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

Abstract

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. Practical applicationsSince the lab scale study was found to be effective against most of the C. maculatus life stages, it is possible to adapt the CP for large-scale disinfestation applications with essential modifications (i.e., pressure, conveyors) in the system's designs. Apart from that, CP also modifies the surface nature of the grains, hence the treatment also assists in increasing the extraction yield (milk, oil, and protein) and germination percentage of food grains.

Plasma Bubbling of Soymilk: Impact on Allergenicity, Antinutritional Factor, and E-Nose-Retrieved Sensory Characteristics

“…Later, the solution was read using a UV spectrophotometer at 550 nm. Meanwhile, 0–2000 μg/mL bovine serum albumin was used as the standard to calculate the protein content. , …”

“…Meanwhile, 0−2000 μg/mL bovine serum albumin was used as the standard to calculate the protein content. 5,10 2.3. Fourier-Transform Infrared and Circular Dichroism Spectrometry.…”

“…The changes in the amide region were plotted as a spectrum between 1200 and 1700 cm −1 . 5 For circular dichroism (CD) spectrometry, 0.1 mg of each freeze-dried sample was dissolved in 10 mM phosphate-buffered saline (PBS, pH 7.4) and scanned (range: 190−260 nm, path length: 1 cm) in a JASCO CD spectrometer (Model: J-1500), and the secondary structures were identified with the help of an in-built multivariate protein secondary structure estimation program. FTIR and CD spectra were plotted using Origin 2021 software.…”

“…2 In earlier studies, plasma was effective against soybean's pre/ postharvest problems such as pesticide contamination, 3 seed germination, 4 soymilk extraction, and infestation. 5 However, the plasma treatment effect on the allergens and antinutritional factors was not evaluated for whole soymilk. Though Marcinkowska-Lesiak et al 6 induced plasma activation in soymilk, the study focused only on meat curing and did not discuss the effect on soymilk's harmful components.…”

“…In earlier studies, plasma was effective against soybean’s pre/postharvest problems such as pesticide contamination, seed germination, soymilk extraction, and infestation . However, the plasma treatment effect on the allergens and antinutritional factors was not evaluated for whole soymilk.…”