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Hot air puffing is the simplest, hazard- and contamination-free, and quickest method, wherein grains are suddenly exposed to a high temperature short time (HTST) process to get puffed. In this study, the continuous hot air puffing system was developed, comprising of grain feeder, heating chamber, puffing chamber, cyclone separator, and recirculation pipe. The experiments were conducted using Central Composite Rotatable Design (CCRD), on pre-processed rice (cv. MTU 1010), with one pre-heating pass of 11.50 s at 150 °C. The results showed that the puffed rice can be produced optimally at a pre-fixed whirling air velocity of 4.75 (± 0.25) m/s, puffing air temperature of 260 °C and with a feed rate of 6500 g/h, resulting in final moisture content (% db), expansion ratio, puffing percentage (%), whiteness index, hardness (kg) and crispness (+ve peaks) as 3.71, 5.68, 95.87, 69.82, 32.12 and 89.81, respectively. Further study on increased time of preheating upto 46 s (4 passes) at 150 °C keeping all other puffing parameters unchanged, showed that final moisture content (% db), expansion ratio, puffing percentage (%), and whiteness index were further improved like final moisture content reduced upto 2.68% db and expansion ratio, puffing percentage, whiteness index increased upto 7.35, 99.58% and 87.76, respectively. Thus, the rice puffing using a continuous hot air puffing system can be accomplished using 4 pre-heating passes (accumulative retention heating time of 46 s) at 150 °C, puffed using a hot air puffing system with whirling velocity of 4.75 m/s at a puffing temperature and feed rate of 260 °C and 6500 g/h. [ABSTRACT FROM AUTHOR]

Ohmic heating is an unconventional rapid sterilizing technique for complex food fluids. In this study, garlic pulp was ohmic heated at 13.33, 20 and 26.66 V/cm and also in conventional means. The effect of high voltage electric field-induced ohmic heating for increasing the shelf-life and maintaining the quality of garlic pulp was investigated. The physicochemical properties like pH and colour were determined and microbial growth study was carried out for both the ohmic heated and conventionally heated garlic pulp throughout the storage period. During storage, the physiochemical changes were at a rapid rate in conventionally heated garlic pulp when compared with the ohmic heated pulp. Garlic pulp ohmic heated at high voltage gradient (26.66 V/cm) could extend the storage period upto 60 days without adding preservatives. Bioactive compounds were analysed using high performance liquid chromatography and found to have 8.83 µg/ mL, 30.28 µg/mL, 9.04 µg/mL of alliin, pyruvic acid and diallyl disulphide content, respectively in garlic pulp ohmic heated at high voltage gradient. Whereas, in conventional heating, alliin, pyruvic acid and diallyl disulphide are found to be 4.71 µg/mL, 22.97 µg/mL, 4.64 µg/mL, respectively. [ABSTRACT FROM AUTHOR]

Ohmic heating is a substitutive rapid heating method for food products. In this study, banana pulp with different concentrations of sugar is ohmically heated and the influence of sucrose concentration on electrical conductivity was investigated. The electrical conductivity, pH, total soluble solids, acidity, ascorbic acid content before and after ohmic heat treatment were also analysed. As the sucrose concentration increased, heating time at various voltage gradients 13.33, 20 and 26.66 V/cm increased, and the electrical conductivity decreased. As the voltage gradient increased, the pH and TSS of treated pulp with different sugar concentration increased followed by decrease in colour and acidity. [ABSTRACT FROM AUTHOR]

