LACTIC FERMENTATION OF PEANUT MILK

Abstract

ABSTRACTThe ability of cultures of 19 lactic acid bacteria to ferment a peanut milk (PM) prepared from blanched, full‐fat Runner Variety peanut kernels was examined. Lactobacillus acidophilus, L. brevis, L. xylosus, L. plantarum, Pediococcus acidifactici and Streptococcus thermophilus after 48 hr produced the highest levels of acid in plain PM, producing respectively 0.25, 0.20, 0.42, 0.42, 0.17 and 0.27% titratable acidity (TA), expressed as lactic acid. Chemical analysis indicated that sucrose at 0.60% (w/v) was the major fermentable carbohydrate present in the PM. Supplementation of the PM with 1% levels of glucose, sucrose, whey, tryptose or yeast extract increased acid production by most cultures. Glucose supplementation of PM enabled L. delbrueckii, L. plantarum, L. helveticus and L. casei to produce 0.69, 0.17, 0.75, and 0.73% TA, respectively. Invertase treatment of the PM led to increases in acid production of 0.23–0.30 TA units by cultures previously unable to ferment the untreated PM.‘In a model system, the addition of 2.3% (w/v) oleic, 1.3% linoleic and 0.4% palmitic acid to a basal Elliker's broth with 1% sucrose (EB‐S) as the sole carbohydrate source, led to 100% inhibition of acid production after 48 hr, compared to controls, for cultures of L. acidophilus, L. cellobiosus and S. thermophilus. For cultures of L. brevis, L. xylosus, L. plantarum and P. acidilactici, the inhibition of acid production by the fatty acids after 48 hr was much less, only about 5%.