Prospective ex vivo Determination of Food Glycemic Index by Yeast Fermentation System

Abstract

Glycemic Index (GI) measures how carbohydrate-containing or sugary foodincreases blood glucose. Consumption of high GI food has been associated withmany chronic conditions like obesity and diabetes; hence, monitoring of dietary GI is important. However, the standard method to determine GI is tedious andcostly as it uses human subjects. This study investigated the possible utilizationof yeast (Saccharomyces cerevisiae) fermentation system in ex vivo determinationof sugar GI. Clonal S. cerevisiae were incubated in separate media containingknown concentrations of test brown and white sugars and glucose as referencesugar. The concentrations of the unfermented sugars were measured at 25-minuteinterval for 100 minutes to plot the yeast response curve to each sugar. Using thestandard incremental area under curve (IAUC) and GI formula, the calculatedGI for brown, 125, was lower than the calculated GI for white sugar, 132,using the yeast system. This sequence is consistent with the sugars’ publishedGIs obtained using human subjects. Hence, S. cerevisiae may be developed asa simple alternative system in measuring food GI. Future biotechnology workon S. cerevisiae carbohydrate metabolism and mathematical remodeling of theIAUC and GI formula to suit GI determination using S. cerevisiae system arerecommended. Keywords: Biotechnology, glycemic index, carbohydrate, Saccharomyces cerevisiae,fermentation, incremental area under curve (IAUC), Philippines