This study was conducted to investigate the effects of pretreatment and different packaging methods on the physicochemical properties of cold vacuum-dried peaches. All the dried peach samples were stored such as N2 gas substitution, vacuum and passive packaged with polyethylene (PE) film and oriented polypropylene (OPP)/aluminum (Al)/PE film at 40℃ for 50 days. The weight change, pH, soluble solids content, titratable acidity, soluble solid-acid ratio (SS/TA), delta E, browning degree and phenolic compounds were analyzed. The weight change and pH were lower in the 0.1% vitamin C-treated group and were significantly lowest in the vacuum-treated OPP/AL/PE. The soluble solids content and the SS/TA were higher in the non-treated groups than in the vitamin C-treated groups. According to the packaging methods, the L* values were higher in the vacuum, N2 gas and passive package, in that order. In addition, the browning degree and the delta E value were lower in the pretreated groups and significantly lowest in the vacuum-treated OPP/AL/PE with 0.1% vitamin C group. The phenolic compounds were high for the pretreated groups, according to the packaging methods (vacuum > N2 gas> passive), and the OPP/AL/PE was significantly higher than the PE. These results suggest that different packaging materials and pretreatment methods affected the quality of the dried peaches, and the vacuum- OPP/AL/PE film packaging group showed a high quality.

This study was conducted to determine the effects of the pretreatment and infrared drying methods on the physicochemical properties and antioxidant activities of dried peaches. The pretreatment methods were the 30 min treatment of NaCl, vitamin C, and soluble Ca (1:5 w/v immersion ratio), and leaving them untreated before infrared drying at 55℃ for 20 hr. The moisture content was lower in the pre-treated group and was significantly lowest in the 0.3% NaCl. The titratable acidity and soluble solid content and acid ratio (SS/TA) were high for the vitamin C and soluble Ca groups. The browning degree and cutting strength of the dried peach were lower in the pre-treated group. The total sugar content in the 0.3% NaCl group was significantly higher than those in the vitamin C and soluble Ca groups. The Ca contents were more effective in the soluble Ca treated group and increased with higher Ca concentration. The sensory evaluation results indicated that the organoleptic scores for the overall preference were higher in the 0.1% vitamin C treated group. The phenolic compounds and ABTS radical scavenging ability were high for the 0.1% vitamin C and 0.1% soluble Ca treated groups. These results suggest that pretreatment affected the qualities of the dried peaches, showing that infrared drying can be applied to the production of high quality dried peach products.

This study was conducted to investigate the pH, soluble solid contents, color difference, mineral contents, free sugar contents, and sensory quality of infrared- and cold-air-dried peaches. The pH, soluble solid contents, and free sugar contents of the infrared-dried peaches were higher than those of the cold-air-dried peaches. In the Hunter’s color value, the L and ΔE values of the infrared-dried peaches were higher than those of the cold-air-dried peaches; but the a and b values of the cold-air-dried peaches were higher than those of the infrared-dried peaches. The major organic acids of the dried peaches were citric acid, malic acid, and oxalic acid. The minerals with the highest to lowest contents, in that order, were K, Mg, Ca, Na, Fe, Zn, Cu, and Al. The mineral contents of the cold-air-dried peaches were higher than those of the infrared-dried peaches. The appearance and taste of the infrared-dried peaches were better than those of the cold-air-dried peaches. These results indicate that infrared drying is the effective drying method for the production of high-quality dried peaches.