Shelf life studies on maize-based 'balahar'.

Balahar (a mixture of maize semolina, edible groundnut flour and defatted soy flour in 70 : 15 : 15 ratio) was heat treated [i) steaming for 30 min and drying at 60 degree C for 60 min to 7.5% moisture; (ii) toasting at 100 degree C for 10 min, (ii) roaster heating (lid closed) at 110 degree C for 10 min, and (iv) as in (iii) but moisture content adjusted to 15%) and butylated hydroxyanisole (BHA) was added at 0.02% along with citric acid (0.005%) or jaggery was added (2%) to extend the shelf life. Samples were packaged in polyethylene pouches (300 gauge) and fumigated with methyl bromide at 32 mg/l for 24 h and stored at 37 degree C and 66-68% RH for 5 months. Free fatty acids (FFA) content increased in non-heat treated balahar during storage from 14 to 21%, but in (i)-(iv) remained constant during storage. Heat treatment also controlled development of alcoholic acidity; the thiobarbituric acid (TBA) value and peroxide value (PV) were higher in (i)-(iv). In heated samples the moisture content was 2-4% (8-12% in untreated) and in storage the moisture pick up was 0.5-1.5%. Antioxidant or jaggery did not prevent FFA development, but retarded increase in TBA value and PV, whereas heat treatment controlled FFA development and favoured a marginal increase in TBA and PV. Heat treated raw materials and balahar were acceptable up to 5 months, while unheated controls developed off-flavour after 6 wk. The results were confirmed by large scale trials.