Optimization of calcium chloride and ultrasonication pre-treatment to mitigate the microbial load on fresh carrots using response surface methodology.

The quality and safety of fruits and vegetables are the major concerns of the food industry. The quality of these foods depends on their safety during storage and processing. The current research was designed to improve the quality by optimizing the safety parameters to minimize the microbial load of carrots during processing and storage. Three process variables including ultrasonication time, ultrasonication temperature, and calcium chloride concentration were optimized, each at five levels, to find the minimum optimal response of microbial load in terms of total plate count (TPC), total coliform count (TCC) and yeast mold count (YMC) using response surface central composite design. The selected factors showed statistically significant (p < 0.05) linear negative effect on TPC and linear positive effect on YMC. The total plate count, total coliform count, and yeast mold count were reduced to 6.117, 5.689, and 6.021 log CFU/mL respectively, under the optimum conditions i.e., ultrasonication time (17.97 min), temperature (43.885 °C), and CaCl concentration (181.211 mg/L). The non-significant interaction or quadratic effect of selected factors was observed on any of the studied responses. Concludingly, the reduction in studied parameters can improve the safety measurements of foods.