PREPARATION AND STORAGE OF DEHYDRATED PADDY STRAW MUSHROOM
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Date
11-06-18
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CAET, OUAT
Abstract
Mushrooms are consumed as a source of protein throughout the world and the drying of mushroom can be employed for extending the shelf life of this highly perishable commodity. However, a standard method for preparation of dried mushroom and its storage is yet to be made available for small processors. Thus, different drying methods and parameters were studied for preparation of dried mushroom. Mushrooms were dried in a tray dryer (50, 60 and 70°C), microwave convective dryer (0.72, 1.44 and 2.16 W/g power levels and constant air temperature of 50°C) and freeze dryer. Results indicated that the Page model offered the best fit for experimental drying data for hot air drying and Wang and Singh model for microwave convective drying. The value of effective diffusivity in MWCD was more than that of hot air drying. The calculated activation energy (Ea) was 0.336 W/g in MWCD and 44.97 kJ/mol in HAD. The mushroom samples were tested for colour, rehydration ratio, shrinkage ratio, proximate composition (moisture, ash, total crude fibre, protein and carbohydrate content), total phenolics, DPPH , hardness, chewiness and minerals. The results and statistical analysis revealed that freeze dried samples were found to be best. Ash, prorein, fibre, reducing sugar and ascorbic acid reduced with increasing drying temperature. Rehydration ratio and water absorption index were maximum in hot air drying after freeze drying. The retention of total phenolic compounds were maximum in freeze dried sample and minimum in hot air (70°C) dried sample. Scanning electron microscopy (SEM) images revealed that a higher temperature or microwave power caused greater damage to the microstructure of the mushroom samples. The current study revealed that the hot air drying at 50°C is suitable to dry the paddy straw mushroom. The flakes and powder were stored for three months in three different packaging materials like LDPE, MPP and PET pouches and the MPP packages offered least change