The non-nutritional performance characteristics of peptones made from rendered protein

Economic considerations require the use of inexpensive feedstocks for the fermentative production of moderate-value products. Our previous work has shown that peptones capable of supporting the growth of various microorganisms can be produced from inexpensive animal proteins, including meat and bone meal, feather meal, and blood meal, through alkaline or enzymatic hydrolysis. In this work, we explore how these experimental peptones compare to commercial peptones in terms of performance characteristics other than chemical make-up; these characteristics can impact fermentation operating cost. It is shown that experimental peptone powders produced through enzymatic hydrolysis are highly hygroscopic and that their physical form is not stable to humid storage conditions; those produced through alkaline hydrolysis and commercial peptones are less hygroscopic. When used in growth medium, all peptones contribute haze to the solution; experiments show that the source of haze is different when using enzyme- versus alkali-hydrolyzed peptones. Alkali-hydrolyzed peptones and all peptones made from blood meal are stronger promoters of media foaming than the commercial peptones; some enzyme-hydrolyzed peptones support very little foam formation and are superior to the commercial peptones in this sense. Alkali-hydrolyzed peptones are roughly equivalent to commercial peptones in the coloration they contribute to media, while enzyme-hydrolyzed peptones contribute intense coloration to media. No peptone caused a significant change in the viscosity of media. The experimental peptones studied here may be acceptable low-cost substitutes for commercial peptones, but none is equivalent to the commercial products in all respects.