Physico-chemical properties of low-pressure plasma treated black gram

Cold plasma technology is an emerging non-thermal food processing technology for microbiological decontamination of food and bio-materials. In the present study, low pressure plasma technology was used as a novel means to modify the surface properties of black gram. The changes imparted on the physico-chemical properties (proximate composition, cooking and textural properties) of black gram was investigated on exposing it to low pressure plasma. The changes in native structure viz., fissures and projections formed on surface were determined by SEM micro-graphs. The cooking time was reduced significantly from 30.25 to 20.45 min with respect to plasma power and treatment durations. Analysis of textural parameters of cooked black gram showed, a decrease in hardness from 22.50 to 12.36 N. SEM micro-graphs confirmed that plasma treatment resulted in surface etching and hydrophilization of surface, allowing easy absorption of water. Extent of hydrophilization was further confirmed by contact angle studies and surface energy analysis. The results showed that plasma treatment decreased the contact angle and increased the surface free energy. Thus, we conclude that low pressure plasma treatment reduces the cooking time of black gram, and perhaps could be employed as an emerging tool for quick cooking process of whole grains.