Cold plasma disinfestation of Callosobruchus maculatus infested soybeans: Its subsequent impact on soymilk extraction yield and quality

Soybeans play a vital role in the world economy as an essential food commodity by fulfilling human dietary needs. Hence, the seeds are commonly transported and stored in bulk quantities in various parts of the world which ultimately results in infestation issues. Callosobruchus maculatus is one of the major storage pests that infest the soybean seeds and cause losses in both the quantity and quality of the seeds. Cold plasma (CP) is an emerging non-thermal disinfestation technique that can disinfest food grain. Hence, we have used low pressure (< 2 mbar) CP at different voltages (1.0-2.0 kV) and exposure times (2-24 min) to disinfest the C. maculatus from soybeans. The maximum mortality of 100.00 +/- 0.00%, 98.89 +/- 1.92%, and 37.33 +/- 8.08% was achieved in adult, pupae, and egg stage insects, respectively, after 24 min of prolonged CP exposure at 2.0 kV voltage. However, CP treatment (1.5 kV- 18 min) induced only 11.11 +/- 3.85% mortality in larval stage insects as they were well protected under soybean seed coat. During the experiment, we also identified the impact of insect sex and egg age on the CP treatment effectiveness. Further, we have also analyzed the egg-producing capacity of CP-treated adult insects before their death. Apart from disinfestation, the CP treatment also assisted the soymilk extraction and increased the extraction yield from 92.44 +/- 1.02% (control) to 97.22 +/- 0.19% after CP treatment (2.0 kV-12 min). Nevertheless, the FTIR and SDS PAGE results had not shown any changes in the quality of soymilk extracted after CP treatment.