Moisture sorption characteristics of wadi, a condiment in the Indian Subcontinent, were investigated at temperature of 15-45°C and water activities (a w ) of 0.11-0.97. The sorption isotherms were sigmoidal. Nine different mathematical models were found to effectively describe the moisture sorption data on the basis of regression analyses and goodness of fit. Each model was statistically evaluated by means of percent root mean square and coefficient of determination. The GAB model gave the best fit in the entire range of a w . Temperature dependence of the GAB constants and good fit were determined. Using the Caurie's model, the properties of sorbed water, such as monolayer moisture content, number of adsorbed monolayers, density of sorbed water, bound water content and surface area of adsorption, which decreased with an increase in temperature, were calculated. The monolayer moisture content ranged from 102.7 to 128.7 g/kg solids in wadi. The optimum storage temperature and a w for wadi were 15-25°C and <0.7, respectively.

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This work was aimed at optimizing the mechanized drying conditions for wadi using response surface methodology. Three separate variables, found to influence the quality of wadi, were selected. The effect of these independent variables, viz. relative humidity (RH) (20-65%), drying time (24-120 h) and sample diameter (15-35 mm), on the overall acceptability (OAA) based on its sensory attributes and the aw was studied using a central composite design. Twenty experimental runs in triplicate were conducted to obtain the optimal conditions as 42.5% RH, 72-h time and a sample diameter of 25 mm. Wadi prepared under these conditions was organoleptically acceptable. Although all the three factors had an influence on the OAA, the present study indicates that the drying time and size of wadi had a greater influence. The experimental value of both the responses OAA and aw obtained had no significant difference from the predicted values. PRACTICAL APPLICATIONSWadi is a legume-based condiment popularly consumed in the Indian subcontinent. In spite of its popularity, a large-scale production by mechanizing the manufacturing process is not carried out. The manufacturers rely on the solar energy for drying wadi, which restricts its production only to the winter season when the temperature and humidity are optimum for proper fermentation and drying. In order to remove this climate-dependent constraint, the present work was taken up with an aim to optimize the drying conditions of wadi inside a dehumidifier. The conditions, thus, optimized were found to produce wadi of satisfactory sensory qualities and aw values. The latter is an important factor determining the shelf stability of any food, and aw beyond the critical limit can lead to food spoilage. So, optimized manufacturing conditions will always ensure quality production.

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The present study aimed to evaluate the effect of adding NaCl prior to fermentation and moisture reduction after the fermentation on the safety and shelf life of kinema, a Bacillus-fermented soybean food. The physicochemical parameters of kinema decreased with an increase in the concentration of NaCl up to 4 g/100 g where there was no significant change in cell count of the fermenting microorganism (Bacillus subtilis) and sensory score of the product but eliminated Bacillus cereus. Escherichia coli was reduced by 1 log cycle in the presence of NaCl but eliminated when the water activity (aw) of kinema was reduced to 0.5 after fermentation. Salt had no effect on its shelf-life. Storage stability was determined in terms of its moisture sorption isotherms. Thermodynamic functions decreased with increasing moisture content. The monolayer moisture content ranged from 6.0 to 8.3 g/100 g and the optimum aw for storage of kinema was ≤0.5. PRACTICAL APPLICATIONSAs producers do not adopt safety measures during its preparation, kinema is not always microbiologically safe for consumption. Through the present study it will be possible to eliminate pathogens like B. cereus and E. coli from kinema by the combined effect of salt and aw. The enhanced safety level achieved opens up a future scope for exploring the possibilities of its use as a flavoring or food supplement ingredient. The sorption study revealed the ideal conditions for storage of kinema and can be utilized in the future for designing packaging materials that will ensure better food quality. The combination of salt and aw is applicable to other traditional Bacillus-fermented legume foods, like Thai thua nao, Korean chongkukjang and African dawadawa. of a white viscous mass on the surface of the grits and a typical pungent odor. Kinema is cooked with salt to prepare curry which is eaten with boiled rice (Tamang et al. 1988).Although the benefit of using salt as a preservative for several fermented foods is well known, salt is neither used in the preparation of kinema nor has there been any study to understand the effect of salt on kinema. Hence, our first objective was to study the effect of salt on the safety and shelf life of kinema.Kinema is prepared at homes with little safety measures which lead to a compromised quality of the final product 1556 4.07 d ± 0.69 68.67 c ± 1.20Note: Values are mean ± SE of three determinations. Means within a column sharing a common superscript letter are not significantly (P < 0.05) different. * The pH and aw of cooked soybeans before addition of salt and fermentation were 6.18 ± 0.18 and 0.99 ± 0, respectively. † Inoculum load, 6 log cfu/g. ‡ Measured as activity on azocasein. for the salt-free kinema, and a1, b1, c1, d1 and e1 for the salted kinema) are not significantly (P < 0.05) different. Means of salt-free (-) and salted (+) kinema in a particular set are not significantly (P < 0.05) different, except the values marked †.* Measured as activity on azocasein. † nd, not determined.