Thesis (MSc Food Sc )--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The rapid urbanisation of the African population has led to the establishment of large low-income communities in and around almost every major town and city in South Africa. Several factors prevent these people from producing or obtaining their traditional fermented milk drink, Maas (Amasi), often resulting in the occurrence of malnutrition in low-income urban African communities. A product with the potential to satisfy the demand for a fermented milk product is Kefir. Kefir, a self-carbonated fermented milk, is commonly manufactured by fermenting unpasteurised or pasteurised milk with re-usable Kefir grains. These Kefir grains consist of a combination of mainly lactic acid bacteria and yeasts. Neither Kefir, nor Kefir grains are as yet marketed in South Africa, thus creating an excellent opportunity to launch these products locally. It is often difficult for the low-income communities to obtain high quality unpasteurised or pasteurised milk, resulting in a serious health risk. The inhibitory activity of Kefir towards certain spoilage and pathogenic microorganisms was, therefore, studied. Strains of Escherichia coli, Staphylococcus aureus, Bacillus cereus, Usteria monocytogenes and Clostridium tyrobutyricum were inoculated (10 ³ - 10 ⁴ cfu.ml⁻¹ ) into pasteurised milk together with Kefir grains (18 gram per litre) and incubated at 25°C. Uninoculated milk samples and milk samples inoculated only with test organisms served as controls. Growth of all the test organisms were inhibited substantially (>-99.9%) in Kefir over the 30 h incubation period and substantial reductions in microbial log cycles were observed for many of the organisms. This coincided with a steep decrease in pH (6.57 - 4.06) and increase in titratabie acidity (0.20 - 0.72%). If Kefir is eventually marketed to low-income urban African consumers, it will have to compete with Maas and, therefore, comparative sensory testing of Kefir and Maas was conducted. The differences in the sensory properties of Kefir, 'laboratory' Maas (representing traditional Maas) and commercial Maas (containing thickener, colourants and flavourants) were determined by a trained panel. These characteristics were identified as "yeasty" and "cowy" tastes (p < 0.05), "effervescence" (p < 0.01), as well as "sourness," "creaminess" and "smoothness" (p < 0.001). The effect of different incubation temperatures (25°, 30° and 35°C) on the Kefir sensory properties was studied to simulate the effect of the large temperature variations that would be found in the dwellings of low-income African urbanites. The "sourness" and "creaminess" of the Kefir was found to increase with increase in incubation temperature but no strong off-flavours were found to develop. Sensory preference testing was conducted by consumer panels consisting of panellists of different ages and population groups to indicate whether the specific panels significantly prefer Kefir, commercial Maas or laboratory Maas. It was found that commercial Maas was significantly (p < 0.001) preferred to Kefir by young African urbanites. Adult Africans, who presumably still have traditional taste preferences, however, equally (p > 0.05) preferred Kefir and laboratory Maas, identifying this segment of the African population as the appropriate starting target market for Kefir. Kefir and laboratory Maas were also tested for preference by a wider panel consisting of people (aged between 18 and 25) representing the different population groups in South Africa. Kefir and laboratory Maas were preferred equally (p > 0.05) by all the groups. Several arguments supporting Kefir marketing to the low-income urban African population of South Africa have been identified. These include: Kefir's ease of preparation; the re-usability of Kefir grains and subsequent affordability; good packaging, distribution and storage possibilities; Kefir's acceptability by lactoseintolerant individuals; high nutritional value; the inhibitory activity of Kefir against potential spoilage and pathogenic organisms and subsequent enhanced safety and keeping ability; and Kefir's acceptable refreshing taste. / AFRIKAANSE OPSOMMING: Die