and fuel fermentation/distillation processes), using corn, wheat and rye may well yield additional protein feed ingredients. Returning to cheese production, the whey co-product can be problematic for artisanal creameries. On a large scale, whey can be effectively processed using a series of filtration steps and diafiltration to produce whey protein concentrates from the retentate which is spray dried and used in food and human supplement production. The lactose in the remaining permeate can be concentrated via crystallization then dried and refined for food manufacture. More recently, vodkas and other ethanol streams made from whey have started to appear in the market, especially in New Zealand, the UK and the USA. There is even a cream gin produced in the UK, where the cream has been used as a botanical, ie before distillation. A production challenge is the fermentation of lactose into ethanol. Traditional fermenting yeasts, such as Saccharomyces cerevisiae, are unable to hydrolyze the lactose disaccharide, so commonly enzymes (lactases) are used to break down lactose into its component sugars glucose and galactose. However there are yeasts that can achieve the conversion of lactose into ethanol without recourse to added enzymes. In our laboratory, we have successfully cultured a yeast strain, Kluyveromyces marxianus, which converts the lactose within whey to ethanol. The initial thinking was that this approach could be used to develop whey neutral spirits for the smaller scale creameries but, analogous with the pot ale story, it seems that there is value in using whey fermentation to remove lactose as it has a
high biological oxygen demand (BOD) that can, certainly in some areas, substantially elevate effluent costs. So the business model becomes one of reduced costs of by-product disposal rather than its valorization. This is partly analogous to the situation for pot ale, where the original focus on a fish feed supplement has shifted somewhat to improving the quality of energy-yielding AD feed, although there are still compelling business arguments to produce and market the supplement protein feed. We have discussed two examples of by-product treatment in which the distilled spirits industry can potentially play a role. We have seen that the production of a by-product that could be monetized both in terms of energy production and yielding a feed protein ingredient solves two challenges: cleaner AD feed and potentially a fish protein supplement that is more suitable to aquaculture diets. Also, the fermentation and distillation of creamery whey to reduce both BOD and COD could in turn result in lower effluent costs and is deliverable on a smaller scale. There is also potential application to produce whey-derived spirits, something that has been commercialized, and indeed this has been achieved to some extent. Both of these concepts are currently in-play but serve to indicate the possibilities that might be available to enhance sustainability and profitability of operations of all scales.
Paul Hughes, Ph.D. is assistant professor of food science and technology at Oregon State University in Corvallis, OR. For more information visit www.oregonstate.edu or call (541) 737-4595.
Published on Dec 14, 2017