Research On Near Infrared Spectroscopy For Rapid Measurements Of SSC, TA And Firmness In Nutmeg Melon

Nutmeg melon belongs to the genus of cucumis and the family of cucurbitacea, which is one of the favorite fruits for consumers. Chemical methods are the common ways for the detection of its quality, but there are lots of shortcomings such as complicated ways of sample preparation, time-consuming analysis and high cost. During these years Near Infrared spectroscopy has been widely used for quality determination of fruits and vegetables owing to its advantages such as convenience, rapidness, non-destruction and full of abundant information. The objective of this research was to establish quantitative models for rapid measurements of soluble solids content, titrable acidity and firmness in nutmet melon using Fourier Transform NIR diffuse reflectance spectroscopy and to determine the best parameters for the established model through optimization. The main results are as follows:1. Using NIR diffuse reflectance spectroscopy as a rapid and non-destructive method for the determination of soluble solids content of nutmeg melon, the results showed that the best statistical model was developed using partial least square regression with respect to vector normalization and 10 as the No. of factors in the wave number range of 6101.9 cm-1～5446.2 cm-1 and 4601.5 cm-1～4246.6 cm-1. The correlation coefficient (R2) of the model was 0.8647 and the root mean square error of cross validation (RMSECV) was 0.412. Using the model to validate 22 samples, the results showed that R2 was 0.8895 and the root mean square error of prediction (RMSEP) was 0.339. It was concluded that the prediction of the model can meet the requirement of rapid measuring of nutmeg melon's soluble solids content.2. Using NIR diffuse reflectance spectroscopy as a rapid and non-destructive method for the determination of titrable acidity of nutmeg melon, the results showed that the best statistical model was developed using PLSR with respect to second derivative and 9 as the No. of factors in the wave number range of 7502.0cm-1～5446.2cm-1. R2 of the model was 0.8617 and RMSECV was 0.245. Using the model to validate 20 samples, the results showed that R2 was 0.8831 and RMSEP was 0.237. It was concluded that the prediction of the model can meet the requirement of rapid measuring of nutmeg melon's titrable acidity.3. Using NIR diffuse reflectance spectroscopy as a rapid and non-destructive method for the determination of firmness of nutmeg melon, the results showed that the best statistical model was developed using PLSR with respect to constant offset elimination and 9 as No. of factors in the wave number range of 6101.9cm-1～5446.2cm-1. R2 of the model was 0.9885 and RMSECV was 0.058. Using the model to validate 30 samples, the results showed that R2 was 0.9858 and RMSEP was 0.063. It was concluded that the prediction of the model can meet the requirement of rapid measuring of nutmeg melon's firmness.