toenemende verstedeliking van Swart Suid-Afrikaners het gelei tot die vestiging van groot lae-inkomste gemeenskappe in en om die meeste groot dorpe en stede. Verskeie faktore verhoed dat hierdie gemeenskappe hul tradisionele gefermenteerde melk, naamlik Maas (Amasi), self kan maak of koop. Dit lei dikwels tot wanvoeding onder lae-inkomste stedelike Swart verbruikers. Kefir het die potensiaal om te voorsien in die vraag na 'n gefermenteerde melk produk in lae inkomste stedelike Swart gemeenskappe. Kefir is 'n selfgekarboneerde, gefermenteerde melk wat vervaarding word deur die fermentasie van ongepasteuriseerde of gepasteuriseerde melk met herbruikbare Kefirkorrels. Hierdie Kefirkorrels bestaan uit 'n kombinasie van hoofsaaklik melksuurbakterieë en giste. Kefir en Kefirkorrels word glad nie in Suid-Afrika bemark nie, en bied 'n fantastiese geleentheid om hierdie produkte plaaslik bekend te stel. Dit is dikwels moeilik om hoë kwaliteit ongepasteuriseerde of gepasteuriseerde melk in lae-inkomste gemeenskappe te verkry. Die risiko om siektes deur die verbruik van hierdie melk op te doen, bestaan dus. Om hierdie rede is die inhiberende effek van Kefir teenoor spesifieke bederf- en patogeniese bakterieë bestudeer. Rasse van Escherichia coli, Staphylococcus aureus, Bacillus cereus, Usteria monocytogenes en Clostridium tyrobutyricum is geïnokuleer (10 ³ - 10 ⁴ cfu.ml⁻¹) in gepasteuriseerde melk tesame met Kefirkorrels (18 gram per liter) en geïnkubeer by 25°C. Melkmonsters wat slegs geïnokuleer is met die toetsorganismes het as kontroles gedien. Die groei van al die toetsorganismes is substansieël geïnhibeer (>-99.9%) in Kefir gedurende die 30 h inkubasieperiode. Substansiële afnames in logsiklusgetalle is waargeneem vir baie van die organismes. Dit het gepaard gegaan met 'n skerp afname in pH (6.57 - 4.06) en toename in titreerbare suurheid (0.20 - 0.72%) vir die Kefirmonsters gedurende die 30 h inkubasieperiode. lndien Kefir bemark word aan lae-inkomste stedelike Swart verbruikers sal dit moet kompeteer met Maas. Vergelykende sensoriese toetse is dus uitgevoer. Die verskille in die sensoriese eienskappe van Kefir, 'laboratorium' Maas (verteenwoordigend van tradisionele Maas) en kommersiële Maas (wat verdikker, kleur- en geurmiddels bevat) is bepaal deur 'n opgeleide paneel en geïdentifiseer as die" "gis-" en "koeismake" (p < 0.05), die "gasserigheid" (p < 0.01) asook die "suurheid", "romerigheid" en "gladheid" (p < 0.001) van die monsters. Die effek van verskillende inkubasietemperature (25°, 30° en 35°C) op die sensoriese eienskappe van Kefir is bestudeer om die effek van die groot temperatuurvariasies wat in laeinkomste behuising mag voorkom, te simuleer. Daar is bevind dat die "suurheid" en "romerigheid" van Kefir toeneem met verhoging in inkubasietemperatuur terwyl geen afsmake ontwikkel nie. Sensoriese voorkeurtoetse is deur verbruikerspanele van verskillende ouderdomme en bevolkingsgroepe uitgevoer om te bepaal of die spesifieke panele 'n beduidende voorkeur toon vir Kefir, laboratorium Maas of kommersiële Maas. Daar is bevind dat stedelike Swart jongmense kommersiële Maas beduidend (p < 0.001) bo Kefir verkies. Swart volwassenes met verwagte tradisionele smaakvoorkeure het egter Kefir en laboratorium Maas ewe veel verkies (p > 0.05). Hierdie segment van die Swart bevolking is dus die geskikte teikenmark vir die bekendstelling van Kefir. Voorkeur vir Kefir en laboratorium Maas is ook getoets deur 'n paneel (ouderdom 18 - 25 jaar) wat bestaan uit mense van verskillende bevolkingsgroepe. AI die groepe het Kefir en Maas ewe veel verkies (p > 0.05). Verskeie argumente ten gunste van die bemarking van Kefir aan lae-inkomste stedelike Swart gemeenskappe in Suid-Afrika is geïdentifiseer. Dit behels die volgende: die gerief van Kefirvervaardiging; die herbruikbaarheid van Kefirkorrels en gevolglike bekostigbaarheid; goeie verpakkings-, verspreidings- en opbergingsmoontlikhede; Kefir se aanvaarbaarheid vir laktose-intolerante individue; Kefir se hoë voedingswaarde; die inhiberende aktiwiteit wat Kefir teenoor potensiële bederf- en patogeniese organismes het en die gevolglike verhoging in veiligheid en rakleeftyd van melk; en Kefir se aanvaarbare verfrissende smaak.

