there was no common significant trend for all three vegetables. Estimates of carbon dioxide emissions reveal that postharvest vegetable losses contribute to unwarranted emissions of at least 1.37 – 13.77 million tonnes of carbon dioxide equivalents (CO2eq.) at the national level. The losses are also accompanied by wastage of approximately 3.74 – 4.35 million m3 of fresh water as well as 14.79 – 111.63 million MJ of fossil energy. The vegetable with highest production volumes and retail price was the tomato and accordingly, its postharvest losses had the severest environmental and resource impacts. / AFRIKAANSE OPSOMMING: Die ná-oes-verliese van drie verskillende groentes (tamatie – 'n vrug, kool – 'n blaar, en wortel – 'n wortelgroente) is direk ná kleinhandelaankope en tydens gesimuleerde verbruikersberging ondersoek. Ten einde hierdie studie uit te voer, is drie kleinhandelsafsetpunte (twee supermarkte en 'n opelugmark) in Stellenbosch, Suid-Afrika gekies. Die kleinhandelpryse van elke groente van die drie onderskeie afsetpunte is opgeteken. Omliggende omgewingstoestande (lugtemperatuur en relatiewe humiditeit) tydens verkope en gesimuleerde verbruikersberging is ook gemonitor. Die ná-oes-verliese van die groentes is bepaal deur die voorkoms van fisiese verlies en veranderings in fisio-chemiese eienskappe (kleur, fermheid, gewigsverlies, askorbiensuur, totale pigmente, totale oplosbare suikers, titreerbare suur en algemene samestelling) met verloop van tyd te versyfer. Die waargenome persentasie verliese is gebruik om die geassosieerde ekonomiese en omgewingshulpbron-impak van ná-oes-groenteverliese op nasionale vlak te beraam. Groenteverliese met kleinhandelaankope was onderskeidelik 14.56%, 21.21% en 17.93% vir tamaties, kool en wortels. Die beraamde saamgestelde volume verlies vir al drie groentes op nasionale vlak was ongeveer 26 460 t, met 'n waarde van R33.70 miljoen. Die algehele ekonomiese verlies was die hoogste vir tamaties en die laagste vir wortels. Die omvang van die waargenome verliese het vir al die afsetpunte verskil. Groenteverliese tydens berging was hoofsaaklik hoog vir die produkte van die opelugmark in vergelyking met dié van die supermark. Tydens die algehele proefneming was meganiese skade verantwoordelik vir ten minste 50 tot 70% van die verliese, terwyl die res aan verrotting en insekskade toegeskryf kan word. Bergingstemperatuur ná kleinhandelaankope: omgewingstemperatuur (22 – 25 ºC) vs. koue berging (0 ºC en 10–12 ºC) het 'n beduidende (P < 0.05) uitwerking op groenteverlies gehad. Dit geld vir sowel kwantitatiewe as kwalitatiewe attribute. Verliese vir tamaties en kool was onderskeidelik 18.52% en 16.67% ná drie dae, terwyl dit vir wortels 11.83% teen sewe dae was nadat dit teen die aanbevole onderskeie koue bergingstemperature geberg is. Bergingsverliese in omgewingstemperatuur was ook die laagste vir wortels teen 22.53% ná sewe dae, terwyl die verlies van tamaties en kool onderskeidelik 24.27% en 34.34% was ná drie dae se berging. Die fermheid van die groente het oor die algemeen met die duur van berging verminder, terwyl gewigsverlies toegeneem het. Kleurontwikkeling het gunstig teen omgewingstemperatuur toegeneem vir die tamaties, terwyl die kleur van kool en wortels beter in die koue berging behou is. Chemiese veranderinge vir al drie groente was die sterkste teen omgewingstemperatuur, met beduidende (P < 0.05) verliese van askorbiensuur wat waargeneem is. Veranderinge is ook gemerk rakende totale pigmente, oplosbare vaste stowwe en suurgehalte. Daar was egter geen algemene beduidende neiging vir al drie groentes nie. Beramings van koolstofvrystellings toon dat ná-oes-groenteverlies tot ongeoorloofde vrystelling van ten minste 1.37 tot 13.77 miljoen ton koolstofekwivalente (CO2eq.) op nasionale vlak bydra. Die verliese gaan ook gepaard met verbruik van ongeveer 3.74 tot 4.35 miljoen m3 vars water asook 14.79 tot 111.63 miljoen MJ fossielbrandstof. Die groente met die hoogste produksievolume en kleinhandelprys was die tamaties, en gevolglik het tamaties se ná-oes-verliese die ernstigste impak op die omgewing en op hulpbronne.

