Effect of Moisture and Air Incorporation in the Batter on the Drying Process and Quality of Sun Dried Nugget (Bori)

Experiments on open air sun drying of bori nuggets (Indian traditional food) prepared from black gram batter having different initial moisture content of 62–72% (wb) and air incorporation of 14·14–18·12% (v/v) showed an initial constant rate period followed by a falling rate period. The drying rate was found to increase with the increase in air incorporation and initial moisture content in the batter. With the increase in either initial moisture content or volume of air incorporation into the batter, the drying time decreased. This decrease in drying time is attributed to larger surface area with spreading of batter and more porous structure in the nuggets respectively for higher initial moisture content and air incorporation in the batter. Response surface analysis was used for optimisation of batter parameters like initial moisture content and air incorporation in the batter with respect to lower values of yellowness index, hardness and optimum cooking time of the finished product with less drying time. Analysis of variance revealed that effect of initial moisture content and air incorporation on these dependent parameters were significant (probability P⩽0·01 or 0·05). Initial moisture content of 67·10–67·95% (wb) and air incorporation of 16·81–17·43% (v/v) was found to be optimum.