99D-18 |
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T. D. BLAGDEN, Oklahoma Food & Agricultural Products Research & Technology Ctr., Oklahoma State Univ., Dept. of Animal Science, Stillwater, OK 74078 and S. E. Gilliland, Dept. of Animal Science, Oklahoma State Univ., 101 Animal Science Bldg., Stillwater, OK 74078-6051. There have been efforts to increase the utilization of soybeans and soy products in the American diet because of their potential beneficial effects on health and nutrition. However, soymilk has a “beany” off flavor that is objectionable to the American consumer. One possible solution in overcoming this off flavor is to use lactic acid bacteria exhibiting reductase activity to ferment the product. Research has shown that growth of certain bacterial cultures in soymilk can reduce the volatile compounds responsible for the “beany” flavor. The objective of this study was to determine if fermenting soymilk with cultures of lactic acid bacteria would reduce or eliminate the volatile components associated with the “beany” flavor. A Hewlett Packard (HP) headspace autosampler coupled to a HP gas chromatograph equipped with a flame ionization detector was used to analyze the headspace samples of the fermented soymilk. The concentrations of the volatile components in the fermented samples were compared to those in the unfermented soymilk. All eight of the cultures tested completely eliminated the hexanal in the soy yogurt-like product and caused significant reduction in the levels of methanol. Streptococcus thermophilus OSU-2 was the only culture tested that significantly lowered the concentration of ethanol. All cultures except Lactobacillus acidophilus C19 and Lactobacillus casei E5 significantly lowered the level of acetaldehyde. Comparison of all of the cultures tested indicates that L. acidophilus L1 offers the best potential for producing fermented soymilk with an improved flavor profile. It completely eliminated the acetaldehyde and hexanal plus caused a significant reduction of the methanol. Although not significant, it also caused reduction in the concentration of ethanol. Fermenting soymilk with selected strains of lactic acid bacteria offers an opportunity for the production of a fermented soy product with a more acceptable flavor in addition to potential health and nutritional benefits.
Session 99D, Food Microbiology: General
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