Quality change law of summer grape during ripening process in south area of Guangxi

【Objective】The present study was conducted to investigate quality change law of summer grape in south area of Guangxi during ripening process to provide some references for producting high-quality grape in south area of Guangxi. 【Method】Using 4 grape varieties viz., "Victoria","Cabernet","Riesling" and "Superier rose" as materials, their soluble sugar,titratable acid,soluble solids,anthocyandin,p H and sugar-acid ratio were determined at different times, respectively, including in two weeks before fruit coloring, at the beginning of coloring(5%), at the end of coloring(100%),and before harvest. 【Result】The result showed that, as for 4 grape varieties, all determined indexes of summer fruit presented an increasing trend except titratable acid content during ripening process, while the titratable acid content first increased and then decreased. As for "Victoria" and "Superier rose" grape varieties, the soluble sugar and soluble solids contents of their summer fruit were first rapidly accumulated, the anthocyandin content rapidly increased later, then the titratable acid rapidly decreased, and the sugar acid ratio rapidly increased. 【 Conclusion 】 In the production of table grape varieties "Victoria" and "Superier rose", the photosynthetic area of leaf is enlarged to increase sugar content by pruning branchs. Two wine grape varieties "Cabernet" and "Riesling" grow badly in south area of Guangxi, which is suitable for brewing wine.