Effects of Pitaya Peel Supplementation on Nutritional Quality, Overall Sensory Acceptance, In Vitro Glycemic Index, and Antioxidant Release from Fiber-Enriched Cookies

Table 2

Changes in phenolic and betacyanin contents and antioxidant activities of cookie samples with different ratios of pitaya peel powder during the in vitro sequential digestion.

Digestion step		Ratio of pitaya peel powder (% of the total weight of pitaya peel powder and wheat flour)	Betacyanin (mg/kg dw)	Total phenolic (mg GAE/100 g dw)	DPPH activity (μmol TE/100 g dw)	FRAP activity (μmol TE/100 g dw)
Salivary digestion		0	—	21.1 ± 1.2^eD	16.6 ± 2.1^eC	26.7 ± 0.7^eB
		10	16.2 ± 0.5^dB	69.7 ± 1.3^dC	60.6 ± 3.9^dD	119.2 ± 2.3^dC
		15	17.8 ± 0.6^cB	78.7 ± 0.2^cC	84.2 ± 6.6^cD	142.9 ± 3.6^cC
		20	20.9 ± 1.2^bB	85.1 ± 1.7^bC	95.9 ± 4.0^bD	172.6 ± 4.9^bC
		25	27.5 ± 0.4^aB	94.4 ± 2.4^aC	105.6 ± 2.8^aD	195.5 ± 8.2^aC
Gastric digestion		0	—	103.3 ± 4.1^dB	52.6 ± 6.6^eA	71.7 ± 1.3^eA
		10	3.8 ± 0.4^dC	154.7 ± 3.8^cB	121.5 ± 5.4^dB	160.3 ± 5.0^dB
		15	6.5 ± 0.9^cC	165.1 ± 5.7^bB	183.0 ± 8.2^cB	199.5 ± 10.4^cB
		20	7.9 ± 0.3^bC	182.8 ± 2.8^aB	227.8 ± 7.9^bB	245.2 ± 6.0^bB
		25	9.4 ± 0.4^aC	188.6 ± 3.3^aB	318.1 ± 11.0^aB	267.8 ± 5.3^aB
Intestinal digestion		0	—	32.4 ± 1.2^dC	39.7 ± 1.2^eB	26.8 ± 2.8^eB
		10	3.2 ± 0.3^bD	42.9 ± 2.8^cD	98.7 ± 4.5^dC	43.4 ± 1.0^dD
		15	3.2 ± 0.5^bD	45.1 ± 1.1^bcD	120.6 ± 5.7^cC	54.7 ± 1.3^cD
		20	3.7 ± 0.5^abD	47.1 ± 0.7^abD	131.2 ± 1.9^bC	60.5 ± 2.1^bD
		25	4.6 ± 0.7^aD	49.5 ± 1.2^aD	138.7 ± 3.4^aC	63.9 ± 1.2^aD
Colon digestion	Pronase E	0	—	9.5 ± 0.4^eE	16.1 ± 1.4^eC	15.8 ± 1.3^eC
		10	2.1 ± 0.8^aE	13.1 ± 0.3^dE	32.1 ± 4.6^dE	35.6 ± 1.1^dE
		15	2.1 ± 0.5^aE	14.6 ± 0.2^cE	71.9 ± 2.4^cDE	44.6 ± 2.6^cE
		20	2.3 ± 0.2^aE	16.2 ± 1.3^bE	90.9 ± 4.7^bD	50.4 ± 1.6^bD
		25	2.9 ± 0.4^aDE	19.4 ± 0.7^aE	106.8 ± 3.8^aD	55.9 ± 2.0^aD
	Viscozyme L	0	—	6.8 ± 0.3^eE	9.7 ± 0.7^eD	9.9 ± 3.0^cD
		10	0.4 ± 0.1^aF	13.8 ± 0.6^dE	39.5 ± 3.4^dE	16.4 ± 0.4^bF
		15	0.4 ± 0.1^aF	15.5 ± 0.2^cE	74.0 ± 5.5^cE	18.2 ± 0.5^abF
		20	0.5 ± 0.2^aF	18.2 ± 0.3^bE	88.4 ± 1.1^bD	18.7 ± 0.2^abE
		25	0.5 ± 0.2^aE	21.0 ± 1.2 ^aE	98.1 ± 3.0^aD	21.2 ± 2.5^aE
Total (for the four steps)		0	—	173.2 ± 6.3^eA	134.8 ± 9.6^eA	150.9 ± 5.1^eA
		10	25.7 ± 1.8^dA	294.1 ± 0.8^dA	352.4 ± 4.7^dA	375.0 ± 2.1^dA
		15	30.0 ± 1.4^cA	319.1 ± 7.0^cA	533.7 ± 6.9^cA	459.9 ± 8.3^cA
		20	35.2 ± 0.4^bA	349.5 ± 0.6^bA	634.3 ± 8.3^bA	547.3 ± 9.5^bA
		25	45.0 ± 0.9^aA	372.9 ± 4.0^aA	767.3 ± 7.1^aA	604.2 ± 14.7^aA

In the same column and in the same step of the in vitro digestion, the values with different lowercase letters (a–e) are significantly different ( < 0.05); in the same column and with the same ratio of pitaya peel powder, the values with different capital letters (A–C) are statistically different ( < 0.05); dw: dry weight; GAE: gallic acid equivalent; DPPH: 2,2-diphenyl-1-picrylhydrazyl; TE: trolox equivalent; FRAP: ferric reducing antioxidant power.