Ontwikkeling van 'n laevetgraanproduk en die effek van verskillende veselvlakke op die glukemiese indeks

De Jongh, Jacolene (2002-03)

Thesis(MSc Food Sc )--Stellenbosch University, 2002.

Thesis

ENGLISH ABSTRACT: Consumers are becoming more health conscious. Furthermore, time is a scarce human resource and therefore convenience is an important consideration when food choices are being made. A South African food company identified this trend and decided to develop a product that capitalised on these demands of health and convenience. The decision was made to develop a low-fat, low-cholesterol, low-saturated fatty acid, low-trans fatty acid, high-fibre wheat product with an intermediate glycemic index (GI). The market in Stellenbosch was scouted to determine whether a similar product already existed. Six products that made nutrient-, health- or any other claims were identified. Not one of the identified products, however, conformed to meet the requirements of the Department of Health for the product characteristics that were set. Therefore, the decision was made to continue the development of the low-fat, low-cholesterol, low-saturated fatty acid, low-trans fatty acid, high-fibre wheat product with an intermediate glycemic index (GI). To qualify as a low-fat product, the product had to contain less than 3 % fat. The ingredients were chosen with their fat content in mind. Fruit pulp is widely used in the preparation of baked low-fat products and was also used in this study to eliminate the use of butter, margarine and oil, but also to achieve the additional product criteria that was set by the food company, namely a chewy texture and a fruity flavour. Ingredients like soya flour, oatmeal, oats and wheat bran were chosen to increase the fibre content of the product, because all of these products have a fibre content of 10 g or more per 100 g. Two products were developed during 23 experiments. Except for the high fibre claim, both products met the criteria that were set before the development started, namely a low-fat, low-cholesterol, low-saturated fatty acid, low-trans fatty acid, high-fibre content and a calculated intermediate glycemic index (GI). One of the two concept products that were developed were chosen by an experienced panel to serve as basic product for an empirical study on the effect of different fibre levels on the glycemic index. Five different fibre levels were formulated by manipulating the amounts of wheat bran and oatmeal. The basic formula contained 6,25 % fibre and the other fibre levels were identified as: 4,39; 5,31; 7,45 en 8,17 %. The fibre levels were equal-distant. The prediction was made that the GI-value of the product will decrease as the fibre levels increase and the theoretical calculations confirmed this prediction. The real GI-values that were determined by blood glucose testings, however, showed an increase in GI-value up to the 6,25 % fibre level, followed by a.decrease in GI-value to the 8,17 % fibre level. It became apparent that more than just fibre played a role in the GI-values of the products. It is proposed that the results explained by fibre behaviour, starch gelatinisation and starch hydrolysis. Hundred households in Stell enbosch tested the developed product. Two fieldworkers identified 25 consumers in four retail stores in Stellenbosch and gave them the product and the questionnaire, which they had to complete at home after tasting the product. The questionnaires were then collected from the respondents' houses. A recognised measurement instrument, which is used by the South African food industry to determine the acceptability of a newly developed product, was used for assesing the results. The results showed that the orange flavour of the product led to a low overall acceptability of the developed product and that the other product concept (that was developed during the recipe development phase and not chosen by the panel) should be considered for testing its market potential. Another facet of the questionnaire determined the effect of buying practices, health consciousness and consumer knowledge on the consumer acceptability of the low-fat, high-fibre wheat product with an intermediate-GI-value. No correlation between these factors and consumer acceptability of the low-fat, high-fibre wheat product with an intermediate-GI-value were found.

