Comprehensive Evaluation of Quality Characteristics of Four Oil-Tea Camellia Species with Red Flowers and Large Fruit

Red-flowered oil-tea camellia (ROC) is an important woody oil species growing in the south, and its oil has high nutritional value. There are four main species ofROCin China, namely,Camellia chekiangoleosa(CCH),Camellia polyodonta(CPO),Camellia semiserrata(CSE) andCamellia reticulata(CRE). Reports on the comprehensive comparative analysis ofROCare limited. This study investigated the fruit characteristics and nutritional components of fourROCfruits, and the results showed thatROChad high oil content with levels of 39.13%–58.84%, especially theCCHfruit, which reached 53.6–58.84%. The contents of lipid concomitants ofROCoil were also substantial, including β-amyrin (0.87 mg/g–1.41 mg/g), squalene (0.43 mg/g–0.69 mg/g), β-sitosterin (0.47 mg/g–0.63 mg/g) and α-tocopherol (177.52 μg/g–352.27 μg/g). Moreover, the transverse diameter(TD)/longitudinal diameter (LD) of fruits showed a significant positive correlation with the oil content, andROCfruits with thinner peels seemed to have better oil quality, which is similar to the result of the oil quality evaluation obtained by the gray correlation coefficient evaluation method. FourROCoils were evaluated using the gray correlation coefficient method based on 11 indicators related to the nutritional value ofROC.CCHoil had the highest score of 0.8365, and YS-2 (a clone ofCCH) was further evaluated as the bestCCHoil. Finally, the results of heatmap analysis showed that triglycerides could be used as a characteristic substance to distinguishCCHoil from the other threeROCoils. The PLSDA (Partial least squares regression analysis) model and VIP (Variable important in projection) values further showed that P/S/O, P/O/O, P/L/L, P/L/Ln, S/S/O, S/O/O and P/S/S (these all represent abbreviations for fatty acids) could be used as characteristic differential triglycerides among the fourROCoils. This study provides a convenient way for planters to assess the nutritional quality of seed oil depending on fruit morphology and a potential way to distinguish between variousROCoils.Keywords:red-flowered oil-tea camellia;Camellia chekiangoleosaoil;correlation analysis;gray correlation coefficient;triglycerides