Optimizing volatile oil retention in ajwain (Trachyspermum ammi L.) through cryogenic grinding techniques

The therapeutic benefits of seed spices have long been acknowledged, and there is growing interest in their potential biological activity in human health. Ajwain (Trachyspermum ammi L.), a significant seed spice from the Apiaceae family, is characterized by its distinct aroma and taste, attributed to its volatile oil content (2.5-5%). In postharvest processing, grinding is a crucial stage requiring careful handling to preserve flavor and aroma constituents. However, conventional grinding methods can lead to volatile oil loss due to varying grinding temperatures. To address this, a study was conducted using cryogenic grinding of ajwain seeds with liquid nitrogen on a laboratory-scale cryogenic grinder. The grinding was performed at temperatures ranging from 0°C to -100°C, with feed rates of 8, 9, and 10 kg/h and sieves of 0.8 and 1.0 mm. The study focused on liquid nitrogen consumption and the volatile oil content of the ground powder. The optimal conditions for producing high-quality ajwain seed powder were determined to be a feed temperature of -60°C, a feed rate of 8 kg/h, and a sieve size of 0.8 mm, achieving the highest retention of volatile oil at 2.9%. This approach highlights the effectiveness of cryogenic grinding in preserving the volatile oil content in ajwain seeds, offering a promising method for maintaining the quality of spice powders.