Thesis (MScFoodSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Postharvest fruit loss is a major challenge in addressing food security, sustainable management of resources and profitability of agribusiness. The incidence of postharvest loss and changes in physico-chemical properties of three types of fruit (peaches, pears and oranges) were evaluated at retail and during post-purchase storage. The amount of physical loss at the three retail outlets studied ranged from 3.61% to 18.09% among the fruit types, with the highest incidence occurring in peaches. The estimated annual national physical loss at retail was 418 tons for pears, 1000 tons for oranges, and 7 240 tons for peaches. Based on the WHO recommended 146 kg per capita per year consumption of fruit, the total loss of the three types of fruit was sufficient to meet the dietary fruit requirements of 50 000 people per annum. Similarly, based on the recommended daily allowance of 50 mg of ascorbic acid, these losses could meet the annual vitamin C needs of 82 000 people. The estimated monetary value of the losses at retail ranged from R2.2 million to R96.87 million per annum depending on fruit type and retail outlet. The land wasted to produce lost fruits was 1965 ha while energy wasted was 32.77 x 106 MJ. Greenhouse gas emission of the losses was 2870 tons CO2eq and total water footprint 68 0000 m3. Losses were mainly due to the presence of severe physical damage, rots and physiological disorders. There were significant variations in physico-chemical properties of fruit of the same type from different retail outlet. Although ambient temperature storage improved fruit colour and some chemical constituents responsible for palatability, it was associated with high physical and nutritional (vitamin C) losses. Results from this study show that appropriate harvesting maturity, packaging and maximum care in fruit handling is essential in reducing postharvest losses. Efficient cold chain management and fruit inspection for rots and damages could help to reduce subsequent spoilage at retail and during post-purchase storage. Given that the incidence of postharvest fruit loss observed at retail is the result of cumulative effects along the supply chain, further studies are warranted to map fruit history and magnitude of losses along the value chain. / AFRIKAANSE OPSOMMING: Naoesvrugteverlies is ‟n groot uitdaging in die strewe na voedselsekerheid, volhoubare hulpbronbestuur en winsgewende landbousake. Die voorkoms van naoesverlies sowel as fisiko-chemiese naoesveranderinge by drie vrugtesoorte (perskes, pere en lemoene) is gevolglik by kleinhandelsafsetpunte én gedurende berging ná aankoop beoordeel. Die graad van fisiese verlies by die drie betrokke kleinhandelspunte het gewissel van 3,61% tot 18,09% tussen die vrugtesoorte, met die hoogste verlies by perskes. Die geraamde jaarlikse nasionale fisiese verlies by die kleinhandelspunte was 418 ton pere, 1 000 ton lemoene en 7 240 ton perskes. Op grond van die Wêreldgesondheidsorganisasie se aanbevole jaarlikse vrugte-inname van 146 kg per persoon, was die totale verlies van die drie vrugtesoorte genoeg om aan die vrugtedieetvereistes van 50 000 mense per jaar te voldoen. Op grond van die aanbevole daaglikse inname van 50 mg askorbiensuur, kan hierdie verlies eweneens in die jaarlikse vitamien C-behoeftes van 82 000 mense voorsien. Die geraamde geldwaarde van die verlies by die kleinhandelspunte strek van R2,2 miljoen tot R96,87 miljoen per jaar, na gelang van die vrugtesoort en bepaalde kleinhandelspunt. Die vermorste grond om die verlore vrugte te produseer, was 1 965 ha, terwyl energievermorsing op 32,77 x 106 MJ te staan gekom het. Kweekhuisgasvrystellings met betrekking tot die verlies was 2 870 ton CO2e, en die totale watervoetspoor 68 0000 m3. Vrugteverlies kon hoofsaaklik aan ernstige fisiese skade, verrotting en fisiologiese afwykings toegeskryf word. Daar was beduidende variasies in die fisiko-chemiese eienskappe van dieselfde vrugtesoort by verskillende kleinhandelaars. Hoewel berging by omgewingstemperatuur vrugtekleur en bepaalde chemiese komponente vir smaaklikheid verbeter, word dit ook met groot fisiese en voedingstof- (vitamien C-) verliese verbind. Die resultate van hierdie studie toon dat toepaslike oesrypheid, die regte verpakking en maksimum sorg in vrugtehantering noodsaaklik is om naoesverlies te verminder. Doeltreffende koelkettingbestuur en vrugte-inspeksie vir verrotting en skade kan latere bederf by kleinhandelsafsetpunte sowel as gedurende berging ná aankoop help beperk. Aangesien die naoesvrugteverlies wat by die kleinhandelspunte waargeneem is uit kumulatiewe faktore in die verskaffingsketting spruit, is verdere studies nodig om vrugtegeskiedenis na te spoor en die omvang van die verlies in die algehele waardeketting te bepaal.

Thesis (MSc Food Sc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Phenolic compounds of the types present in plums have been found to exhibit health-promoting properties associated with their antioxidant capacity. Fruits with red peel and/or flesh are thus sought-after for their high antioxidant levels. In the current study South African plum (Prunus salicina Lindl.) cultivars and selections, harvested during two consecutive fruit seasons, were compared in terms of general fruit attributes (colour, firmness, °Brix, pH, titratable acidity), phenolic composition and antioxidant capacity. The effect of season and a commercial cold storage and ripening regime was also investigated. A reversed-phase high-performance liquid chromatography-diode-array-fluorescence detection (HPLC-DAD-FLD) method suitable for use with mass spectrometry (MS) detection, was optimised for separation and identification of phenolic compounds from four phenolic groups (phenolic acids, anthocyanins, flavan-3-ols and flavonols) in six South African plum cultivars and five selections. Parameters that were optimised include the mobile phases, analysis temperature and gradient program. Good stability, linearity and inter- and intra-day precision were obtained. Identification of compounds was based on comparison of retention times, UV-Vis spectra and mass fragments with available authentic phenolic standards and/or literature data. The optimised method allowed identification or tentative identification of twenty-four phenolic compounds, including cyanidin-3-O-glycosides, quercetin