54F-20 |
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B. DE ANCOS, R. Lloria, E. Roldán, C. Sánchez-Moreno, and M. P. Cano. Plant Foods Science and Technology Dept., Instituto del Frío-CSIC, José Antonio Novais 10, Ciudad Universitaria, Madrid, 28040, Spain Nowadays, the consumer demand for healthy, safe, free-additives, natural, fresh-like food, requires only minimum amount of effort and time for preparation. High hydrostatic pressure offers new advantages to process plant derived products free of additives minimizing chemical changes. Consumption of fruits and vegetables has been associated with important health benefits. Onions are recognized as the major dietary source of flavonol quercetin (aglycon or 0-glycosylated derivatives) related with certain benefits to human health which include anticarcinogenic properties, antiplatelet and antithrombotic activity. Our objective was to study the effect of high-pressure combined with temperature on antioxidant capacity and flavonols content (quercetin-3, 4'-diglucoside, quercetin-4'-glucoside and quercetin) in chopped onion. The experimental design comprised a response surface methodology according to a central composite face-centred design. The variable ranges were 100-400 MPa (pressure) and 5 to 50 ºC (temperature). The method used to evaluate the antioxidant activity was the measurement of the DPPH• radical scavenging. Quercetin and quercetin derivatives were quantified by HPLC. Total quercetin concentration in edible portion of unprocessed ‘Grano de Oro' onion was 557 mg/kg fw. Combined treatments high-pressure/temperature produced a significant decrease in both, quercetin and quercetin derivatives, in onion flesh due to lixiviation. Treatments at 100 MPa combined with low temperature (5º C) and at 400 MPa combined with high temperature (50º C) showed the highest quercetin content with 289 and 206 mg/kg fw, respectively. Non-significant positive correlation was found between high-pressure and quercetin aglycon concentration. Therefore, high-pressure does not significant affect glicosidic link in quercetin derivatives. Increasing pressure from 100 to 400 MPa lead to an increase in antioxidant capacity (17%) of onion flesh from EC50=60 to EC50=50 mg dw/g DPPH•, which was not correlated with quercetin and quercetin derivatives concentration. High-pressure/temperature treatments decrease quercetin and quercetin derivatives concentration but increase antioxidant capacity of flesh onion.
Session 54F, Nonthermal Processing: General I
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |