No abstract

ABSTRACT:The application of low temperature grinding shows promising pathway to produce higher quality ground product in terms of flavour and volatile oil retention of spices. 49.19 ± 0.99 (L*), 17.35 ± 1.62 (a*), 23.38 ± 1.29 (b*) and 47.52 ± 1.74 (L*), 18.38 ± 0.14 (a*) and 26.93 ± 0.68 (b*). This study revealed that the water can be effectively used as a coolant for reducing temperature rise during grinding in order to preserve the quality of chilli.

Size reduction is one of the steps in processes where the raw materials are converted into final products. When considering spices, size reduction must be performed carefully because of the loss of aroma due to temperature increase during milling. These problems are encountered with conventional grinding of chili. Therefore, grinding under reduced temperature by means of water vapor was tested as a novel application. A pin mill with 5hp motor was used to grind chili with water mixing during milling in which water is considered as the coolant. The temperature of the conventionally ground and evaporative water cooled ground chili were 58 ± 2.65 0 C and 36 ± 1.5 0 C respectively and the corresponding amounts of heat removed by water vapor were 29.33 kJ and 186.50 kJ. The moisture content of conventionally ground chili and evaporative water cooled ground chili with water spraying were 9.06 ± 0.41 and 9.65 ± 0.23 percent on wet basis and the corresponding color values were 49.19 ± 0.99 (L*), 17.35 ± 1.62 (a*), 23.38 ± 1.29 (b*) and 47.52 ± 1.74 (L*), 18.38 ± 0.14 (a*), 26.93 ± 0.68 (b*). Retention of capsicum oleoresin in two grinding methods; conventional and EWC are 0.0217± 1.27 and 0.0129 ± 1.00 mg/ml respectively. The results proved that the use of water vapor is applicable as the coolant in size reduction confirming reducing temperature rise during grinding, controlling the color weakening after grinding, preferable final moisture content with higher oleoresin retention than that of conventional grinding.

Gelatinization of rough rice is an important unit operation in the rice parboiling process. The possibility of applying far-infrared (FIR) radiation for gelatinization of rough rice was investigated in this study. The soaked rough rice was exposed to FIR radiation at 5 s intervals up to 30 s and moisture content, degree of gelatinization & color of rice were measured. The moisture content of rough rice immediately after exposing to FIR radiation was in the range of 27.8±0.1 -21.4±0.6 % and it decreased with the increase of exposure time. The degree of gelatinization increased with exposure time and was in the range of 20.51% and 100%. The optimum degree of starch gelatinization of 40% was achieved in an exposure time of 20 s. The yellowness index was in the range of 21. 95 -34.54. The lightness (L*) of soaked rough rice exposed to FIR radiation was decreased with time from 60.30 to 52.72.According to Srinivas et al. (1981) dry heating of soaked paddy provides a better alternative for both gelatinization and drying. In dry heat parboiling the soaked rough rice, instead of being steamed, is subject to quick conduction heating at a high temperature. The paddy with

A control system was developed for optimizing the electrical energy consumption while preserving the required quality of withered tea leaves. The electrical energy saving was achieved by controlling the speed of the fan through a variable speed drive (VSD) and controlling the hot and ambient air delivering into the trough. The fan speed was determined based on the theoretical mass flow rate requirement of air calculated by the mathematical model developed for withering, while calculating the thermodynamic properties of withering air and the moisture content of tea leaves in real time. A single board computer, Raspberry pi 3 model B, was used as the controller to run the mathematical model and the software programme to control the VSD for controlling the mass flow rate of air delivered, the air temperature and the relative humidity. Finally, the electrical energy consumption of the fan and the quality parameters of tea were measured through experiments and compared in the withering process with or without control system. The specific energy consumption of withering was in the range of 0.17 to 0.18 kWh/kg of made tea with the control system and it was 0.27 to 0.35 kWh/kg of made tea without control system. The electrical energy consumption was 36 kWh to 39 kWh with the control system and it was in the range of 55 kWh to 67 kWh in without control system. Therefore, 39% of electrical energy was saved by introducing the control system compared to the withering process without control system.