935 PB 521 MAIN SUGAR ANALYSIS OF FRUITS AND VEGETABLES BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

A rapid and sensitive high performance liquid chromatography method for quantifying simultaneously sucrose, fructose and glucose in fruits and vegetables is reported. Samples were extracted in 95% ethanol, homogenized and treated at 95C for 20 min. The supernatant was stored at -20C overnight and filtered through a G-25 Sephadex column. Aliquots were evaporated, redissolved in water, filtered, and injected. A Sorbex NH2 column operated at room temperature was used for separations. The sugars were detected at 192 nm. The retention times were 4.8, 5.9 and 10.3 min for fructose, glucose and sucrose, respectively. The method was applied to twenty-one fruit and vegetable species with different maturity stages. In addition, quality characteristics such as firmness, pH, acidity, soluble solids and color were evaluated. Main sugars for the different samples varied among species. In temperate fruits, fructose and glucose were the predominant sugars, while in tropical and subtropical fruits, the main sugar was sucrose. On the sampled vegetables, fructose was the primary sugar, although at very low levels. Quality characteristics coincided with sugar levels found among the different species.