Commercial varieties of peaches and plums contain a mixture of phenolics that may possess anticancer activity. Our objectives were to evaluate extracts from a commercial variety of yellow fleshed peach "Rich Lady" (RL) and of the red fleshed plum "Black Splendor" (BS) on tumor breast cells in vitro and in vivo, to elucidate the molecular mechanisms behind the cancer growth-suppression of the phenolics identified in peach and plum extracts for their chemopreventive potential and to evaluate the tumor growth-suppression in vivo. The RL extract preferentially inhibited the proliferation of the estrogen-independent MDA-MB-435 breast cancer cells over the estrogen-dependent MCF-7 or the normal MCF-10A breast cells. Similarly, BS extracts, though less effective than RL extracts, showed greater effects on MDA-MB-435 cells compared to the other cell lines. Fractionation of RL extracts into different groups of phenolic compounds allowed the identification of a fraction of phenolic acids (F1) with the major components of chlorogenic and neo-chlorogenic acid with potential in chemoprevention because of the relatively high growth-inhibition exerted on MDA-MB-435 and low toxicity exerted on MCF-10A cells. The F1 isolated from RL, and its major components, chlorogenic and neo-chlorogenic acids, triggered the extrinsic and intrinsic apoptotic pathways. The extrinsic death-receptor pathway involved the activation of caspase-8 followed by caspase-6, caspase-7, and PARP cleavage. By targeting the intrinsic pathway, the pro-apoptotic proteins cytochrome c, EndoG and AIF were released from mitochondria. The relatively higher cell-growth inhibition exerted by neo-chlorogenic acid was associated with its ability to inhibit the pro-survival Akt pathway. In contrast, F1 isolated from the red flesh genotype BY00P6653, induced apoptosis mainly through the intrinsic mitochondrial pathway upon sustained MAPK-ERK1/2 phosphorylation. The tumor growth-suppression of RL extracts was confirmed in vivo. Moreover, a dose-dependent decrease in lung metastasis was found, even at doses that showed no effect in tumor growth-suppression. These results suggest that peach phenolics may have potential in therapy and chemoprevention of metastatic breast cancer. Specifically chlorogenic and neo-chlorogenic acids, widely distributed among food plants, may be a useful therapeutic tool for targeting multiple cell signaling pathways in the treatment and chemoprevention of metastatic breast cancer.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The export of Japanese plums from South Africa is challenging. Exporting late season plums require fruit to last as long as 8 weeks in cold-storage. Prolonged storage periods can cause some cultivars to develop a shrivelled appearance due to moisture loss. Moisture loss from perishable commodities manifests mainly as shrivelling due to a loss in the turgidity of the surface cells of the fruit, or weight loss. ‘African DelightTM’ (highly susceptible to shrivel), ‘Laetitia’ (shrivel susceptible), ‘Sapphire’ (shrivel susceptible) and ‘Songold’ (not shrivel susceptible) plums were investigated by means of fluorescent microscopy for cracks and openings in the fruit peel. Only ‘African DelightTM’ had open hairline cracks in its peel, and fruit with wider cracks were associated with higher water vapour permeabilities. Open lenticels were found in the peels of ‘African DelightTM’, ‘Laetitia’ and ‘Sapphire’ plums. For ‘Songold’ no peel cracking or open lenticels were observed. The fact that the cuticle of this cultivar is mostly intact may be the reason why it is not susceptible to postharvest shrivel manifestation. The water vapour permeance of the fruit peel determines how easily fruit lose moisture. In this study it was determined to what extent fruit, trees, orchards, harvest date and cultivar contribute to the total variation in plum peel water vapour permeability. The permeabilities of ‘African DelightTM’, ‘Laetitia’, and ‘Songold’ were determined weekly from 4 weeks before harvest until post optimum maturity. Fruit to fruit variation made the largest contribution towards the total variation (> 45%), followed by harvest date (> 20%) and orchard (> 15%) effects. The permeability across all cultivars increased two-fold as fruit became over mature. The contribution of cultivar differences to fruit peel permeability varied greatly between seasons (42% in 2013/2014 and 5% in 2014/2015). Differences between cultivars may include cuticle thickness and composition, micro cracks in the peel and/or open lenticels. Current handling protocols suggest that fruit should be cooled as soon as possible after harvest, but this is not always possible. ‘African DelightTM’ plums were exposed to various handling scenarios in order to determine the handling protocol with the least risk of moisture loss. The control consisted of packaging and cooling the fruit within 6 h of harvest. Fruit quality was comparable or even better than the control when the fruit were pre-cooled to 0 °C and 15 °C for up to 72 h. High vapour pressure deficits caused fruit to lose more moisture, especially when fruit were exposed to ambient temperatures for 48 h and 72 h. It is recommended that handling protocols for plums should be followed stringently in order to reduce mass loss and shrivel manifestation. Since other studies found that silicate (Si) has positive effects on fruit quality, we applied potassium silicate preharvest to ‘African DelightTM’ trees. However, we did not find significant differences between treatments regarding crack width or crack incidence in the fruit peel, shrivel, decay, internal browning, gel breakdown or aerated tissue levels. Currently preharvest potassium silicate applications are not recommended to improve plum quality. / AFRIKAANSE OPSOMMING: Die uitvoer van die Japanese pruime uit Suid-Afrika is 'n uitdaging, omrede daar verwag word dat laatseisoen kultivars tot 8 weke in koelopberging moet bly. Lang opbergingsperiodes veroorsaak dat sommige kultivars 'n verrimpelde voorkoms ontwikkel a.g.v. vogverlies. Vogverlies uit vars produkte manifesteer hoofsaaklik as verrimpeling a.g.v. 'n verlies in die turgiditeit van die selle in en onder die vrugskil, en as massaverlies. ‘African DelightTM’ (hoogs vatbaar vir verrimpeling), ‘Laetitia’ (vatbaar vir verrimpeling), ‘Sapphire’ (vatbaar vir verrimpeling) en ‘Songold’ (nie vatbaar vir verrimpeling) pruime is ondersoek deur middel van fluoressensie mikroskopie vir krake en openinge in die vrugskil. Slegs ‘African DelightTM’ het oop haarlyn krake in sy skil gehad en vrugte met wyer krake het ʼn hoër waterdamp deurlaatbaarheid gehad. Oop lentiselle is gevind in die skille van ‘African DelightTM’, ‘Laetitia’ en ‘Sapphire’ pruime. ‘Songold’ het geen krake of oop lentiselle getoon nie. Die feit dat ‘Songold’ se kutikula meestal ongeskonde was, mag die rede wees waarom hierdie kultivar nie vatbaar vir verrimpeling is nie. Die waterdamp deurlaatbaarheid van 'n vrugskil bepaal hoe maklik vrugte vog verloor. In hierdie studie is bepaal tot watter mate vrugte, bome, boorde, oesdatum en kultivar bydra tot die totale variasie in die pruimskil se waterdamp deurlaatbaarheid. Die deurlaatbaarheid van ‘African DelightTM’, ‘Laetitia’, en ‘Songold’ is weekliks bepaal vanaf 4 weke voor die verwagte oesdatum tot die vrugte oorryp was. Vrug tot vrug variasie het die grootste bydrae tot die totale variasie gemaak (> 45%), gevolg deur oesdatum (> 20%) en boord (> 15%). Die skildeurlaatbaarheid van al die kultivars het verdubbel in die tyd van net voor oes tot die vrugte oorryp was. Die kultivar se bydrae tot die deurlaatbaarheid van die vrugskil het baie gewissel tussen seisoene (42% in 2013/2014 en 5% in 2014/2015). Verskille in skil-deurlaatbaarheid tussen kultivars kan kutikula-dikte en -samestelling, mikro-krake in die skil en/of oop lentiselle insluit. Huidige hanteringsprotokolle stel voor dat vrugte so spoedig moontlik afgekoel word na oes, maar dit is nie altyd moontlik nie. In hierdie studie is 'African DelightTM' pruime is blootgestel aan verskeie hantering scenario's om die hanteringsprotokol met die laagste risiko vir vogverlies te bepaal. Die kontrole vrugte is gepak en onder geforseerde verkoeling geplaas binne 6 ure na oes. Vrugkwaliteit was vergelykbaar of selfs beter in vergelyking met die kontrole wanneer die vrugte voorverkoel is tot 0 °C en 15 °C vir tot 72 uur. Hoë dampdrukverskille het veroorsaak dat vrugte meer vog verloor, veral wanneer vrugte aan kamertemperatuur blootgestel was vir 48 h en 72 h na oes. Dit word aanbeveel dat hanteringsprotokolle vir pruime streng gevolg moet word om massaverlies en verrimpeling te beperk. Aangesien ander studies gevind het dat silikaat (Si) ‘n positiewe uitwerking op vrugkwaliteit het, het ons kaliumsilikaat vooroes aan ‘African DelightTM’ bome toegedien. Daar was egter geen beduidende verskille tussen behandelings met betrekking tot kraakbreedte of kraakvoorkoms in die vrugskil of t.o.v. gehalte eienskappe soos die voorkoms van verrimpeling, bederf, interne verbruining, gelverval of deurlugte weefsel nie. Tans word voor-oes kaliumsilikaat spuite nie aanbeveel om pruimkwaliteit te verbeter nie.

Thesis (Ph. D.)--Princeton University, 1987. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (v. 1, leaves 391-406).

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: In order to export South African plums to overseas markets strict quality standards must be maintained. Among these quality classifications are specifications about the presence of cavities and pieces of broken stone/pit within the flesh of the fruit. If more than 10% of the fruit in a carton are affected by severely broken stones or large flesh cavities, the fruit have to be marketed as Class 2. A substantial amount of plums destined for export from South Africa is affected by broken stones and thus have to be marketed as Class 2. Lower prices are attained for Class 2 fruit, therefore, the presence of broken stones has a detrimental effect on the income generated from these fruit. The main aim of this study was to gain a better understanding of broken stone development and compare the growth characteristics of Japanese plum cultivars differing in their susceptibility to broken stones. Stone breakage in ‘Laetitia’ was observed as soon as stone hardening was initiated. At the start of stone hardening the parts of the stone that are still ‘soft’ are not strong enough to resist the pulling forces of the growing mesocarp and the stone is subsequently pulled apart. Regression analysis indicated that lengthwise growth of the fruit, fresh weight of the endo- and mesocarp, minimum orchard temperature and orchard night temperature, and relative humidity (RH) early in the growing season could possibly be used to predict the incidence of broken stones at harvest. Differences in the incidence of broken stones were observed between ‘Laetitia’, ‘Sapphire’ and ‘Songold’ plums and between seasons. Furthermore, significant differences were observed in the density of the endocarp in different parts of the stone. For ‘Laetitia’ and ‘Songold’, stone breakage was observed when rapid increases in stone density coincided with rapid increases in fruit growth. The stones broke in positions where an interface exists between high and low density parts in the stone and when rapid radial growth takes place in the direction where the stone is least dense. In contrast, in ‘Sapphire’, stone breakage was observed before the stones had started to lignify, indicating that the endocarp was pulled apart by the expanding flesh because it was too soft to withstand the strong pulling forces created by the flesh. The incidence of broken stones was influenced by environmental factors, as higher temperatures during the stone development and hardening period could lead to more complete endocarp formation (more stone cells are formed under such conditions). Such fruit would thus have higher endocarp density, which, if coupled with rapid radial growth, could lead to a higher incidence of broken stones. Foliar and/or root applications of calcium nitrate and potassium silicate were applied to ‘Laetitia’ plums to determine whether the incidence of broken stones could be reduced by increasing the strength of the endocarp cell walls. However, no such effect was observed. Hence, neither calcium nor silicate treatments can be recommended for reducing broken stones in plums. / AFRIKAANSE OPSOMMING: Om Suid-Afrikaanse pruime na oorsese markte uit te voer moet vrugte aan streng kwaliteitstandaarde voldoen. Daar is ondermeer spesifikasies in verband met die teenwoordigheid van holtes en stukkies gebreekte pit binne die vrug. Indien meer as 10% van die vrugte in ʼn karton deur ernstige gebreekte pit of groot vrugholtes geaffekteer word, moet die vrugte as Klas 2 bemark word. Aangesien ʼn groot hoeveelheid van die pruime wat vir uitvoer bestem is, geaffekteer word deur gebreekte pit en gevolglik as Klas 2 bemark moet word, word aansienlike finansiële verliese gelei. Laer pryse word behaal vir Klas 2 vrugte, en dus het die teenwoordigheid van gebreekte pitte ʼn negatiewe effek op die wins wat deur die uitvoer van hierdie vrugte gegenereer kan word. Die hoofdoel van hierdie studie was om die ontwikkeling van gebreekte pit in Japannese pruime te ondersoek en om die groei-patrone van kultivars wat geneig is tot gebreekte pit te vergelyk met ʼn nie-sensitiewe kultivar. Gebreekte pit in ‘Laetitia’ is opgemerk sodra die pit begin verhard het. Met die aanvangs van pit- verharding is die gedeeltes van die pit wat nog nie volkome verhard het nie, nie sterk genoeg om die sterk trekkragte van die groeiende mesokarp te weerstaan nie en die pit word gevolglik uitmekaar- getrek. Regressie-analise het gewys dat lengtegroei van die vrugte, vars massa van die endo- en mesokarp, minimum boordtemperatuur en boord-nagtemperatuur, asook relatiewe humiditeit gedurende die vruggroei-periode moontlik gebruik kan word om die voorkoms van gebreekte pit by oes te voorspel. Verskille in die voorkoms van gebreekte pit is opgemerk tussen ‘Laetitia’, ‘Sapphire’ en ‘Songold’ pruime, en ook tussen seisoene. Verder is beduidende verskille opgemerk in die digtheid van die endokarp in verskillende dele van die pit. By beide ‘Laetitia’ en ‘Songold’ is gebreekte pit opgemerk wanneer vinnige toename in pit-digtheid saamgeval het met ʼn vinnige toename in vruggroei. Die pitte breek veral in die oorgang tussen dele van die pit met hoë en lae digtheid en as dit gekombineer is met vinnige radiale vruggroei in die rigting waar die pit die minste dig is. In teenstelling hiermee is gebreekte pit in ‘Sapphire’ opgemerk selfs voordat die pitte begin verhard het. Dit dui daarop dat die endokarp uitmekaargetrek is deur die vinnig groeiende mesokarp, omdat dit te sag was om die trekkragte van die groeiende vrugvlees te weerstaan. Die voorkoms van gebreekte pit word ook deur weerstoestande beïnvloed, want hoër temperature gedurende die pit-ontwikkeling en verhardingsperiode, kan lei tot die ontwikkeling van endokarpe met meer steenselle. Hierdie vrugte sal dus ʼn hoër digtheid hê, en as dit saamval met vinnige radiale groei, kan dit lei tot ʼn groter voorkoms van gebreekte pit. Blaar- en/of worteltoedienings van kalsiumnitraat en kaliumsilikaat is gemaak om te bepaal of die voorkoms van gebreekte pit in ‘Laetitia’ verminder kon word deur die versterking van die endokarp-selwande. Geen van hierdie behandelings het tot ʼn vermindering in gebreekte pit gelei nie en nie kalsiumnitraat of kaliumsilikaat kan dus aanbeveel word om gebreekte pit in pruime te verminder nie.

Fruits and vegetables are known to play an important role in human health due to the range of phytochemicals they contain. Twenty-one peach genotypes and 45 plum genotypes with different flesh and skin color were analyzed for their antioxidant content and antioxidant activity. Anthocyanin content, phenolic content and antioxidant activity were higher in red-flesh than in light-colored flesh peaches. Carotenoid content was higher in yellow-flesh peaches. Among the peaches, the antioxidant activity was well correlated with phenolic content. The anthocyanin content among the plums increased with the red color intensity. Red-flesh plums generally had higher phenolic content than the other plums. Antioxidant activity was higher in red-flesh genotypes; however, it was strongly correlated only with the phenolic content in light-colored flesh plums. Extracts from selected genotypes of peaches and plums and their fractions were evaluated against two breast cancer cell lines (MDA-MB-435 and MCF-7) and one non-cancerous breast line (MCF-10A). The cells were cultured in the presence of peach and plum extracts and their fractions at various concentrations (0-500 µg/ml) and the cell viability and antiproliferation activity was evaluated by MTT assay and Coulter Counter. There was a dose-dependent reduction on cell viability of estrogen-negative MDA-MB-435 breast cancer cells. Only weak activity against MCF-7 was observed at high extract concentrations. There was no activity against MCF-10A after 24 h treatment. Fraction I, which consists of mainly phenolic acids such as chlorogenic acid and a caffeic acid derivative, reduces MDA-MB-435 breast cancer cell viability with the lowest IC50. The second most effective fraction was Fraction II which contained anthocyanins. Fraction III (flavonols) and Fraction IV (polymerized compounds) had no effect on the cell lines. Phenolic acids present in fraction I induced apoptosis in MDA-MB-435 estrogen receptor-negative cell line. Fraction I did not induced apoptosis in MCF-10A, a noncancerous cell line even at higher concentrations than the ones tested in MDA-MB- 435. Apoptosis induced by Fraction I was caspase 3 and PARP independent. After treatment with 50 µg of chlorogenic acid equivalent/ml there was an activation of p- ERK.

