Optimization Of Conditions And Effect Of Hot Air Treatment On The Quality, Physiology And Biochemistry Of Red Fuji Apple Fruits

Apple fruits (Malus domestica Borkh., cv. Red Fuji) were treated by postharvest heat treatment, the effect of postharvest heat treatment on quality was evaluated by response surface methodology (RSM) in different temperature-time combinations. The quality and physiological indexes changes of apple fruits during cold storage were focused on.1. The effect of hot-air treatment on quality of apples (cv: Red Fuji) was evaluated by response surface methodology (RSM) in different temperature-time combinations. The changes of L, a*, H, firmness, SSC/TA and juice pH of apples were the measured dependent variables. Six second order quadratic equations for heat treatment were built. The adequacy of the model equation for predicting the optimum response values was verified effectively by the validated data. By analyzing the response surface plots and their corresponding contour plots as well as solving the quadratic equation, the optimum process parameters were obtained as: temperature 36.3℃, time 75.4h.2. Fresh harvested apples (cv. Red Fuji) were classified into four groups: (1)Control group: apples were stored in cold storage (0℃ for 4 months) and then on shelf (20℃for 7 days). (2) Hot-air treatment 1: apples were treated with 38℃ for 96 hours and then moved to cold storage and then shelf life. (3) Hot-air treatment 2: apples were treated with 36.3℃ for 75.4 hours and then moved to cold storage and shelf life. Afterwards, the fruit's quality indexes were monitored during the cold storage and shelf life conditions. It was found that hot-air treatment was remarkably effective in the raise of SSC(soluble solid content)/TA(titrable acidity). It maintained higher Na₂CO₃-soluble pectin and lower water-soluble pectin. Heat treatment delayed the senescence process in the cold storage. 36.3℃ treatment delayed the decrease of TA content, and maintained high firmness and a better apparent quality.3. Hot air treatment could maintain postharvest quality of Fuji apple fruit treated 36.3℃,75.4h or38℃,96h. During the hot-air treatment, ethylene release rate and respiration rate of treatments were higher than control group. On the second day of heating of heating...