Study of continuous flow ultrasonication to improve total phenolic content and antioxidant activity in sorghum flour and its comparison with batch ultrasonication.

Ultrasonic technology was applied to release the phenolics bound with starch and protein matrix in order to enhance total phenolic content (TPC) and antioxidant activity (AA) of the sorghum flour. Both the continuous flow and batch ultrasonication were implied with independent variables such as flour to water ratio (FWR), ultrasonication intensity (UI), and ultrasonication time (UT) with an additional variable as flow rate (FR) in continuous flow ultrasonication. All the process variables showed a significant effect on the corresponding ultrasonication process. The optimal conditions for the continuous flow ultrasonication were a FWR of 10% w/v, an UI of 20 W/cm2, an UT of 130 s, and 15 ml/s FR which produced a maximum values of 70.9 mg GAE/100 g dry matter (d.m.) for TPC and 143.9 µmol TE/100 g d.m. for AA. Regarding the batch ultrasonication, the maximum values were 65.6 mg GAE/100 g d.m. and 141.0 µmol TE/100 g d.m. for TPC and AA, respectively at optimum conditions of 10% w/v FWR, 30 W/cm2 UI, and 200 s UT. When comparing with the batch ultrasonication, the continuous flow process saved 35% time and 33% of energy consumption to obtain comparatively higher TPC and AA of the sorghum flour. Ultrasonication improved free phenolic acid content by releasing bound phenolics in the sorghum flour. Impact of various process parameters on specific energy was analyzed during both the processes, and influence of energy on TPC and AA of the sorghum flour was also observed for the batch and continuous flow ultrasonication.

Development of polyhouse type solar dryer for Kashmir valley.

Polyhouse type solar dryer (PSD) consist of drying chamber, drying trays and exhaust fan was developed for drying fruits and vegetables. The relative humidity (RH) inside the PSD varied in between 21 to 74% as compared to outside RH which ranged from 40 to 75%. The performance was found suitable and resulted in efficient drying at low RH. The thermal performance test for PSD under full and no load testing conditions were calculated. The temperature inside the dryer was 62 to 76% higher than the ambient conditions. PSD was helpful in reducing the drying ranging from 33 to 53%. The capacity of PSD was 100-150 kg per batch. The economic cost of solar dryer was compared with mechanical drying for beneficial to local producer. The cost of PSD Rs 80,000 could recover within the period of 1.5 years by adopting solar drying technology.