Watermelon is a highly perishable fruit with a niche for majority of microrganisms. It comprises of 91% water and hence it is very difficult to preserve watermelon based products by application of conventional means. Ohmic heating, also known as Joule heating is an electrothermal technique of processing. In this study, the effect of ohmic heating on the electrical conductivity, pH and colour of the watermelon juice at various voltage gradients (10-23.33V/cm) was investigated. The change in the pH and colour of the watermelon juice during storage was studied. The bubbling of juice was observed above 60°C at all voltage gradients. As the voltage gradient increased the time required to reach the desired temperature decreased. The electrical conductivity was observed to increase with increase in temperature. Linear model gave the best fit to the electrical conductivity of watermelon juice. The change in pH and colour has increased with increase in voltage gradient, ohmic heating time and storage period. Ohmic heated watermelon juice showed better retention of physicochemical properties when compared to conventional heating. [ABSTRACT FROM AUTHOR]

Sapota fruits are highly perishable and have short shelf life at the ambient conditions. The edible coatings have been used on different agricultural products in order to extend their post harvest life. In the present study, the polysaccharide based edible coating made up of sodium alginate and pectin (2%) was studied on the shelf life of sapota fruits. The coating of the fruits is done by dipping method with two dipping time (2 and 4 min). The both control and coated sapota fruits were stored at refrigerated temperature (4?}1oC). The physico-chemical analysis including acidity, total soluble solids, ascorbic acid, pH, weight loss, colour and firmness were measured on 1, 8, 15, 23 and 30th day of storage. There was significant difference (p≤0.05) in these physico-chemical parameters between control and coated sapota fruits with 2 and 4 min dipping time. The sensory analysis of control and coated sapota fruits showed that, the polysaccharide coating with 2 minutes dipping time was effective in maintaining the organoleptic properties of the fruits. [ABSTRACT FROM AUTHOR]

Studies were conducted to use ultrasound treatment in watermelon (Citrulus lanatus) rind as a pre-treatment prior to osmotic-drying. A comparison with the conventional heating as pretreatment prior to osmotic-drying was also carried out. Effects of treatment time (10, 20 and 30 min in ultrasound and 1, 2 and 3 min in conventional method), sugar concentration (40, 50 and 60°Brix) and immersion time (0 - 6 h) on water loss and solid gain in watermelon rind were studied. Second order regression equations describing the effects of these factors on the water loss and solid gain were developed. Results shows the maximum water loss and solid gain of 81 and 46%, respectively for the watermelon rind treated for 30 min under ultrasound and immersed in 60°Brix solution for 6 h. In conventional pretreatment the maximum water loss and solid gain in water melon rind to the tune of 73 and 59%, respectively was achieved on treating the water melon rind for 3 min and immersed in 60°Brix solution for 6 h. The combined process (ultrasound pretreatment and osmotic-drying) was optimized for the operating conditions that minimize total processing time. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the physical and biochemical properties of guava, sapota, and papaya. The physical properties studied were: dimensions, shell ratio, surface area, bulk and true density, porosity, sphericity, packing coefficient, aspect ratio, and roundness index. The specific heat at various mass fractions, biochemical properties like pH, titratable acidity, total soluble solids, and colour analysis were studied for fruit pulps. The viscosity of fruits was studied at various mass fractions. The high sphericity of guava and sapota indicated that those fruits had high rolling capability, which is an important factor for designing hoppers. Biochemical analysis showed that sapota was the sweetest fruit amongst the three studied. [ABSTRACT FROM AUTHOR]

The effect of osmotic dehydration pretreatment on water loss, solid gain, colour and textural change was investigated. Watermelon rind 1 x 1 cm size was immersed in sucrose solution of 40, 50 and 60° Brix after pretreatment with microwave and conventional boiling in water for 1, 3, and 5 min, respectively. Water loss and solid gain increased with the time of cooking and sugar concentration. Microwave pretreated samples showed higher water loss and solid gain. Increase in the time of cooking decreased the brightness of all the samples. Microwave pretreated samples showed higher 'b' values than conventionally pretreated ones. There was no significant difference (P≤0.05) in texture profile analysis parameters except for hardness. Hardness decreased with increase in time of cooking and sugar concentration. Second order regression model was developed for water loss and solid gain of microwave and conventional pretreated watermelon rind. [ABSTRACT FROM AUTHOR]