Chemical and Cosmetics Applications of Whey Permeate
Industrial biotechnology requires high availabilities of low-cost and easily-accessible carbon as feedstock for the production of bio-based chemicals and components. In order to be commercially viable and truly adoptable in light of heavy petrochemical influence, the fermentable feedstock must be plentiful and inexpensive. In fact, the cost of feedstock is a main determining factor for the production and impact of biotechnologically-produced chemicals and products . Biobased chemicals can be used in several key industries such as the chemical, cosmetics, and biofuels industries. In pilot and lab scales, whey permeate has been shown to meet the needs of the industrial biotechnology sector as a potential feedstock.
One method of reducing the environmental impact of whey permeate while producing a useful end product is by solventogenic fermentation. Most commonly, Clostridium acetobutylicum is used to produce acetone, butanol, and ethanol (ABE). Grain or molasses, depending on the region, are the most common industrial feedstock for ABE fermentation. Until the end of World War II, most of the butanol and some of the acetone produced was via fermentation, but this application declined rapidly in the following decades due to a boom in the oil industry . Due to inherent political instability surrounding the oil industry, plants producing ABE via fermentation located in China and the United States have faced pressure from the petrochemical industry and have shut down and resumed production several times. As of the early 2000s, bio-based solvents were projected to have captured 12.5% market share for the following several years . Both acetone and butanol are important solvents in the chemical industry, while the latter has shown promise as a biofuel .
Solventogenic fermentation was first adapted for whey permeate in 1985, due in large part to its high content of low-cost lactose . While in the early investigations of solventogenic fermentations of whey permeate the yield was low and lactose consumption was incomplete, processes such as membrane perstraction to reduce the effects of product inhibition have dramatically improved yields of solvents on a small scale. For example, only 60% of lactose was utilized in a solventogenic fermentation of whey permeate due to toxicity of the solvents in the culture broth. By removing the solvent using membrane perstraction with oleyl alcohol, the yield was increased from 9.34 g/L to nearly 100g/L . A major challenge associated with biobutanol and acetone production via fermentation is the substrate cost, which is addressed by the readily available, cheap and fermentable lactose in whey permeate. Downstream processing, especially in a dilute solution such as whey permeate, poses a large problem for future commercialization of solventogenesis with whey permeate .Upstream concentration of whey permeate by membrane filtration prior to solventogenic fermentation may be necessary to reduce the initial volume of diluted whey permeate.