Thesis (PhD(Agric) (Horticulture))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Plums with good taste, aroma and eating quality lead to repeat purchases and sustained demand. Taste includes non-volatile compounds, e.g. sugars and acids, and has been well researched to meet the consumers’ preferences. Plum aroma, however, has not enjoyed the same attention. Limited literature is available on the aroma of Japanese plums and none could be found on the effects of relatively long cold storage on the profiles. The main aim of this study is to investigate the changes in aroma compounds of Japanese plums throughout maturation and ripening and the effects of commercial cold storage regimes. Near infra-red (NIR) spectroscopy was also evaluated as a non-destructive method to determine plum quality parameters aimed at minimising sample variability. In Paper 1, NIR spectroscopy was used to develop prediction models for total soluble solid (TSS), total acidity (TA), sugar-to-acid ratio, firmness and weight in three cultivars (Pioneer, Laetitia and Angeleno) and a multi-cultivar model. Samples were collected for seven consecutive weeks and repeated over two seasons. TSS results showed excellent predictability (R2 = 0.817-0.955; RMSEP= 0.453-0.610 % Brix) but the TA models did not perform well. The sugar-to-acid ratio models had results comparable to that of TSS. Both the firmness and weight models had acceptable results. The models of ‘Pioneer’ and ‘Laetitia’ had a better predictability capacity than the ‘Angeleno’ model. Although the multi-cultivar models outperformed the single cultivar models on R2 values it had higher prediction errors. The robustness of all the TSS, TA and firmness models is high in terms of seasonality, range and cultivar. Papers 2 and 3, the main focus of the study, are concerned with the aroma profile dynamics of Japanese plums. HS-SPME was used in both papers to extract the aroma compounds followed by GC-TOFMS for separation and identification. In Paper 2, the aroma volatile compounds of three cultivars (Pioneer, Laetitia and Angeleno) were determined for a seven week period including samples from three maturity stages (immature, harvest and tree-ripe). A total of 35 compounds were identified of which ten were generic. Each cultivar had five unique compounds resulting in different aroma profiles for each of the maturity stages and distinct separation patterns using discriminant analysis. The study was extended in Paper 3 where the aroma volatile compounds of six cultivars (Pioneer, Sapphire, Laetitia, Songold, Larry Anne and Angeleno) and one plumcot (Flavor King) were determined at three functional stages (commercial harvest, tree-ripe fruit and cold stored fruit). A total of 62 compounds were identified and classified into three groups (‘unique’ (31), ‘generic’ (11) and ‘frequent’ (20)) based on their frequency of occurrence. The aroma profiles of ‘Larry Anne’ and ‘Flavor King’ are the most affected by cold storage conditions and ‘Pioneer’ appears to be the least affected. All the cultivars have significantly different aroma profiles at all three of the functional stages with ‘Sapphire’, ‘Larry Anne’ and ‘Flavor King’ showing the largest differences. ‘Flavor King’, a plumcot, presented a ripe aroma profile that was much diverged from that of the true plums. / AFRIKAANSE OPSOMMING: Pruime met ‘n goeie smaak, aroma en eetkwaliteit lei tot herhaalde verkope en volhoubare aanvraag. Smaak sluit die nie-vlugtige stowwe (suikers en sure) in en is goed nagevors om die verbruikersvoorkeure te bevredig. Pruim aroma het egter nie dieselfde aandag geniet nie. Daar is beperkte literatuur beskikbaar wat handel oor die aroma van Japanese pruime en geen kon gevind word oor die effekte van lang koelopberging op die aromaprofiele nie. Die hoof doel van hierdie studie is om die veranderinge in die aromatiese komponente van Japanese pruime te ondersoek tydens die volwassewording- en rypwordingsprosesse asook die effekte van kommersiele koelopberging. Naby infrarooi (NIR) spektroskopie is ook geevalueer as ‘n nie-destruktiewe manier om pruim kwaliteitsparameters te bepaal met die doel om monstervariasie te beperk. In Artikel 1 is NIR spektroskopie gebruik om voorspellingsmodelle vir totale oplosbare suikers (TOS), totale suur (TS), suiker-tot-suur verhouding, fermheid en gewig te bepaal in drie kultivars (Pioneer, Laetitia en Angeleno) asook ‘n multi-kultivar model. Monsters is vir sewe opeenvolgende weke versamel en herhaal oor twee seisoene. TOS resultate toon uitstekende voorspelbaarheid (R2 = 0.817-0.955; RMSEP= 0.453-0.610 % Brix) maar TS modelle het egter nie so goed gevaar nie. Die suiker-tot-suur verhoudingsmodelle se resultate was vergelykbaar met die van TOS. Beide die fermheid- en gewigsmodelle het aanvaarbare resultate opgelewer. Die modelle vir ‘Pioneer’ en ‘Laetitia’ het ‘n beter voorspelbaarheidskapasiteit getoon as die van ‘Angeleno’. Alhoewel die multi-kultivar model beter presteer het as die enkel kultivar modelle op die R2-waardes was daar meer voorspellingsfoute. Hoe robuustheid is gevind i.t.v. seisoene, datagrense en kultivar vir al die TOS, TA en fermheidsmodelle. Artikels 2 en 3, die fokuspunt van die studie, handel oor die dinamika van die aromaprofiel van Japanese pruime. HS-SPME is in beide artikels gebruik on die aromatiese verbindings te ekstraeer gevolg deur GCTOFMS vir skeiding en identifikasie. In Artikel 2 is die aromatiese stowwe van drie kultivars (Pioneer, Laetitia en Angeleno) bepaal vir sewe opeenvolgende weke en sluit monsters van drie volwassenheidsstadiums in (onvolwasse, oes en boom-rypgemaakte pruime). ‘n Totaal van 35 verbindings is geidentifiseer waarvan tien as generies beskou kan word. Elke kultivar het vyf unieke komponente gehad en het gelei tot verskillende aromaprofiele vir elk van die volwassenheidsstadiums en diverse skeidingspatrone tydens die gebruik van diskriminant analise. Die studie is uitgebrei in Artikel 3 waartydens die aromatiese vlugtige stowwe van ses kultivars (Pioneer, Sapphire, Laetitia, Songold, Larry Anne en Angeleno) en een plumcot (Flavor King) bepaal is tydens drie funksionele stadiums (oes, boom-rypgemaak en koelopgebergde pruime). ‘n Totaal van 62 verbindings is geidentifiseer en in drie groepe geklassifiseer (‘uniek’ (31), ‘generies’(11) en ‘gereeld’ (20)) gebaseer op voorkomsfrekwensie. Die aromaprofiele van ‘Larry Anne’ en ‘Flavor King’ is die meeste deur die koelopberging geaffekteer en ‘Pioneer’ die minste. Al die kultivars het kenmerkend verskil t.o.v. hul aromaprofiele in al drie die funksionele groepe en ‘Sapphire’, ‘Larry Anne’ en ‘Flavor King’ het die grootste verskille getoon. ‘Flavor King’, die plumcot, het ook ‘n ryp aromaprofiel gehad wat baie van die van die egte pruime verskil het.

