Preparation of Standardized Powders of Cumin and Fenugreek Seeds by Cryogrinding Technology

In conventional grinders, the oxidation and heat lead to degradation of vitamins, enzymes, volatile components and many other active substances in the plant. While using cryogenic and an inert environment (such as liquid nitrogen) prevent deterioration of active substances and the produced powder does not suffer any alteration compared with the original plant in quality and quantity. In this research work, using a cryogenic grinding system designed in our lab, qualitative and quantitative comparative studies between cryogenic and conventional grinding systems using fenugreek and cumin seeds have been done. Some processing parameters such as feeding rate, liquid nitrogen flow, screw conveyor rotation speed, grinder speed and plant temperature at the end of the screw conveyor have been set to obtain the optimum production conditions. The results showed a higher quality of the products processed with the cryogrinding system (color, appearance, odor, particle size distribution and active substance amount). A complete listing of technical data such as production capacity, parameters of cryogrinding process, raw material feeding rate, and technical datasheets for each part of the cryogrinding system and product certificate of analysis are provided. An increase of 16.3% in the volatile oil and 7% in cuminaldehyde was observed for the cryogrinded relative to the normal grinded cumin seeds. Cryogrinding showed better performances for particle and distribution (50% of the total powder volume) size in comparison with conventional grinding (respectively 1/10 and 1/2 for cumin and fenugreek ground samples). Finally the cryogrinded powders were standardized according to the known pharmacopeia and food standards.