Analysis Of Chemical Content And Adulteration Of Camellia Oleifera Oil By Near Infrared Spectroscopy

As the high quality of edible oil, Camellia oleifera oil （C. oil） is the consumers’ attentionand market demands. The serious adulteration of C. oil has destroyed original quality andnutritional characteristics. The accurate examination for quality trait of C. oil is extremelyurgent.This paper would present the analysis of fatty acid composition, volatile unique flavorand the unsaponifiable matter of C. oil, in order to build the characteristic and standard oforigin oil, and adulteration of quality trait of C. oil by near infrared spectroscopy.Main contents and rerults are summarized as follows:（1） Analysis of the chemical content of C. oilThe oil content concentrated between30%and60%, and the average was38.39%. C. oilwas mainly composed of palmitic acid, stearic acid, oleic acid and linoleic acid. The content ofoleic acid ranged from70.33%～86.21%, the average was78.24%; linoleic acid ranged from3.25%～17.18%，the average was9.50%; palmitic acid ranged from7.03%～13.85%,theaverage was9.63%; stearic acid ranged from1.35%～5.49%, the average was2.61%.Volatile unique flavor of C. oil, detected by SMPE-GC-MS, was mainly composed ofaldehydes, terpenes and acids. The unsaponifiable matter of C. oil was examined byPy-GC-MS, it was mainly composed of acyclic monoterpenoid, diterpene, triterpene, amyloseof olefins, long-chain alcohol （ester, ketone） and alkylphenol, steride.（2）Rapid analysis of chemical content of C. oil by near infrared spectroscopyCombined with the near infrared reflectance spectroscopy and transmittance spectroscopy,NIRS and NITS models were well established with different pretreatment methods andregression analysis. The results demonstrated that, for the NIRS model, the correlationcoefficients of calibration （R_c） and the root mean square errors of calibration （RMSEC） were0.92567and2.53；the correlation coefficients of cross-validation (R_cv) and the root meansquare errors of cross-validation（RMSECV） were0.91727and2.67. for the NITS, R_c, RMSEC, R_cv, RMSECV were0.95079,2.10,0.86792and3.41. The correlation coefficients of externalvalidation （R²） were0.806and0.7651.NITS models for oleic, linoleic, palmitic acids were better than stearic acid, unsaturationfatty acids. The three models of R_cwere0.93446,0.96538and0.88789, R_cvwere0.91987,0.95755and0.84447. The two models of R_cwere0.73378and0.78823, R_cvwere0.69114and0.67440.The practical validation results demonstrated prediction ability of NITS modelsfor oleic, linoleic, palmitic acids were more accurate and reliable than stearic acid, unsaturationfatty acids. R²were0.9424,0.9682,0.8862,0.6834and0.8575, respectively.（3）Rapid analysis of adulteration of C. oil by near infrared spectroscopyQuantitative models of C. oil adulterated with one or two kinds edible oils were welldeveloped by the near infrared transmittance spectroscopy with different spectral pretreatmentmethods and regression analysis. The results demonstrated that, for the best model mixeddifferent proportions soybean oil（0%～50%）, R_cand RMSEC were0.99999and0.05770；R_cvand RMSECV were0.99999and0.0719. For the best model mixed different proportionsmaize oi（l0%～50%）, R_cand RMSEC were0.99997and0.113；R_cvand RMSECV were0.99996and0.128. For the best model mixed different proportions maize （0%～40%）and soybeanoil, R_cand RMSEC were0.99979and0.236；R_cvand RMSECV were0.99961and0.323.Moreover, R²were0.9998,0.9999and0.9967, respectively.From the external validation of each NIRS model, we could see that the near infraredspectroscopy could analyse the oil content, each fatty acid and the adulterated oil in the two orthree system of mixed C. oil, effectively, rapid and nondestructively.