Effect of blending ratio and fermentation time on the physicochemical, microbiological, and sensory qualities of injera from teff, pearl millet, and buckwheat flours

Figures & data

Figure 1. Effect of blending ratio and fermentation time on (a) pH of batter; (b). Titratable acidity of batter; (c) pH of injera; (d) Titratable acidity of injera. The values expressed were mean±sd with triplicate experiments. Bars with different superscript (a, b, c.) letters are significantly different at p < .05. Where BR1 (Perl millet flour 40: Teff flour 55: Buckwheat flour 5), BR2 (Perl millet flour 30: Teff Flour 60: Buckwheat flour 10), BR3 (Perl millet flour 20: Teff flour 65: Buckwheat flour 15), BR4 (Perl millet flour 10: Teff Flour 70: Buckwheat flour 20), and Control (100% Teff Flour).

Table 1. Effect of blending ratio and fermentation time on color (L*, a* and b*) of different injera samples stored for four days.

Blending Ratio (%)	Fermentation Time (h)	Day-1			Day-2			Day-4
		L*	a*	b*	L*	a*	b*	L*	a*	b*
BR1	36	58.34±0.27^bc	2.85±0.10^d	19.10±1.93^a	55.49±0.35^ab	2.90±0.07^e	15.41±0.09^a	52.37±0.26^a	3.21±0.09^fg	13.24±0.18^a
	72	59.77±0.11^a	2.73±0.12^de	15.95±0.76^b	56.97±0.17^a	2.90±0.04^ef	14.44±0.08^b	52.82±0.11^a	2.87±0.05^g	12.81±0.10^ab
	108	59.82±0.33^a	2.35±0.10^e	14.69±0.23^bcd	57.23±0.05^a	2.23±0.11^f	13.73±0.24^c	53.11±0.15^a	2.84±0.06^g	11.66±0.11^bc
BR2	36	53.32±0.16^d	3.56±0.08^c	15.67±0.20^b	52.27±0.22^def	3.65±0.23^d	11.38±0.08^ef	49.38±0.19^c	3.97±0.15^e	11.19±0.09^cd
	72	54.38±0.09^d	3.44±0.08^c	12.42±0.23^ef	52.52±0.36^de	3.79±0.42^d	11.19±0.07^fg	50.61±0.57^bc	4.50±0.37^d	10.46±0.13^def
	108	54.84±0.24^e	3.33±0.08^c	11.65±0.19^ef	53.04±0.19^cde	4.11±0.14^cd	10.86±0.10^fgh	51.51±0.29^ab	4.41±0.31^de	9.53±0.41^fg
BR3	36	50.51±0.14^g	4.15±0.32^b	12.47±0.21^ef	49.51±0.52^g	4.95±0.18^ab	10.66±0.12^gh	42.49±1.35^e	5.51±0.06^ab	10.46±0.49^def
	72	51.21±0.28^fg	3.72±0.20^c	11.64±0.25^ef	50.13±0.19^fg	4.58±0.17^bc	10.36±0.08^hi	44.85±0.19^d	5.24±0.08^bc	9.59±0.26^fg
	108	51.76±0.35^f	3.58±0.03^c	10.73±0.36^fg	52.03±1.02^ef	4.35±0.11^c	10.03±0.44^i	46.18±1.23^d	4.84±0.12^cd	9.17±0.94^gh
BR4	36	47.18±0.44^j	4.67±0.13^a	10.59±0.20^fg	44.58±0.48^h	5.40±0.36^a	9.84±0.52^i	40.92±0.18^e	5.87±0.12^a	9.73±0.54^efg
	72	48.82±0.22^i	4.41±0.13^ab	9.45±0.10^g	45.29±1.97^h	4.65±0.11^bc	9.91±0.04^i	40.98±0.55^e	5.64±0.08^ab	9.14±0.08^gh
	108	49.72±0.30^h	4.22±0.10^b	9.39±1.08^g	46.33±1.32^h	4.57±0.11^bc	9.13±0.10^j	41.58±0.41^e	5.46±0.12^ab	8.09±0.24^h
Control	36	57.93±0.26^c	2.64±0.20^de	15.00±0.68^bc	54.38±0.37^bcd	2.93±0.04^e	13.07±0.06^d	51.82±0.11^ab	3.33±0.09^f	11.57±0.07^cd
	72	58.88±0.16^b	1.89±0.06^f	13.51±0.30^cde	55.21±0.35^abc	2.65±0.11^ef	12.87±0.12^d	52.76±0.28^a	3.19±0.07^fg	11.19±0.26^cd
	108	59.74±0.28^a	1.79±0.05^f	12.77±0.16^de	56.38±0.08^a	2.46±0.09^ef	11.82±0.09^e	52.83±0.27^a	2.92±0.03^fg	10.78±0.58^cde
CV (%)	CV(%)	0.47	4.19	5.07	1.39	6.80	1.73	1.14	3.55	3.62
p-value	BR	<.0001	<.0001	<.0001	<.0001	<.0001	<.0001	<.0001	<.0001	<.0001
	FT	<.0001	<.0001	<.0001	<.0001	.0009	<.0001	<.0001	<.0001	<.0001
	BRxFT	.0027	.0055	<.0001	.3501	.0018	.0001	.0013	<.0001	.4410