glycosides, monomeric, dimeric and trimeric flavan-3-ols, and hydroxycinnamic acids. An on-line ABTS•+ (2,2ʹ-azinobis-(3-ethyl-benzothiazoline-6-sulfonic acid)) antioxidant assay, performed for qualitative evaluation of the antioxidant response of individual phenolic compounds, indicated the flavan-3-ols as major antioxidants in plums. Eighteen phenolic compounds were quantified, including anthocyanins and flavonol glycosides, flavan-3-ols (monomers and dimers) and hydroxycinnamic acids. Phenolic composition differed greatly between cultivars and selections. Cyanidin-3-O-glucoside was the predominant anthocyanin in plums with red peel and/or flesh, followed by cyanidin-3-O-rutinoside. Cyanidin-3-O-galactoside was present only in the cultivar Laetitia (red peel, yellow flesh). The ripe fruit of Ruby Red and PR04-19, both with red peel and flesh, had the highest anthocyanin content for the first and second harvest season, respectively. Neochlorogenic acid and quercetin-3-O-glucoside were the major phenolic acid and flavonol, respectively. Chlorogenic acid, 3-O-p-coumaroylquinic acid and several quercetin-glycosides and -diglycosides were also present in some cultivars and selections. Procyanidin B1 was the flavan-3-ol present in the highest concentration in the majority of cultivars and selections and its content correlated with the (+)-catechin content, while the same was observed for procyanidin B2 and (-)-epicatechin. The effect of cold storage and ripening on fruit attributes differed greatly between cultivars and selections. The increase and decrease in pH and titratable acidity, respectively, were as expected for ripe fruit as opposed to unripe fruit. Ripe fruit had higher a*-values and lower L*-values. The cold storage and ripening regime had no significant effect on total polyphenol and total flavan-3-ol content of the cultivars and selections, but the anthocyanin content increased in some cases. In terms of in vitro antioxidant capacity, the selections PR04-32 and PR04-35, both with red peel and flesh, had the highest antioxidant capacity, irrespective of assay. Sapphire (red peel, yellow flesh), with the lowest total polyphenol content, also had the lowest antioxidant capacity in the ORAC and FRAP assays. Both the total polyphenol and flavan-3-ol contents correlated significantly to antioxidant capacity, irrespective of assay. / AFRIKAANSE OPSOMMING: Fenoliese verbindings, soos teenwoordig in pruime, is bekend vir hul gesondheidsbevorderende eienskappe wat geassosieer word met antioksidant kapasiteit. Vrugte met ‘n rooi skil en/of vleis is veral gesog as gevolg van hul hoë antioksidant aktiwiteit. Met hierdie studie is Suid-Afrikaanse pruim (Prunus salicina Lindl.) kultivars en seleksies, geoes tydens twee opeenvolgende seisoene, vergelyk in terme van algemene vrug einskappe (kleur, fermheid, °Brix, pH en titreerbare suurheid), fenoliese samestelling en antioksidant kapasiteit. Die effek van ‘n kommersiële koelopberging en rypwording prosedure is ook ondersoek. ‘n Omgekeerde-fase hoë-druk vloeistof chromatografie (HPLC) metode met diode-opstelling en fluoressensie deteksie, maar wat ook geskik is vir massa spektrometrie (MS), is geoptimiseer om fenoliese verbindings te skei en te identifiseer in Suid-Afrikaanse pruime. Verbindings van vier fenoliese groepe (fenoliese sure, antosianiene, flavan-3-ole en flavonole) wat in ses kultivars en vyf seleksies voorgekom het, is ondersoek. Die vloeistof fases, skeidingstemperatuur en gradiënt van die metode is geoptimiseer. Goeie resultate vir stabiliteit, lineariteit en inter- en intra-dag akkuraatheid is verkry. Verbindings is geïdentifiseer deur vergelyking van retensie tye, UV-Vis spektra en massa fragmente met dié van egte fenoliese standaarde en/of met literatuur data. Vier-en-twintig fenoliese verbindings is geïdentifiseer of voorlopig geïdentifiseer, insluitende sianidien- en kwersetien glikosiede, flavan-3-ol monomere, dimere en trimere, en hidroksikaneelsure. ‘n Aanlyn ABTS•+ (2,2 ʹ-azino-di-(3-etielbensotialosien-sulfoon suur) radikaal katioon blussingstoets is gebruik om die antioksidant reaksie van individuele polifenole op ‘n kwalitatiewe wyse te evalueer en flavan-3-ole is as hoof antioksidante in pruime aangetoon. Kwantifisering van agtien verbindings, insluitende antosianiene, flavonol glikosiede, flavan-3-ole (monomere en dimere) en hidroksikaneelsure, was moontlik met hierdie geoptimiseerde metode. Die fenoliese samestelling het aansienlik verskil tussen kultivars en seleksies. Sianidien-3-O-glukosied was die hoof antosianien in pruime met ‘n rooi skil en/of vleis, gevolg deur sianidien-3-O-rutinosied. Sianidien-3-O-galaktosied het slegs in Laetitia (rooi skil en geel vleis) voorgekom. Ryp vrugte van Ruby Red en PR04-19, beide met rooi skil en vleis, het onderskeidelik die hoogste antosianieninhoud gehad met die eerste en tweede seisoen se oeste. Neochlorogeniese suur en kwersetien-3-O-glukosied was die hoof fenoliese suur en flavon-3-ol, onderskeidelik. Chlorogeniese suur, 3-O-p-kumarienkwiniensuur en verskeie kwersetien glikosiede en diglikosiede was teenwoordig in sekere kultivars/seleksies. Die flavan-3-ol, prosianidien B1, was teenwoordig in die hoogste konsentrasie in die meerderheid kultivars/seleksies. Die prosianidien B1 inhoud het met die (+)-katekien inhoud gekorreleer, terwyl dieselfde gevind is vir prosianidien B2 en (-)-epikatekien. Die effek van koelopberging en rypwording op die algemene vrug einskappe het tussen kultivars en seleksies verskil. Die pH en titreerbare suurheid het onderskeidelik toegeneem en afgeneem, soos verwag is vir ryp vrugte teenoor onryp vrugte. Ryp vrugte het hoër a*-waardes en laer L*-waardes getoon. Koelopberging en rypwording het geen beduidende effek op die totale polifenol- en totale flavan-3-ol inhoud gehad nie, maar die antosianieninhoud het vir sommige kultivars en seleksies toegeneem. In terme van in vitro antioksidant kapasiteit het die seleksies PR04-32 en PR04-35, beide met rooi skil en vleis, die hoogste antioksidant kapasiteit getoon, ongeag die antioksidant toets wat gebruik is. Sapphire (rooi skil en geel vleis) het die laagste totale polifenolinhoud gehad, asook die laagste antioksidant kapasiteit soos bepaal deur die ORAC en FRAP toetse. Beide die totale polifenol- en flavan-3-ol inhoud het beduidend met die antioksidant kapasiteit korreleer, ongeag van die toets wat gebruik is.

