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.

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Purpose: Mee (Madhuca longifolia) is an economically important tree growing throughout Sri Lanka. Its importance is mainly attributed to its oil with high nutritional and medicinal values. However, an inefficient extraction method limits its use. This study revealed the possibility of extracting oil from mee seeds by using a screw-type oil expeller. Methods: A popular screw-type oil expeller was used in the experiment. Extract bar clearance and speeds of the main spiral shaft were altered to increase the oil expelling efficiency of the machine. The quality of refined oil at the optimum oil yield was determined by measuring the refractive index, saponification value, iodine value, unsaponifiable matter, free fatty acid, and specific gravity. Results: An optimum yield of 35% oil was obtained when the machine capacity was 30 kg/h and energy consumption was 0.13 kWh/kg. This optimum machine condition was observed at an extract bar clearance of 0.5 mm and a main spiral shaft speed of 90 rpm. The refractive index, saponification value, iodine value, unsaponifiable matter, free fatty acid, and specific gravity of the oil were 1.4, 203, 59, 3.5%, 0.2%, and 0.907 g/cm3 respectively. Color of the mee oil was closer to yellow, which is revealed by the lightness value (L) of 24.93 and positive value (b) of 11.81. Conclusion: The screw-type oil expeller can be used for economically extracting mee oil on a commercial scale.

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