Pre-Cooked Fiber-Enriched Wheat Flour Obtained by Extrusion: Rheological and Functional Properties

Figures & data

Figure 1 Schematic of the laboratory-scale extruder screw profile¹ and barrel temperatures.^{2 1}All screws are forward and intermeshing. ²LTLS process temperatures (shown above) were 30-32-34-36-38-40°C; and HTHS process temperatures were 30-40-50-60-70-80°C.

Figure 2 Flow diagram of the cookie making method. ¹Mixer had speed settings from 1–3. ²BLV = Butter Lemon Vanilla.

Figure 3 Flow diagram of the tortilla making method. ¹Mixer had settings from 1–3.

Table 1 Rheological properties ¹ of uncooked flour and HTHS ² pre-cooked flour ³ prepared by oven drying and lyophilization

Flour type	RVA peak visc (cP)	RVA peak time (min)	Mixograph peak height (%)	Mixograph peak time (min)
Uncooked	2237^a	5.92^a	45.4^a	3.5^a
Lyophilized HTHS	1480^b	5.5^b	22.9^b	0.5^b
Oven dried HTHS	1160^c	5.8^a	13.8^c	0.5^b
^1Mean, n = 3; means with same superscript in the same column are not significantly different (p < 0.05). ^2High-temperature-high-shear extrusion processing conditions. ^3All flours had 0% bran substitution.

Table 2 Rheological data ¹ for uncooked and pre-cooked ² wheat flour with 0–30% bran substitution–using (a) rapid visco analyzer (RVA) and (b) mixograph

(a)
Flour type	Bran level (%)	Peak Visc (cP)	Peak Time (min)
Uncooked	0	1059^b	4.9^h
	10	998^bc	5.0^g
	20	935^bc	5.2^e
	30	930^bc	5.1^f
LTLS pre-cooked	0	786^d	5.3^d
	10	783^d	5.3^d
	20	1‘231^a	5.3^d
	30	709^cd	5.2^e
HTHS pre-cooked	0	982^bc	5.6^a
	10	894^cd	5.4^c
	20	601^e	5.5^b
	30	527^e	5.6^a
(b)
Flour type	Bran level (%)	Peak Time (min)	Peak Height (%)
Uncooked	0	4.1^bcd	44.6^b
	10	5.2^abcd	37.9^bc
	20	3.7^cde	33.2c^cd
	30	3.6^def	34.4^cd
LTLS precooked	0	0.8^h	26.8^d
	10	0.7^h	16.2^e
	20	6.0^a	31.3^cd
	30	1.0^gh	36.5^bc
HTHS Pre-cooked	0	5.8^ab	66.1^a
	10	4.9^abcd	66.6^a
	20	1.8^fgh	44.0^b
	30	2.2^efgh	61.6^a
^1Mean, n = 3; means with same superscript in the same column are not significantly different (P < 0.05).^2 HTHS = high-temperature-high-shear extrusion processing conditions; and LTLS = low-temperature-low shear extrusion processing conditions.

Table 3 Quality parameters ¹ of cookies from uncooked and pre-cooked ² wheat flour with 0–30% bran substitution

	Bran level (%)	Weight (g)	Width (cm)	Thickness (mm)
Uncooked	0	49.8^e	11.0^a	0.7^f
	10	52.7^c	10.9^b	0.7^f
	20	53.9^b	10.4^c	0.7^f
	30	54.5^a	9.3^f	1.2^e
LTLS precooked	0	42.0^h	8.8^j	1.3^d
	10	42.4^g	9.0^i	1.2^e
	20	49.9^e	9.8^e	1.2^e
	30	51.1^d	8.0^l	1.7^b
HTHS precooked	0	41.0^i	8.7^k	1.8^a
	10	41.1^i	10.1^d	1.2^e
	20	43.8^f	9.2^g	1.5^c
	30	42.5^g	9.1^h	1.5^c
^1Mean, n = 3; means with same superscript in the same column are not significantly different (P < 0.05). ^2HTHS = high-temperature-high-shear extrusion processing conditions; and LTLS = low-temperature-low shear extrusion processing conditions.

Figure 4 Spread (W/T ratio) of cookies from uncooked and pre-cooked wheat flours with 0–30% bran substitution. ¹Y error bars denote the least significant difference, n = 3. ²HTHS = high-temperature-high-shear extrusion processing conditions and LTLS = low-temperature-low shear extrusion processing conditions.

Table 4 Quality parameters ¹ of tortillas from uncooked and pre-cooked ² wheat flour with 0–30% bran substitution

	Bran level (%)	Weight (g)	Diameter(cm)	Height (mm)	Opacity (%)	Sp.Vol (m^3/g)	Aw
Uncooked	0	37.7^c	18.1^a	1.5^e	76.3^b	1.01^b	0.91^f
	10	38.4^b	14.4^i	2.2^a	73.4^d	0.94^e	0.93^d
	20	38.7^a	15.3^d	1.9^c	76.2^b	0.95^d	0.94^c
	30	38.7^a	15.6^c	1.9^c	72.4^e	0.95^d	0.95^b
LTLS Precooked	0	37.6^cd	16.4^b	1.7^d	71.5^f	0.95^d	0.92^e
	10	36.6^f	14.3^j	2.0^b	77.4^a	0.88^f	0.94^c
	20	37.2^e	14.4^i	1.9^c	76.0^b	0.87^g	0.97^a
	30	36.3^g	15.3^d	1.7^d	77.8^a	0.87^g	0.95^b
HTHS Precooked	0	38.4^b	14.6^h	2.2^a	74.2^c	0.95^d	0.94^c
	10	37.6^cd	14.9^g	2.2^a	74.1^cd	1.02^a	0.95^b
	20	37.4^de	15.1^f	2.0^b	74.8^c	1.01^b	0.94^c
	30	37.4^de	15.2^e	2.0^b	72.2^ef	0.99^c	0.93^d
^1Mean, n = 3; means with same superscript in the same column are not significantly different (P ≤ 0.05). ^2HTHS = high-temperature-high-shear extrusion processing conditions; and LTLS = low-temperature-low shear extrusion processing condition.

Figure 5 Rollability of tortillas from (a) uncooked flour, (b) LTLS pre-cooked flour, and (c) HTHS pre-cooked flour, after storage for 4, 8, 12, and 16 d. ¹Y error bars denote the least significant difference, n = 3. ²HTHS = high-temperature-high-shear extrusion processing conditions and LTLS = low-temperature-low shear extrusion processing conditions.

Figure 6 Extensibility (force) data for tortillas from (a) uncooked flour, (b) LTLS pre-cooked flour, and (c) HTHS pre-cooked flour, after storage for 4, 8, 12, and 16 d. ¹Y error bars denote the least significant difference, n = 3. ²HTHS = high-temperature-high-shear extrusion processing conditions and LTLS = low-temperature-low shear extrusion processing conditions.

Figure 7 Extensibility (distance) data for tortillas from (a) uncooked flour, (b) LTLS pre-cooked flour, and (c) HTHS pre-cooked flour, after storage for 4, 8, 12, and 16 d. ¹Y error bars denote the least significant difference, n = 3. ²HTHS = high-temperature-high-shear extrusion processing conditions and LTLS = low-temperature-low shear extrusion processing conditions.