Thesis (MScFoodSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The flavanone aglycones, hesperetin and eriodictyol, have been identified as potential taste modulators with reported sweetness-enhancing and bitterness-masking properties, respectively. Reduction of the sugar content of food products has become important in view of the global obesity epidemic. Taste modulators have shown potential to enhance the sweet taste of reduced-sugar foods without unfavourably affecting their flavour profile. On the other hand, bitterness-masking taste modulators are useful to mask the bitter taste of functional phytochemical ingredients. In the current study, Cyclopia maculata (honeybush) was investigated as potential source of hesperetin- and eriodictyol-enriched extracts. Hesperetin and eriodictyol were present mainly below the quantification limit in C. maculata plant material, including unfermented leaf and stem material, unfermented and fermented tea, as well as the fermented by-product (< 40 mesh and > 12 mesh). Conversely, their rutinoside and modulatinginactive derivatives, hesperidin and eriocitrin were present at substantially higher concentrations in the plant material. The stems and by-product were shown to be good sources of hesperidin, but not eriocitrin. The qualitative and quantitative phenolic profile of the by-product was similar to that of the stems. The tea processing by-product was therefore selected to optimise extraction of flavanone glycosides for subsequent de-glycosylation of the flavanone glycosides to aglycones. The by-product was subjected to ultrasound-assisted extraction to investigate its potential as renewable source of the flavanone glycosides. Response surface methodology (RSM) was employed to optimise and study the individual and interactive effects of the process variables, namely ethanol concentration (% v/v), time (min), temperature (°C), and solvent:solid ratio (mL/g), on flavanone glycoside extraction. The hesperidin yield and content (of extract), as well as extract yield, increased with an increase in extraction time, temperature and solvent:solid ratio. Practical process restrictions limited global optimisation and only an optimum of 52.8% (v/v) ethanol for extract and hesperidin yield could be reached. Temperature was the parameter with the most significant effect (p < 0.05) on extraction efficiency among those studied. Practical process parameter values that were feasible for industrial application (52.8% (v/v) ethanol, 20 mL/g solvent:solid ratio, 60°C and 30 min) were selected for the preparation of a flavanone glycoside-enriched extract from the tea processing by-product. The flavanone glycoside-enriched extract was subjected to acid-catalysed hydrolysis to deglycosylate hesperidin and eriocitrin to hesperetin and eriodictyol, respectively. RSM was employed to optimise the acid hydrolysis process and to study the effect of the hydrolysis parameters (temperature (°C) and time (min)) on hydrolysis efficiency. At the maximum temperature (92.1°C) and corresponding optimum time (98.4 min) ca 80% conversion of hesperidin to hesperetin was achieved. Substantially more eriodictyol formed during acid hydrolysis than eriocitrin present in the initial extract owing to the deglycosylation of unidentified glycosides with the same aglycone. Unidentified breakdown products imparting a red colour to the acid-hydrolysed extract were also observed. The total phenolic content of the acid-hydrolysed extract was significantly higher (p < 0.05) than that of the unhydrolysed extract, indicating the formation of unidentified compounds with the ability to reduce the Folin-Ciocalteau reagent, although no significant difference (p ≥ 0.05) between the antioxidant activities of these extracts, as assessed with the DPPH radical scavenging and ORAC assays, was observed. The potential of enzymatic bioconversion as an alternative to acid-catalysed hydrolysis was investigated using commercial hesperidinase. Bioconversion resulted only in de-rhamnosylation with ca 100% conversion of hesperidin to hesperetin-7-O-glucoside in an aqueous C. maculata extract at pH 4.0 and 40°C. / AFRIKAANSE OPSOMMING: Die flavanoon aglikone, hesperetien and eriodiktiol, is geïdentifiseer as potensiële smaakmoduleerders met berigte soetheid-versterkende en bitter-maskerende eienskappe, onderskeidelik. Vermindering van die suikerinhoud van voedselprodukte het belangrik geword in die lig van die wêreldwye vetsugepidemie. Smaakmoduleerders het die potensiaal getoon om die soet smaak van voedsel met verlaagde suikerinhoud te versterk sonder om hul geurprofiel ongunstig te beïnvloed. Andersyds is bittermaskerende smaakmoduleerders nuttig om die bitter smaak van funksionele fitochemiese bestanddele te maskeer. In die huidige studie is Cyclopia maculata (heuningbos) ondersoek as ‘n potensiële bron van hesperetien- and eriodiktiol-verrykte ekstrakte. Hesperetien and eriodiktiol was hoofsaaklik teenwoordig onder die kwantifiseringsperk in C. maculata plantmateriaal, insluitend ongefermenteerde blaar- en stokmateriaal, ongefermenteerde en gefermenteerde tee, asook die gefermenteerde byproduk (< 40 maas en > 12 maas). Hierteenoor was hul rutinosiedes en modulerend-onaktiewe derivate, hesperidien and eriositrien, teenwoordig in aansienlik hoër konsentrasies in die plantmateriaal. Die stokmateriaal en byproduk is getoon om goeie bronne van hesperidien, maar nie eriositrien nie, te wees. Die kwalitatiewe en kwantitatiewe fenoliese profiel van die byproduk was soortgelyk aan dié van die stokke. Die teeprosesseringsbyproduk is dus geselekteer om die ekstraksie van flavanoonglikosiede, voorafgaande hul de-glikosilering na aglikone, te