Correlation Analysis of Mineral Element Content and Sensory Quality of National Geographical Sign Product--Olecranon Peaches in Lianping

. Microwave digestion-inductively coupled plasma astigmatism (ICP-AES) was used to analyze the contents of mineral elements (including K, P, Mg, Ca, Na, Fe, Cu, Mn, B, Zn, Se, Li) in 54 Olecranon Peaches collected from Shangping town, Lianping County. The obtained data was analyzed by Correlation analysis （ CA ） , combined with fruit reducing sugar (RS%), sugar-acid ratio (S/A) and sensory scores. The results showed that in the tested samples, it had a significant positive correlation between S/A sugar-acid ratio and sensory evaluation. S/A was negatively correlated with P contents. The P contents were positively correlated with the K 、 Mg contents. The Mg contents were positively correlated with the K 、 Na contents. The Na contents were positively correlated with the Mn contents. The contents of Mn were positively correlated with RS% ratios of reducing sugar.

Ca, Mg, Na were verified to determine the origin of milk powder by Dang et.al [6]. Zhao Qian [7] thought that Zn, Pb, Fe, Mg, Cu in Meihe Rice have good stability and space representativeness, which can be used as the confirmation index of rice producing area.
Organic component traceability is also one of the effective analysis methods to evaluate the quality of famous and special products and to distinguish the origin of food. The traceability model established by Wang Kaiqiang [8] using Gas Chromatography to detect fatty acids in pork was better than that established by nuclear magnetic resonance technique. And the accuracy was 100%. The correct discrimination rate of soybean monomers, such as Daidzin, Glycitin and Genistein, screened by Liu Wenjing [9] was 81.1% , which met the requirements of the discrimination analysis of soybean origin.
In 2015, permission was granted for Lianping Olecranon Peaches to be protected with a geographical sign product. Olecranon Peaches are not only planted in Lianping, but also Fujian Longyan , Wuping Yao Lu , Guangdong Wengyuan (Jiuxian peach). In addition, near the surrounding areas of Lianping there are planting olecranon peach, such as Liyuan Town Heping County , Tianxin Town Longchuan County. But Lianping Olecranon Peachs, especially Shangping are the most delicious as consumers reflected . For the protection of national geographical sign products and the need of construction of Olecranon Peache industry park in Lianping County, it has great significance to analyze the mineral element content and nutrient content of Lianping Olecranon Peache, and to establish a discriminant model combined with sensory evaluation.

Fruit Pretreatment
The samples were peeled and nucleated after ultra-pure water washing and controlled dry water, evenly distributed, and divided into two parts.A part was placed in a fresh-keeping bag-80℃ frozen and stored, and the other part was used for sensory evaluation and nutritional determination.

Microwave digestion and analysis of samples
The 0.5000 g sample was taken and placed in the polytetrafluoroethylene(PTFE) microwave digestion tank, with 6 mL of concentrated nitric acid, the inner cover was covered and the coat was tightened, and the microwave digestion system was put in. The digestion conditions were shown in table 1. After digestion, cooled to 60-70℃ temperature in the tank, removed the digestion tank from the ventilation cabinet to remove acid, transfered the solution to 10 mL capacity bottle, fixed the volume with ultra-pure water, mixed well and set aside. A 7000 DV ICP-AES was used to determine the content of 12 mineral elements in the samples.

Determination of Nutrient Components of Olecranon Peaches
Direct titration was used for the determination of reducing sugar(RS) according to GB 5009.7-2016. GB 5009.8-2016 was used for determination of total soluble sugar (S)with acid hydrolysis titration. GB 5009.239-2016 was used for determination of titratable acid (A) with NaOH titration. Reduction sugar ratio (RS%)= reducing sugar content / soluble total sugar content 100; sugar-acid ratio (S/A)= soluble total sugar content / titratable acid content.

