Effect of processing on the mineral status of selected pulses

Abstract

The present study entitled “ Effect of processing on mineral status of selected pulses” was an assessment of the effect of various processing techniques viz, drying, germination, pretreatment for loosening and splitting and dehusking, on mineral status as well as on the antinutritional factors present in the pulses. Role of antinutritional factors or the immobilization of minerals in the pulses were also ascertained. The pulses selected for this study were blackgram (CO4) and greengram (Pusa 91-92).

The processed pulses were subjected to various cooking treatments such as boiling, soaking and boiling , steaming, soaking and steaming, cooking under pressure, roasting, frying and micro oven cooking.

Processing techniques as a whole reduced the mineral contents of fresh pulses. Among different processing techniques applied on blackgram and greengram, minimum mineral loss was observed in dried samples, followed by germinated samples, pulses in which outer husk were loosened and pulses which were split and dehusked. Drying resulted in a significant loss of Ca and Mg while germination resulted in the loss of Ca, Fe, Zn and Cu. Significant retention of Ca, Mg and Zn were observed in germinated samples compared to husk loosened pulse samples. Significant variations in P, Ca, Fe and Mg were observed between husk loosened and split / dehusked samples.

All the cooking treatments reduced the mineral contents of processed pulse samples. Dried samples cooked in water media retained minerals more than other samples. Maximum loss of Mn, Zn and Cu in dried greengram was observed in the samples cooked in micro oven and maximum retention of these minerals in samples, when cooked under pressure. Roasting retained Ca better than other cooking methods.

In the germinated samples also, boiling was found to retain more minerals. Soaking and cooking retained phosphorous better when compared to other cooking methods in both the pulses, while cooking in micro oven resulted in maximum loss of minerals. Cooking in watermedia ensured maximum retention of Mg, Mn, Zn and Cu in both the pulses.

In split and dehusked blackgram and greengram, steaming resulted in maximum loss of Ca, Fe and Mg in blackgram. While in greengram, this treatment resulted in maximum loss of Ca.

Processing as a whole reduced the fibre, phytin and tannin levels of fresh pulses. Among processing techniques applied husk loosening and splitting and dehusking were most effective in reducing the fibre and tannin contents while germination reduced phytin.

All the cooking treatments applied on processed pulses significantly reduced the fibre, phytin and tannin levels. Among cooking treatments applied soaking and cooking was most effective in reducing the phytin and tannin levels of all the processed samples. Pressure cooking and roasting reduce were also observed to the phytin and tannin levels considerably.

There was association between loss of minerals and antinutritional constituents in processed and cooked pulses. Correlation between the important minerals P, Ca and Fe and phytin, tannin and fibre was found to be significant in various processed and cooked samples of both pulses. A position correlation was observed between minerals and antinutritional constinuents, phytin, tannin and fibre in both the pulses except between Ca and fibre in split and dehusked blackgram when cooked.

Among the different processing techniques administered germination was found to be ideal for improving minerals , while among cooking treatments applied boiling, steaming and pressure cooking had depicted similar trends. Since pulses are moderate sources of mineral and since mineral deficiency are common antinutritional problem prevalent in our state, information on ideal cooking method of pulses need t be established in the community.