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Abstract: watermelon is a popular fruit in the world with soluble solids content (SSC) being one of the major characteristics used for assessing its quality. This study was aimed at obtaining a method for nondestructive SSC detection of watermelons by means of visible/near infrared (Vis/NIR) diffuse transmittance technique. Vis/NIR transmittance spectra of intact watermelons were acquired using a low-cost commercially available spectrometer operating over the range 350~1000 nm. Spectra data were analyzed by two multivariate calibration techniques: partial least squares (PLS) and principal component regression (PCR) methods. Two experiments were designed for two varieties of watermelons [Qilin (QL), Zaochunhongyu (ZC)], which have different skin thickness range and shape dimensions. The influences of different data preprocessing and spectra treatments were also investigated. Performance of different models was assessed in terms of root mean square errors of calibration (RMSEC), root mean square errors of prediction (RMSEP) and correlation coefficient (r) between the predicted and measured parameter values. Results showed that spectra data preprocessing influenced the performance of the calibration models. The first derivative spectra showed the best results with high correlation coefficient of determination [r=0.918 (QL); r=0.954 (ZC)], low RMSEP [0.65 °Brix (QL); 0.58 °Brix (ZC)], low RMSEC [0.48 °Brix (QL); 0.34 °Brix (ZC)] and small difference between the RMSEP and the RMSEC by PLS method. The nondestructive Vis/NIR measurements provided good estimates of SSC index of watermelon, and the predicted values were highly correlated with destructively measured values for SSC. The models based on smoothing spectra (Savitzky-Golay filter smoothing method) did not enhance the performance of calibration models obviously. The results indicated the feasibility of Vis/NIR diffuse transmittance spectral analysis for predicting watermelon SSC in a nondestructive way.

[1] Birth, G.S., Dull, G.G., Renfore, W.T., Kays, S.J., 1985. Nondestructive spectrophotometric determination of dry matter in onions. J. Am. Soc. Hort. Sci., 110:297-303.

[2] Chen, C., Shaw, J., 1999. Determination of the sugar content and acidity of pears by a portable near-infrared spectrophotometer. J. Agric. Machinery, 8(1):49-57.

[3] Chen, H., Baerdemaeker, J.D., Bellon, V., 1996. Finite element study of the melon for nondestructive sensing of firmness. Transactions of the ASAE, 39(3):1057-1065.

[4] Diezma-Iglesias, B., Ruiz-Altisent, M., Barreiro, P., 2004. Detection of internal quality in seedless watermelon by acoustic impulse response. Biosystems Engineering, 88(2):221-230.

[5] Dull, G.G., Birth, G.S., Leffler, R.G., 1989a. Use of near infrared analysis of nondestructive measurement of dry matter in potatoes. J. Amer. Potato, 66:215-225.

[6] Dull, G.G., Birth, G.S., Smittle, D.A., Leffler, R.G., 1989b. Near infrared analysis of soluble solids in intact cantaloupe. J. Food Sci., 54(2):393-395.

[7] Dull, G.G., Leffler, R.G., Birth, G.S., Smittle, D.A., 1992. Instrument for nondestructive measurement of soluble solids in honeydew melons. Transactions of the ASAE, 35(2):735-737.

[8] Kawano, S., Fujiwara, T., Iwamoto, M., 1993. Nondestructive determination of sugar content in satsuma mandarin using near infrared (NIR) transmittance. J. Jpn. Soc. Hort. Sci., 62(2):465-470.

[9] Lammertyn, J., Nicolay, B., Ooms, K., Semedt, V.D., Baerdemaeker, J.D., 1998. Non-destructive measurement of acidity, soluble solids and firmness of Jonagold apples using NIR-spectroscopy. Transactions of the ASAE, 41(4):1089-1094.

[10] Liu, Y.D., Ying, Y.B., 2004. Measurement of sugar content in Fuji apples by FT-NIR spectroscopy. J. Zhejiang Univ. Sci., 5(6):651-655.

[11] Liu, Y.D., Ying, Y.B., Fu, X.P., 2005. Prediction of valid acidity in intact apples with Fourier transform near infrared spectroscopy. J. Zhejiang Univ. Sci. B, 6(3):158-164.

[12] Lu, R., 2001. Predicting firmness and sugar content of sweet cherries using near-infrared diffuse reflectance spectroscopy. Transactions of the ASAE, 44(5):1265-1271.

[13] Mahayothee, B., Mühlbauer, W., Neidhart, S., Leitenberger, M., Carle, R., 2004. Non-destructive of maturity of Thai mangoes by near-infrared spectroscopy. Acta Hort., 645:581-588.

[14] Nourain, J., Ying, Y.B., Wang, J.P., Rao, X.Q., Yu, C.G., 2005. Firmness evaluation of melon using its vibration characteristic and finite element analysis. J. Zhejiang Univ. Sci. B, 6(6):483-490.

[15] Peiris, K.H.S., Dull, G.G., Leffler, R.G., Kays, S.J., 1997. Nondestructive Determination of Sugar Content of Peach by Near Infrared Spectroscopy. Proceedings of Conference on ‘Sensors for Non-destructive Testing’. Orlando, FL, p.77-87.

[16] Peiris, K.H.S., Dull, G.G., Leffler, R.G., Kays, S.J., 1999. Spatial variability of soluble solids or dry-matter content within individual fruits, bulbs, or tubers: implications for the development and use of NIR spectrometric techniques. HortScience, 34(1):114-118.

[17] Slaughter, D.C., 1995. Nondestructive determination of internal quality in peaches and nectarines. Transactions of the ASAE, 38(2):617-623.

[18] Slaughter, D.C., Thompson, J.F., Tan, E.S., 2003. Nondestructive determination of total and soluble solids in fresh prune using near infrared spectroscopy. Postharvest Biol. Technol., 28(3):437-444.

[19] Yamamoto, H., Iwamoto, M., Haginuma, S., 1981. Nondestructive acoustic impulse response method for measuring internal quality of apples and watermelons. J. Jpn. Soc. Hort. Sci., 50(2):247-261.