optimeer. Die byproduk is aan ekstraksie met behulp van ultrasoniese klank onderwerp om die potensiaal daarvan as hernubare bron van flavanoonglikosiede te ondersoek. Respons-oppervlak Metodologie (ROM) is gebruik om die individuele en wisselwerking effekte van die proses veranderlikes, naamlik etanolkonsentrasie (% v/v), tyd (min), temperatuur (°C), en oplosmiddel:vastestof verhouding (mL/g), op flavanoonglikosied ekstraksie te optimiseer en te bestudeer. Die hesperidienopbrengs en -inhoud (van ekstrak), sowel as die ekstrakopbrengs, het toegeneem met ‘n toename in die ekstraksietyd, - temperatuur en oplosmiddel:vastestof verhouding. Praktiese prosesbeperkings het die globale optimisering beperk en slegs ‘n optimum van 52.8% (v/v) etanol vir ekstrak- en hesperidienopbrengs kon bereik word. Temperatuur was die parameter met die mees beduidende effek (p < 0.05) op ekstraksie doeltreffendheid van dié wat bestudeer is. Praktiese prosesparameterwaardes wat haalbaar is vir industriële toepassing (52.8% (v/v) etanol, 20 mL/g oplosmiddel:vastestof verhouding, 60°C en 30 min) is geselekteer vir die voorbereiding van 'n flavanoonglikosied-verrykte ekstrak uit die teeprosesseringsbyproduk. Die flavanoonglikosied-verrykte ekstrak is aan suur-gekataliseerde hidrolise onderwerp om hesperidien en eriositrien na hesperetien en eriodiktiol, onderskeidelik, te de-glikosileer. ROM is gebruik om die suurhidrolise proses te optimeer en die effek van die hidrolise parameters (temperatuur (°C) en tyd (min)) op hidrolise doeltreffendheid te bestudeer. Ongeveer 80% omskakeling van hesperidien na hesperetien is behaal teen die maksimum temperatuur (92.1 °C) en ooreenstemmende optimum tyd (98.4 min). Aansienlik meer eriodiktiol is tydens suurhidrolise gevorm as eriositrien wat in die oorspronklike ekstrak teenwoordig was, as gevolg van de-glikosilering van ongeïdentifiseerde glikosiede met dieselfde aglikoon. Ongeïdentifiseerde afbreekprodukte, wat 'n rooi kleur aan die suurgehidroliseerde ekstrak gegee het, is ook waargeneem. Die totale fenoliese inhoud van die suurgehidroliseerde ekstrak was beduidend hoër (p < 0.05) as dié van die ongehidroliseerde ekstrak, wat die vorming van onbekende verbindings met die vermoeë om die Folin-Ciocalteau reagens te reduseer aandui, hoewel daar geen beduidende verskil (p ≥ 0.05) tussen die antioksidant-aktiwiteite van hierdie ekstrakte, soos bepaal met die DPPH radikaal blussings- en ORAC toetse, waargeneem is nie. Die potensiaal van ensiematiese bio-omskakeling as 'n alternatief vir suur-gekataliseerde hidrolise is ondersoek met behulp van kommersiële hesperidinase. Bio-omskakeling het slegs tot de-ramnosilering gelei met ca 100% omskakeling van hesperidien na hesperetien-7-O-glukosied in 'n C. maculata waterekstrak by pH 4.0 en 40°C.

Thesis (MScFoodSc) Stellenbosch University, 2014 / ENGLISH ABSTRACT: We aimed to determine how canopy position influences fruit quality and consumer preference for the eating quality and appearance of ‘Forelle’, ‘Bon Chrétien’ and ‘Bon Rouge’ pears. Our hypothesis was that consumer preference would be higher for the appearance and eating quality of outer canopy fruit. Our first trial investigated the effect of canopy position and cold storage duration on quality attributes and consumer preference for ‘Forelle’ pears. Mealiness was much more prevalent in outer canopy fruit in 2012 and after 9 and 12 weeks cold storage in 2011. In 2011, consumers preferred the eating quality of inner canopy pears that had been subjected to 12 and 16 weeks of cold storage while inner canopy pears were generally preferred in 2012. This study provides support for the mandatory 12 weeks cold storage of ‘Forelle’ pears. Our second trial investigated the effect of canopy position and harvest maturity within the commercial picking window on the quality attributes and consumer preferences for ‘Forelle’ pears. Inner canopy pears of harvest 1 (23 February) and harvest 2 (27 February) were significantly preferred in terms of eating quality. The general dislike for harvest 3 (13 March) pears and outer canopy fruit seemed to relate to an incidence of mealiness. Our results suggest that harvesting ‘Forelle’ pears at a firmness ≈6.2 kg will ensure that both inner and outer canopy pears have acceptable eating quality. In our third trial, fruit were harvested at commercial firmness from two orchards in each of Elgin and Ceres to assess the effect of orchard site on quality attributes of ‘Forelle’ pears. Total soluble solids (TSS) were higher in Elgin while flavour attributes were more pronounced in Ceres. In both areas, outer canopy pears were higher in TSS and lower in titratable acidity (TA) but canopy position had no effect on sweet and sour taste. Mealiness incidence was high in outer canopy fruit from Elgin, as well as in one Ceres orchard. Further research over consecutive seasons is needed to determine the reasons for orchard differences in mealiness incidence. Our fourth trial investigated the effect of canopy position on quality attributes and consumer preference for ‘Bon Chrétien’ and ‘Bon Rouge’ pears. Despite a higher TSS:TA ratio in outer canopy ‘Bon Rouge’ pears and a higher TSS and dry matter concentration in outer canopy ‘Bon Chrétien’ pears, canopy position did not affect sensory eating quality attributes. Seen overall, results indicate that canopy position has a minor effect on consumer preference for ‘Bon Chrétien’ and ‘Bon Rouge’ eating quality. No significant differences in colour and consumer preference for appearance were found between outer and inner canopy ‘Bon Chrétien’ pears. Consumers slightly preferred the redder outer canopy ‘Bon Rouge’ pears over the less red inner canopy