Studies Of Factors Influenceing The Post-haze Of Apple Juice Concentrate

Studies were carried out on processing indexes of fruits of nine apple cultivars ('Lujia 1','Lujia 2','Lujia 3','Lujia 4','Lujia 5','Fuji','Granny Smith','Ralls Janet','Jude Lin'), the changes of T625,A420,yellow color aberration, total color aberration, haze value of apple juice concentrates and the contents changes of total phenolics, phenolics of flavanols, condensed tannins, soluble protein and protein of apple juice concentrate of these nine apple cultivars during the course of storage. Evaluations were made on the influence of simple phenolic compounds(Catechin, Epicatechin, Chlorogenic acid, Caffeic acid,β-Coumaric acid and Ferullic acid) on the storage stability of apple juice concentrates, and the changes of contents and kinds of simple phenolic compounds in apple juice concentrates of these nine apple cultivars during the course of storage by using High Performance Liquid Chromatography (HPLC). The main results were as follows:1. There were great differences of processing indexes among different apple cultivars. The rate of juice output of'Lujia 1','Lujia 2','Lujia 4'were significantly higher than those of'Fuji','Granny Smith','Ralls Janet'and'Jude Lin'. The sugar (soluble solid substance) contents of'Fuji'and'Ralls Janet'were significantly higher than those of'Granny Smith','Lujia 1'and'Lujia 2'. The titrable acids of raw apple juice and apple juice concentrate of'Lujia 4'were the highest among the nine apple cultivars, and titrable acids of'Rall Janet','Fuji'and'Jude Lin'were significantly lower than those of other six apple cultivars. The yellow color aberration and total color aberration of raw apple juice and apple juice concentrate of'Lujia 3'were the lowest, and the T625 was the highest among the nine apple cultivars. The A420 of raw apple juice of'Lujia 5'was the lowest, and A420 of the apple juice concentrate of'Lujia 2'was the lowest. The haze values of raw apple juice and apple juice concentrate of'Lujia 1'were the lowest among the nine apple cultivars.2. After six months storage at 25℃, the T625 values, A420 values, yellow color aberration, total color aberration and haze values of juice concentrates of'Lujia 2','Lujia 3'and'Lujia 5'were less changeable during the course of storage, and, the storage stability of juice concentrates of these three apple cultivars were relatively better than those of other apple cultivars. The storage stability of juice concentrates of'Jude Lin'was stable during the early period of storage, but after 3 months storage, the T625 values were decreased obviously and the A420 values, yellow color aberration, total color aberration and haze values were increased quickly, and the juice concentrate of'Jude Lin'was not suitable for long term storage. During the course of storage, the T625 values, A420 values, yellow color aberration, total color aberration and haze values of juice concentrates of'Granny Smith'changed obviously larger than those of other eight cultivars. Therefore, the storage stability of apple juice concentrate of'Granny Smith'was the worst among these nine apple cultivars.3. There were correlations between post-haze of apple juice concentrate and total phenolics, phenolics of flavanols, condensed tannins, soluble protein and protein in apple juice concentrates. Higher contents of flavanols and soluble protein contents of apple juice concentrates would result in lower T625 values and higher haze values and A420 values. During the course of storage, there were significant correlations between the changes of flavanols and soluble protein of apple juice concentrate and the post-haze of apple juice concentrate. Higher contents changes of flavanols and soluble protein would result in higher changes of the haze values of apple juice concentrates. The influences of different simple phenolic compounds on post-haze of apple juice concentrate were also different. The contents of Catechin, Epicatechin, Caffeic acid and Ferullic acid had a significant influence on the haze values of apple juice concentrate. During the course of storage, the contents changes of Catechin, Epicatechin and Caffeic acid had extremely significant influence on the changes of haze values of apple juice concentrate. The experimental result indicated that the post-haze of apple juice concentrate was mainly related to the contents and the contents changes of phenolics of flavanols and soluble protein, Catechin, Epicatechin and Caffeic acid.