Author(s): Abhishek Chitranashi, Mahesh Kumar, Ashok Kumar, Jyoti Prakash and Vinutha T

Abstract: Despite being a rich source of nutrition, with 9-11% protein, 6% lipid, and essential micronutrients like iron and zinc, as well as providing 361 kcal/100 gm of energy, pearl millet flour is not widely consumed due to its propensity to develop rancidity within a short storage period (less than 30 days). This rancidity is primarily enzymatic, involving lipase, lipoxygenase (LOX), polyphenol oxidase, and peroxidase. Lipase generates free fatty acids from lipids, which serve as substrates for LOX. LOX catalyzes the formation of hydroperoxides, which further degrade into aldehydes, ketones, and polymers, causing off-odors and rancidity. This study focused on the LOX 2 isoform, chosen for its substrate specificity and hydroperoxide production, to evaluate different treatments aimed at mitigating flour rancidity. Various physical treatments were applied to assess LOX 2 activity, including dry heat, microwave heat, vacuum packaging, and a combination of microwave and vacuum treatments at different storage intervals (0, 10, 20, and 30 days). Results indicated that the Dhanshakti genotype exhibited the highest LOX activity (39.75 U/mg) on day 10, while Pusa Purple 1 showed the lowest (30 U/mg). A dry heat treatment (90 °C for 2 minutes) followed by 4°C incubation significantly reduced LOX activity in Dhanshakti (28.95 U/mg). All genotypes demonstrated reduced LOX activity compared to the control, with Dhanshakti showing a significant decrease (14.17 U/mg) at day 30. Vacuum treatment effectively reduced LOX activity in the WGI-100 genotype (17.76 U/mg), followed by Pusa Purple 1 (20.35 U/mg) and Dhanshakti (26.8 U/mg). The combined microwave and vacuum treatment further reduced LOX activity, especially in Dhanshakti (12.23 U/mg), followed by WGI-100 (16.34 U/mg) and Pusa Purple 1 (19.77 U/mg).

DOI: 10.33545/26174693.2024.v8.i6h.1414