Integrated Analysis of Morphological and Physicochemical Traits in “Liuyuehong” Soft-Seed Pomegranate Fruit

The grain-level heterogeneity of fruit morphological characteristics significantly determines their sensory performance and intrinsic quality, providing a quantitative basis for commercial grading. This study utilized “Liuyuehong” soft-seeded pomegranate (Punica granatum L.) as experimental material. Fruits were classified into three size grades based on individual fresh weight: large (107–125 g), medium (74–92 g), and small (47–67 g). Fresh weights of whole fruits, exocarp, and outer seed coat were measured for each grade, followed by analysis of key quality indicators, including seed count, 100-seed weight, Brix degrees, pH, single-seed dimensions, vitamin C content, and edible fraction. Subsequently, correlation analysis, principal component analysis (PCA), and the entropy weight-TOPSIS method were employed to evaluate the integrated quality of different fruit grades comprehensively. The results indicate that the fruit morphological characteristics of “Liuyuehong” soft-seed pomegranate have a significant impact on its sensory and physicochemical qualities. (1) Large and medium fruits are superior to small fruits in terms of single fruit size, exocarp color uniformity, seed color, and mouthfeel, with large fruits having the highest comprehensive evaluation score (0.7). (2) Mouthfeel is correlated with the number of seeds in the fruit; the number of seeds in large and small fruits shows a significant negative correlation with Brix degrees (p < 0.05). (3) Small fruits exhibit greater individual variation within the group, with outliers and a tendency for late maturation. In conclusion, the fruit morphological characteristics of “Liuyuehong” soft-seed pomegranate significantly affect seed maturity and quantity, thereby determining the fruit’s sensory quality and physicochemical properties. The results indicate that fruits with a single- weight below 70 g commonly exhibit delayed development. It is therefore recommended to raise the lower threshold for commercial grading to above 75 g to enhance overall fruit quality and market consistency.