Abstract The fat content of spices poses problems of temperature rise and sieve clogging during grinding. Due to this temperature rise, spices lose a signi®cant fraction of their volatile oil or avouring components. Therefore, a cryogenic grinding system was designed and developed to cool the spices before feeding to the grinder and also maintain the cryogenic temperature in the grinding zone. The main components of the cryogenic grinding system are a precooler and grinder. The precooler consists of a screw conveyor assembly, a compressor, a liquid nitrogen dewar and power transmission unit. The design considerations, calculations and development of the precooler have been discussed in the paper. A commercially available grinder was adopted for this purpose. The tests conducted on grinding of cumin seed revealed that it could be successfully ground below the temperature of ÿ70°C. Above this temperature, sieve clogging took place. The increase in grinding temperature fromÿ160°C toÿ70°C resulted in a signi®cant increase in particle size of the product and speci®c energy consumption in grinding. A variation in volatile oil content was obtained in the range of 3.30±3.26 ml/100 g with increasing temperature from ÿ160°C to ÿ70°C, but this variation was found to be non-signi®cant at 5% level. ó 1999 Elsevier Science Ltd. All rights reserved SPEX6770 全自動(dòng)冷凍研磨機(jī) SPEX6870 全自動(dòng)冷凍研磨機(jī) SPEX6970EFM 冷凍研磨機(jī)