Effects of geographical origin on fruit quality and antioxidant activity of Akizuki pear

【Objective】Akizuki pear (Pyrus pyrifolia) is a perennial fruit tree. As a common fruit with a cultural history spanning thousands of years, China leads the world in both planting area and yield of pears. Akizuki pear is one of the important varieties of sand pears and is highly favored by consumers for its attractive appearance and unique flavor. However, significant differences in fruit appearance and internal quality indicators have been observed due to variations in growing regions, leading to mixed market evaluations and hindering the development of the Akizuki pear industry and related sectors. This study investigates the effects of different growing regions on the fruit quality and antioxidant activity of Akizuki pear, aiming to provide a scientific basis for evaluating and improving its quality.【Methods】 Using fruits of Akizuki pear from five distinct origins as experimental materials, this study measured their external quality (fruit mass, transverse diameter, longitudinal diameter, fruit shape index), internal quality (moisture content, stone cells, soluble solids content, total sugars, total acids, sugar-acid ratio, soluble solid-acid ratio), and the content of nutritional components (ascorbic acid content, total phenolic content, total flavonoid content, uronic acid). The contents of glucose, fructose, sucrose, and sorbitol in the fruits were determined using ultra-high performance liquid chromatography (UHPLC). The enzyme activities in Akizuki pear fruits were measured using Acid Invertase (AI) activity and Neutral Invertase (NI) activity assay kits. The antioxidant activity of Akizuki pear fruits from different growing regions was also determined, Using ascorbic acid as the positive control, the antioxidant capacity of Akizuki pears from different growing regions was evaluated by determining their DPPH free radical inhibition ability and ABTS+ free radical scavenging ability. Difference analysis and correlation analysis were performed on the experimental results, and the fruit quality was comprehensively evaluated using principal component analysis (PCA). The experimental data were organized using Microsoft Excel 2019. Data processing, analysis of variance, and correlation analysis among various indicators were performed using IBM SPSS Statistics 27.0, with a significance level set at P＜0.05. Figures were generated using OriginPro 2024 and GraphPad Prism 10.1.2.【Results】Akizuki pears from different growing regions exhibited significant quality variations. In terms of external fruit quality, fruits from the warm and humid Zhijiang region had a larger single fruit mass (469.85 g), demonstrating advantages for developing fresh edible pear products. The coefficient of variation for the fruit shape index among the five regions was relatively low (5.95%). Regarding internal quality, fruits from Jinan had the highest soluble solids content (12.53%), while those from Dangshan had the highest total sugar content (8.28%). Fruits from Zhaoxian were characterized by high acidity (titratable acid 0.48%), which significantly reduced their sugaracid and solid-acid ratios; however, they contained high levels of total polyphenols (0.46 mg · g- 1 ). The flavor profiles were distinct across different regions. In terms of monosaccharide composition, significant differences were observed in the soluble sugar components of Akizuki pears from different regions. Dangshan fruits were characterized by high fructose content (47.9 mg · g- 1 ), while Jinan fruits had the highest sorbitol (47.04 mg·g-1 ) and sucrose (8.76 mg·g-1 ) contents. The sweetness values between these two regions were comparable (116.01-117.31 mg · g-1 ). The study found that neutral invertase (NI) and acid invertase (AI) activities were significantly positively correlated with glucose and fructose contents, while being significantly negatively correlated with sucrose content. In terms of antioxidant activity, Akizuki pears from Zhaoxian outperformed those from other regions.Correlation analysis revealed significant relationships between the external and internal quality attributes of fruits from the five growing regions. The impact of different growing regions on the external and internal qualities of pears varied significantly. Single fruit mass exhibited highly significant positive correlations (P＜0.01) with transverse diameter, longitudinal diameter, and ascorbic acid content. Soluble solids content showed highly significant positive correlations (P＜0.01) with total sugars, sugar-acid ratio, solid-acid ratio, glucose, sucrose, and sweetness value, while demonstrating a significant negative correlation (P＜0.05) with titratable acid content. Total sugar content demonstrated a highly positively correlation (P＜0.01) with glucose, fructose, and sweetness value, as well as a significantly positively correlation (P＜0.05) with the sugar- acid ratio. Using the indicators measured in this study, a comprehensive evaluation of fruit quality was conducted. Principal component analysis (PCA) was employed to comprehensively assess the fruit quality of pears from different growing regions and identify the optimal region. Six principal components with eigenvalues greater than one were extracted, collectively accounting for 90.796% of the cumulative variance contribution rate. This indicates that these components capture the majority of the information from all measured indicators. Based on the aforementioned analytical results, Akizuki pears from Dangshan received the highest overall ranking.【Conclusion】Akizuki pears from differentregions exhibit variations in fruit quality and antioxidant activity, yet each possesses its own unique advantages. By fully leveraging these regional characteristics and strengths, the quality of Akizuki pears can be further enhanced, thereby fostering the development of the related industry.