Study on the characteristics of quality and mineral content in different parts of pulp of Hongmeiren tangor

Abstract:【Objective】Zhejiang is one of the nine major citrus producing areas. The traditional main variety in this area is Satsuma mandarin, the maturity period of fruits is mainly concentrated in October to December. Citrus hybrids are derived from natural or artificial hybridization among different citrus species, so they have similar nutrition, flavor, and easy peeling. Therefore, citrus hybrids could be good choices for structural adjustment of citrus varieties. In recent years, Hongmeiren tangor (Citrus hybrid) has been widely cultivated in Zhejiang, and previous studies have focused on botanical characteristics, biological characteristics and cultivation techniques. It was found that the fruit quality of Hongmeiren showed obvious non-uniformity in the sampling process. The quality and mineral contents in different parts of the fruits were studied in order to further explore the quality characteristics of this species. Furthermore, a sampling method for quality evaluation was proposed.【Methods】The mature fruits of Hongmeiren were sampled at different times in the same orchard or the orchards in different regions re-spectively in Zhejiang province. The flesh of each group of fruit samples was divided into three parts, including the stem end, mid and top. The quality indexes, such as soluble solid (TSS) and titratable acid (TA), were determined by physical and chemical analysis, and the atomic absorption analysis was used to analyze the 8 kinds of mineral nutrients. The data were statistically analyzed by SPSS.19.0.【Results】The contents of TSS and sugar acid ratio (TSS / TA) in the three parts of pulp were the stem end＜the mid＜the top of the fruits, and there were significant differences between the stem end and the top of the fruits, while the variation of TA was not obvious. The contents of TSS and TA of the whole fruit were closest to those of the mid of the fruit, with no significant difference. The corresponding correlation coefficients R2 of TSS and TA were 0.980 7 and 0.946 9, respectively. Therefore, the middle part of the fruit could best represent the whole fruit. The content of element K was the highest in the stem end of fruit and showed a downward trend in the order of the stem end, the mid and the top of the fruit, while the content of element P was opposite. The contents of medium elements Ca and Mg in each part of the fruit were basically the same, showing a V-shaped distribution, and the content of Fe was relatively high within four kinds of trace elements, followed by B. Additionally, there was no significant difference between Fe and Cu in each part of the pulp, and the largest accumulation of trace elements of Zn and B were found at the top of the fruit. Most of the elements were positively correlated, while K was negatively correlated with some elements, such as Ca and P. The TSS and sugar acid ratio of fruit were extremely positively correlated with P and negatively correlated with K and longitudinal diameter. The TSS was also significantly negatively correlated with Zn and fruit shape index, while solid acid ratio was significantly positively correlated with Ca. The TA was significantly positively correlated with K and negatively correlated with Ca and P.【Conclusion】The fruit quality of Hongmeiren tangor in different parts of the pulp was obviously inconsistent and showed a polar distribution, and the accumulation of large and medium-amount mineral elements in each part had a certain regularity. The quality of the middle part of the fruit was the most representative of the whole fruit, so the middle part of the fruit could be sampled and juiced in the field, but it is better to juice the whole fruit and prepared multiple samples in the quality evaluation process. Fruit longitudinal diameter, fruit shape index and elements such as K, P, Ca, Zn are most related to the fruit quality. These results would provide a scientific basis for quality evaluation and quality improvement of tangor in practice.