Sensory evaluation of Olecranon Peaches
Nine peach evaluators were invited to conduct training, and then the color, taste and aroma of the Olecranon Peaches were evaluated. The scoring table is shown in table 2.

Data analyses
The correlation analysis (CA) was carried out by SPSS 23.0 software to find out the mineral elements and nutrient components significantly related to the sensory evaluation of Olecranon Peaches.

Trace element content of Olecranon Peaches
According to 1.3 method, the mineral elements content of Olecranon Peachest were determined. The results were shown in Fig.1-12. (FW means fresh fruit weight. )   Fig.1-12 showed that, in the 54 samples tested, The K contents were between 1205-1820 mg/kg. The Mg contents were between 39.29-60.65 mg/kg. The P contents were between 89.4-136.6 mg/kg. The Ca contents were between 7.75-26.99 mg/kg. The Na contents were between 5.80-18.43 mg/kg. The Fe contents were between 1.08-6.32 mg/kg. The Zn contents were between 0.10-5.89 mg/kg. The B contents were between 88.51-136.6 mg/kg. The Mn contents were between 0.24-0.89 mg/kg. The Cu contents were between 0.20-0.72 mg/kg. The Li contents were between 0.012-0.027 mg/kg. The Se content were between 0.001-0.041 mg/kg.

Nutrient Content and Sensory Evaluation Score of Olecranon Peaches
According to 1.4 and 1.5 methods, the nutritional contents and sensory evaluation of the fruit were determined. The results were shown in Fig.13-15.

Correlation analyses
The composition of mineral elements, RS%, S/A and sensory evaluation of 54 samples were divided into independent variables. Using SPSS 23.0 software, pearson correlation was used to establish the correlation analysis between mineral elements, RS%, S/A and sensory evaluation score. The results were shown in table 3. Table 3 showed that, K contents and P, Mg contents were significantly positively correlated. The P contents were positively correlated with the K, Mg contents and negatively correlated with the S/A contents. The Mg contents were positively correlated with the K, P, Na contents. And it had a significant positive correlation with B, Li contents. The Ca contents were positively correlated with the Zn contents. And it had a significant positive correlation with Li contents. The Na contents were positively correlated with the Mg, Mn contents. And it had a significant positive correlation with Cu contents. The Zn contents were positively correlated with the Ca, Cu contents. And it had a significant negative correlation with B contents. The B contents were positively correlated with the Mg contents. And it had a significant negative correlation with Zn contents. The Mn contents were positively correlated with the Na contents. And it had a significant positive correlation with RS% ratios. The Li contents were positively correlated with the Mg, Ca contents. The Cu contents were positively correlated with the Zn contents. And it had a significant positive correlation with Na contents, also had a significant negative correlation with Se contents. The Se contents and the Cu contents were significantly negative correlation. And there were significant positive correlation between reducing sugar contents and Mn contents. A significant negative correlation was exited between sugar-acid ratios and P contents, it was positively correlated with the senses. In this paper, the contents of mineral elements (including K, P, Mg, Ca, Na, Fe, Cu, Mn, B, Zn, Se, Li) in 54 Olecranon

Conclusions
Peaches were collected. Reducing sugar(RS), total soluble sugar (S) and titratable acid (A) were determined by the National Standard. The correlation analysis (CA) was carried out by SPSS 23.0 software to find out the mineral elements and nutrient components significantly related to the sensory evaluation of Olecranon Peaches. The results showed that in the tested samples, it had a significant positive correlation between S/A sugar-acid ratio and sensory evaluation. S/A was negatively correlated with P contents. The P contents were positively correlated with the K、Mg contents. The Mg contents were positively correlated with the K、Na contents. The Na contents were positively correlated with the Mn contents. The contents of Mn were positively correlated with RS% ratios of reducing sugar. Systematic studies on the relationship between mineral elements, nutritional components and sensory evaluation of Olecranon Peaches were few. This paper is just a simple preliminary study. Further research is needed to collect relevant data for different years in order to establish a complete and reliable correlation model.