Die belang van giste tydens weifermentasie

[摘要] English: Cheese processed by traditional or modern methods inevitably produces large quantities ofwhey (approximately 84% of the volume of milk used). The disposal of whey is becominga major industrial and environmental health problem and is difficult to separate fromcheese technology. However, since a greater appreciation of the inherent nutritional valueof whey constituents for both humans and livestock has become apparent, various newresearch projects have been initiated.In the light of growing global food shortages, the most logical use of whey wouldbe to return it, in a palatable form, to the human food chain. The high salt content, lowenergy ratio and sweetening power of lactose, however, place constraints in the way ofdeveloping whey-derived food products. Single-cell protein, using deproteinized wheyoffer attractive new possibilities, not only from the standpoint of the current exhaustion ofprotein sources, but also because such food products have great potential for acceptance.The use of deproteinized whey offers attractive financial opportunities for the dairyindustry by providing good quality whey protein on the one hand and by furtherprocessing of the deproteinized whey on the other. This can lead to even greater economicadvantages if the deproteinized whey is enriched by means of suitable yeast strains toenhance the single-cell protein content. This protein enriched whey can primarily beapplied for stockfeed with the envisaged development of a whey based food product forhuman consumption later.Fourteen lactose utilizing yeast strains, capable of fermenting lactose andproducing high protein contents when grown on whey, were isolated from whey and itsimmediate environment. Priority selection studies were performed by growing each strainon whey, obtained during the processing of Cheddar cheeses, while monitoring theirfermentative abilities, protein production capacity and the depletion of lactose. Based onthese results, a yeast species namely Kluyveromyces marxianus var. lactis were selectedfor detailed fermentation studies. The yeast species were used for producing a wheyfermentedproduct with high single-cell protein but low alcohol content. High levels. ofprotein 1.18 mg/ml were obtained in a 22 h fermentation period without any enrichmentwhich reflects well on the possibility of implementing the system in the dairy industry.

[发布机构] University of the Free State