Análise de ácido fítico e minerais nos processos de maceração e cocção de soja

AUTOR(ES)

Elisa Noemberg Lazzari

DATA DE PUBLICAÇÃO

2006

RESUMO

With the increase in soy consumption due to its bioactive compounds, there is great importance in knowing the grain s constitutes and their variation during processing. Phytic acid (PA) has been the aim of much research. It chelates essential minerals but also has strong antioxidant and anticarcinogenic effects. This study evaluated the variation of PA, phosphorus (P), calcium (Ca), magnesium (Mg), zinc (Zn) and iron (Fe) during soaking and cooking of soybeans. Cultivars (BR 36, BRS 213, BRS 216, BRS 232, BRS 155 and Embrapa 48) selected for food use, were grown in Londrina, Parana State. The cooking kinetics of each cultivar was determined. After soaking for 12 h at room temperature, the grains were cooked for 200 min. Samples were collected every 10 min to determine the hardness of the grains using a TA.XT2i texture analyzer (Stable Micro Systems). The data was treated using the fractional conversion technique and a first order equation was found for each cultivar. Considering an optimal texture of 23 N, the cooking time was calculated. A sample of each cultivar was soaked and cooked for the optimal time. PA, P, Ca, Mg, Zn and Fe were determined in raw, soaked and cooked grains. PA in the three phases varied from 1.19-1.81; 0.76-1.40 and 1.04-1.50 g/100 g (dry basis). Soaking caused a significant reduction in PA level, but cooking caused no further reduction. The variation of P, Ca, Mg, Zn and Fe in raw, soaked and cooked grains was of, respectively, 6.6-8.9; 6.1-10.6 and 7.1-8.7 g/kg; 1.4-2.9; 1.6-3.8 and 2.1-3.9 g/kg; 2.3-2.6; 2.9-4.0 and 2.5-3.1 g/kg; 44.5-56.2; 54.2-73.9 and 59.9-69.3 mg/kg; and 96.2-135.8; 136.3-171.3 and 112.1-155.8 mg/kg. There was no correlation between cooking time and PA or any of the analyzed minerals. The softening constant, however, was negatively correlated with P and Zn in soaked grains. The AF:Zn molar ratio was 20, indicating that zinc absorption could be impaired. The AF:Fe molar ratio was 8, below the risk levels.

ASSUNTO(S)

alimentos - conservação química maceração de soja Ácido fítico cinética química chemical kinetics

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