The values expressed in mean ± standard deviation with triplicate experiments Means with different letters (a, b, c.) in columns were significantly different at the level of p < .05. Where: BR1 (Perl Millet Flour 40: Teff Flour 55: Buckwheat flour 5), BR2 (Perl Millet Flour 30: Teff Flour 60: Buckwheat flour 10), BR3 (Perl Millet Flour 20: Teff Flour 65: Buckwheat flour 15), BR4 (Perl Millet Flour 10: Teff Flour 70: Buckwheat flour 20), and Control (100% Teff Flour); CV = Coefficient of Variation.

Table 2. Effect of blending ratio and fermentation time on texture (N)of different injera.

Blending Ratios (%)	Fermentation Time (h)	Storage days
		Initial	2^nd	4^th
BR1	36	13.64±0.04^a	20.10±0.10^a	28.55±0.04^a
	72	13.46±0.08^a	19.81±0.11^ab	27.91±0.07^b
	108	13.15±0.09^b	19.49±0.18^ab	27.53±0.14^b
BR2	36	12.99±0.07^bc	19.86±0.91^ab	26.13±0.09^c
	72	12.83±0.04^cd	19.04±0.58^b	25.74±0.07^c
	108	12.46±0.03^ef	17.73±0.06^b	25.01±0.08^d
BR3	36	12.39±0.09^f	15.95±0.11^de	19.20±0.17^h
	72	12.34±0.09^f	15.47±0.17^ef	18.95±0.11^h
	108	11.25±0.04^g	14.21±0.29^gh	18.08±0.13^i
BR4	36	10.13±0.10^h	15.08±0.29^efg	16.06±0.10^j
	72	9.87±0.04i	14.48±0.43^eg	16.01±0.09^jk
	108	9.66±0.14^i	13.20±0.34^h	15.50±0.58^k
Control	36	12.66±0.03^de	18.99±0.03^b	22.97±0.06^e
	72	12.41±0.06^f	17.66±0.04^c	21.78±0.08^f
	108	12.39±0.07^f	16.51±0.05^d	21.11±0.07^g
CV (%)		0.60	1.99	0.81
p-value	BR	<.0001	<.0001	<.0001
	FT	<.0001	<.0001	<.0001
	BRxFT	<.0001	.0049	<.0001

The values expressed in mean ± standard deviation with triplicate experiments. Mean with different letters (a, b, c.) in columns were significantly different at the level of p < .05.

where BR1 (Perl Millet Flour 40: Teff Flour 55: Buckwheat flour 5), BR2 (Perl Millet Flour 30: Teff Flour 60: Buckwheat flour 10), BR3 (Perl Millet Flour 20: Teff Flour 65: Buckwheat flour 15), BR4 (Perl Millet Flour 10: Teff Flour 70: Buckwheat flour 20), and Control (100% Teff Flour), N= Newton, CV (%) = coefficient of variation.

Table 3. Effect of blending ratio and fermentation time on proximate composition (on dry base) of different injera samples.

