Study on nondestructive detecting sugar content and pH value of pear by using near infrared diffuse reflectance Spectroscopy

【Objective】 The objectives of the study were to predict sugar content and pH value of pear fruit by using the near-infrared diffuse reflectance(NIR) spectra.【Method】 After three point windows moving smooth treatment,the first derivative D1log(1/R) and multivariant scattering correction were used to preprocess the primitive spectrum(350-1 800 nm) of pear fruit respectively.Multi-linear regression(MLR),principal component regression(PCR) and partial least square(PLS) regression were taken to build prediction models which were used to quantitatively analyze sugar content and pH value of pear fruit respectively.【Result】 The PLS model with D1log(1/R) data treatment is prior to the other two ways based on the comparative analysis.The results show that the correlation coefficients of sugar and pH value are 0.928 5 and 0.858 4 respectively,and root mean standard error of sugar and pH is 0.436 4 and 0.120 5 respectively.【Conclusion】 The research indicates that NIR spectroscopy could provide an accurate,reliable and nondestructive method for assessing the internal quality index sugar content and pH value of pear fruit.