Optimization of pretreatments to enhance quality characteristics and storage period of kinnow (Citrus reticulata Blanco) using response surface methodology

An investigation was carried out to evaluate the impact of pretreatments viz. wax coating, hot water dipping, and fungicide treatment on quality characteristics of kinnow. In the present study, a trial was conducted to extend the shelf life of kinnow fruits by maintaining the initial quality characteristics with three wax-to-water dilution ratios (1:1, 1:2, 1:3), hot water dipping at 56 °C with varying time (40, 60, 80 s) along with fungicide treatment at various concentration (150, 200, 250 ppm). Both treated and untreated (experimental control) samples were kept at refrigerated conditions (5-8 °C) and 90-95% RH for 60 days. The effect of the storage period on quality parameters was recorded regarding weight loss, TSS, titrable acidity, ascorbic acid, and total color difference (TCD). The process parameters i.e. wax dilution, hot water dipping time, and fungicide concentration were optimized using response surface methodology (RSM). Optimized process parameters were 1:2.66 waxing dilution, 80 s hot water dipping time, and 250 ppm fungicide concentration. It could be concluded from the results that a combination of wax coating, hot water dipping, and fungicide treatment can help to prolong the storage period of kinnow up to 60 days with retained quality, as compared to 30 days in untreated control kinnow fruits when stored at 5-8 °C and 90-95% relative humidity.