Thesis (MSc Food Sc)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Nectar formulations containing red-fleshed plum pulp and varying amounts of red-fleshed plum skin extract were developed. Red-fleshed plum nectar formulations containing 0, 8, 16, 24, and 32% skin extract were benchmarked against twenty-two commercial beverages containing red, violet and blue fruits. The total soluble solid content, pH, titratable acidity, colour, total polyphenolic, individual polyphenolic, total anthocyanin, and ascorbic acid contents, as well as antioxidant activity (oxygen radical antioxidant capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, and ferric reducing/antioxidant power (FRAP)) of the commercial beverages and plum formulations were determined. The plum nectar formulations had similar or higher total polyphenolic content, antioxidant activity, and colour values than the average for the commercial beverages. The individual polyphenolic compounds analysed in the nectar formulations were cyanidin-3-glucoside, cyanidin-3- rutinoside, quercetin-3-glucoside, quercetin-3-rutinoside, quercetin-3-xyloside, and neochlorogenic acid. Increasing polyphenolic content and antioxidant activity was observed with an increase in skin extract content of the formulations. The sensory attributes of the formulations were plum and plantlike aroma, plum and plantlike flavour, sweetness, acidity, and astringency. Increases in plantlike aroma and flavour, acidity, and astringency in conjunction with decreases in plum aroma, plum flavour, and sweetness extract were observed with an increase in skin extract. Consumer analysis indicated that all formulations were acceptable. The 0 and 16% skin extract formulations were most preferred, while the 32% skin extract formulation was least preferred. A shelf-life study was conducted in two phases. In Phase 1, the 0, 16 and 24% skin extract formulations were stored at 0 and 5°C (analysis time points: before pasteurisation, after pasteurisation (week 0), and after 1, 2, 4, 6, 8, 12, 16, 18, 20, and 24 weeks of storage). Chemical analyses conducted included colour, total polyphenolic, individual polyphenolic compound, and total anthocyanin contents, and antioxidant activity (DPPH• scavenging activity). Results from Phase 1 indicated close associations between the 16 and 24% skin extract formulations, and between these formulations and all chemical attributes. Regression analysis of results indicated significant (P 0.05) decreases in red colour, total anthocyanins, cyanidin-3-glucoside, cyanidin-3- rutinoside, DPPH• scavenging activity, total polyphenolic content, quercetin-3-rutinoside, and quercetin- 3-xyloside for formulations stored at 0°C. The total and red colour, total anthocyanins, cyanidin-3- glucoside, and cyanidin-3-rutinoside in formulations stored at 5°C showed similar results. During Phase 2 of the shelf life study, sensory analysis was conducted on the 0 and 24% skin extract formulations stored at 5°C (preparation time points: 0, 1, 2, and 3 months). Sensory attributes, including plum, plantlike, and raisin flavour, sweetness, acidity, and astringency, were stable during storage. Chemical results from Phase 2 were similar to those of Phase 1. The chemical and sensory stability of formulations after 24 weeks of storage in Phase 1 and Phase 2 indicated that, with the exception of the anthocyanin degradation, the formulations could be beneficial to juice industries. Thus, red-fleshed plum nectars have the potential to compete with high-antioxidant fruit beverages. / AFRIKAANSE OPSOMMING: Nektarformulasies wat rooivleis pruimpulp en varieërende hoeveelhede rooivleis pruimskilekstrak bevat, is ontwikkel en ondersoek. Rooivleis pruimnektarformulasies wat 0, 8, 16, 24, en 32% skilekstrak bevat, is vergelyk met twee-en-twintig kommersiële drankies wat rooi, violet en blou vrugte bevat. Die totale oplosbare vastestof, totale polifenoliese, individuele polifenoliese, totale antosianien- en askorbiensuur inhoude, sowel as die pH, titreerbare suurheid, kleur, antioksidant aktiwiteit (suurstofradikale antioksidantkapasiteit (ORAC), 2,2-difeniel-1-pikrielhidrasiel (DPPH) radikaal blussingsaktiwiteit, en ysterreduserende/antikoksidantkrag (FRAP)) van die kommersiële drankies en pruimnektarformulasies, is bepaal. Die pruimnektarformulasies het soortgelyke of hoër totale polifenoliese inhoud, antioksidantaktiwiteit, en kleurwaardes gehad in vergelyking met die gemiddelde vir die kommersiële drankies. Die individuele polifenoliese verbindings wat in die nektarformulasies geanaliseer is, was sianidien-3-glukosied, sianidien-3-rutinosied, kwersetien-3-glukosied, kwersetien-3-rutinosied, kwersetien-3-xylosied, en neochlorogeniese suur. ‘n Toenames in die kleurwaardes, polifenoliese inhoud, en antioksidantaktiwiteit is waargeneem met ‘n toename in skilekstrak is in die formulasies. Die sensoriese eienskappe van die formulasies was pruim- en plantagtige aroma, pruim- en plantagtige geur, soetheid, suurheid, en frankheid. Toenames in plantagtige aroma en geur, suurheid en frankheid, sowel as ‘n afname in pruimaroma, pruimgeur, en -soetheid, is met ‘n toename in skilekstrak waargeneem. Verbruikersanalise het aangedui dat al die formulasies aanvaarbaar was. Die 0 en 16% skilekstrakformulasies was die mees aanvaarbaarste, terwyl die 32% skilekstrakformulasie die minste aanvaarbaar geag is. ‘n