Characterization and antioxidant evaluation of phenolic compounds extracted from the protein concentrate and protein isolate produced from pawpaw (Carica papaya Linn.) seeds

Figures & data

Figure 1. Preparation of whole and defatted flour.

Figure 2. Scheme for the production of protein concentrate. Adapted from Cheftel et al. ^[47] as modified by Gbadamosi et al.^[12]

Figure 3. Scheme for the production of protein isolate. Adapted from Chavan et al.^[4]

Table 1. The individual flavonoids and phenolic compounds in the extracts (mg/DWg) of understudy Carica papaya samples.

Peak	Compounds	MF	λ(nm)	Fragmentor (v)	Precursorion	Collision Energy (V)	Quantitative transition (m/z)
	Phenolic acids (PA)
1	Caffeic acid*	C9H8O4	325	90	179	15	179 > 135
2	Ferulic acid*	C10H10O4	323,292	90	137	15	193 > 134
3	p-hydroxybenzoic acid	HOC6H4CO2H	256	90	198	15	137 > 93
4	p-coumaric acid*	C9H8O3	236,310	90	354	15	163 > 119
	Flavonoids (FLA)
5	Kaempferol-3-glucoside*	C21H20O11	348	90	447	15	447 > 285
6	Quercetin-3-galactoside*	C21H20O12	353	90	463	15	609 > 301

Table 2. Phenolic content of understudy Carica papaya samples (mg/DWg sample).

Phenolic Compounds	Caffeic acid	Ferulic acid	p-Hydroxybenzoic acid	p-Coumaric acid	Kaempferol-3-glucoside	Quercetin-3-galactoside	Total
PI	0.43 ± 0.00	0.62 ± 0.01	0.39 ± 0.01	0.35 ± 0.00	0.05 ± 0.00	0.16 ± 0.00	2.05 ± 0.01
PC	0.33 ± 0.01	0.41 ± 0.02	0.28 ± 0.00	0.29 ± 0.00	0.03 ± 0.01	0.09 ± 0.01	1.45 ± 0.01
DF	0.27 ± 0.00	0.38 ± 0.01	0.19 ± 0.02	0.21 ± 0.01	0.08 ± 0.00	0.14 ± 0.03	1.25 ± 0.00
WF	0.19 ± 0.00	0.26 ± 0.00	0.07 ± 0.00	0.13 ± 0.02	0.12 ± 0.02	0.11 ± 0.01	0.88 ± 0.02
Min	0.19	0.26	0.07	0.13	0.03	0.09	0.77
Max	0.43	0.62	0.39	0.35	0.12	0.16	2.09
Mean	0.36	0.88	0.23	0.24	0.08	0.13	1.96

WF: Full-Fat flour of Carica papaya seed, DF: Defatted flour of Carica papaya seed, PC: Protein concentrate of Carica papaya seed, PI: Protein isolate of Carica papaya seed; mDPPH, mMC, mFRAP, mTPC: Absolute methanolic extracts; DPPH, MC, FRAP, TPC: Aqueous methanolic extracts.

Table 3. Antioxidant activities of Carica papaya full-fat, defatted flour, protein concentrate and protein isolate.

	DPPH Radical Scavenging (mg/ml)			Metal Chelating Abilities (mg/ml)			Ferric Reducing (AAE µg/g)		Total Phenol Content (GAE µg/g)
Samples	mDPPH	DPPH	DPPH IC50	mMC	MC	MC IC50	mFRAP	FRAP	mTPC	TPC
PI	0.344 ± 0.04^b	0.441 ± 0.04^a	0.266 ± 0.018^a	0.569 ± 0.01^b	0.652 ± 0.03ab	0.202 ± 0.001a	0.783 ± 0.01a	0.521 ± 0.01^a	0.17 ± 0.01^d	0.29 ± 0.01^d
PC	0.321 ± 0.14^c	0.429 ± 0.03^ab	0.227 ± 0.005^b	0.409 ± 0.01^c	0.534 ± 0.11d	0.157 ± 0.001^b	0.722 ± 0.01b	0.478 ± 0.01^b	0.24 ± 0.01^b	0.50 ± 0.01^b
DF	0.332 ± 1.17^c	0.402 ± 0.06^abc	0.289 ± 0.057^c	0.334 ± 0.07^d	0.565 ± 0.56c	0.151 ± 0.004^c	0.626 ± 0.01c	0.462 ± 0.01^bc	0.45 ± 0.01^a	0.64 ± 0.01^a
WF	0.302 ± 0.07^cd	0.370 ± 0.11^d	0.155 ± 0.004^d	0.282 ± 0.06^e	0.432 ± 0.14e	0.119 ± 0.001^d	0.651 ± 0.01c	0.405 ± 0.03^d	0.20 ± 0.03^c	0.43 ± 0.01^c
ASC	0.448 ± 0.04^a	0.448 ± 0.04^a	0.109 ± 0.001^e	–	–	–	–	–	–	–
EDTA	–	–		0.677 ± 0.04^a	0.677 ± 0.04^a	0.091 ± 0.001^d	–	–	–	–

Values reported are means ± standard deviation of triplicate determinations. Mean values with different superscript within the columns are significantly (P < 0.05) different.

WF: Full-Fat flour of Carica papaya seed, DF: Defatted flour of Carica papaya seed, PC: Protein concentrate of Carica papaya seed, PI: Protein isolate of Carica papaya seed; Absolute methanolic extracts; mDPPH, mMC, mFRAP, mTPC: Aqueous methanolic extracts; DPPH, MC, FRAP, TPC.

Figure 4. DPPH radical scavenging activities of pawpaw whole seed flour, defatted flour, protein concentrate and protein isolate (a) 100% methanolic extract (b) 80% methanolic extracts.WF: Whole flour of Carica papaya seed, DF: Defatted flour of Carica papaya seed, PC: Protein concentrate of Carica papaya seed, PI: Protein isolate of Carica papaya seed.

Figure 5. Ferric reducing activity (FRAP) of pawpaw whole seed flour, defatted flour, protein concentrate and protein isolate (a) 100% methanolic extract (b) 80% methanolic extracts.WF: Whole flour of Carica papaya seed, DF: Defatted flour of Carica papaya seed, PC: Protein concentrate of Carica papaya seed, PI: Protein isolate of Carica papaya seed.

Figure 6. Metal chelating abilities of pawpaw whole seed flour, defatted flour, protein concentrate and protein isolate (a) 100% methanolic extract (b) 80% methanolic extracts.WF: Whole flour of Carica papaya seed, DF: Defatted flour of Carica papaya seed, PC: Protein concentrate of Carica papaya seed, PI: Protein isolate of Carica papaya seed.

Figure 7. Radical scavenging and antioxidant activity: correlation of polyphenols on free radical scavenging and total antioxidant activities in Carica papaya protein isolate.

Cheftel, J.C.; Cuq, J.L.; Lorient, D. Food Chemistry: Amino Acids, Peptides and Proteins. Eds. Fennema, O.R. New York, NY: Marcel Dekker, 1985, pp. 127−228.

 Google Scholar

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 PubMed Web of Science ®Google Scholar