Blending Ratio (%)	Fermentation Time (h)	Moisture (%)	Crude Protein (%)	Crude Fat (%)	Crude Fiber (%)	Total Ash (%)	Carbohydrate (%)	Gross Energy (kcal/100g)
BR1	36	8.34±0.12^ab	10.55±0.01^g	5.10±0.10^a	2.41±0.00^c	1.81±0.03^cd	71.79±0.17^f	375.29±0.41^a
	72	8.38±0.16^ab	11.38±0.01^d	4.70±0.06^b	2.18±0.00^ef	1.79±0.03^cd	71.56±0.11^f	374.10±1.13^ab
	108	8.45±0.25^a	11.82±0.00^a	4.50±0.10^bc	2.02±0.00^hi	1.78±0.01^d	71.43±0.15^f	373.49±1.43^ab
BR2	36	8.13±0.10^abcd	10.52±0.00^f	4.40±0.10^d	2.45±0.00^bc	1.91±0.02^bc	72.59±0.20^e	372.05±0.15^bc
	72	8.22±0.21^abc	11.19±0.01^e	3.93±0.06^d	2.24±0.00^e	1.89±0.03^bcd	72.52±0.23^e	370.28±0.46^cde
	108	8.34±0.16^ab	11.49±0.00^c	3.50±0.15^f	2.05±0.00^h	1.88±0.03^bcd	72.73±0.15^e	368.39±0.91^ef
BR3	36	7.31±0.19^efg	10.30±0.00^j	4.07±0.06^d	2.52±0.01^ab	1.99±0.05^b	73.82±0.17^d	373.05±0.93^abc
	72	7.48±0.20^ef	11.04±0.00^f	3.50±0.10^f	2.32±0.06^d	1.96±0.04^b	73.70±0.32^d	370.43±0.59^cde
	108	7.56±0.10^def	11.70±0.00^d	3.07±0.15^h	2.10±0.01^gh	1.95±0.01^b	73.63±0.08^d	368.92±1.15^def
BR4	36	6.52±0.17^h	10.17±0.00^k	3.83±0.06^de	2.56±0.01^a	2.16±0.03^a	74.76±0.16^abc	374.21±1.05^ab
	72	6.77±0.13^gh	11.02±0.01^f	3.37±0.06^fg	2.40±0.06^cd	2.15±0.04^a	74.29±0.21^bcd	371.55±0.84^bcd
	108	6.95±0.49^fgh	11.40±0.00^d	3.10±0.10^gh	2.23±0.00^e	2.14±0.04^a	74.19±0.57^cd	370.23±1.37^cde
Control	36	7.58±0.14^de	9.06±0.01^m	3.33±0.06^ef	2.14±0.01^fg	2.24±0.07^a	75.34±0.13^a	370.32±1.03^cde
	72	7.61±0.21^cde	9.97±0.00^l	2.87±0.06^hi	2.08±0.00^gh	2.23±0.05^a	75.24±0.27^a	366.62±1.02^fg
	108	7.83±0.13^bcde	10.46±0.00^i	2.60±0.10^i	1.97±0.01^i	2.20±0.07^a	74.94±0.05^ab	364.99±0.95^g
CV(%)		2.67	0.07	2.42	1.16	1.99	0.32	0.26
p-value	BR	<.0001	<.0001	<.0001	<.0001	<.0001	<.0001	<.0001
	FT	.0085	<.0001	<.0001	<.0001	.1357	.0085	<.0001
	BRxFT	.9612	<.0001	.0025	<.0001	.9992	.3070	.1961

The values expressed in mean ± standard deviation with triplicate experiments. Mean with different letters (a, b, c.) in columns were significantly different at the level of p < .05.

Where: BR1 (Perl Millet Flour 40: Teff Flour 55: Buckwheat flour 5), BR2 (Perl Millet Flour 30: Teff Flour 60: Buckwheat flour 10), BR3 (Perl Millet Flour 20: Teff Flour 65: Buckwheat flour 15), BR4 (Perl Millet Flour 10: Teff Flour 70: Buckwheat flour 20) and Control (100% Teff Flour), CV (%) = coefficient of variation.

