Internal quality assessment of mandarin fruit by vis/NIR spectroscopy

Different measurement modes (reflectance, interactance and transmission) and spectral windows (500-1100 nm) were compared for their ability to predict non-destructively the harvest soluble solids content (SSC) and titratable acidity (TA) of Satsuma Mandarin (Citrus reticulata cv. "Miyagawa"). A direct transmission measurement mode (source and sensor opposite sides of fruit) coupled with a single spectral window from 700 to 930 nm delivered the most accurate SSC predictions (R-2 = 0.93, RMSEP = 0.32%). Accurate TA prediction was not possible with any measurement mode and the predictive ability that was achieved (best results: R-2 similar to 0.65, RMSEP similar to 0.15 %) was only afforded indirectly through a correlation with the skin chlorophyll changes that occur as the fruit mature.