Textural and organoleptic attributes and antioxidant activity of goat milk yoghurt with added oat flour

Figures & data

Table 1. Physicochemical parameters of goat milk and oat flour used in goat milk yogurt formulations

Parameters	Goat milk
Total solids, TS (g per 100 g)	12.07 ± 0.12
Protein (g per 100 g)	3.19 ± 0.04
Fat (g per 100 g)	3.11 ± 0.05
Ash (g per 100 g)	0.70 ± 0.02
pH	6.72 ± 0.03
Parameters	Oat flour
Moisture (g per 100 g)	5.68 ± 0.07
Protein (g per 100 g)	11.63 ± 0.10
Fat (g per 100 g)	6.57 ± 0.50
Ash (g per 100 g)	1.93 ± 0.11
Total carbohydrates, TC (g per 100 g)*	74.19 ± 0.73
Dietary fiber (g per 100 g)	5.64 ± 0.13
TPC (mg GAE/g)	115.68 ± 1.75
DPPH• inhibition %	39.20 ± 2.54

Values are means ± SD of three independent replicates. *Calculated by difference – TC % = [100 – (moisture + protein + fat + ash)]. GAE: gallic acid equivalent, DPPH: 2, 2-diphenyl-1-picrylhydrazyl

Figure 1. pH profile during fermentation of goat milk yogurt with added oat flour. Y0, Y1, Y2, and Y3: goat milk yogurt with 0, 1, 2, and 3% oat flour added

Table 2. pH values and viable cell counts (log CFU/g) of lactic acid bacteria in goat milk yogurt with added oat flour

	Storage time (days)	pH	L. acidophilus	B. bifidum	S. thermophilus
Y0	1	4.62 ± 0.02^a	7.04 ± 0.00 ^f	7.03 ± 0.03 ^f	7.16 ± 0.02 ^g
	7	4.41 ± 0.01^d	7.20 ± 0.01^e	7.26 ± 0.03^d	7.35 ± 0.03 ^f
	14	4.14 ± 0.01 ^f	7.01 ± 0.01 ^f	7.02 ± 0.02 ^f	7.05 ± 0.01 ^g
Y1	1	4.54 ± 0.02^b	7.24 ± 0.02^e	7.19 ± 0.03^d	7.34 ± 0.02 ^f
	7	4.41 ± 0.02^d	7.41 ± 0.01 ^c	7.46 ± 0.01^b	7.67 ± 0.01^b
	14	4.12 ± 0.02 ^f	7.32 ± 0.02^d	7.39 ± 0.01 ^c	7.39 ± 0.03^e
Y2	1	4.50 ± 0.02^b	7.44 ± 0.02 ^c	7.35 ± 0.02 ^c	7.48 ± 0.01^d
	7	4.31 ± 0.01^e	7.49 ± 0.01^b	7.56 ± 0.01^a	7.71 ± 0.02^b
	14	4.11 ± 0.01 ^f	7.48 ± 0.01 ^c	7.50 ± 0.01^b	7.60 ± 0.01 ^c
Y3	1	4.45 ± 0.02 ^c	7.52 ± 0.02^b	7.45 ± 0.01^b	7.70 ± 0.01^b
	7	4.29 ± 0.02^e	7.6 ± 0.01^a	7.61 ± 0.01^a	7.81 ± 0.02^a
	14	4.09 ± 0.01 ^f	7.5 ± 0.01^b	7.59 ± 0.01^a	7.77 ± 0.01^a

Values are means ± SD of three independent replicates. Means in the same columns with different superscripts are significantly different (P < .05). Y0, Y1, Y2, and Y3: goat milk yogurt with 0, 1, 2, and 3% added oat flour. CFU: colony-forming unit.

Figure 2. Syneresis values (%) of goat milk yogurt with added oat flour during cold storage. Y0, Y1, Y2, and Y3: goat milk yogurt with 0, 1, 2, and 3% oat flour added. Values are mean ± SD of three independent replicates. Column charts with different letters are significantly different (p < 0.05)

Table 3. Texture properties of goat milk yogurt with added oat flour

	Hardness (N)	Cohesiveness (ratio)	Springiness (mm)	Chewiness (m.j)	Adhesiveness (m.j)
Y0	0.70 ± 0.07 ^c	0.16 ± 0.01 ^c	0.72 ± 0.04^b	0.80 ± 0.05 ^c	1.32 ± 0.04^d
Y1	0.87 ± 0.01^b	0.19 ± 0.02^b	0.84 ± 0.03^b	0.99 ± 0.06^b	1.02 ± 0.05 ^c
Y2	0.94 ± 0.10^b	0.22 ± 0.01^a	1.01 ± 0.10^a	1.08 ± 0.09^ab	0.83 ± 0.13^b
Y3	1.13 ± 0.08^a	0.24 ± 0.01^a	1.09 ± 0.08^a	1.20 ± 0.04^a	0.60 ± 0.05^a

Values are means ± SD of three independent replicates. Means in the same columns with different superscripts are significantly different (P < .05). Y0, Y1, Y2, and Y3: goat milk yogurt with 0, 1, 2, and 3% added oat flour. m.j: milli-joule, N: newton, mm: millimeter.