Rakleeftydstudie is in twee fases gedoen. In Fase 1 is die 0, 16, en 24% skilekstrakformulasies by 0 en 5°C gestoor (analiseringstydpunte: voor pasturisasie, na pasturisasie (week 0), en na 1, 2, 4, 6, 8, 12, 16, 18, 20, en 24 weke van berging). Chemiese analise wat gedoen is, sluit totale polifenoliese, individuele polifenoliese verbinding, en totale antosianien inhoude, sowel as kleur en antioksidantaktiwiteit (DPPH• blussingsaktiwiteit) in. Resultate van Fase 1 het ‘n nou verband tussen die 16 en 24% skilekstrakformulasies, sowel as tussen hierdie formulasies en hul chemiese kenmerke aangedui. Regressie-analise van resultate het betekenisvolle (P 0.05) afnames geïllustreer in rooi kleurwaardes, DPPH• blussingsaktiwiteit, sowel as totale antosianiene, sianidien-3-glukosied, sianidien-3-rutinosied, totale polifenoliese, kwersetien-3-rutinosied, en kwersetien-3-xylosied inhoude van die formulasies wat by 0°C gestoor is. Die totale kleur-, rooi kleurwaardes, sowel as totale antosianien, sianidien-3-glukosied, en sianidien-3-rutinosied in die formulasies wat by 5°C gestoor is, het soortgelyke resultate gegee. Gedurend Fase 2 van die rakleeftydstudie is sensoriese analise op die 0 en 24% skilekstrakformulasies wat by 5°C gestoor is, gedoen (voorbereidingstydpunte: 0, 1, 2, en 3 maande). Sensoriese eienskappe, insluitend pruim-, plantagtige-, en rosyntjiesmake, soetheid, suurheid, en frankheid, was stabiel gedurende berging. Chemiese resultate van Fase 2 was soortgelyk aan dié van Fase 1. Die chemiese en sensoriese stabiliteit van die formulasies na 24 weke van opberging in Fase 1 en Fase 2 nieteenstaande antosianienafname, het aangedui dat die formulasies voordelig kan wees vir die vrugtedrankiebedryf. Dus het rooivleis pruimnektars die vermoeë om met hoë antioksidant vrugtedrankies mee te ding.

La quantité de déchets augmente depuis plusieurs décénies, issus principalement de l'industrie du plastique. La production cumulée de matières plastiques au cours des dix dernières années est supérieure que pendant le dernier millénaire. Une des solutions pour réduire les impacts écologiques et économiques est de dévelopement de films et enrobages biodégradables et/ou comestibles.L'objectif de cette thèse est d'étudier des films et enrobages comestibles à base d'amidon. Quinze types de solutions filmogènes ont été formulés: 3 types d’amidons, amidon + protéines, amidon + huile de colza, amidon + plastifiant. Afin de mieux comprendre le rôle des constituants et les interactions mises en jeu, les propriétés physico-chimiques et structurales des films ont été réalisées. Enfin, les films présentant les meilleurs compromis ont été appliqués sur des prunes.L’étude physico-chimique des films à base d’amidon de maïs, de pommes de terre et de de blé ont permis de retenir l’amidon de blé pour les études suivantes. Une quantité de plastifiant de 50% (par rapport à la masse sèche de biopolymère) a été sélectionnée car elle permet d'obtenir des films souples et resistants sans blanchiment. Afin d'améliorer l'efficacité barrière à l'humidité, de l'huile de colza a été ajoutée par laminage sur le film d’amidon. Les observations de la microstructure montrent une dispersion de gouttelettes d’huile dans la matrice à la place d’une structure multicouche amidon-huile-amidon. Diverses proportions amidon/protéine ont été testées pour améliorer les propriétés fonctionnelles des films. Plus la teneur en protéines est élevée, meilleure est l'efficacité barrière à la vapeur d'eau, à l'oxygène ou aux arômes. En effet, les films sont plus denses et homogènes en présence des protéines. A partir de la meilleure compréhension du rôle de la composition et de la structure sur les performances des films, plusieurs formulations ont été testées comme enrobage ou film sur des prunes fraîches. L’analyse thermographique a été utilisée pour étudier le comportement des prunes pendant le stockage, l’enrobage/film composé de l’amidon enrobage s’est avéré efficace pour retarder la dégradation des fruits. / The amount of waste increased annually, mainly from plastic industry. Plastic materials were more produced during the only last ten years than during the last millennium. A potential solution of the ecological and economic problems can be biodegradable or edible films and coatings. The goal of this thesis was to study edible films and coatings based on starch. Fifteen types of film-forming solutions were made: 3 types of starch, starch + different amounts of plasticizer, starch + proteins, starch + oil. To better understanding the interaction between film components, physical, chemical and functional tests were done. Finnaly, validation on real foods (plums) as coatings and films helped to improved edible barrier films for fruit and vegetable preservation.Preliminary physico-chemical studies of corn, potato and wheat starch film properties allowed choosing the wheat starch-based films further experiments. Then, a 50% amount of plasticizer related to dry biopolymer weight was selected aiming to obtain films being not too rigid, that did not break and without blooming. To prove the barrier moisture efficacy, rapeseed oil was added as multilayers films. Microstructure observations displayed that oil was dispersed as droplets instead of layer, thus emulsion-based films were obtained instead of multilayer starch-oil-starch films. Various ratios of starch/protein were assessed to improve functional properties of films. The more the protein content was, the better the barrier efficiency against water vapour, oxygen or aroma were. Indeed, higher protein content films were more dense and homogeneous. From these data obtained on films, and the better understanding how composition and structure affect film performances, several recipes were tested as coatings or films for wrapping fresh plums. Thermographic analysis was used to study the plums behavior during storage, and starch coating was efficient to delay fruit degradation. / Z każdym rokiem wzrasta liczba produkowanych odpadów, w szczególmości tych z plastiku. W ciągu pierwszych dziesięciu lat wyprodukowano więcej tworzyw sztucznych niż w przeciągu całego ubiegłego tysiąclecia. Rozwiązaniem tych ekologicznych i ekonomicznych problemów mogą okazać się filmy i powłoki do żywności. Celem tej pracy były studia nad jadalnymi filmami i powłokami na bazie skrobi. Piętnaście rodzajów roztworów powłokotwórczych zostało wytworzonych: z 3 typów skrobi, skrobia + różne stężenia plastyfikatora, skrobia + białka, skrobia + olej. W celu lepszego zrozumienia interakcji pomiędzy komponentami filmu właściwości fizyczne, chemiczne i funkcjonalne zostały zmierzone. W ostatnim etapie walidacja na prawdziwej żywności (powlekanie i pakowanie śliwek) pomogła w udowodnieniu istnienia właściwości barierowych owoców i warzyw podczas przechowywania.Próbne testy fizyko-chemiczne skrobi kukurydzianej, ziemniaczanej i pszenicznej pomogły w wyborze skrobi otrzymywanej z pszenicy do dalszych badań. Następnie wybrano zawartość plastyfikatora. 50% glicerolu względem suchej masy substancji powłokotwórczej nie powodowało twardości i pękania filmów ani też tzw. efektu kwitnienia (intensywnie żółty/ pomarańczowy kolor filmów). W celu poprawy właściwości barierowych olej rzepakowy został dodany. Zdjęcia mikroskopowe obrazują zawieszone krople oleju w matrycy jako emulsja zamiast dodatkowej warstwy, której oczekiwano. Do skrobi zostały dodane również białka serwatkowe w kilku proporcjach. Im więcej białek jest w stosunku procentowym skrobia/proteiny tyym lepsze są właściwości barierowe dla pary wodnej, tlenu i aromatów. Dodatkowo filmy zawierające więcej protein w stosunku procentowym są bardziej gęste i jednolite. Uzyskane informacje pozwoliły na lepsze zrozumienie wpływu kompozycji i struktury filmów i powłok na pakowanie świeżych śliwek. Analiza z użyciem kamery termowizyjnej pozwoliła na ocenę zmian w owocach podczas przechowywania, zaś powłoka skrobiowa efektywnie opóźniała procesy degradacyjne w owocach.

ENGLISH ABSTRACT: The export of Japanese plums from South Africa is challenging, since most cultivars are prone to develop chilling injury (CI) when stored at low temperatures. This injury manifests as gel breakdown or internal browning in the mesocarp tissue of the fruit on removal from low storage temperature conditions, i.e. in the consumer’s fruit basket, who subsequently does not buy plums again. Loss of cell membrane integrity and oxidative stress are, respectively, the primary and secondary physiological responses to CI. The main aim of this study was to investigate changes in cell membrane composition and levels of antioxidants in plums throughout fruit development and maturation, during forced air cooling (FAC) and storage under different temperature regimes. ‘Sapphire’ (a chilling susceptible cultivar) accumulated high levels of glutathione and polyunsaturated fatty acids (PUFAs) during fruit development. Therefore, the cultivar is protected against lipid peroxidation while developing on the tree, but the high levels of PUFAs, which are easily oxidised, may cause this cultivar to be chilling susceptible when stored at low temperatures. It is suggested that the high levels of monounsaturated fatty acids (MUFAs), which are not easily oxidised, and ascorbic acid that accumulated in ‘Angeleno’ (a chilling resistant cultivar) during fruit development, render this cultivar CI resistant during long-term cold-storage. When stored at -0.5 °C, CI development increased at a higher rate, ethylene evolution rates were higher and water soluble antioxidant activity (HAA), ascorbic acid and glutathione levels, and the MUFA:PUFA ratio were lower in H2 (more mature) ‘Sapphire’ plums than H1 fruit (less mature). Therefore, concurrent with H2 fruit having lower levels of antioxidants to quench free radicals caused by chilling stress, their cell membranes were more vulnerable to oxidation due to their phospholipid fatty acid composition. H2 fruit also had higher levels of saturated fatty acids, and hence less fluid cell membranes than H1 fruit when stored at -0.5 °C. An intermittent warming (IW) regime delayed symptom appearance and reduced CI severity in plums significantly compared to storage at -0.5 °C. Fruit stored under the IW regime had a more optimal phospholipid fatty acid composition and lower membrane sterol levels under shelf-life conditions to keep the membranes fluid. It also had higher levels of HAA and lipid soluble antioxidant activity, ascorbic acid and glutathione, which rendered fruit better protected against oxidation. Elevated storage temperatures (2.5 °C to 7.5 °C) caused higher levels of lipid peroxidation or low ascorbic acid levels and poor fruit quality compared to the IW regime in ‘Sapphire’ plums. ‘Laetitia’ plums stored at 5 °C and 7.5 °C had