Die belang van giste tydens weifermentasie

English: Cheese processed by traditional or modern methods inevitably produces large quantities of whey (approximately 84% of the volume of milk used). The disposal of whey is becoming a major industrial and environmental health problem and is difficult to separate from cheese technology. However, since a greater appreciation of the inherent nutritional value of whey constituents for both humans and livestock has become apparent, various new research projects have been initiated. In the light of growing global food shortages, the most logical use of whey would be to return it, in a palatable form, to the human food chain. The high salt content, low energy ratio and sweetening power of lactose, however, place constraints in the way of developing whey-derived food products. Single-cell protein, using deproteinized whey offer attractive new possibilities, not only from the standpoint of the current exhaustion of protein sources, but also because such food products have great potential for acceptance. The use of deproteinized whey offers attractive financial opportunities for the dairy industry by providing good quality whey protein on the one hand and by further processing of the deproteinized whey on the other. This can lead to even greater economic advantages if the deproteinized whey is enriched by means of suitable yeast strains to enhance the single-cell protein content. This protein enriched whey can primarily be applied for stockfeed with the envisaged development of a whey based food product for human consumption later. Fourteen lactose utilizing yeast strains, capable of fermenting lactose and producing high protein contents when grown on whey, were isolated from whey and its immediate environment. Priority selection studies were performed by growing each strain on whey, obtained during the processing of Cheddar cheeses, while monitoring their fermentative abilities, protein production capacity and the depletion of lactose. Based on these results, a yeast species namely Kluyveromyces marxianus var. lactis were selected for detailed fermentation studies. The yeast species were used for producing a wheyfermented product with high single-cell protein but low alcohol content. High levels. of protein 1.18 mg/ml were obtained in a 22 h fermentation period without any enrichment which reflects well on the possibility of implementing the system in the dairy industry.