Thesis (M.Tech.: Food Technology)-Dept. of Biotechnology, Durban University of Technology, 2007 xiii, 100 leaves / There are many ways for milk and dairy products to develop flavour defects. Sensory evaluation, has been the traditional approach to characterize off flavours. The need for odour sensing devices becomes greater when volatile and semi-volatile organic compounds are present in the product in parts per billion or even in the parts per trillion concentration range that cause off flavours. Today, sophisticated, sensitive instrumental tests such as electronic nose technology coupled with gas chromatography are capable of detecting, identifying and quantifying the specific chemical agents responsible for off flavours. This study focused on the use of the electronic nose as a novel technology for the detection and monitoring of milk quality by testing the effects of heat treatment at 63˚C and shelf life. Microbiological testing, sensory evaluation and gas chromatographic analysis were carried out together with aroma profiling using the electronic nose to determine milk quality.

Thesis (M.Tech.: Food Technology)-Dept. of Biotechnology, Durban University of Technology, 2007 xiii, 100 leaves / There are many ways for milk and dairy products to develop flavour defects. Sensory evaluation, has been the traditional approach to characterize off flavours. The need for odour sensing devices becomes greater when volatile and semi-volatile organic compounds are present in the product in parts per billion or even in the parts per trillion concentration range that cause off flavours. Today, sophisticated, sensitive instrumental tests such as electronic nose technology coupled with gas chromatography are capable of detecting, identifying and quantifying the specific chemical agents responsible for off flavours. This study focused on the use of the electronic nose as a novel technology for the detection and monitoring of milk quality by testing the effects of heat treatment at 63˚C and shelf life. Microbiological testing, sensory evaluation and gas chromatographic analysis were carried out together with aroma profiling using the electronic nose to determine milk quality.

No description available.

Call number: LD2668 .T4 1984 J32 / Master of Science

Call number: LD2668 .T4 1985 L96 / Master of Science

Call number: LD2668 .T4 1985 R422 / Master of Science

Thesis (PhD)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Wine is the result of a variety of biochemical reactions and microbial interactions which contribute to the organoleptic properties of wine. Wine aroma and flavour encapsulate the sensory experience of wine and could ultimately determine wine quality and consequently influence consumer acceptance and preference of a product. A thorough understanding of potential factors influencing wine aroma and flavour is therefore needed in order to exploit such factors. The aim of this study was to evaluate the influence of commercial malolactic fermentation (MLF) starter cultures on wine composition, aroma and flavour and the potential impact on consumer preference of experimentally produced red wines. An analytical platform was established to capture the compositional changes induced by different MLF bacteria in experimentally produced red wines. A fast gas chromatography flame ionisation detection (GC-FID) method was developed to determine 39 wine volatile compounds in less than 15 minutes per sample. A 3-fold reduction in analysis time was achieved in comparison to a conventional GC-FID method (40 minutes). Analytes quantified comprise a large boiling point and polarity range which illustrates the robustness of the method. A method was also developed for the direct quantification of carbonyl compounds including diacetyl, acetoin, 2,3-pentanedione and certain aldehydes using headspace solid phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME GC-MS). Both analytical methods showed satisfactory linearity, repeatability and limits of quantification. The contribution of four commercial Oenococcus oeni malolactic fermentation (MLF) starter cultures to the volatile composition, organic acid content and infrared spectral properties of experimentally produced South African red wines, showed significant strain-specific variations in the organic acid profiles, especially for the production of citric acid and lactic acid during MLF. Subsequently, concentrations of compounds related to citric acid metabolism, namely ethyl lactate, acetic acid, diacetyl and acetoin, were influenced accordingly. Bacterial metabolic activity increased the concentration of higher alcohols, fatty acids and esters, with a larger increase observed in ethyl esters compared to acetate esters. A strain-specific tendency to reduce total aldehyde concentrations was found at the completion of MLF, however, further investigation is needed to clarify this observation. Infrared spectral fingerprints were used to characterise the different bacteria and in addition, the prediction of MLF related compounds, diacetyl, acetoin and 2,3-pentanedione, from mid-infrared spectra was explored by partial least squares (PLS) models. Quantitative descriptive analysis (QDA) results depicted significant differences between wines fermented with different starter cultures, in terms of sensory attributes including buttery, fruity, nutty and yoghurt/buttermilk aroma as well as smoothness and mouth-feel attributes. Consumer preference testing results indicate that sensory differences imparted by different MLF bacteria could influence consumer-liking. Preference mapping revealed interesting relationships between sensory attributes and consumer-liking, that can be used for preliminary interpretative purposes. In conclusion, this study illustrated the potential impact of bacterial strains on wine aroma and flavour, resulting sensory properties and consumer preference through an integrative approach combining compositional, spectral, sensory and consumer data. The results presented in this study are of significance to the wine industry since they illustrate and reiterate the potential of different MLF starter cultures as an additional tool to contribute to wine aroma and flavour, and potentially influencing consumer preference and product liking. / AFRIKAANSE OPSOMMING: Wyn is die resultaat van ‘n verskeidenheid biochemiese reaksies en mikrobiologiese interaksies wat tot die organoleptiese eienskappe van die finale produk bydra. Wynaroma en geur vang die sensoriese ervaring van wyn vas en dit kan dus wynkwaliteit bepaal en gevolglik verbruikersaanvaarding asook voorkeur van ‘n produk beïnvloed. Die potensiële faktore wat wynaroma en geur kan beïnvloed moet dus vir hierdie rede deeglik bestudeer word ten einde sulke faktore ten volle te benut. Die doel van hierdie studie was om die invloed van kommersiële applemelksuurgisting (AMG) aanvangskulture op wynsamestelling, die gevolglike aroma en geur eienskappe en die potensiële impak op verbruikersvoorkeure te ondersoek. ‘n Analitiese platform is gevestig om die veranderings in samestelling veroorsaak deur verskillende AMG bakterieë in eksperimenteel bereide rooi wyne vas te vang. ‘n Vinnige gas chromatografiese vlam geïoniseerde deteksie (GC-FID) metode is ontwikkel vir die meting van 39 vlugtige komponente in minder as 15 minute per wynmonster. In vergelyking met ‘n konvensionele GC-FID metode (40 minute) is ’n 3-voudige vermindering in analise tyd behaal. Gekwantifiseerde komponente bestaan uit ‘n wye kookpunt- en polariteitsreeks wat die robustheid van die metode illustreer. ‘n Metode vir die direkte kwantifisering van karboniel komponente, insluitende diasetiel, asetoïen, 2,3-pentanedioon en verskeie aldehiede is ontwikkel met die gebruik van dampfase soliede fase mikroekstraksie gekoppel aan gas chromatografie massa spektrometrie (HS-SPME GC-MS). Albei analitiese metodes besit voldoende lineariteit, herhaalbaarheid en lae deteksie limiete. Die bydrae van vier kommersiële Oenococcus oeni AMG aanvangskulture tot die vlugtige samestelling, organiese suurinhoud en infrarooi spektrale eienskappe van Suid-Afrikaanse rooiwyn het beduidende ras spesifieke variasies in die organiese suur profiele, spesifiek vir die produksie van sitroensuur en melksuur gedurende AMG, vertoon. Gevolglik is die konsentrasies van komponente verwant aan sitroensuur metabolisme, naamlik etiellaktaat, asynsuur, diasetiel en asetoïen, dien ooreenkomstig beïnvloed. Bakteriese metaboliese aktiwiteit het ‘n toename tot gevolg gehad in die hoër alkohole, vetsure en algemene ester konsentrasies met ‘n groter toename in etiel-esters in vergelyking met asetaat-esters. ‘n Ras-spesifieke tendens om die totale aldehiedkonsentrasie te verminder na afloop van AMG, is waargeneem alhoewel verdere ondersoek in hierdie area nodig is. Infrarooi spektrale patrone is gebruik om verskillende bakterieë te karakteriseer asook om die voorspelling van spesifieke AMG verwante komponente soos diasetiel, asetoïen en 2,3-pentanedioon met die gebruik van mid-infrarooi spektrala parsiële kleinste kwadraat verskille (PLS) modelle te ondersoek. Kwantitiewe beskrywende sensoriese analise illustreer beduidende verskille tussen wyne wat gefermenteer is met verskillende aanvangskulture in terme van geure soos botteragtigheid, vrugtigheid, neutagtigheid, joghurt/karringmelkgeur, asook gladheid en mondgevoel eienskappe. Verbruikersvoorkeur resultate illustreer die groot invloed wat sensoriese verskille veroorsaak deur verskillende AMG bakterieë op verbruikersvoorkeure kan hê. Voorkeur kartering het interessante verhoudings tussen sensoriese eienskappe en verbruikersvoorkeure uitgelig. Hierdie studie illustreer die impak van bakteriese rasse op wynaroma en geur en verbruikersvoorkeure deur ‘n geïntegreerde benadering waarin samestellende, spektrale, sensoriese en verbruikersdata gekombineer is. Die resultate van hierdie studie is van belang vir die wynindustrie deurdat dit die potensiële bydrae van verskillende AMG kulture tot wynaroma en geur asook die potensiaal om verbruikersvoorkeure te beïnvloed, illustreer en beklemtoon.

