The Main Physicochemical Characteristics and Nutrient Composition during Fruit Ripening of Stauntonia obovatifoliola Subsp. Urophylla (Lardizabalaceae)

Abstract

Stauntonia obovatifoliola Hayata subsp. urophylla is a novel edible and healthy fruit in China, commonly known as “Jiuyuehuang” (September yellow). The fully ripe fruit of S. obovatifoliola subsp. urophylla has a soft fruit pulp texture, golden flesh, and sweet flavor which is very popular with the locals. In this paper, we have investigated the fruit appearance quality, physiochemical quality, and nutritional quality of S. obovatifoliola subsp. urophylla that was harvested at six stages (S1: 60 DAFB, S2: 90 DAFB, S3: 130 DAFB, S4: 160 DAFB, S5: 190 DAFB, S6: 205 DAFB). An increase in fruit size (including single fruit weight, fruit length, and fruit diameter) was related to the ripeness stage of fruit development. The total soluble solids, firmness, dry matter, sugar and starch showed remarkable changes as the fruit approached ripening (S5–S6 stage). The main sugar components in the fruit were fructose, glucose, and maltose. The contents of fructose, glucose, and total sugars in S. obovatifoliola subsp. urophylla fruit progressively increased from the S1 to the S6 stage while increasing sharply from the S4 to the S5 stage. As for the content of maltose and starch, they both showed an increasing trend from the S1 to the S4 stage but decreased sharply at the S5 stage. The vitamin B, vitamin C, total phenolics, total flavonoids, and amino acid levels showed an overall downward trend during fruit development. To our knowledge, this is the first study to compare the phytochemical characteristics, nutrient composition, and antioxidant content during the different fruit development stages. The results of this study may provide a scientific basis for clarifying the growth and development characteristics of S. obovatifoliola subsp. urophylla fruit and the further utilization of these excellent medicinal and edible germplasm resources.