Moisture sorption behaviour and packaging of papads.

Moisture sorption studies of black gram (Phaseolus mungo) papads, and studies of effects of commonly used additives have shown that: (i) NaCl contributes to increased moisture sorption, while alkaline additives or Ca and Mg, present as impurities in common salt, have no significant effect; (ii) papad khar, an alkaline salt commonly used in papad making, could be conveniently replaced by food grade carbonates; (iii) to prevent fungal spoilage in papads, the package should not allow the moisture to exceed the critical limit of 21% (dry wt. basis) at the end of the desired storage period; and (iv) a level of common salt greater than 8% should be avoided as it affects organoleptic acceptability, crystallizes on the surface at low RH and increases moisture pick-up significantly at higher RH, thereby rendering papads susceptible to fungal spoilage. Packaging studies with respect to ingress of moisture in polyethylene bags have revealed that 340 g unit pack of 200 gauge low density polyethylene (LDPE) or 170 g unit pack of 400 gauge LDPE has a shelf life of greater than 4 months at 92% RH and 38 degree C. This corresponds to a shelf life of nearly 12 months under normal conditions of storage. 350 gauge high density polyethylene was 2-2 times as protective as the 400 gauge LDPE against ingress of moisture.