Physicochemical and antioxidant properties of extruded Rhodiola as affected by twin-screw extrusion

Figures & data

Figure 1. The screw configuration of twin-screw extruder.

Table 1. Effects of extrusion operation parameters on physical properties of extruded Rhodiola.

Order	Moisture content /%	Barrel temperature /°C	Screw speed /rpm	Water solubility index /%	Water absorption index/%	L*	a*	b*	Extraction yield of soluble substances /%
Raw material				14.79 ± 0.03 ^m	6.71 ± 0.02^a	57.46 ± 0.50^b	11.03 ± 0.10^a	18.57 ± 0.13^b	18.66 ± 0.09 ^h
1	24	120	250	20.10 ± 0.05^d	3.47 ± 0.01^fg	51.10 ± 0.15 ^h	9.23 ± 0.04^b	20.94 ± 0.06^a	34.27 ± 0.07^c
2	24	130	200	15.89 ± 0.05 ^l	3.66 ± 0.02^b	55.34 ± 0.28^d	8.91 ± 0.10^d	21.38 ± 0.24^b	27.92 ± 0.04 ^g
3	24	130	300	16.85 ± 0.02 ^j	3.60 ± 0.08^bc	58.24 ± 0.10^a	8.9^3±0.02cd	21.92 ± 0.04^b	35.91 ± 0.02^a
4	24	140	250	17.19 ± 0.02^i	3.53 ± 0.03^cdef	57.35 ± 0.08^b	8.87 ± 0.06^d	21.65 ± 0.14^b	35.33 ± 0.04^ab
5	26	120	200	15.96 ± 0.02 ^j	3.56 ± 0.02 ^cde	55.91 ± 0.10^c	8.99 ± 0.04^c	21.81 ± 0.13^b	31.52 ± 0.04^d
6	26	120	300	16.29 ± 0.03^k	3.57 ± 0.03 ^cd	50.67 ± 0.03^i	7.97 ± 0.02^h	19.20 ± 0.02^b	29.73 ± 0.06^e
7	26	130	250	17.57 ± 0.02 ^h	3.49 ± 0.07^efg	53.17 ± 0.04 ^g	7.86 ± 0.03^ijk	19.49 ± 0.04^b	29.36 ± 0.05^ef
8	26	130	250	18.93 ± 0.04 ^f	3.45 ± 0.02 ^g	53.20 ± 0.02 ^g	7.85 ± 0.01^ijk	19.47 ± 0.03^b	29.08 ± 0.03^ef
9	26	130	250	19.25 ± 0.04^e	3.51 ± 0.02^defg	53.22 ± 0.04 ^g	7.79 ± 0.03^kl	19.54 ± 0.02^b	29.71 ± 0.03^ef
10	26	130	250	18.35 ± 0.05 ^g	3.49 ± 0.07^efg	53.20 ± 0.04 ^g	7.84 ± 0.05^ijkl	19.47 ± 0.43^b	29.48 ± 0.04^ef
11	26	130	250	19.11 ± 0.04^ef	3.54 ± 0.04^cdef	53.21 ± 0.03 ^g	7.89 ± 0.02^ij	19.55 ± 0.02^b	29.58 ± 0.07^ef
12	26	140	200	22.06 ± 0.05^a	3.22 ± 0.02 ^hi	54.18 ± 0.02^e	8.11 ± 0.05 ^g	21.15 ± 0.05^b	29.75 ± 0.05^e
13	26	140	300	21.38 ± 0.43^b	3.14 ± 0.02 ^j	53.85 ± 0.04 ^f	7.76 ± 0.05 ^l	19.36 ± 0.06^b	33.80 ± 0.05^c
14	28	120	250	21.03 ± 0.02^c	3.27 ± 0.02 ^h	54.02 ± 0.04^ef	8.77 ± 0.05^e	21.93 ± 0.03^b	34.45 ± 0.28^bc
15	28	130	200	21.99 ± 0.04^a	3.26 ± 0.02 ^h	53.16 ± 0.05 ^g	8.29 ± 0.04 ^f	21.22 ± 0.04^b	31.68 ± 0.17^d
16	28	130	300	21.89 ± 0.09^a	3.19 ± 0.01^ij	53.90 ± 0.04 ^f	7.84 ± 0.03^jkl	20.11 ± 0.04^b	32.27 ± 0.35^d
17	28	140	250	19.93 ± 0.04^d	3.18 ± 0.04^ij	53.32 ± 0.02 ^g	7.93 ± 0.03^hi	19.74 ± 0.06^b	28.66 ± 0.17^fg

Note: Different letters marked in the table indicate significant differences between means (P < 0.05)

Table 2. Effects of extrusion operation parameters on chemical and antioxidant properties of extruded Rhodiola.

