To analyze the characteristics of sugar and acid components in fruits of different Syzygium samarangense germplasms resources, screen key indicators suitable for evaluating the sugar and acid quality of Syzygium samarangense.

The sugar and acid components of 18 Syzygium samarangense germplasms were determined by high performance liquid chromatography, and principal component analysis and cluster analysis were used to analyze the characteristics of sugar and acid components.

The total sugar content of Syzygium samarangense fruits ranged from 35.12 to 114.29 mg/g, with an average of 59.66 mg/g and a coefficient of variation of 38.88%. The germplasms ‘Zihong’ and ‘Daye’ exhibited the highest total sugar contents, whereas ‘Malaysia Green’ had the lowest. Fructose and glucose were the main sugar components, accounting for 51.78% and 46.00% of the total sugar respectively. Total acid content ranged from 0.403 to 3.654 mg/g, with an average of 1.396 mg/g and a coefficient of variation of 57.64%. The germplasm ‘Heitang Barbie’ had the highest total acid content. Citric acid and malic acid were the major organic acids, together constituting 90.26% of the total acid content. Correlation analysis revealed that total sugar was highly positively correlated with fructose and glucose (r=0.9963 and 0.9961, P<0.01), whereas the sweetness-acid ratio showed highly significant negative correlations with citric acid and total acid(r=–0.6222 and –0.6998, P<0.01). Principal component analysis selected total sugar, total acid and sweetness-acid ratio as the core evaluation indices for sugar-acid quality.

The sugar and acid components of Syzygium samarangense exhibit significant differences. Fructose and glucose are the main sweet substances in the fruit, while citric acid and malic acid are the main acidic substances. Total sugar, total acid and the sweetness-acid ratio can be used as core indicators for evaluating the sugar-acid quality of Syzygium samarangense.