Influence of processing methodology on phenolic acid content, fatty acid profile and oxidative stability of Macrotyloma uniflorum

Study was conducted to determine the influence of different cooking methods namely pressure, flaking, infra-red, microwave and extrusion processing on rate of oxidative stability, fatty acid profile and functional properties of horse gram. The rate of auto-oxidation was significantly (p < 0.05) affected during storage and found maximum at 0.00 aw and minimum at 0.33 aw for both varieties namely GPM-6 and PAIYUR-2. The extrusion processed grains were more susceptible to auto-oxidation. The iron content of grain increased significantly (p < 0.05) during extrusion (1.22 ± 0.50 to 1.65 ± 0.15 mg 100 g⁻¹ for PAIYUR-2 and 1.19 ± 0.45 to 1.59 ± 0.12 mg 100 g⁻¹ for GPM-6). Whereas, tocopherol content decreased during extrusion (8.05 ± 0.15 to 2.28 ± 0.23 mg 100 g⁻¹ for PAIYUR-2 and 6.48 ± 0.46 to 1.68 ± 0.15 mg 100 g⁻¹ for GPM-6). Ellagic (12.36 ± 0.35 and 10.71 ± 0.29 mg 100 g⁻¹), vanillic (15.20 ± 0.23 and 12.48 ± 0.18 mg 100 g⁻¹), and coumaric acid (14.68 ± 0.71 and 8.97 ± 0.66 mg 100 g⁻¹) were the major phenolic acids whereas, linoleic (35.53 ± 0.30 and 35.46 ± 0.19%), palmitic (26.08 ± 0.26 and 25.97 ± 0.33%), and linolenic acid (13.44 ± 0.18 and 10.13 ± 0.21%) were the major fatty acids present in raw grain for PAIYUR-2 and GPM-6 respectively. Phenolic and fatty acids were significantly (p < 0.05) affected during processing. The oxidative stability of microwave processed grains was maximum whereas, extrusion processed grains showed minimum oxidative stability during storage. Study explicitly describes that native grains and the grains which did not undergo destruction of naturally present cellular structure, were less prone to oxidation. The oxidation rate of grains was found dependent on composition, processing and storage environment of grains. Hence, all these factors need to be considered to ensure the stability of processed food during storage.