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OPTIMIZATION OF CONVECTIVE-CUM-MICROWAVE DEHYDRATION OF OYSTER MUSHROOMS (Pleurotus sajor-caju)
(2013) Sakti Bansal
Investigations were carried out to study the effect of drying parameters viz. loading density, air velocity, power level on convective-cum-microwave dehydration of oyster mushroom. Multi layer drying of commercially grown mushroom cv. Pleurotus sajor-caju was carried out at 3 levels of loading densities (26-52 kg/m2) and air velocities, 3-5 m/s and microwave drying was carried out at 3 power levels (270-810 W). The drying parameters studied were drying rate, temperature and relative humidity of outgoing air, product temperature and heat utilization factor. Quality attributes included rehydration ratio, shrinkage ratio, texture (hardness and chewiness), colour and overall acceptability. Multi layer drying of mushroom with an initial moisture content of 91% wb was carried out at 60°C in a mechanical drier till the moisture content reached 27% wb followed by drying in microwave oven to a final moisture content of 6.89% wb. It was observed that drying rate, relative humidity of outgoing air and heat utilization factor decreased with drying time but opposite trend was observed for temperature of outgoing air and product. The decline in drying rate increased with increase in air velocities and power level whereas opposite trend was observed for loading densities. Increase in loading density and air velocity resulted in decrease in heat utilization factor and relative humidity however temperature of outgoing air and product showed the opposite trend. Logarithmic model showed the highest adequacy of fit for multi layer drying and two term exponential model for microwave drying. The effective moisture diffusivity increased with increase in both loading density and air velocity. The increase in loading density resulted in increase in rehydration ratio, shrinkage ratio, colour change but decrease in texture and overall acceptability. The increase in air velocity resulted in increase in rehydration ratio, hardness, colour change overall acceptability but decrease in shrinkage ratio and chewiness. The increase in power level resulted in increase in rehydration ratio, texture, colour change and decrease in shrinkage ratio and overall acceptability. The optimum conditions for convective-cum-microwave drying of mushroom were found to be 38.80 kg/m2 loading density, 3.86 m/s air velocity and 413.6 W power level. Keywords: Oyster mushroom, drying kinetics, quality, optimization
Open Access
Development of extruded snacks from potato chickpea blends
(PAU Ludhiana, 2011) Rachna; Baljit Singh
The aim of the present study was to investigate the effects of feed moisture, barrel temperature and screw speed on product responses viz. specific mechanical energy (SME), bulk density (BD), water absorption index (WAI), water solubility index (WSI) and hardness using a response surface methodology. The blend of potato-rice and chickpea was extruded at different moisture content (14 -18%), screw speed (400 - 550 rpm) and barrel temperature (130 - 170°C). Feed moisture had significant effect on all product responses. Whereas screw speed and barrel temperature both independent variable had significant effect on SME, WSI and hardness of the product. Increase in feed moisture reduces SME and WSI and increases BD, WAI and hardness. Increase in screw speed decreases the bulk density (BD), water absorption index (WAI) and hardness of the snacks. Whereas increase in barrel temperature decreases the specific mechanical energy (SME), bulk density (BD), water absorption index (WAI) and hardness but increases the water solubility index (WSI). Optimized condition for preparation of snacks were 14% moisture, 550 rpm screw speed, 170°C temperature. The final product was having 12.04% protein, 2.79% fibre, 0.86% fat, 1.79% ash.
Open Access
Effect of controlled ripening and storage on processing quality of tomato.
(Punjab Agricultural University, 2011) Harjot Khaira; Sandhu, K.S.
The present investigation entitled, “Effect of controlled ripening and storage on processing quality of tomato” was undertaken with objectives to study the effect of different ripening treatments on the quality of tomato and fresh tomato juice during storage. For this study, three tomato genotypes viz. Namdhari-524, Varkha Bahar-1 and Varkha Bahar-2 at breaker stage were procured and the ripening treatments viz. control, ethylene gas (100 ppm), ethephone (500 ppm) and ethephone (1000 ppm) were given to the tomatoes and they were kept under ripening conditions (20±1°C and 90-95% RH) for interval of 6 days. After ripening, they were then shifted to storage conditions (12±1°C and 90-95% RH) for period of 15 days. They were analyzed after 3 days interval for various physico-chemical changes. During storage, two products viz. tomato juice and tomato soup were prepared from tomatoes and were analyzed for sensory scores. Ready-to-serve tomato juice was also prepared from ripened tomatoes and was analyzed monthly for physicochemical parameters and sensory scores. At the end, it was found that winter tomato can be successfully ripened by exposure to ethylene gas (100 ppm) at 20±1°C and 90-95% relative humidity within 6 days. The ripened tomato can be successfully stored at the temperature of 12±1°C and 90-95% relative humidity for the period of 15 days. Among three genotypes used, hybrid Namdhari-524 had best physico-chemical characteristics. Highly acceptable ready-to-serve bottled juice prepared from ripe tomatoes from can be successfully stored for 4 months at ambient temperature.
Open Access
Effect of enzymatic and ultrasound assisted mechanical extraction on canola oil recovery
(Punjab Agricultural University, Ludhiana, 2016) Sreenija, Meesala; Singh, A. K.
The experiments were carried out to determine the physical, chemical and frictional properties of GSC 7 cultivar of canola seeds and also to find the effect of independent parameters i.e. ultrasound time (30.0, 52.5 & 75 min), enzyme concentration (2, 4 & 6%), moisture content (5, 9 & 13%), heating time (4, 5 &6 min) and heating temperature (60, 80 & 1000C) on oil recovery and oil quality of canola seeds obtained through mechanical extraction. Box Behnken design of experiments of RSM was used for statistical analysis. The values for geometric mean diameter, sphericity, surface area, bulk density, true density, porosity and thousand grain weight at 7.5 % moisture content were 1.798 mm, 0.999, 10.157 mm2, 0.718 g/cc, 1.079 g/cc, 33.52 and 4.25 g respectively. The coefficient of external friction on GI sheet and plywood were 0.35 and 0.45 where as coefficient of internal friction was 0.85 and angle of repose was 38.050. The chemical properties obtained for ultrasound treated seeds were in the range of 32.98-34.66% fat content, 12.23-12.53% fibre content and 17.94-18.45% protein content where as for ultrasound and enzyme treated, the ranges were 33.02-34.41% fat content, 12.33-12.88% fibre content and 17.9718.67% protein content. Oil recovery of 87.41% was found for ultrasound treated sample at 52.5 min ultrasound time, 5% moisture content, 6 min heating time and 800C heating temperature where as 91.11% oil recovery was obtained under the combined effect of ultrasound and enzyme at 52.5 min ultrasound time, 5% moisture content, 6% enzyme, 6 min heating time and 800C heating temperature when compared to 67.75% oil recovery for control sample. The oil quality parameters i.e. acid value, FFA, density and color were found to be in the range of 0.8-1.63 mg KOH/g, 0.4-0.82%, 860-920 kg/m3, and 10.1-16 b value for ultrasound treated samples whereas for the seeds treated with ultrasound and enzyme, the oil quality parameters were found in the range of 0.56-1.59 mg KOH/g acid value, 0.28-0.8% FFA, 863-920 kg/m3 density and 10.9-15.7 b value. It was found that ultrasound time, moisture content, enzyme and heating temperature had significant effect on oil recovery whereas the effect of heating time on oil recovery was found non-significant. The effect of ultrasound time, moisture content, heating temperature on acid value, FFA and color were found significant where as only moisture content and heating temperature had significant effect on density.