Difference Analysis of Postharvest Quality and Volatile Substance in Different Varieties of Apple Cultivars

In order to clarify the changes of postharvest quality and volatile substances in different varieties of apple, the different varieties (‘Goldencrown’, ‘Gala’, ‘Jonahking’, ‘Hanfu’) of volatile composition and relative content were determined by electronic nose combined with headspace solid-phase micro-extraction and gas-mass spectrometry (HS-SPME-GC-MS), and the quality indexes were discussed. The results showed that, ‘Goldencrown’ was bright green-yellow and its fruit shape index was the highest, ‘Gala’was a shiny red, but the edible rate was not high, ‘Jonahking’was a red-yellow and had the lowest fruit shape index, and ‘Hanfu’ was a red-orange and had the biggest flesh mass. ‘Hanfu’ apple had the highest soluble solids content, ‘Goldencrown’ apple had the largest titratable acid content and vitamin C content, and the firmness and brittleness of ‘Goldencrown’and ‘Gala’ were higher than the others. The main component analysis and linear discriminant analysis of the electronic nose could completely distinguish the four apple varieties. GC-MS results showed that, 7 types of 33 compounds in total were detected. The main volatile substances were alcohols, aldehydes and esters. Characteristic aroma in four varieties of apples were hexanal (green grass flavor), 2-hexenal (green apple flavor), and hexyl acetate (fruit flavor), 1-hexanol (green grass flavor) was the characteristic aroma of ‘Gala’and ‘Goldencrown’, and acetic acid hexyl ester (fruity flavor) was the unique characteristic aroma of ‘Gala’. As a whole, ‘Gala’apple had a strong aroma, and ‘Hanfu’apple had a lighter aroma, which was identical to the analysis result of electronic nose.