Figure 2. Effect of blending ratio and fermentation time on the mineral content and total phenolic contents of injera (a). Iron; (b) Calcium; (c) Zinc; (d) Total phenolic contents. The values expressed were mean±sd with triplicate experiments. Bars with different superscript (a, c, b, c.) letters are significantly different (p < .05). Where BR1 (Perl Millet Flour 40: Teff Flour 55: Buckwheat flour 5), BR2 (Perl Millet Flour 30: Teff Flour 60: Buckwheat flour 10), BR3 (Perl Millet Flour 20: Teff Flour 65: Buckwheat flour 15), BR4 (Perl Millet Flour 10: Teff Flour 70: Buckwheat flour 20), and Control (100% Teff Flour).

Figure 3. Effect of blending ratio and fermentation time on anti-nutritional factors of injera (a). Phytate; (b) Tannin. The values expressed were mean±sd with triplicate experiments. Bars with different superscript (a, b, and c) letters are significantly different (p < .05). Where BR1 (Perl Millet Flour 40: Teff Flour 55: Buckwheat flour 5), BR2 (Perl Millet Flour 30: Teff Flour 60: Buckwheat flour 10), BR3 (Perl Millet Flour 20: Teff Flour 65: Buckwheat flour 15), BR4 (Perl Millet Flour 10: Teff Flour 70: Buckwheat flour 20), and Control (100% Teff Flour).

Figure 4. Effect of blending ratio and fermentation time on Microbial quality of Injera. (a). Total aerobic plate count; (b). Total yeast and mold count of injera.

The values expressed were mean±SD with triplicate experiments. FT=fermentation time and SD=Storage days. Bars with different superscript (a-g) letters are significantly different (p < .05). Where BR1 (Perl Millet Flour 40: Teff Flour 55: Buckwheat flour 5), BR2 (Perl Millet Flour 30: Teff Flour 60: Buckwheat flour 10), BR3 (Perl Millet Flour 20: Teff Flour 65: Buckwheat flour 15), BR4 (Perl Millet Flour 10: Teff Flour 70: Buckwheat flour 20), and Control (100% Teff Flour).

Figure 5. Effect of blending ratio and fermentation time on sensory acceptability of injera. Where, BR1 (Perl Millet Flour 40: Teff Flour 55: Buckwheat flour 5), BR2 (Perl Millet Flour 30: Teff Flour 60: Buckwheat flour 10), BR3 (Perl Millet Flour 20: Teff Flour 65: Buckwheat flour 15), BR4 (Perl Millet Flour 10: Teff Flour 70: Buckwheat flour 20), and Control (100% Teff Flour). 36, 72 and 108 in the graph represents the hours of fermentation taken place.

Figure A1. Injera samples prepared from the different Blending ratios and Fermented durations. Where, BR1 (Perl Millet Flour 40: Teff Flour 55: Buckwheat flour 5), BR2 (Perl Millet Flour 30: Teff Flour 60: Buckwheat flour 10), BR3 (Perl Millet Flour 20: Teff Flour 65: Buckwheat flour 15), BR4 (Perl Millet Flour 10: Teff Flour 70: Buckwheat flour 20) and Control (100% Teff Flour).

Table A1. Effect of blending ratio and fermentation time on sensory quality of injer on five-point hedonic scale.