Table 4. Total phenolic content (TPC, mg GAE/g) in undigested and digested goat milk yogurt with added oat flour

Sample	TPC (mg GAE/g) in undigested GMY			TPC (mg GAE/g) in digested GMY
	1 d	7 d	14 d	1 d	7 d	14 d
Y0	9.3 ± 3.1^e	12.9 ± 0.7^de	12.5 ± 2.7^de	13.2 ± 2.7^e	17.2 ± 1.3^e	13.3 ± 2.4^e
Y1	15.9 ± 2.8^d	23.6 ± 4.3^bc	20.9 ± 2.^6c	23.2 ± 0.9^d	30.7 ± 2.5^bc	27.6 ± 0.8 ^cd
Y2	20.8 ± 3.1 ^c	27.6 ± 2.4^ab	25.3 ± 2.4^bc	27.5 ± 4.6 ^cd	34.4 ± 1.6^ab	32.4 ± 7.1^bc
Y3	27.6 ± 3.5^ab	31.4 ± 2.6^a	27.9 ± 0.5^ab	32.5 ± 1.8^bc	38.8 ± 3.2^a	35.4 ± 2.5^ab

Values are means ± SD of three independent replicates. Means in the same columns with different superscripts are significantly different (P < 0.05). Y0, Y1, Y2, and Y3: goat milk yogurt with 0, 1, 2, and 3% added oat flour. GMY: goat milk yogurt, TPC: total phenolic content, GAE: gallic acid equivalent.

Table 5. DPPH• inhibition (%) in undigested and digested goat milk yogurt with added oat flour

Sample	DPPH• inhibition (%) in undigested GMY			DPPH• inhibition (%) in digested GMY
	1 d	7 d	14 d	1 d	7 d	14 d
Y0	13.7 ± 1.6 ^g	15.4 ± 0.6^fg	14.1 ± 0.8 ^g	19.6 ± 0.7 ^h	24.9 ± 0.9 ^g	22.6 ± 1.3 ^g
Y1	17.6 ± 1.6 ^f	27.4 ± 0.8^d	23.6 ± 1.8^e	35.1 ± 0.9 ^f	39.2 ± 3.5^e	36.2 ± 1.1^ef
Y2	26.5 ± 1.4^d	32.9 ± 1.7^b	30.4 ± 1.2 ^c	41.5 ± 1.4^e	47.7 ± 2.0 ^cd	46.1 ± 1.0^d
Y3	31.1 ± 0.7^bc	38.2 ± 0.6^a	32.4 ± 1.6^bc	50.2 ± 0.5 ^c	58.6 ± 1.5^a	55.0 ± 1.8^b

Values are means ± SD of three independent replicates. Means in the same columns with different superscripts are significantly different (P < 0.05). Y0, Y1, Y2, and Y3: goat milk yogurt with 0, 1, 2, and 3% added oat flour. DPPH: 2, 2-diphenyl-1-picrylhydrazyl, GMY: goat milk yogurt.

Table 6. Sensory properties of goat milk yogurt with added oat flour

	Color (5)	Texture (5)	Flavor (5)	Overall acceptability (5)
Y0	5.0 ± 0.0 ^a	2.0 ± 0.5 ^c	1.0 ± 1.0 ^d	1.0 ± 0.5 ^c
Y1	4.5 ± 0.5 ^a	3.0 ± 2.0 ^b	2.0 ± 2.1 ^c	2.0 ± 2.5 ^b
Y2	4.5 ± 0.5 ^a	4.5 ± 1.5 ^a	5.0 ± 0.3 ^b	4.5 ± 2 ^a
Y3	4.5 ± 0.5 ^a	4.5 ± 0.6 ^a	4.0 ± 1.0^a	4.0 ± 1.8 ^a

Values are means ± SD of three independent replicates. Means in the same columns with different superscripts are significantly different (P < 0.05). Y0, Y1, Y2, and Y3: goat milk yogurt with 0, 1, 2, and 3% added oat flour.