| The'Nanguo' pear is a kind of high-quality fruit belong to Pyrus ussuriensis Maxim, which is a specialty and widely cultivated in Anshan and Haicheng districts of Liaoning province for hundreds of years.Aroma of the fruit is strong,the juice is abundant,the quality and taste are very good,it could satisfy the demand of consumer,and therefore it is honored with'the queen of pears'.For the moment,the grading of quality on'Nanguo' pears still depends on manpower,and the grading index mainly are sample sizes,color,scabs and so on. This method has some disadvantages,such as the quantum of labor is great,the rate of production is low,also the method is not fit for the detecting of internal quality and industrialized development of'Nanguo' pears.Near infrared spectroscopy nondestructive detecting technique is a green analytical technique,which has developed faster in resent years, has fast,accurate and nondestructive merits.It can evaluate internal quality and external quality of fruit simultaneously without destroying samples.The factors(spectrometer parameter setting,sample conditions,spectral pretreatment methods and modeling methods) that influenced quality analysis of'Nanguo' pears by using NIRS analytical technique were studied in this research.Based on the proper parameters which were determined by factor analyzing,the nondestructive detecting models for the internal quality of pears(SSC,TA,firmness,brown heart) were established,then the predictive ability and applicability of models were analyzed.This study would provide supports to automation grading for'Nanguo' pears.Mainly research results were as follows:(1)Proper scanning conditions which were used for establishing NIRS nondestructive detecting models were confirmed.The results of test indicated that proper scanning times was 1 times to one point;proper scanning manner was 2 times by 180°running to several points; the enactment of scanning parameters simply satisfied the condition that the spectral line of samples and the spectral line of contrast were tangent in conquest line;it can obtain the greatest prediction performance with the spectral data which were determined in an aphotic room absolutely.(2)The influence degree of peer and color to NIR process for'Nanguo' pears were not prominence,whereas the degree of sample sizes and temperature were prominence.;In order to avoiding the disadvantages of sizes and temperature,different temperature and medium-sized pears were chosen to established calibration models;Disparity analysis results of models with different maturity degree samples demonstrated that the predictive ability of model with high maturity degree samples was better than the other two which were established with lower maturity degree samples.(3)The results of test indicated that second derivative method was proper derivative methods.Savitzky-Golay smoothing with 20 points was proper smoothing means.The contents of soluble solids and total acidity were proper chemic indices.(4)Based on proper modeling parameters and different optimization methods,uniform models were established,which were used for predicting SSC and TA content of'Nanguo' pears produced in Anshan and Haicheng districts at Liaoning province.For the results of SSC and TA models,correlation coefficient of calibration was 0.935 and 0.911;RMSEC was 0.212 and 0.018.(5)This trail utilized above two models to predict SSC and TA of'Nanguo' pears samples which were hoarding in different storage periods during room temperature and refrigeration,respectively,the predictive ability and applicable range of models were ascertained.The results of this test indicated that the NIRS nondestructive detecting models can be used for predicting SSC and TA of'Nanguo' pears samples which were in 12 days on the storage conditions of room temperature and in 4 months on the cold storage conditions.At the same time,the dynamic application of models to unknown samples from different years were completed;It showed that models were fit for predicting SSC and TA content of pears that produced in Anshan and Haicheng districts during different periods.(6)Based on the PLS method,uniform firmness model was established for'Nanguo' pears produced in Anshan and Haicheng districts of Liaoning province.For the results of firmness model,correlation coefficient of calibration and RMSEC were 0.970 and 0.124;the optimal predictive scope of firmness model was 2-15kg/cm2.(7)The brown results detecting by optical density difference methods showed that the value measurement order of△OD(712.92nm～672.93nm) were:0 degree＜1 degree＜2 degree＜3 degree,and the discipline was that the more brown heart areas,the lower the value of△OO(712.92nm～672.93nm);At last the assessment standard was instituted,when the value was high than 0.305,the pear was a good one,yet when the value was lower than or equal to 0.305,the pear was a brown one.According to the standard,2 pears from 100 brown pears were misjudged(false rate 2%) to good pears,2 pears from 30 good pears were misjudged to brown pears(false rate 6.67%).(8)The brown results detecting by brown areas methods showed that brown model with samples spectrum which were gathered under all wavelength band was better than the others, For the results of brown areas model,correlation coefficient of calibration and RMSEC were 0.965 and 0.016;The estimated performance of the brown model was that correlation coefficient of prediction and RMSEP were 0.811 and 0.059;When the area ratio was lower than 0.1,the misjudgments probability would raise.
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