Relationship between bulk scattering, sensory texture and water spectral pattern in 'Braeburn' apples

A. Rizzolo, M. Vanoli, M. Buccheri, M. Grassi, F. Lovati, A. Torricelli, L. Spinelli, N. Sadar, A. Zanella
In this research, the relationship between scattering properties, texture sensory profile and Water Matrix Coordinates (WAMACs) during shelf life was studied on 'Braeburn' apples. In this regard, 20 fruit samples kept at 20°C were selected at 0, 2, 4, 6, 8, 10, 14 and 21 days and measured non-destructively by TRS for bulk μ's estimation, and by a MicroNIR spectrometer for determining WAMACs; afterwards, apples were assessed for texture sensory characteristics. 'Braeburn' apples underwent changes in sensory texture from the firm/crispy/juicy ones at day 0 to the very mealy at day 21, which caused the increase of TRS bulk scattering. Regression analysis showed that μ's significantly increased with time of shelf life following a linear model (R2adj=48.6%) and the performance of the model greatly increased when the probelation approach, i.e. the position according to increasing μ's value within each sampling time (POS), was included (R2adj=87.3%). PCA analysis carried out on μ's, firmness, juiciness, mealiness and crispiness sensory scores and on the absorbance at the 12 wavelengths of NIR analysis bound to WAMACs in the 1342-1515 nm range explained 85% of variance. PC-1 opposed μ's, mealiness and the NIR wavelengths 1342, 1366, 1373, 1385 and 1397 - related to water structure with weak-hydrogen bonds (positive) - to firmness, crispiness, juiciness and the NIR wavelengths 1410, 1435, 1447, 1466, 1472, 1490, 1515 - related to more organized water structures with medium-strong hydrogen bonds (negative). PC-1 showed an increasing trend with time of shelf life and POS. PC-2 opposed μ's and mealiness (negative) to firmness, juiciness and crispiness (positive), decreased till 6 days of shelf-life and was not influenced by POS. Concluding, results underline that μ's is positively related to the WAMACs corresponding to water weak-hydrogen bonds and confirmed the correlation between μ's and mealiness.
Rizzolo, A., Vanoli, M., Buccheri, M., Grassi, M., Lovati, F., Torricelli, A., Spinelli, L., Sadar, N. and Zanella, A. (2021). Relationship between bulk scattering, sensory texture and water spectral pattern in 'Braeburn' apples. Acta Hortic. 1311, 141-148
DOI: 10.17660/ActaHortic.2021.1311.18
time-resolved reflectance spectroscopy, scattering coefficient, water matrix coordinates, mealiness

Acta Horticulturae