Serial number	Moisture content (%)	Barrel temperature (°C)	Screw speed (rpm)	Rhodiolosides (mg/g)	Total flavonoids (mg/g)	Total Phenol (mg/g)	DPPH (%)	ABTS (%)
Raw material				10.94 ± 0.28^e	6.42 ± 0.28 ^g	18.32 ± 0.28 ^m	53.24 ± 0.37^i	51.35 ± 0.21^fgh
1	24	120	250	5.23 ± 0.02^k	11.45 ± 0.02^a	75.61 ± 0.02^c	69.59 ± 0.47^a	55.02 ± 0.48^b
2	24	130	200	7.19 ± 0.40 ^j	10.40 ± 0.40^b	79.18 ± 0.40^b	68.91 ± 0.49^ab	58.12 ± 0.64^a
3	24	130	300	7.99 ± 0.16^i	9.70 ± 0.16 ^cd	90.63 ± 0.16^a	69.43 ± 0.58^a	57.14 ± 0.75^a
4	24	140	250	9.57 ± 0.30 ^g	9.10 ± 0.17^de	69.69 ± 0.17^d	70.12 ± 0.69^a	52.63 ± 0.88^def
5	26	120	200	8.86 ± 0.31 ^h	9.38 ± 0.37 ^cd	65.02 ± 0.16^e	66.54 ± 0.79^cdef	52.17 ± 0.61^efg
6	26	120	300	10.45 ± 0.04 ^f	7.79 ± 0.13 ^f	61.79 ± 0.27 ^f	66.95 ± 1.05^cdef	54.33 ± 0.24^bc
7	26	130	250	12.12 ± 0.13^d	9.49 ± 0.04 ^cd	60.01 ± 0.07 ^g	67.26 ± 0.68^cde	53.01 ± 0.59^cde
8	26	130	250	12.12 ± 0.06^d	9.64 ± 0.30 ^cd	59.96 ± 0.17 ^g	67.15 ± 0.41^cdef	52.45 ± 0.91^def
9	26	130	250	12.67 ± 0.04^c	9.41 ± 0.07 ^cd	59.94 ± 0.07 ^g	67.95 ± 0.78^bc	52.94 ± 0.58^cde
10	26	130	250	12.83 ± 0.08^bc	9.59 ± 0.07 ^cd	59.81 ± 0.07 ^g	67.35 ± 0.91 ^cd	52.97 ± 0.59^cde
11	26	130	250	13.30 ± 0.13^a	9.61 ± 0.11 ^cd	59.81 ± 0.13 ^g	67.06 ± 0.49^cdef	52.49 ± 0.93^def
12	26	140	200	10.60 ± 0.08^ef	9.51 ± 0.07 ^cd	54.26 ± 0.08^i	65.77 ± 0.17^efg	53.69 ± 0.75^bcde
13	26	140	300	12.63 ± 0.13^c	9.20 ± 0.06^de	56.45 ± 2.67 ^h	66.03 ± 0.35^defg	53.85 ± 0.89^bcd
14	28	120	250	13.10 ± 0.03^ab	10.41 ± 0.03^e	48.45 ± 0.28^k	67.03 ± 0.54^cdef	50.15 ± 0.59^i
15	28	130	200	13.08 ± 0.08^ab	10.41 ± 0.07^b	62.12 ± 0.01 ^f	65.94 ± 1.10^defg	50.85 ± 0.37^gh
16	28	130	300	12.75 ± 0.06^bc	9.35 ± 0.10 ^cd	49.88 ± 0.01 ^j	65.67 ± 0.59 ^g	53.46 ± 0.47 ^cd
17	28	140	250	10.57 ± 0.04^ef	11.75 ± 0.06^a	40.01 ± 0.07 ^l	64.81 ± 0.35 ^g	50.54 ± 0.24 ^h

Note: Completely different letters marked in the table indicate significant differences between each other (P < 0.05)

Table 3. Variance analysis of regression model for chemical and antioxidant properties in extruded Rhodiola.

Source	Rhodiolosides		Total flavonoids		Total phenol		DPPH radical scavenging rate		ABTS radical scavenging rate
	P value	Significant	P value	Significant	P value	Significant	P value	Significant	P value	Significant
Model	0.0005	**	< 0.0001	**	< 0.0001	**	< 0.0001	**	< 0.0001	**
X1	< 0.0001	**	0.4578		< 0.0001	**	< 0.0001	**	< 0.0001	**
X2	0.0673		0.0017	**	< 0.0001	**	0.0063	**	0.0046	**
X3	0.0399	*	< 0.0001	**	0.2185		0.3302		0.0011	**
X1X2	0.008	**	< 0.0001	**	0.1306		0.0031	**	< 0.0001	**
X1X3	0.3626		0.2778		0.0002	**	0.2445		0.0002	**
X2X3	0.7476		0.0041	**	0.0436	*	0.8163		0.0066	**
X1^2	0.0027	**	< 0.0001	**	< 0.0001	**	0.0008	**	0.2726
X2^2	0.0132	*	0.1784		< 0.0001	**	0.0756		< 0.0001	**
X3^2	0.0249	*	0.0004	**	0.0004	**	0.0021	**	< 0.0001	**
Residual error
Lack of fit	0.1624		0.0857		0.152		0.7023		0.573
Error term
Total variation

Note: X₁: Moisture content, X₂: Barrel temperature, X₃: Screw speed. “**” in the table indicates highly significant (P < 0.01), “*” indicates significant (P < 0.05). *Highlights (for review)

Figure 2. Effect of extrusion operating parameter on DPPH radical scavenging rate (A) and ABTS radical scavenging rate(B) of extruded Rhodiola.