Quality of Textured Soya Protein During Storage in Different Packaging Materials

The shelf stability of textured soya protein (TSP) procured from a single source and packaged in seven different packaging materials [viz. low density polyethylene (LDPE), HDPE, and polypropylene (PP) of 300 and 500 G and HDPE–LDPE–HDPE] in quantities of 10 kg each and stored at three different climatic conditions (viz hot and dry—Jodhpur; hot and humid—Tezpur; normal Mysore) for one year was studied. At the end of 6, 9, and 12 months, samples were drawn and analyzed for the quality parameters like moisture, browning, thiobarbituric acid reactive substances (TBARS), uric acid, water holding capacity (WHC), available lysine, in vitro digestibility, and sensory attributes. Anti nutritional factors like trypsin inhibitor activity (TIA) and phytic acid were also evaluated. The changes in the moisture content and non‐enzymatic browning correlated well with the relative humidity of the place of storage. However the TBARS showed wide variations while the WHC varied between 2.6 and 2.9 of water/g material. Interestingly the TIA showed a ten‐fold decrease (6.65 vs. 0.68 mg/g). The reduction in available lysine (6.33 vs. 5.29/16 g N) correlated well with the observed reduction in in vitro digestibility (84% vs. 73%). Although the sensory quality showed a decline by the end of 12 months storage period, the overall acceptability of the product on the 9 point Hedonic scale, remained very good. It is inferred from the present study that packaging of TSP in HDPE‐500 Primary Sac and HDPE woven Secondary Sac, keeps the product shelf stable up to one year even under diverse climatic conditions.