Thesis (MAgricAdmin)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The objective of this study was to determine the sensory characteristics of Cheddar cheese that drive consumer acceptance. In addition, it investigated whether specific sensory profiles would satisfy specific consumer segments to ultimately facilitate greater acceptance and consumption of Cheddar cheese. A trained panel applied descriptive sensory analysis (DSA) to characterise the sensory attributes of six commercially produced cheeses ranging in maturity from 1 to 32 months. The cheese samples were differentiated by appearance, aroma, flavour and textural attributes. A consumer panel comprising of 115 target consumers rated preference for the cheeses on a 9-point hedonic scale. Moreover consumers completed a screener designed to collect socio-demographic information and opinions on cheese and cheese products. Instrumental colour analysis was performed on the cheese samples and in-depth consumer opinions and attitudes towards cheese were examined using the focus group technique. Analysis of variance (ANOVA) was conducted on the sensory and instrumental data, as well as the consumer liking and perception data. Additionally, a t-test was performed at a 5% significance level to determine the direction of the difference between the mean values. Multivariate analyses were performed on the sensory and consumer data to determine whether relationships existed between sample attributes and consumer liking. Consumer acceptability scores were segmented by agglomerative hierarchical clustering (AHC) using Ward’s test. ANOVA was performed on the consumer data per cluster for colour liking, texture liking, flavour liking and overall liking. Partial least squares regression (PLS) was performed in an attempt to relate consumer degree of liking data, the socialdemographic and attitudinal data, as well as the sensory and instrumental data. The younger cheeses; Gouda at one month, Edam at two months and Cheddar at 4 months were characterised as glossy, with a buttery and creamy aroma; creamy flavour, salty and slightly sour taste combined with lingering cheese flavour. Textures were described as creamy, springy and rubbery. Sensory attributes of visible white crystals, moisture seepage, brothy and Cheddar aromas; brothy, Cheddar and prickle flavours together with textural attributes of firm, hard, crumbly, grainy and teeth-coating characterised the aged Cheddar cheeses. Flavour development was not progressive as the cheeses aged and atypical flavour development was identified in the Cheddar cheese aged to 8 and 15 months, respectively. Flavour followed by price and convenience drive cheese purchase amongst this group of consumers. From a sensory perspective, glossy appearance, a red hue and yellow colour drive cheese colour liking. Texture liking is driven by springy and hard attributes. Flavour liking is driven by cooked milk, buttery and creamy aroma and creamy flavour. Finally overall cheese liking is driven by glossy appearance; cooked milk, buttery and creamy aroma; creamy flavour; springy and creamy texture; specific instrumental colour values, as well as fat, moisture and salt content. Three clusters per variable of colour, texture, flavour and overall liking of cheese were identified through segmentation performed on the preference data. Results indicate that consumers are not homogenous in their sensory requirements, attitudes and behaviour towards cheese. Based on the consumer preference for specific sensory characteristics of cheese, consumer segments can be identified and cheese can be optimised to satisfy these sensory requirements. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was eerstens om te bepaal watter spesifieke sensoriese eienskappe van Cheddarkaas verbruikersaanvaarbaarheid dryf, en tweedens om verbruikersdata te segmenteer ten einde vas te stel of verskillende verbruikersegmente verskillende voorkeure het wat betref Cheddarkaas. Kennis hiervan sal uiteindelik bydra tot verhoogde verbruikerstevredentheid, en dus verhoogde verkope van Cheddarkaas op die plaaslike mark. Beskrywende sensoriese analise en ’n opgeleide paneel is gebruik om die sensoriese eienskappe van ses kommersiële kaas variante te bepaal. Instrumentele kleuranalise is ook bepaal. Die monsters kaas het gewissel in ouderdom (van 1 tot 32 maande veroudering), asook in voorkoms, aroma, geur, smaak en teksturele eienskappe. ’n Verbruikerspaneel bestaande uit 115 individue het die voorkeur en aanvaarbaarheid van die ses variante kaas ge-evalueer deur gebruik te maak van die 9-punt hedoniese skaal. Sosio-demografiese inligting en verbruikeropinies betreffende kaas is ook versamel. Ten laaste is die fokusgroep tegniek gebruik om in-diepte inligting te verkry wat betref verbruikeropinies en –houdings ten opsigte van Cheddarkaas. Analise van variansie (ANOVA) is op sensoriese, instrumentele en verbruikersdata toegepas. T-toets is by ‘n betekenispeil van 5% uitgevoer om te bepaal of daar per eienskap betekenisvolle verskille tussen monstergemiddeldes was. Meerveranderlike analise is uitgevoer op die sensoriese en verbruikerdata ten einde te bepaal of spesifieke sensoriese produkeienskappe verbruikersvoorkeur dryf. Ward se statistiese groepering is gebruik om te bepaal of die verbruikers in verskillende voorkeursegmente gegroepeer kan word. Hierna is ANOVA op elke segment uitgevoer ten einde per segment verbruikersvoorkeur van die onderskeie produkte te bepaal wat betref voorkoms, geur en tekstuur. Meervoudige regressie analise is toegepas om die verwantskap tussen verbruikervoorkeur-, houding- en sosio-demografiese eienskappe van die verbruikers te bepaal, asook tussen die sensoriese en instrumentele produkeienskappe. Die kase wat vir ‘n kort tydperk verouder is, m.a.w. Gouda, Edam en Cheddar na 4 maande veroudering is beskryf as glansend, met ‘n ryk botter en romerige aroma, romerige geur, sout en effense suur smaak, asook ‘n standhoudende kaasgeur. Teksturele eienskappe van hierdie drie kaassoorte is beskryf as romerig, veerkragtig en effe rubberig. Die Cheddar kase wat langer verouder is, het tekens getoon van sigbare wit kristalle en sinerese op die kaasoppervlak, ‘n prikgevoel op die tong, asook sopagtige (“brothy”) en Cheddaragtige aromas en geure. Die teksturele eienskappe van die verouderde Cheddar kase is beskryf as ferm, hard, krummelagtig en greinerig, asook met’n geneigdheid van die kaas om aan die tande vas te kleef. Geurontwikkeling het nie progressief plaasgevind soos die kase verouder het nie. Die Cheddar kase wat onderskeidelik vir 8 en 15 maande verouder is, het atipiese geurontwikkeling getoon. Belangrike faktore wat tydens die aankoop van kaas’n rol speel, en dus voorkeur dryf is eerstens geur, tweedens prys en derdens produk-gemak. Sensoriese aspekte wat voorkeur dryf, is ‘’n glansende voorkoms en effe rooierige-gelerige kleur. Tekstuur voorkeure sluit in veerkragtiheid en hardheid, terwyl geur voorkeure die volgende insluit: romerige, botterige en melk aromas, asook ‘n romerige geur. In die geheel gesien, dryf die volgende eienskappe dus verbruikersvoorkeur: kaas met ‘n glansende voorkoms, geure soos botteragtig, roomagtig en melkerig en teksture soos veerkragtig en romerig. Voedinstofinhoud beȉnvloed ook verbruikersvoorkeur, nl. soutinhoud, vetinhoud en voginhoud. Segmentasie van verbruikersdata het getoon dat die onderskeie verbruikersegmente nie ooreenstem wat betref hul verbruikersvoorkeure, houdings en persepsies van kaassorte nie. Die resultate het egter spesifike sensoriese rigtingwysers geidentifiseer wat die bedryf kan gebruik om kaas te produseer vir elk van die onderskeie marksegmente.