significantly less CI than under the IW regime, but softened quicker due to higher ethylene evolution rates. ‘Sapphire’ tolerated both long and short FAC durations, but a slower initial FAC rate prevented CI manifestation and caused a higher HAA after cold-storage in this fruit. ‘Laetitia’ cooled with a slower initial FAC rate and for a longer duration resulted in the best fruit quality and had higher HAA, total phenolic, phospholipid and saturated phospholipid fatty acid concentrations during storage. / AFRIKAANSE OPSOMMING: Die uitvoer van Japanese pruime vanaf Suid-Afrika hou talle uitdagings in, want die meeste van die kultivars ontwikkel koueskade wanneer hulle by lae temperature opgeberg word. Koueskade manifesteer as gelverval of interne verbruining in die mesokarpweefsel van die vrugte wanneer die vrugte verwyder word uit die lae opbergingstemperatuuromstandighede, m.a.w. in die verbruiker se vrugtemandjie, wat nie weer pruime koop nie. Verlies aan selmembraanintegriteit en oksidatiewe druk is, respektiewelik, die primêre and sekondêre fisiologiese reaksies op koueskade. Die hoofdoel van hierdie studie was om die veranderinge in selmembraansamestelling en antioksidantkonsentrasie in pruime te ondersoek tydens vrugontwikkeling en volwassewording, tydens geforseerde lugverkoeling (GLV) en tydens opberging onder verskillende temperatuurregimes. ‘Sapphire’ (‘n koueskade sensitiewe kultivar) het hoër konsentrasies van glutatioon en polionversadigde vetsure (POV) tydens vrugontwikkeling geakkumuleer. Dié kultivar is dus voldoende beskerm teen lipiedperoksidasie tydens vrugontwikkeling aan die boom, maar die hoë konsentrasies van POVs, wat maklik oksideer, mag veroorsaak dat hierdie kultivar meer koueskadesensitief is wanneer dit by lae temperature opgeberg word. Die hoë konsentrasies van mono-onversadigde vetsure (MOV), wat nie maklik oksideer nie, en askorbiensuur wat in ‘Angeleno’ (‘n koueskade weerstandbiedende kultivar) geakkumuleer het tydens vrugontwikkeling, verleen moontlik weerstandbiedendheid teen koueskade aan hierdie kultivar tydens langtermyn koelkopbering. Tydens opberging by -0.5 °C het koueskade ontwikkeling vinniger toegeneem, was etileenvrystellingstempos hoër en die wateroplosbare antioksidantaktiwiteit (HAA), askorbiensuuren glutatioonkonsentrasies en die MOV:POV verhouding laer in H2 (meer volwasse) ‘Sapphire’ pruime as in die H1 vrugte (minder volwasse). Dus, tesame met die laer antioksidantkonsentrasies in die H2 vrugte om die vry radikale veroorsaak deur koelopbering te verminder, was hul selmembrane ook meer vatbaar vir oksidasie a.g.v. die vetsuursamestellling van hul membraanfosfolipiede. Die H2 vrugte het ook ‘n hoër konsentrasie van versadigde vetsure, en dus minder vloeibare membrane as die H1 vrugte gehad tydens opberging by -0.5 °C. Die dubbeltemperatuurregime (DT) het simptoomontwikkeling vertraag en koueskade-intensiteit betekenisvol verminder in vergelyking met pruime wat by -0.5 °C opgeberg is. Vrugte wat met die DT regime opgeberg is, het ‘n meer optimale fosfolipiedvetsuursamestelling en laer konsentrasie van membraansterole tydens gesimuleerde raklewe gehad wat meer vloeibare membrane verseker het. Hierdie behandeling het ook hoër HAA en lipiedoplosbare antioksidantaktiwiteit (LAA), askorbiensuur- en glutatioonkonsentrasies gehad wat die vrugte beskerm het teen oksidatiewe druk. Verhoogde opbergingstemperature het hoër vlakke van lipiedperoksidasie of lae askorbiensuurkonsentrasies asook swak vrugkwaliteit in ‘Sapphire’ pruime veroorsaak in vergelyking met die DT regime. ‘Laetitia’ pruime wat by 5 °C en 7.5 °C opgeberg is, het betekenisvol minder koueskade gehad in vergelyking met die DT regime, maar het vinniger sag geword a.g.v. hoër etileenvrystellingstempos. ‘Sapphire’ kon lang en kort GLV tye weerstaan, maar ‘n stadiger inisiële GLV spoed het die manifestasie van koueskade voorkom en het ‘n hoër HAA in die vrugte tot gevolg gehad na koelopberging. ‘Laetitia’ wat met ‘n stadiger inisiële GLV spoed en oor ‘n langer tyd verkoel is, het die beste vrugkwaliteit, en hoër HAA, totale fenool-, fosfolipied- en versadigde fosfolipiedvetsuurkonsentrasies as die ander behandelings tydens koelopberging gehad

abstract: After being awarded the Nobel Prize for Literature in 2009, Herta Müller attained great prominence around the world. Commentators, especially in English-speaking countries, seemed shocked by the decision. One of the primary concerns was that Müller was relatively unknown. This thesis seeks to address this and other concerns by looking at reviews of her works in German- and English-language publications both before and after the Nobel Prize was awarded. This thesis analyses chronologically the reception of her books beginning with Niederungen in 1982 and ending with the reception of her novel Atemschaukel in 2009. It compares the reception of the original German text to that of the English translation; therefore only works which have been translated and published in English are discussed. The study also shows that while Müller's work did not top the bestseller charts, at least before the Nobel Prize, she was hardly the completely unknown author that some in the English-language media believed. This thesis seeks to present trends in the reception as well as provide a basis for further study of the reception of Herta Müller. / Dissertation/Thesis / M.A. German 2011