fruit. Although consumers preferred the red blush colour of outer canopy ‘Forelle’ pears, inner canopy pears also received high scores. Inner canopy ‘Forelle’ pears should not be viewed as inferior to outer canopy fruit with regard to both eating quality and appearance. / AFRIKAANSE OPSOMMING: Ons het gepoog om die effek van boomposisie op vrugkwaliteit en verbruikersvoorkeur vir die eetkwaliteit en voorkoms van ‘Forelle’, ‘Bon Chrétien’ en ‘Bon Rouge’ pere te ondersoek. Ons hipotese was dat verbruikersvoorkeur hoër sou wees vir die voorkoms en eetkwaliteit van pere van die buitekant van die boom se blaredak. Ons eerste proef se doelstelling was om die effek van boomposisie en koelopberging op die kwaliteitseienskappe en verbruikersvoorkeur vir ‘Forelle’ pere te bepaal. Melerigheid was beduidend meer aanwesig in buitevrugte in 2012 asook na 9 en 12 weke koelopberging in 2011. Verbruikersvoorkeur vir eetkwaliteit was die hoogste vir binnevrugte na 12 en 16 weke koelopberging in 2011 terwyl binnevrugte in die algemeen voorkeur geniet het in 2012. Hierdie studie steun die bevindinge van vorige studies dat ‘Forelle’ pere vir ten minste 12 weke koelopgeberg moet word. Die doel van ons tweede proef was om te bepaal of ‘Forelle’ pere wat by verskillende ryphede binne die kommersiële oesperiode geoes is, verskille toon in kwaliteitseienskappe en of hierdie verskille, indien enige, verband hou met verbruikersvoorkeur vir eetkwaliteit. Die eetkwaliteit van binnevrugte van oes 1 (23 Februarie) en oes 2 (27 Februarie) is verkies bo buitevrugte. Die algemene afkeur vir oes 3 (13 Maart) en buitevrugte kan moontlik toegeskryf word aan die hoë voorkoms van melerigheid. Ons resultate dui aan dat beide binne- en buitevrugte aanvaarbare eetkwaliteit behoort te hê indien ‘Forelle’ pere by ‘n fermheid van ≈6.2 kg geoes word. Vir ons derde proef is ‘Forelle’ pere geoes by kommersiële fermheid (≈6.4 kg) vanaf twee boorde in elk van Elgin en Ceres. Totale opgeloste vastestowwe (TOV) was hoër in Elgin pere terwyl geur-eienskappe meer prominent was in Ceres pere. In beide areas het buitevrugte hoër TSS en laer titreerbare sure (TS) gehad, maar boomposisie het egter geen effek op soet en suur smaak gehad nie. Die voorkoms van melerigheid was hoog in buitevrugte van die Elgin boorde, sowel as in een van die Ceres boorde. Verdere navorsing oor opeenvolgende seisoene word benodig om redes vir die verskille in die voorkoms van melerigheid tussen boorde te ondersoek. Die doelstelling van ons vierde proef was om die effek van boomposisie op die kwaliteitseienskappe en verbruikersvoorkeur vir ‘Bon Chrétien’ en ‘Bon Rouge’ pere te ondersoek. Ondanks ‘n hoër TOV:TS ratio in ‘Bon Rouge’ buitevrugte en ‘n hoër TOV en droë massa konsentrasie in ‘Bon Chrétien’ buitevrugte, het boomposisie ‘n minimale impak gehad op sensoriese eetkwaliteitseinskappe en verbruikervoorkeur vir die pere. Boomposisie het geen effek op die kleur en verbruikersvoorkeur vir die voorkoms van ‘Bon Chrétien’ pere gehad nie. Verbruikers het ‘n effense hoër voorkeur getoon vir die rooier ‘Bon Rouge’ buitevrugte. Alhoewel verbruikers die aantreklike rooi bloskleur van ‘Forelle’ buitevrugte verkies het, het die groen tot geel binnevrugte ook hoë voorkeurpunte behaal. Rakende voorkoms en eetkwaliteit, is ‘Forelle’ binnevrugte glad nie minderwaardig teenoor buitevrugte nie.

Thesis (MScFoodSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Cyclopia genistoides (honeybush) has been identified as an excellent resource for the production of a xanthone-enriched extract due to its high mangiferin content and successful cultivation. The predominant xanthone present in C. genistoides is mangiferin, a potent antioxidant proven to exhibit a wide range of bioactivities that contribute greatly to the health-promoting abilities of honeybush extracts. Isomangiferin, the regio-isomer of mangiferin and of comparable antioxidant capacity to mangiferin, is another valuable compound present in substantial quantities in C. genistoides. A xanthone-enriched extract would find possible application in functional food/beverage products that provide health benefits beyond basic nutrition. In the current study, the effect of ethanol (EtOH) concentration (0-100%, v/v), plant material size (milled vs. teabag fraction), extraction time (0-60 min) and elevated extraction temperatures on the extraction of xanthones from unfermented C. genistoides was investigated. Single factor experiments showed the best extraction efficiency, evaluated in terms of extract yield, xanthone yield and xanthone content of the extract, was achieved by extracting milled plant material with 20-60% EtOH (v/v) for 30 min at elevated temperatures (70°C). Response surface methodology (RSM) to evaluate the individual and interaction effects of process variables, namely EtOH concentration (0-100%, v/v) and temperature (0-70°C) was used to further optimise the extraction process. EtOH concentration was found to have the largest effect on extraction efficiency (p < 0.05), whilst temperature had a negligible effect. Optimal levels of EtOH concentration (40%, v/v) and temperature (70°C) for maximum extract and mangiferin yields were successfully achieved within the experimental domain, using 10 mL/g solvent:solid ratio and 30 min extraction time. Ultrafiltration (UF) was subsequently employed to facilitate further xanthone enrichment of the unfermented C. genistoides extract (40% EtOH, v/v). A series of laboratory scale membrane devices (centrifugal membrane units, stirred cell and tangential flow ultrafiltration (TFU) system) were used in an up-scale approach to determine the effect of membrane material (regenerated cellulose (RC) vs. polyethersulphone (PES)), molecular weight cut off (MWCO; 3 kDa, 10 kDa, 30 kDa), feed concentration (1% vs. 3% soluble solids (SS)) and operating parameters (transmembrane pressure (TMP) and feed flow rate) on membrane performance and permeate quality. The best performing membrane in terms of productivity and xanthone enrichment was the 10 kDa RC membrane when using an extract concentration close to that of industrially prepared extracts (3% SS). RSM was used to further optimise UF of unfermented C. genistoides through a 10 kDa RC membrane in the TFU system. The individual and interaction effects of TMP (0.82-2.04 bar) and feed flow rate (200-444 mL/min) on permeate flux, xanthone enrichment and the fouling index were investigated. The individual effects of TMP and feed flow rate had a significant effect on all measured responses, while their interaction only affected average permeate flux and fouling index significantly. Optimal TMP and feed flow rate values of 2.04 bar and 444 mL/min, respectively, were selected within the experimental domain, restricted by equipment constraints. Validation of the combined protocol including ethanol-water extraction and UF using plant material from ten different unfermented C. genistoides batches resulted in enriched extracts containing 10.6-17.8% xanthone content. During UF, average mangiferin and isomangiferin enrichments of 20% and 22%, respectively, were obtained. Whilst no correlation was found between the feed concentration of the extracts, xanthone enrichment and fouling index, a strong linear correlation (R2 = 0.98) was found between feed concentration and permeate yield. / AFRIKAANSE OPSOMMING: Cyclopia genistoides (heuningbos) is geidentifiseer as ‘n uitstekende bron vir die produksie van ‘n xantoon-verrykte ekstrak weens sy hoë mangiferien-inhoud sowel as suksesvolle verbouing daarvan. Die oorheersende xantoon teenwoordig in C. genistoides is mangiferien, ‘n kragtige antioksidant met ‘n bewese wye reeks bioaktiwiteite wat grootliks bydra tot die gesondheidsvoordele van heuningbosekstrakte. Isomangiferien, die regio-isomeer van mangiferien met vergelykbare antioksidant-aktiwiteit as mangiferien, is nog ‘n waardevolle verbinding teenwoordig in aansienlike hoeveelhede in C. genistoides. ‘n Xantoon-verrykte ekstrak kan moontlik toegepas word in funksionele voedsel- of drankie-produkte, wat gesondheidsvoordele bo en behalwe die basiese voedsaamheid inhou. Die effek van etanol (EtOH)-konsentrasie (0-100%, v/v), plantmateriaal grootte (gemaal teenoor teesakkie-fraksie), ekstraksietyd (0-60 min) en ekstraksietemperatuur op die ekstraksie van xantone uit ongefermenteerde C. genistoides is ondersoek. Enkelfaktor eksperimente het getoon dat die beste ekstraksie-effektiwiteit, in terme van ekstrakopbrengs, xantoonopbrengs en xantooninhoud van die ekstrak, bereik is deur gemaalde plantmateriaal met 20-60% EtOH (v/v) vir 30 min by verhoogde temperature (70°C) te ekstraheer. Respons-oppervlak Metodologie (ROM) is aangewend om die individuele en interaktiewe effekte van die veranderlikes, naamlik EtOH-konsentrasie (0-100%, v/v) en temperatuur (0-70°C) te ondersoek asook om die ekstraksieproses verder te optimiseer. EtOH-konsentrasie het die grootste effek op die ekstraksie-effektiwiteit gehad (p < 0.05), terwyl die effek van temperatuur onbeduidend was. Optimale vlakke van EtOH-konsentrasie (40% v/v) en temperatuur (70°C) vir maksimum ekstrak- en mangiferienopbrengs is binne die eksperimentele domein is gevind, met die gebruik van 10 mL/g oplosmiddel:vastestof verhouding en ‘n ekstraksietyd van 30 min. Ultrafiltrasie (UF) is daarna gebruik om verdere xantoon-verryking van die ongefermenteerde C. genistoides ekstrak (40% EtOH, v/v) te fasiliteer. ‘n Reeks labratoriumskaal membraantoestelle (sentrifugale membraaneenhede, ‘n geroerde selsisteem en ‘n kruisvloei-ultrafiltrasie (KVU) sisteem) is gebruik in ‘n opskaleringsbenadering om die effek van die membraanmateriaal (geregenereerde sellulose (RS) vs. polyetersulfoon (PES)), molekulêre gewig afsnit (MWCO; 3 kDa, 10 kDa, 30 kDa), voerkonsentrasie (1% vs. 3% oplosbare vastestowwe (OV)) en operasionele parameters (transmembraandruk (TMD) en voervloeispoed) op membraanprestasie en permeaatkwaliteit te bepaal. Die membraan met die beste prestasie in terme van produktiwiteit en xantoon-verryking was die 10 kDa RS membraan wanneer gebruik met ‘n ekstrakkonsentrasie na aan dié van die industrieel vervaardigde ekstrakte (3% OV). ROM is gebruik om die KVU van ongefermenteerde C. genistoides deur ‘n 10 kDa RS membraan verder te optimiseer. Die indiwiduele en interaktiewe effekte van TMD (0.82-2.04 bar) en voervloeispoed (200-444 mL/min) op permeaatvloei, xantoon-verryking en die blokkeringindeks is ondersoek. Die individuele effekte van TMD en voervloeispoed het ‘n betekenisvolle effek op alle gemete response gehad, terwyl hul interaksie net gemiddelde permeaatvloei en besoedelingsindeks beduidend beïnvloed het. Optimale TMD en voervloeispoed waardes van 2.04 bar en 444 mL/min, onderskeidelik, is geselekteer binne die eksperimentele domein, wat bepaal is deur die beperkings van die toerusting. Die geldigheid van die gesamentlike protocol, insluitende etanol-water ekstraksie en UF, is getoets deur plantmateriaal van tien verskillende ongefermenteerde C. genistoides monsters te gebruik. Dit het gelei tot verrykte ekstrakte wat 10.6-17.8% xantone bevat het. UF het onderskeidelik gemiddelde mangiferien- en isomangiferien-verryking van 20% en 22% gelewer. Geen korrelasie is gevind tussen die voerkonsentrasie van die ekstrakte en die besoedelingsindeks nie, maar ‘n goeie liniêre korrelasie (R2 = 0.98) is tussen voerkonsentrasie en permeaatopbrengs gevind.