Assignment (MComm)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: This study is the result of part-time work done at a product development centre. The organisation extensively makes use of trained panels in sensory trials designed to asses the quality of its product. Although standard statistical procedures are used for analysing the results arising from these trials, circumstances necessitate deviations from the prescribed protocols. Therefore the validity of conclusions drawn as a result of these testing procedures might be questionable. This assignment deals with these questions. Sensory trials are vital in the development of new products, control of quality levels and the exploration of improvement in current products. Standard test procedures used to explore such questions exist but are in practice often implemented by investigators who have little or no statistical background. Thus test methods are implemented as black boxes and procedures are used blindly without checking all the appropriate assumptions and other statistical requirements. The specific product under consideration often warrants certain modifications to the standard methodology. These changes may have some unknown effect on the obtained results and therefore should be scrutinized to ensure that the results remain valid. The aim of this study is to investigate the distribution and other characteristics of sensory data, comparing the hypothesised, observed and bootstrap distributions. Furthermore, the standard testing methods used to analyse sensory data sets will be evaluated. After comparing these methods, alternative testing methods may be introduced and then tested using newly generated data sets. Graphical displays are also useful to get an overall impression of the data under consideration. Biplots are especially useful in the investigation of multivariate sensory data. The underlying relationships among attributes and their combined effect on the panellists’ decisions can be visually investigated by constructing a biplot. Results obtained by implementing biplot methods are compared to those of sensory tests, i.e. whether a significant difference between objects will correspond to large distances between the points representing objects in the display. In conclusion some recommendations are made as to how the organisation under consideration should implement sensory procedures in future trials. However, these proposals are preliminary and further research is necessary before final adoption. Some issues for further investigation are suggested. / AFRIKAANSE OPSOMMING: Hierdie studie spruit uit deeltydse werk by ’n produk-ontwikkeling-sentrum. Die organisasie maak in al hul sensoriese proewe rakende die kwaliteit van hul produkte op groot skaal gebruik van opgeleide panele. Alhoewel standaard prosedures ingespan word om die resultate te analiseer, noodsaak sekere omstandighede dat die voorgeskrewe protokol in ’n aangepaste vorm geïmplementeer word. Dié aanpassings mag meebring dat gevolgtrekkings gebaseer op resultate ongeldig is. Hierdie werkstuk ondersoek bogenoemde probleem. Sensoriese proewe is noodsaaklik in kwaliteitbeheer, die verbetering van bestaande produkte, asook die ontwikkeling van nuwe produkte. Daar bestaan standaard toets- prosedures om vraagstukke te verken, maar dié word dikwels toegepas deur navorsers met min of geen statistiese kennis. Dit lei daartoe dat toetsprosedures blindelings geïmplementeer en resultate geïnterpreteer word sonder om die nodige aannames en ander statistiese vereistes na te gaan. Alhoewel ’n spesifieke produk die wysiging van die standaard metode kan regverdig, kan hierdie veranderinge ’n groot invloed op die resultate hê. Dus moet die geldigheid van die resultate noukeurig ondersoek word. Die doel van hierdie studie is om die verdeling sowel as ander eienskappe van sensoriese data te bestudeer, deur die verdeling onder die nulhipotese sowel as die waargenome- en skoenlusverdelings te beskou. Verder geniet die standaard toetsprosedure, tans in gebruik om sensoriese data te analiseer, ook aandag. Na afloop hiervan word alternatiewe toetsprosedures voorgestel en dié geëvalueer op nuut gegenereerde datastelle. Grafiese voorstellings is ook nuttig om ’n geheelbeeld te kry van die data onder bespreking. Bistippings is veral handig om meerdimensionele sensoriese data te bestudeer. Die onderliggende verband tussen die kenmerke van ’n produk sowel as hul gekombineerde effek op ’n paneel se besluit, kan hierdeur visueel ondersoek word. Resultate verkry in die voorstellings word vergelyk met dié van sensoriese toetsprosedures om vas te stel of statisties betekenisvolle verskille in ’n produk korrespondeer met groot afstande tussen die relevante punte in die bistippingsvoorstelling. Ten slotte word sekere aanbevelings rakende die implementering van sensoriese proewe in die toekoms aan die betrokke organisasie gemaak. Hierdie aanbevelings word gemaak op grond van die voorafgaande ondersoeke, maar verdere navorsing is nodig voor die finale aanvaarding daarvan. Waar moontlik, word voorstelle vir verdere ondersoeke gedoen.