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20231
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Subject: Processing and Food Engineering × Author: Kulwinder Kaur ×
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    Development of protocol for postharvest quality management of stored mung bean using microwave and ozone
    (Punjab Agricultural University, 2023) Kulwinder Kaur; Satish Kumar
    The study aimed to optimize process parameters for ozone gas and microwave energy pre-treatment to maximize the mortality of C. maculatus (also known as pulse beetle) while minimizing the adverse effects on grain quality. Response surface methodology (RSM) was used, employing a Box-Behnken design (3x3) for ozone gas treatment and a full factorial design (2x3) for intermittent microwave heating. The optimized conditions for ozone gas treatment were moisture content: 11.28 %, ozone concentration: 939.98 ppm and exposure time: 2 h. For intermittent microwave heating, the optimal conditions were moisture content: 11.60 %, microwave power level: 435 W at a constant exposure time: 48 s, bed thickness: 4.5 cm, and air velocity: 3 m/s. These optimized conditions resulted in maximum mortality of all stages of C. maculates along with improved grain quality parameters. A grain recirculatory type ozone gas-based fumigation system was designed using Solid Works CAD software. The system showed a saturation time of 21.77 min, a saturated concentration of 1836.96 µg/L, an estimated half-life period of ozone as 10.35 min, and specific energy consumption of 524.62 kJ/kg. The proximate and mineral analysis of mung bean treated in the developed system showed a significant (p<0.05) decrease in protein, fat, and mineral content compared to the untreated samples but it varied non-significantly (p>0.05) vis-à-vis microwave treatment. Fourier Transform Infrared Spectroscope and Scanning Electron Microscope micrographs further confirmed molecular and structural modification in treated mung bean leading to reduced cooking time and enhanced functional, thermal, and pasting properties. The relationship between equilibrium moisture content and water activity predicted storage conditions as safe moisture content at aw 0.6: 11.80- 12.64 %, db and 7.87-13.43 %, db for ozone and microwave-treated mung bean respectively. The storage behavior of treated samples was studied over a 12-months using different packaging materials at retail and bulk levels. Variation in moisture content, headspace CO2 gas, and cumulative weight loss remained within safe limits while phytic acid content, total flavonoid content and antioxidant activity decreased with an increase in storage period with slight variation under high barrier films. Germination percentage was much higher than the Indian minimum Seed Certification Standards and was above 80 % for all treated samples. Ozone and microwave- treated mungbean grains packed in metalized laminated polymer (MLP) or cast polypropylene (CPP) bags at the retail level exhibited the longest shelf life of more than 12 months with acceptable quality, while LDPE (400-gauge) was found suitable for bulk packaging. Techno-economic analysis showed storage of treated and suitably packed grains has the potential to ensure long-term financial stability with an average payback period of less than one year.