AFRIKAANSE OPSOMMING: Die verbruiker word al meer gesondheidsbewus: Terselfdertyd is tyd 'n skaars menslike hulpbron, en word gerief gevolglik 'n belangrike oorweging tydens voedselkeuses. 'n Suid-Afrikaanse voedselmaatskappy het hierdie neigings geidentifiseer en besluit om 'n produk te ontwikkel wat aan hierdie vereistes van gesondheid en gerief voldoen. Daar is besluit om 'n lae vet-, lae cholesterol-, lae versadigdevetsuur-, lae transvetsuur-, hoe veselgraanproduk met 'n intermediere glukemiese indeks (GI) te ontwikkel. Die Stellenbosse mark is verken om vas te stel of daar reeds soortgelyke produkte op die mark was. Ses produkte wat nutrientinhoud-, gesondheid- of ander aansprake maak, is geidentifiseer. Geeneen van die produkte het egter aan die Departement van Gesondheid se konsepregulasies betreffende die etikettering van voedingsmiddels vir bogenoemde produkeienskappe voldoen nie. Gevolglik is besluit om met die ontwikkeling van die lae vet-, lae cholesterol-, lae versadigdevetsuur-, lae transvetsuur-, hoe veselgraanproduk met 'n intermediere GI voort te gaan. Om as 'n laevetproduk te kon kwalifiseer, moes die produk minder as 3 % vet bevat. Die bestanddele moes dus met inagneming van hul vetinhoud gekies word. Vrugtepulp word algemeen gebruik in die bereiding van gebakte laevetprodukte en is ook in hierdie studie gebruik om die gebruik van botter, margarien of olie te vermy, maar ook om aan die addisionele produkkriteria wat deur die maatskappy gespesifiseer is, naamlik 'n sagte tekstuur en vrugtige geur, te voldoen. Bestanddele soos soja-, hawermeel, hawer- en koringsemels is gekies om die veselinhoud van die produk te verhoog, aangesien hierdie bestanddele meer as 10 g vesel per 100 g bevat. Twee produkte is deur middel van 23 eksperimente ontwikkel. Met die uitsondering van die hoeveselinhoudaanspraak, het beide produkte aan die vereistes wat gestel is, naamlik 'n laevet-, laecholesterol-, laeversadigdevetsuur-, laetransvetsuur- en 'n hoeveselinhoud en 'n beraamde intermediere GI, voldoen. Een van die konsepprodukte is deur 'n ervare paneel gekies vir die empiriese studie waar die effek van verskillende veselvlakke op die GI bepaal is. 'n Standaard formule is aangepas om vyf verskillende veselvlakke te verkry deur die koringsemel- en hawermeelhoeveelhede te manipuleer. Die basisformule het 6,25 % vesel bevat en twee veselvlakke is daarbo en -onder as ge·identifiseer: 4,39; 5,31; 7,45 en 8,17 %, dit wil sê, veselvlakke met dieselfde grootte verskille. Daar is voorspel dat die GI-waarde van die produkte sou daal met 'n toename in die veselinhoud van die produk en die teoretiese berekeninge van die GI-waarde het hierdie voorspelling gestaaf. Die werklike GI-waardes wat met behulp van bloedglukoseresponse bepaal is, het egter 'n toename in GI-waarde tot by die 6,25 % veselvlak, gevolg deur 'n afname tot by die 8,17 % veselvlak aangedui. Dit het duidelik geword dat meer as slegs die veselinhoud 'n rol gespeel het by die GI-waarde van die produk. Die resultate is gevolglik aan die hand van die veselgedrag, styselgelatinisasie en styselhidrolise verklaar. Die verbruikersaanvaarbaarheid van die ontwikkelde laevet-, hoeveselproduk is by 100 huishoudings in Stellenbosch getoets. Twee veldwerkers het die verbruikers in vier kleinhandelaars in Stellenbosch genader en produkte met 'n gepaardgaande vraelys aan hulle oorhandig. Die produkte is tuis qeevalueer en die vraelyste is weer ingesamel. Ook vervat in die vraelys was 'n erkende meetinstrument wat deur die Suid-Afrikaanse voedselindustrie gebruik word vir die bepaling van verbruikersaanvaarbaarheid van 'n nuutontwikkelde produk. Uit die resultate het dit geblyk dat die lemoengeur van die produk gelei het tot die lae verbruikersaanvaarbaarheid van die ontwikkelde produk, en dat die ander produkkonsep (wat tydens die resepontwikkelingsfase ontwikkel is, en nie deur die ervare paneel gekies is nie) vir bemarkingspotensiaal getoets hoort te word. Die data wat uit die vraelyste ingesamel is, is ook gebruik om die effek van aankooppraktyke, gesondheidsbewustheid en verbruikerskennis op die verbruikersaanvaarbaarheid van die laevet-, hoeveselgraanproduk met 'n interrnediere-Gl-waarde te bepaal. Daar is geen verwantskap tussen hierdie faktore en die verbruikersaanvaarbaarheid van die laevet-, hoëveselgraanproduk met 'n intermedlere-Gl-waarde, gevind nie.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/52975
This item appears in the following collections: