14B-42

J. LEE, W. D. Rogers, and R. R. Eitenmiller. Department of Food Science and Technology, University of Georgia, Athens, GA 30602

Peanuts are considered to be an excellent folate source; however, discrepancies exist in international composition handbooks regarding folate in peanuts. Additionally, available data are based on small sample numbers.

Our objective was to optimize folate extraction prior to microbiological assay by lactobacillus rhamnosus and to apply the assay to samples of raw and processed products of known history.

The extraction protocol was examined by initially testing 4 commonly used folate extraction buffers for their efficiency. In this phase, folate was assayed by the trienzyme procedure using conjugase, a-amylase and Pronase digestions. Next, response surface methodology was used to optimize the conjugase, a-amylase and Pronase digestions. All samples used in the study were obtained directly from peanut processors in the U.S.

Similar and significantly higher folate values (a=0.05) were obtained with 0.1M sodium phosphate, pH 6.8 with 1% ascorbic acid and 0.075M phosphate buffer, pH 6.0 with 1% ascorbic acid and 0.1% 2-mercaptoethanol. RSM studies in the pH 6.0 phosphate buffer showed that Pronase digestion was not required to release folate from peanuts. a-Amylase and conjugase digestions required a minimum 3h and 4h, respectively, to obtain maximal folate assay values. Folate values did not increase or decrease with extended digestion times. The optimized extraction using conjugase and a-amylase gave the following folate values (n=15) in ug/100g: raw peanut 94.4, dry-roasted 88.1, oil roasted 68.7, peanut butter 84.9.

The study provides a reliable extraction procedure for the assay of folate in peanuts and peanut products.