Dielectric heating‐assisted disinfestation of black gram and its effect on protein profile: A comparative study on radio frequency and microwave heating

Abstract

Abstract Pulse beetle, Callosobruchus maculatus, is the major pest infesting in the stored legumes. The present study is aimed to evaluate the comparative efficacy of radio frequency (RF) and microwave (MW) heating treatments to eradicate the problem of infestation at all four life stages in blackgram (Vigna mungo). Infested blackgram kernels in a single egg, larvae, pupae, and adult stage were subjected to RF and MW irradiation at 180‐, 190‐, 200‐, and 210‐mm electrode heights for RF and at 365, 295, 250, and 230 W MW power. The lethal time for 99.99% mortality (LT99.99) was found to be 3.62 to 8.23 min for the egg stage, 4.70 to 7.27 min for larvae, and 7.10 to 8.96 min for pupae, and 5.40 to 7.73 min for adults. For MW heating treatment, the time for complete mortality of the single egg stage, larvae, pupae, and adult was found to be in the range of 5.33 to 7.83, 8.28 to 9.82, 8.87 to 10.68, and 8.86 to 10.18 min, respectively. The pupa stage was found to be the most heat tolerant in comparison with other life stages. The MW‐treated blackgram samples depicted a significant decrease in the lysine, aspartic acid, and proline content as compared with RF‐treated samples. This suggests a negative effect of the MW on the amino acids which in turn led to its deterioration. Therefore, the RF heating holds potency to disinfest legumes without affecting the major properties of legumes which was the major drawback of using the MW heating.

Keywords

• amino acid profile
• internal feeders
• legumes
• pulse beetle
• radio frequency