Thesis (MScFoodSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: In light of the limited and inconsistent supply of good quality honeybush tea, a species-specific sensory profile and the physicochemical characteristics of Cyclopia intermedia (honeybush) tea were determined to ultimately establish the optimum fermentation parameters for this herbal tea on laboratory-scale and to validate these findings on commercial-scale. The characteristic sensory profile of C. intermedia can be described as sweet tasting and slightly astringent with a combination of “fynbos-floral”, “fynbos-sweet”, “fruity” (specifically “apricot jam”, “cooked apple”, “raisin” and “lemon/lemon grass”), “woody”, “caramel/ vanilla” and “honey-like” aromas. The flavour can be described as distinctly “fynbos-floral”, “fynbos-sweet” and “woody”, including hints of “lemon/lemon grass” and “hay/dried grass”. The results of the sensory study were used to create a C. intermedia sensory wheel and lexicon, and an elementary grading system that categorised samples into “good”, “average” and “poor” sensory quality was proposed. Physicochemical parameters, i.e. soluble solids (SS) content, absorbance as a measure of colour, and turbidity, were evaluated as possible rapid predictors of sensory quality. High SS content, absorbance and turbidity correlated strongly with “poor” sensory quality. A linear relationship existed between the physicochemical parameters. The effect of fermentation temperature (70, 80 and 90°C) and time (12, 16, 24, 36, 48 and 60 h) on the sensory and physicochemical characteristics of C. intermedia was determined on laboratory-scale. Increasing fermentation time increased the intensity of positive sensory attributes, while decreasing the intensity of negative sensory attributes. The SS content, colour and turbidity of infusions decreased with increasing fermentation time, while the SS content and turbidity of infusions increased with increasing fermentation temperature. Fermentation at 90°C for 36 h on laboratory-scale produced C. intermedia with the best sensory properties, while preserving the SS content and colour of infusions. Fermentation at 70°C and 80°C required longer fermentation times for development of positive sensory attributes. Fermentation at 90°C was subsequently validated on commercial-scale. Laboratory-scale fermentation of the same batches of plant material was also carried out concurrently to allow direct comparison of the scale of fermentation on tea quality. Commercial-scale fermentation, despite increased variability as a result of increased batch volumes and heating difficulties, produced C. intermedia of “good” sensory quality after 24 and 36 h of fermentation. Increasing fermentation time had little effect on the SS content and colour of infusions of tea produced on commercial-scale, but turbidity increased significantly after 36 h. Thus, to produce C. intermedia with consistently good quality on commercial-scale, fermentation at 90°C for 24 to 36 h is recommended. Increasing fermentation time past 48 h should be avoided to prevent turbidity and the development of sensory attributes characteristic of over-fermented tea. However, due to the large variability of commercial-scale honeybush tea production, it is recommended that each batch be monitored between 24 and 36 h to determine when optimum fermentation has been obtained. / AFRIKAANSE OPSOMMING: Beperkte en wisselvallige beskikbaarheid van goeie gehalte heuningbostee noodsaak die optimisering van fermentasie parameters vir Cyclopia intermedia. Optimisering van fermentation parameters is op laboratorium skaal gedoen, gevolg deur validasie van die parameters op kommersiële skaal. Vooraf is die spesie-spesifieke sensoriese profiel en die fisies-chemiese eienskappe van C. intermedia tee bepaal. Die kenmerkende sensoriese profiel van C. intermedia kan beskryf word as soet en effens vrank met 'n kombinasie van "fynbos-blomagtige", "fynbos-soet", "vrugtige" (spesifiek "appelkooskonfyt", "gekookte appel", "rosyntjie” en “suurlemoen/sitroen gras"), "houtagtige", "karamel/vanilla" en "heuningagtige" aromas. Die smaak kan beskryf word as "fynbos-blomagtig", "fynbos-soet" en "houtagtig", met 'n tikkie "suurlemoen/sitroen gras" en "hooi/gedroogde gras". Die resultate van die sensoriese studie is gebruik om 'n C. intermedia sensoriese wiel en leksikon, asook 'n basiese graderingstelsel wat tee monsters in "goeie", "gemiddelde" en "swak" sensoriese kwaliteit klassifiseer, te ontwikkel. Fisies-chemiese parameters: oplosbare vastestof (SS) inhoud; absorbansie as 'n maatstaf van kleur; en troebelheid, is geëvalueer as moontlike indikasies van sensoriese kwaliteit. Hoë SS inhoud, absorbansie en troebelheid waardes het sterk met "swak" sensoriese kwaliteit gekorreleer. 'n Lineêre verwantskap bestaan tussen die fisies-chemiese parameters en kwaliteit. Die effek van fermentasie temperatuur (70, 80 en 90°C) en -tyd (12, 16, 24, 36, 48 en 60 h) op die sensoriese en fisies-chemiese eienskappe van C. intermedia is op laboratorium skaal bepaal. Verlenging van fermentasie tyd het die intensiteit van die positiewe sensoriese eienskappe verhoog, terwyl dit die intensiteit van negatiewe sensoriese eienskappe verminder het. Die SS inhoud, kleur en troebelheid van die tee het met verlengde fermentasie tyd afgeneem, terwyl die SS inhoud en troebelheid met verhoging van fermentasie temperatuur toegeneem het. Fermentasie by 90°C vir 36 h op laboratorium skaal het tee met die beste sensoriese eienskappe geproduseer, met behoud van die SS inhoud en kleur. Fermentasie by 70°C en 80°C het 'n langer fermentasie tyd vir die ontwikkeling van positiewe sensoriese eienskappe vereis. Fermentasie by 90°C is daaropvolgens op kommersiële skaal uitgevoer, met gelyktydige laboratorium skaal fermentasie van dieselfde plantmateriaal lotte om die direkte effek van die skaal van fermentasie op tee kwaliteit te bepaal. Kommersiële fermentasie, ten spyte van verhoogde wisselvalligheid as gevolg van groot volumes tee en probleme met verhitting, het tee van "goeie" sensoriese kwaliteit na fermentasie periodes van 24 en 36 h geproduseer. Verlenging van fermentasie tyd het min uitwerking op die SS inhoud en kleur van kommersiel gefermenteerde tea gehad, maar troebelheid het beduidend na 36 h toegeneem. Fermentasie by 90°C vir 24 - 36 h word gevolglik aanbeveel om tee met goeie gehalte op kommersiële skaal te produseer. Fermentasie vir langer as 48 h moet vermy word om troebelheid te voorkom en die ontwikkeling van sensoriese eienskappe kenmerkend van oor-gefermenteerde tee te vermy. As gevolg van faktore wat groot variasie in kommersiële skaal heuningbostee produksie kan teweegbring, word aanbeveel dat elke produksielot tussen 24 en 36 h gemonitor word om die optimum fermentasie tyd te bepaal.