44E-25 |
Stability of fructooligosaccharides added to carrot-orange juice |
D. D. G. C. FREITAS, Departament of Food Technology - FEA, Universidade Estadual de Campinas, Cidade Universitária Zeferino Vaz Caixa Postal 6121, Campinas, 13083-970, Brazil and M. D. N. H. Jackix. Fructooligosaccharides (FOS) are added to foods to stimulate growth of bifidobacteria, that regulate the intestinal flora, alleviating constipation, reducing cholesterol levels, and inhibiting the production of putrefiable compounds and the incidence of colon cancer. They have excellent flavor and texture properties. Their thermal stability is higher than that of sucrose solutions and are stable within the pH range of 4.0-7.0. The purpose of this research was to evaluate fructooligosaccharides stability under pasteurization and storage when added to a carrot-orange juice. The juice was heated to 85-90°C, hot-filled and pasteurized by immersion in boiling water for 10 minutes, followed by cooling. Three formulations were made to quantify fructooligosaccharides (added to the juice in 5%, 10% e 15%. Frutooligosaccharides quantification was made by liquid chromatography analysis, in duplicate, soon after processing and after three-months storage under refrigeration. An acetonitrile solution at 75% was used as the mobile phase. The samples and standards were filtered, using 0.45 mm cellulose ester filters. FOS loss was observed after juice pasteurization, varying from 42% to 64%. After storage, FOS concentration remained constant. Only in the formulation with 5 g FOS/100mL, the loss increased to 86.6% with time. FOS reduction may have occurred due to the pasteurization temperature, which caused FOS to hydrolyze into fructose. It may furthermore be considered that the product pH was between 3.55 and 3.92, lower than the FOS stability pH range. Transformation of FOS into fructose was monitored by liquid chromatography. The fructose concentration of the juice increased by 2.1g/100mL, 4.4g/100mL and 8.3g/100mL with the addition of 5, 10 and 15% FOS, respectively. We may conclude that FOS hydrolysis into fructose occurred due to pasteurization and the pH effect, storage being a significantly lower factor.
Session 44E, Nutraceuticals & Functional Foods
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