Table 2.

Conditions employed to obtain antioxidant peptides from fruit residues.

Fruit Residue	Enzyme/Microorganisms	Buffer (pH)	Temperature (°C)	Time (h)	Refs.
RELEASE OF PEPTIDES BY MICROBIAL FERMENTATION
Tomato seed	Lactobacillus plantarum	—	37	24	[36]
Tomato seed	Water kefir microbial mixture	—	37	24	[37,41]
Tomato seed	Bacillus subtilis	—	40	20	[38]
Tomato seed	Bacillus subtilis	—	37	24	[39,40]
RELEASE OF PEPTIDES BY ENZYMATIC DIGESTION
Pumpkin oil cake	Alcalase	Tris-HCl (0.1 M and pH 8.0)	50	1	[58]
	Flavourzyme			1
	Alcalase and flavourzyme			2
Pumpkin oil cake	Alcalase	Phosphate (pH 8.0)	50	0–2.5	[62]
	Flavourzyme	Phosphate (pH 7.0)	50
	Pepsin	Phosphate (pH 3.0)	37
Pumpkin oil cake	Alcalase	Tris-HCl (pH 9.0)	50	3.5	[59]
	Trypsin	Tris-HCl (pH 8.0)	35	5
Pumpkin seed	Acid protease	pH 2.5	50	5	[60]
Pumpkin meal	Alcalase	pH 8.0	55	5	[63]
	Flavourzyme	pH 7.0	50
	Protamex	pH 6.5	50
	Neutrase	pH 7.0	50
Peach, plum, apricot, and olive seeds	Pepsin and pancreatin	pH 2.0 and pH 8.0	37	3	[11]
Apricot seeds	Alcalase	Borate (5 mM and pH 8.5)	50	4	[11]
	Thermolysin	Phosphate (5 mM and pH 8.0)		4
	Flavourzyme	Phosphate (5 mM and pH 7.5)		8
Plum seeds	Alcalase	Borate (5 mM and pH 8.5)	50	3	[14,35]
	Thermolysis	Phosphate (5 mM and pH 8.0)	50	4
	Flavourzyme	Phosphate (5 mM and pH 7.0)	50	7
	Protease P	Phosphate (5 mM and pH 7.5)	40	24
Apricot seeds	Alkaline and flavor proteases	-	-	-	[27]
Peach seeds	Alcalase	Phosphate (5 mM and pH 8.0)	50	4	[28]
	Thermolysin	Phosphate (5 mM and pH 8.0)	50	4
	Flavourzyme	Ammonium bicarbonate (5 mM and pH 6.5)	50	3
	Protease P	Phosphate (5 mM and pH 7.5)	40	7
Cherry seeds	Alcalase	Borate (pH 8.5)	50	7	[33]
	Thermolysin	Phosphate (pH 8.0)
	Flavourzyme	Bicarbonate (pH 6.0)
Chinese cherry seeds	Alcalase and Neutrase	Water (pH 7.5)	50	2	[55]
Olive and peaches seeds	Alcalase	Borate (5 mM and pH 8.5)	50	4	[16]
Olive seeds	Alcalase	Phosphate (5 mM and pH 8.0)	50	2	[17]
	Thermolysin	Phosphate (5 mM and pH 8.0)
	Flavourzyme	Ammonium bicarbonate (5 mM and pH 6.0)
	Trypsin	Tris-HCl (5 mM and pH 9.0)
	Neutrase	Phosphate (5 mM and pH 7.0)
Tomato seeds	Alcalase	Phosphate (pH 8.0)	50	0.5–3	[43]
Tomato seeds	Alcalase	Phosphate (pH 8.0)	50	2.3	[21]
Milled rapeseed	Pepsin	Phosphate (0.1 M and pH 2.0)	40	3	[23]
	Trypsin	Phosphate (0.1 M and pH 7.0)	40	3
	Alcalase	Phosphate (0.1 M and pH 7.0)	50	3
	Subtilisin	Phosphate (0.1 M and pH 8.0)	60	3
	Thermolysin	Phosphate (0.1 M and pH 8.0)	60	24
Jujube seeds	Papain	Tris-HCl (50 mM and pH 6.5–7.5)	65	1.5	[45,46]
	Alcalase	Tris-HCl (50 mM and pH 6.5–8.5)	60
	Protease P	Tris-HCl (50 mM and pH 7.5)	37
Muskmelon seeds	Pepsin and Trypsin	pH 2.0 and pH 7.0	37	6	[47]
Pumpkin (Cucurbita moschata), watermelon, and bottle gourd seeds	Trypsin	Tris-HCl (50 mM and pH 7.5)	-	4	[32]
Watermelon seeds	Alcalase	Phosphate (5 mM and pH 8.0)	60	5	[48,50]
	Trypsin	Phosphate (5 mM and pH 8.0)	37
	Pepsin	Glycine (5 mM and pH 2.2)	37
Watermelon seeds	Alcalase	pH 8.5	55	3	[51]
Watermelon seeds	Papain	—	—	—	[52]
	Pepsin	pH 2.4	37	3
	Protease	—	—	—
	Pancreatin	—	—	—
	Trypsin	—	—	—
	Chymotrypsin	—	—	—
Watermelon seeds	Alcalase	NaOH aq. (pH 9.0)	50	0.8	[53]
African breadfruit seeds	Trypsin, pepsin, and pancreatin	Water	-		[56]
Date palm seeds	Alcalase	pH 8.0	50	1	[65,66]
	Flavourzyme	pH 7.0		2
	Thermolysin	pH 8.0		3
Pomegranate peel	Alcalase	Borate (5 mM and pH 9.0)	50	2	[3]
	Thermolysin	Phosphate (5 mM and pH 7.5)	70	1
Pomegranate peel	Alcalase Thermolysin	Borate (5–10 mM and pH 9.0) Phosphate (5 mM and pH 7.5) or borate (100 mM and pH 7.5)	50 70	2 1	[25]

Note: Enzymes in bold characters are the ones which yielded the higher quantity of antioxidant peptides in each research work.