Table 1.

Overview of the non-destructive methods for the assessment of fruit ripening and their correlation with internal characteristics. Abbreviations: SSC (Soluble solid content), DM (Dry matter), MC (Moisture content), TTA (Titratable acidity), TSS (Total soluble solid) and WC (Water content).

	Colorimetry	Visible Imaging	Spectroscopy	Fluorescence	Hyperspectral Imaging	Multispectral Imaging
Apple	Colour [21]	Colour [22]	Chlorophyll [23], anthocyanins [24], carotenoids [24], flavonols [25], SSC [26], firmness [27]	Chlorophyll [28], anthocyanins [29], flavonols [29], firmness [29], SSC [29]	Firmness [30], SSC [31]	Firmness [32], SSC [33]
Pear			Firmness [34], SSC [35]		SSC [36]
Peach	Colour [37]		Firmness [38], chlorophyll [39], colour [37]	Firmness [40]	Firmness [41]	Firmness [9], SSC
Avocado			MC [42], DM [42]		DM [43]
Nectarine	Colour [44]		SSC [45], firmness [45]	Firmness [40]
Mango	Colour [46]		DM [47], starch [48], SSC [47], colour [49], firmness [50]		Firmness [8], SSC [8], WC [8]
Banana	Colour [51]	Colour [51]	TSS [52], Chlorophyll [53]		Firmness [54], TSS [54]
Tomato	Colour [55], firmness [56], TSS [57]	Colour [58], firmness [59]	Lycopene [60], SSC [61]	Chlorophyll [62]		Phenolic [63], lycopene [63]
Melon			SSC [64]
Mandarin			TTA [65], SSC [66], firmness [67], DM [68]
Cherry	Colour [69]		Firmness [70], SSC [71]
Strawberry			Colour [72], TSS [73], Firmness [72], TTA [73]		Firmness [74], TSS [75], TTA [75]	SSC [76], firmness [77]
Apricot			SSC [78], firmness [78], TTA [78]
Kiwifruit			TSS [79], SSC [79], firmness [80], DM [81], Starch content [79]
Persimmon			SSC [82]		Firmness [83]
Grape			SSC [84], TTA [84], anthocyanin [85]	Chlorophyll [86], anthocyanin [86], TSS [86], flavonols [87]	SSC [88], TTA [88]
Pineapple		Colour [89]	DM [90], SSC [91]
plum			Firmness [92], SSC [93], colour [92]