Optimization of a microwave assisted process for improving shelf-life of onion-ginger-garlic paste
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Date
2021-10
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The present work has been undertaken with the objectives of standardization of process parameter onion, ginger, and garlic paste using microwave heating based on quality characteristics and to study the shelf-life of the optimized paste. The study started with the development of the onion-ginger-garlic paste using salt and sunflower oil. After the development of the paste, microwave was used for heating treatment. Based on the temperature attained by the samples and quality characteristics, the three levels of independent parameters onion % in onion-ginger-garlic ratio (55%, 65% and 75%), sunflower oil concentration (40, 50 and 60ml/100g), microwave power (160, 320 and 480W) and processing time (1, 2 and 3min) were selected. Response surface methodology was used for designing the experiments and to select optimum levels of onionginger- garlic ratio, sunflower oil concentration, microwave power and processing time. Box- Behnken design with three replications was chosen to determine the levels of each experiment. Standardization of process parameters (i.e. onion % in onion-ginger-garlic ratio, sunflower oil concentration, microwave power and processing time) was carried out based on quality attributes (i.e. moisture content, total soluble solids, pH, total phenolic content, total flavanoid content, antioxidant activity, colour difference). The study showed that the moisture content ranged from 63.73 to 74.83%, A minimum total soluble solid of the paste was about 21.25 to 27.48ºBrix, pH from 4.406 to 4.804, total phenolic content from 110.88 to 117.56 mg GAE/100g, total flavanoid content from 277.3 to 292.275 mg CE/100g, Antioxidant Activity from 80.82 to 87.62 % and colour difference from 10.648 to 13.171. The study showed that all the independent parameters had significant effect on the responses. The optimum conditions of onion-ginger-garlic ratio, sunflower oil concentration, microwave power and processing time as computed by response surface methodology were 75:10:10, 60 ml/100g, 480W and 1.5min. After getting the optimized sample ratio with microwave treatment and control as untreated sample, shelf-life studies were carried out by storing the sample in air tight glass containers at ambient temperature (27 ± 2°C) and relative humidity (57±2%) for 60 days at 15 days interval. From the study it was observed that microwave treated sample got deteriorated from 58 days while the control sample from 27 days of storage. Colour difference in case of untreated sample was more compared to the treated sample.