Anthocyanin profile, color and antioxidant activity of blueberry (Vaccinium ashei) juice as affected by thermal pretreatment

Figures & data

Figure 1. Juice yield, total phenolic content (TPC), and anthocyanin content (TAC) of juices pressed from blueberries that were blanched by steaming or hot water bath for 0, 1, 2, 3, 4, 5, or 6 min. Different upper cases in the same series represent significant differences within one pretreatment group over time (P < .05). Error bar indicates mean value ± SD (n = 3)

Table 1. LC–MS data of anthocyanins in juice pressed from control, hot water bath (5 min) and steam (3 min) blanching blueberries

				Sample
Peak no.	Total (m)	Aglycone (z)	Anthocyanin	Control	Hot water bath	Steam
1	465	303	Delphinidin-3-galactoside	ND	D	D
2	465	303	Delphinidin-3-glucoside	D	D	D
3	449	287	Cyanidin-3-galactoside	ND	ND	D
4	449	287	Cyanidin-3-glucoside	D	D	D
5	479	317	Petunidin-3-galactoside	D	D	D
6	479	317	Petunidin-3-glucoside	D	D	D
7	463	301	Peonidin-3-galactoside	ND	D	D
8	463	301	Peonidin-3-glucoside	D	D	D
9	493	331	Malvidin-3-galactoside	D	D	D
10	493	331	Malvidin-3-glucoside	D	D	D
11	463	331	Malvidin-3- arabinoside	D	D	D

control: untreated; boiled: hot water bath blanching for 5 min; steamed: steam blanching for 3 min; D: Detected; ND: Not Detected.

Figure 2. Contents of individual anthocyanins in juices from control, hot water bath (5 min) and steam blanching (3 min) on the day of pressing (0 day). Different lowercase letters represent significant differences between three pretreatment groups (P < .05). Error bar indicates mean value ± SD (n = 3). Dpd: Delphinidin glycosides; Cyd: Cyanidin glycosides; Ptd: Petunidin glycosides; Pnd: Peonidin glycosides; Mvd: Malvidin glycosides

Figure 3. The total anthocyanin content (TAC) and retention rate of TAC (%) in juices from control, hot water bath (5 min) and steam (3 min) blanching blueberries during storage. Different uppercase letters represent significant differences within one pretreatment group over storage time, and different lowercase letters represent significant differences between three pretreatment groups on the same day (P < .05). Error bar indicates mean value ± SD (n = 3)

Figure 4. The total phenolic content (TPC) and antioxidant capacity in juices from control, hot water bath (5 min) and steam (3 min) blanching blueberries during storage. Different uppercase letters represent significant differences within one pretreatment group over storage time, and different lowercase letters represent significant differences between three pretreatment groups on the same day (P < .05). Error bar indicates mean value ± SD (n = 3). DPPH: free radical-scavenging capacity; FRAP: ferric reducing antioxidant power; T-AOC: total antioxidant capacity; ORAC: oxygen radical absorbance capacity

Table 2. Color parameters of lightness (L*) and hue angle (H°) of stored juice pressed from control, hot water bath (5 min) and steam (3 min) blanching blueberries

		Storage time (days)
Color index	Sample	0	2	5	7	10
L*	Control	13.87 ± 0.00^Aa	13.54 ± 0.01^Ba	13.42 ± 0.01^Ca	12.89 ± 0.01^Ea	13.0 ± 0.02^Da
	hot water bath	3.07 ± 0.01^Ab	3.07 ± 0.01^Ab	2.42 ± 0.01^Bb	1.78 ± 0.00^Dc	1.83 ± 0.01^Cb
	Steamed	1.58 ± 0.01^Dc	1.80 ± 0.01^Cc	2.03 ± 0.00^Ac	1.81 ± 0.01^Bb	1.64 ± 0.01^Ec
H°	Control	28.69 ± 0.01^Aa	28.47 ± 0.02^Ca	28.59 ± 0.03^Ba	27.98 ± 0.01^Da	28.47 ± 0.04^Ca
	Hot water bath	13.97 ± 0.02^Bb	14.03 ± 0.02^Ab	13.96 ± 0.01^Bb	13.88 ± 0.01^Cb	13.89 ± 0.02^Cb
	Steamed	13.79 ± 0.02^Dc	13.69 ± 0.01^Cc	13.78 ± 0.02^Ac	13.76 ± 0.01^Bc	13.58 ± 0.02^Ac

*Means ± SD having different uppercase letters in the same row represents significant differences within one pretreatment group over storage time, and different lowercase letters represent significant differences between three pretreatment groups on the same day (P < 0.05). control: untreated; boiled: hot water bath blanching for 5 min; steamed: steam blanching for 3 min.