Blending Ratio	Fermentation Time (hr)	The mean score of the sensory attribute of injera
		Color	Taste	Texture	Rollability	Top and bottom surface	Eye uniformity	Overall acceptability
BR1	36	4.39 ± 0.59^abc	3.20 ± 0.93^d	2.78 ± 1.06^e	2.95 ± 0.73^f	3.78 ± 0.65^bcdef	3.66 ± 0.57^cd	3.15 ± 0.53^e
	72	4.59 ± 0.55^a	3.76 ± 0.93^bcd	3.07 ± 1.17^e	3.44 ± 0.73^def	4.24 ± 0.66^abc	3.80 ± 0.87^bcd	3.46 ± 0.87^de
	108	4.56 ± 0.63^a	3.68 ± 0.89^cd	3.37 ± 0.94^cde	3.54 ± 0.73^cde	4.12 ± 0.56^abcd	3.76 ± 0.86^bcd	3.39 ± 0.80^de
BR2	36	3.66 ± 0.88^def	3.39 ± 0.92^d	2.98 ± 0.96^e	3.15 ± 0.73^ef	3.78 ± 0.79^bcdef	3.68 ± 0.61^bcd	3.51 ± 0.55^de
	72	3.76 ± 0.92^def	3.41 ± 0.87^d	3.22 ± 1.17^de	3.17 ± 0.73^ef	4.05 ± 0.63^abcde	3.59 ± 0.77^cd	3.61 ± 0.54^cde
	108	3.93 ± 0.98^bcd	3.73 ± 0.78^bcd	3.51 ± 0.93^bcde	3.63 ± 0.73^edf	3.76 ± 0.73^bcdef	3.51 ± 0.84^d	3.51 ± 0.55^de
BR3	36	3.20 ± 0.90^fg	3.63 ± 1.02^cd	3.54 ± 1.23^bcde	3.17 ± 0.73^ef	3.41 ± 0.74^f	3.39 ± 0.83^def	4.02 ± 0.57^bc
	72	3.51 ± 0.81^defg	4.12 ± 0.78^abc	3.88 ± 1.31^abcd	3.63 ± 0.73^cde	3.58 ± 0.77^ef	3.80 ± 0.75^bcd	4.22 ± 0.57^ab
	108	3.80 ± 0.81^cde	3.68 ± 0.85^cd	4.02 ± 0.96^abc	3.85 ± 0.73^abcd	3.73 ± 0.81^cdef	3.49 ± 1.08^de	3.76 ± 0.62^bcd
BR4	36	3.00 ± 1.07^g	4.32 ± 0.76^ab	4.20 ± 1.21^ab	3.51 ± 0.73^cde	3.76 ± 0.73^bcdef	2.95 ± 0.74^f	3.24 ± 0.49^e
	72	3.17 ± 0.97^fg	4.59 ± 0.50^a	4.37 ± 0.97^a	3.78 ± 0.73^bcd	3.49 ± 0.71^f	3.59 ± 0.71^cd	3.59 ± 0.71^cde
	108	3.32 ± 0.69^efg	4.02 ± 0.76^abc	4.59 ± 0.59^a	4.02 ± 0.73^abc	3.61 ± 0.67^def	2.88 ± 0.78^ef	3.44 ± 0.55^de
Control	36	4.37 ± 0.62^abc	4.51 ± 0.60^a	3.98 ± 1.01^abcd	4.24 ± 0.73^ab	4.27 ± 0.71^ab	4.10 ± 0.83^abc	4.15 ± 0.61^b
	72	4.51 ± 0.55^ab	4.56 ± 0.63^a	4.15 ± 1.17^abc	4.39 ± 0.73^a	4.51 ± 0.55^a	4.63 ± 0.49^a	4.68 ± 0.47^a
	108	4.54 ± 0.60^a	4.37 ± 0.77^a	4.29 ± 1.12^ab	4.20 ± 0.73^ab	4.10 ± 0.77^abcde	4.24 ± 0.83^ab	4.05 ± 1.05^bc
CV (%)		20.36	20.60	28.66	19.77	21.29	21.33	17.53
p-value	BR	<.0001	<.0001	<.0001	<.0001	<.0001	<.0001	<.0001
	FT	.0004	.0042	.0001	<.0001	<.0001	<.0001	<.0001
	BR X FT	.7765	.0016	.9975	.0162	.9901	.0433	.0274

The values expressed in mean ± standard deviation of three observations; Means with different letters (a, b, c.) in columns were significantly different at the level of p ˂ .05 CV (%) = coefficient of variation.

Where: BR1 (Perl Millet Flour 40: Teff Flour 55: Buckwheat flour 5), BR2 (Perl Millet Flour 30: Teff Flour 60: Buckwheat flour 10), BR3 (Perl Millet Flour 20: Teff Flour 65: Buckwheat flour 15), BR4 (Perl Millet Flour 10: Teff Flour 70: Buckwheat flour 20) and Control (100% Teff Flour). CV = Coefficient of Variation.

Data availability statement

Data available within the article or its supplementary materials.