Evaluation of flavor quality in relation to sugars and acids of six Prunus domestica×armeniaca cultivars

Abstract:【Objective】Soluble sugars and organic acids are important factors for fruit quality at harvesttime. Prunus domestica×armeniaca is an interspecific hybrid via complex crosses of plums and apricots.Previous studies reported the composition of sugars and organic acids in apricots and plums. However, in⁃formation on the profiles of sugars and organic acids is limited in Prunus domestica×armeniaca. Determi⁃nation of sugar and organic acid profiles in main stone fruits can benefit breeding with particular intereston flavor quality. Soluble sugars and organic acids of six Prunus domestica×armeniaca cultivars were ana⁃lyzed in order to provide a theoretical basis for quality evaluation and improvement.【Methods】HLPCmethod was used to measure the soluble sugars and organic acids in fruit flesh of six Prunus domestica×ar⁃meniaca cultivars. The HPLC system contained a quaternary pump, an autosampler, and a reflective indexdetector (Waters410) with HyperREZ XP Carbohydrate Ca2 + 8 μm column at 80 °C with a flow rate 0.8 mL·min^-1. The mobile phase was performed with an isocratic elution of ultrapure water for peak separa⁃tion. Organic acids were analyzed by Agilent 1100 high performance liquid chromatography (HPLC) sys⁃tem (Waters1525 Series) containing quaternary pump, autosampler, and diode array detector with ZorbaxSB-Aq C18 column (4.6 mm ×250 mm, 5 μm). Chromatography separation was performed at 35 °C with aflow rate of 0.7 mL·min^-1. The mobile phase was carried out with 2% methanol and 98% of 20 mmol·L^-1 disodium hydrogen phosphate buffer (NaH2PO4, pH 2.56). The detected organic acids were oxalic acid, tar⁃taric acid, quinic acid, malic acid, shikimic acid, citric acid and succinic acid. Absorbance was measuredat 210 nm. The data were analyzed with ANOVA using SAS statistical software. The means were separat⁃ed using the Duncan’s multiple range test at confidence level P≤0.05. The data were presented as themean ± standard deviation of triplicate.【Results】(1) Four soluble sugars and seven organic acids wereidentified and quantified. The total sugar content of six Prunus domestica × armeniaca cultivars rangedfrom 75.25 to 126.66 mg∙g^-1, the mean content of total sugar was 105.44 mg∙g^-1. The single sugar contentin fruit flesh of six Prunus domestica×armeniaca cultivars was glucose > fructose > sucrose > sorbitol. Thetotal sugar content was‘Fengweihuanghou’>‘Weiwang’>‘Konglongdan’>‘Weidi’>‘Weihou’>‘Fen⁃gweimeigui’. The highest content of fructose was found in‘Weidi’with 40.23 mg∙g^-1, the highest con⁃tent of glucose in‘Fengweihuanghou’with 48.73 mg∙g^-1, the highest content of sucrose in‘Weiwang’with 44.44 mg∙g^-1, the highest content of sucrose in‘Weihou’with 31.99 mg∙g^-1. (2) The total acid con⁃tent of six Prunus domestica×armeniaca cultivars ranged from 7.28 to 9.99 mg∙g-1, the mean content of to⁃tal acid was 8.57 mg∙g^-1. The single acid content was malic acid> tartaric acid > quinic acid> succinic ac⁃id > oxalic acid > critic acid > shikimic acid, of which the content of malic acid was the highest. Tartaricacid was not detected in‘Weidi’‘Weiwang’and‘Fengweihuanghou’, succinic acid was not found in‘Fengweihuanghou’. (3)The fruit flavor of six Prunus domestica × armeniaca cultivars was sweet or soursweet. The sweetness value and the value of sweetness/acid were high. The ratio of sweetness and aciditywas‘Fengweihuanghou’>‘Konglongdan’>‘Weidi’>‘Weiwang’>‘Weihou’>‘Fengweimeigui’.Themean value of sweetness, sweetness/acidity and sugar/acid of six Prunus domestica × armeniaca cultivarswere high.‘Fengweihuanghou’had the highest values of sweetness, sweetness/acidity and sugar/acid.The sweetness was‘Fengweihuanghou’>‘Weiwang’>‘Weidi’>‘Konglongdan’>‘Weihou’>‘Feng⁃weimeigui’. The value of sweetness/acidity was‘Fengweihuanghou’>‘Konglongdan’>‘Weidi’>‘Wei⁃wang’>‘Weihou’>‘Fengweimeigui’. The value of sugar/acid was‘Fengweihuanghou’>‘Konglong⁃dan’>‘Weiwang’>‘Weihou’>‘Weidi’>‘Fengweimeigui’.【Conclusion】The main soluble sugars inthe flesh of six Prunus domestica × armeniaca cultivars were glucose and fructose, the main organic acidwas malic acid. Two cultivars (‘Weidi’and‘Fengweihuanghou’) rich in fructose and one cultivar‘( Wei⁃hou’) rich in sorbitol were identified in this study. Six Prunus domestica×armeniaca cultivars were sweetor sour sweet, which was appreciated by the consumers.