190: Cold Plasma Treatment as an Intervention Strategy to Achieve Safety in Pearl Millet Flour: Kinetics of Pathogen Inactivation and Mycotoxin Degradation

Introduction

Pearl millet is a nutrient-rich staple grain widely consumed in developing countries. However, it is susceptible to ochratoxin A contamination, a toxic secondary metabolite produced by Aspergillus ochraceus and Penicillium verrucosum. The ochratoxin A levels in pearl millet (3.5-69.4 µg/kg) often exceed the European safety limit (3 µg/kg). High moisture and poor post-harvest handling contribute to contamination, increasing dietary exposure risks.

Methods

In this study, a pearl millet sample inoculated with the mold species (Aspergillus ochraceus and Penicillium verrucosum) was treated with cold plasma at voltages ranging from 5-25 kV for 2-10 min, along with steam treatment at 100°C for 1-5 min. Mycotoxin inactivation was quantified using lateral flow immunochromatographic assays. The inactivation of E. coli and Salmonella was determined using culture techniques. Kinetic modeling was applied to optimize conditions for achieving over 90% reduction. Statistical analysis was performed using Origin Pro 2023b.

Results

Cold plasma treatment reduced ochratoxin A by 95% at 20 kV for 10 minutes. 92% of ochratoxin A is inactive by steam treatment at 100 °C for 4 minutes. Ochratoxin showed the maximum inactivation at 20 kV/10 min cold plasma treatment, while salmonella and E. coli showed a 5-log reduction. All of the flour's physicochemical characteristics, including moisture, ash, fat, water activity, and protein, were unaffected by cold plasma treatment (p > 0.05). Cold plasma treatment reduces the antinutrient properties (tannins and phytic acid) in grain when compared to the steam treatment, which helps enhance nutrient availability.

Significance

Cold plasma is an effective, non-thermal intervention for decontaminating pearl millet without heat damage or chemical residues. It not only inactivates mycotoxins and pathogens but also reduces antinutritional factors and enzymatic activity, which helps to extend the shelf life of pearl millet flour.

Authors: Bindusri Naraharasetti, Snehasis Chakraborty, Kaliramesh Siliveru, P.V. Vara Prasad