Evaluation of Markers Associated with Physiological and Biochemical Traits during Storage of 'Nam Dok Mai Si Thong' Mango Fruits

Mango 'Nam dok mai si thong' is in high demand worldwide, displaying desirable attributes which include a particularly sweet flavour and visually appealing appearance. Physiological and biochemical changes that occur in the fruit post-harvest are key factors in determining fruit quality and, consequently, predicted shelf life. In order to understand which post-harvest markers play crucial roles during the ripening process, as well as those which are a consequence of disease infection and physical damage caused by essential oil vapour, partial least squares (PLS) correlation models were used. During storage, physiochemical (percent weight loss, peel colour, firmness, pH, and peel electrolyte leakage) and biochemical (titratable acidity, total soluble solids, total phenolic compounds, total flavonoid compounds, antioxidants, total sugar, and reducing sugar content) parameters, as well as near-infrared (NIR) spectra, were monitored and correlated with visual post-harvest physiological responses. The majority of analysed markers displayed distinct relationships with the ripening process of mangoes, where for non-destructive parameters (R-2 = 0.86), lightness (L*) and b* value were notably significant, and for destructive parameters (R-2 = 0.79), pH and total soluble solids were notably significant. Similarly, the same markers were also correlated with physical damage and post-harvest mango disease infection severity, possibly through polysaccharide deformation and activation of browning-related enzymes. NIR imaging results also revealed the absorbent regions involved in biochemical alterations (water and enzymes; absorbance at 1170 nm, 1400-1500 nm, and 2150-2250 nm) that pertain to the fruit's quality. The findings from this work provide an initial step towards the development and assessment of quality measures for 'Nam dok mai si thong' mango.