Solutions for effective prevention of after-cooking discoloration in deep-fried eggplant (Solanum melongena L.)

Abstract

Importance of the work: Deep-fried eggplant often undergoes the negative impact of after-cooking discoloration (ACD). The pretreatment method and deep-frying parameters are critical factors that can minimize ACD in deep-fried eggplant. Objectives: To investigate the effects of different calcium chloride soaking and deep-frying conditions on the after-cooking discoloration of deep-fried eggplant. Materials & Methods: A series of preliminary experiments was conducted to investigate the effect of calcium chloride concentration, soaking time, frying temperature and frying time on the ACD of deep-fried eggplant and identify the important factors. Frying temperature and frying time were chosen for further optimization study using response surface method (RSM). Results: All the mentioned factors had positive effects on mitigating the ACD. Overall, the results demonstrated that pretreatment using calcium chloride helped to minimize the ACD of deep-fried eggplant, with the appropriate concentration and soaking time being 2% and 5 min, respectively. The results indicated that frying temperature and frying time were the most important parameters affecting the response. The RSM optimization results showed that the minimum color difference could be obtained at the optimum frying conditions of temperature = 161°C and time = 209 seconds and their factor contributions were 22 and 78%, respectively. The achieved color difference was about 3.48, which was close to 2.3, the "just noticeable color difference". Main finding: The results provide a strategy for the development of industrial-scale production of deep-fried eggplant.