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Fully matured fresh guava fruits (Lucknow-49) were precooled at 10°C for 1 h and pretreated with 500-ppm benomyl for 5 min. The fruits were packed in 25-μm and 50-μm LDPE bags with active modified atmosphere packaging of 3% O 2 + 5% CO 2 , 6% O 2 + 5% CO 2 and 9% O 2 + 5% CO 2 gas concentrations and stored at 5 ± 1°C and 10 ± 1°C temperatures as well as non-packaged as control. The shelf life of guava could be increased up to 42 days by packaging in 50-μm LDPE bags with a gas concentration of 9% O 2 + 5% CO 2 and stored at 10°C without much change in physical, biochemical and sensory characteristics. Physico-chemical changes viz., PLW, pulp to peel ratio, firmness, TSS, total sugar, ascorbic acid and titratable acidity were observed minimum for fruits packed in 50-μm LDPE bags at 3% O 2 + 5% CO 2 gas concentration at 5°C storage temperature, but sensory score decreased drastically after 21 days of storage. Chilling injury was observed for the fruits packed at 5°C storage temperature after 21 days of storage, and it was severe in 25-μm LDPE bag at later stage. Control fruits over-ripened with the highest weight loss (12.47%) on 6 days of storage and discarded from the storage.

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Abstract. Raw juice of prickly pear is viscous and turbid in nature. The clarity of such juice can be improved through enzymatic clarification. An experiment was conducted to standardize the process parameters for clarification of prickly pear juice using pectinase enzyme. Experiment was designed according to response surface methodology (RSM) by keeping three selected independnt variables at five different levels, i.e. enzyme concentrations (0.01, 0.026, 0.050, 0.074 and 0.09%), incubation temperatures (40, 44, 50, 56 and 60 °C), and incubation time (60, 84, 120, 156 and 180 min). Second order central composite rotatable design was employed to study the effect of enzymatic treatments on yield, viscosity, clarity, and turbidity of juice. Response surface modeling showed that the generated regression models were adequate to explain the data variation as well as the the actual relationship between independent variables and responses. The coefficient of determination, R 2 values for all the selected parameters were greater than 0.9. Through response surface analysis, the optimum conditions for enzymatic clarification of prickly pear juice were established as 0.056% enzyme concentration, 47 °C incubation temperature, and 155 min incubation time. This interaction of process parameteres was able to improve the yield by up to 88.83% and clarity up to 52.86% as well as decreasing the viscosity by up to 1.60 cP, and turbidity by up to 123.02 NTU.

Wheat is the most important mainly due to its use in the flour production. An experiment was conducted to study the feasibility of evaporative water cooled grinding for wheat flour production. Wheat was mixed with water (0%, 3%, 6% and 9% w/w) and grinded immediately using domestic hammer mill before the surface water penetrated into the grain. The different grinding characteristics were studied for the grinding operation. This process resulted in cooling since the evaporating particles carried away the heat generated inside the grinding mill resulting in decrease of the temperature of the system. The temperature during grinding was found to be decreased by 11°C under for the sample wetted with 9% (w/w) of water as compared to conventional grinding. No sieve clogging was observed during evaporative water cooled grinding. Grinding time was observed to be increased by 155 sec for the evaporative water cooled ground sample. This study revealed that the evaporative water cooled grinding method can be effectively used for avoiding the rise in temperature during grinding in order to preserve the quality of wheat.