Study On Flavor Quality Of Early Apple Cultivars

Flavor quality is an important part of the fruit internal quality, which is determined by the composition and content of flavor matters. Recently, although the studies on apple flavor have made great progress, the studies on flavor of early apple cultivars remain little. In this study, new early apple cultivar'Taishan Zaoxia'which had excellent flavor and several other early apple cultivars (i.e.,'Liaofu','Vista Bella') were used as materials. Their constituents of aroma, sugar and acid were studied in different cultivars and at different developmental stages with'Taishan Zaoxia'and'Liaofu'by gas chromatography -mass spectrometry (GC-MS) and Capillary Electrophoresis (CE). The aim of the study was to give theoretical support and reference for quality breeding and quality regulating of early apple, and to provide basic information for constructing the system of criterions in breeding evaluation of early apple cultivars. The main results were as follows:1. 136 aromatic components were identified, which belonged to twelve categories in fruits of'Taishan Zaoxia','Vista Bella'and'Liaofu'. According to different categories and relative contents of arome, Taishan Zaoxia could be classified as an ester-type apple and Vista Bella as alcohol-type. There were differences in both aromatic components and relative contents among early apple cultivars, so aroma was one of the important criteria in evaluation of early apple in apple breeding.2. The fructose was the most sugar constituent in all six tested cultivars, and its C·V% was smallest (14.59%) in three different sugar constituents, but there were significant differences in the contents of sucrose and glucose among different cultivars, and C·V% of the former was 67.58%, and the later was 29.94%, which showed the total content of sugar was determined by the contents of fructose and sucrose in early apple cultivars.3. The results of the mensuration of soluble sugar, titratable acid, aromatic components and organoleptic evaluation were different in three early apple cultivars ('Taishan zaoxia','Vista Bella'and'Liaofu'). The difference in organoleptic evaluation accorded with the differences in soluble sugar, titratable acid, and aromatic components in these cultivars. So in the experimental conditions, the criteria in flavor evaluation of the three early apple cultivars should comprise the contents of sugar and acid, sugar-acid ratio and total content of three main aromatic components(1-Butanol, (E)-2-Hexenal, Butyl acetate).4. Eight character impact components (CICs) were identified in Taishan Zaoxia, including butyl acetate, 2-methyl-1-butyl acetate, hexyl acetate, ethyl butanoate, ethyl 2-methylbutanoate, propyl butanoate, butyl 2-methylbutanoate and ethyl hexanoate. Meanwhile, six CICs were found in Liaofu and they were hexanal, (E)-2-hexenal, hexyl acetate, ethyl butanoate, ethyl 2-methylbutanoate and ethyl hexanoate. The quantitatively significant components were esters in Taishan Zaoxia and alcohols in Liaofu during fruit maturation, respectively. It showed difference in ester types between two cultivars that the major ester components were acetate esters in Taishan Zaoxia and butanoate esters in Liaofu.5. It was also observed that the contents of esters and alcohols increased significantly during fruit maturation of Taishan Zaoxia and Liaofu. The total content of ester in Taishan Zaoxia at 45 days after full bloom (DAFB) was obviously higher than the contents of its other components and the ester in Liaofu, which implied the starting of ester synthesis in Taishan Zaoxia was earlier. However, the stage of alcohol synthesis largely in Liaofu was from 45 to 60 DAFB, earlier than the stage from 60 to 75 DAFB in Taishan Zaoxia, which indicated the difference between apple cultivars.6. The increase of soluble sugar was caused by fructose in fruit of Taishan zaoxia. In late developmental stage, the effect of sucrose on content of soluble sugar began greater than the former. Malic acid was the most important factor causing change of content of titratable acid. The influence of fructose and sucrose on sweetness enhanced gradually. Glucose content decreased continuously and approached its threshold in late developmental stage, which resulted in its smallest contribution to fruit sweetness. Malic acid on sourness rose first and falled later with fruit ripening.