Steady and dynamic shear rheology of starches from different oat cultivars in relation to their physicochemical and structural properties

Figures & data

Table 1. Proximate composition, amylose content, swelling power, and solubility of starches from different oat cultivars.

Cultivars	Moisture (g/100g)	Ash (g/100g)	Nitrogen (g/100g)	Amylose (g/100g)	SP (g/g)	Solubility (g/100g)
OL-9	10.22 ± 0.1^d	0.51 ± 0.06^d	0.03 ± 0.002^b	29.7 ± 0.35^cd	13.1 ± 0.90^a	12.4 ± 1.2^a
OL-10	8.13 ± 0.2^bc	0.61 ± 0.04^d	0.04 ± 0.001^c	21.8 ± 0.42^a	16.1 ± 0.62^bc	18.2 ± 0.91^b
Kent	6.91 ± 0.8^ab	0.81 ± 0.05^e	0.05 ± 0.002^d	27.1 ± 0.43^b	15.3 ± 0.91^b	20.1 ± 0.81^c
OS-6	9.02 ± 0.3^c	0.19 ± 0.05^ab	0.04 ± 0.001^c	30.3 ± 0.52^d	14.1 ± 0.54^ab	19.1 ± 0.93^bc
OS-7	7.45 ± 0.4^b	0.11 ± 0.02^a	0.05 ± 0.003^d	30.2 ± 0.49^d	19.1 ± 0.76^d	21.1 ± 0.23^cd
OS-346	6.43 ± 0.1^a	0.25 ± 0.05^b	0.05 ± 0.004^d	31.1 ± 0.29^de	16.2 ± 0.73^bc	19.1 ± 0.42^bc
HFO-114	10.13 ± 0.3^d	0.19 ± 0.04^ab	0.04 ± 0.003^c	28.7 ± 0.37^c	18.7 ± 0.53^d	22.0 ± 0.76^d
PLP-1	9.52 ± 0.2^cd	0.56 ± 0.06^cd	0.02 ± 0.002^a	32.3 ± 0.36^e	17.0 ± 0.81^c	21.0 ± 0.54^cd

Values are an average of triplicate observations; ±standard deviation.

Values followed by similar superscripts in a column do not differ significantly (p < 0.05).

Figure 1. Transmittance (Abs.) of starches from different oat cultivars.

Figure 2. Freeze thaw stability of starches from different oat cultivars.

Figure 3. X-ray diffraction of starches from different oat cultivars at 2θ (4–30°).

Figure 4. Scanning electron micrograph of starches from different oat cultivars: (A) OL-9, (B) OL-10, (C) Kent, (D) OS-6, (E) OS-7, (F) OS-346, (G) HFO-114, and (H) PLP-1.

Table 2. Herschel-Bulkley model parameters for starch pastes from different oat cultivars.

Cultivars	σo (Pa)	K (Pa.s^n)	n(-)	R^2
OL-9	1.78	1.69 ± 0.08	0.67 ± 0.01	0.999
OL-10	0.45	2.09 ± 0.09	0.66 ± 0.01	0.987
Kent	2.10	0.45 ± 0.01	0.77 ± 0.01	0.999
OS-6	2.80	3.08 ± 0.10	0.59 ± 0.01	0.999
OS-7	2.50	0.06 ± 0.02	0.94 ± 0.01	0.992
OS-346	1.00	0.67 ± 0.13	0.69 ± 0.01	0.993
HFO-114	2.40	2.19 ± 0.01	0.60 ± 0.01	0.999
PLP-1	2.80	0.49 ± 0.07	0.89 ± 0.01	0.998

Values are an average of triplicate observations; ± standard deviation.

K: Consistency index, n: Flow behaviour index, σ_o: Yield stress.

Figure 5. (a) Flow curves of starch pastes (10%) from different oat cultivars. (b) Changes in storage modulus (G′) and changes in Loss modulus (G′′) of 15% oat starch suspensions during heating: (A) OL-9 (B) OL-10 (C) Kent (D) OS-6 (E) OS-7 (F) OS-346 (G) HFO-114 (H) PLP-1. (c) Changes in storage modulus (G′) and changes in Loss modulus (G′′) of 15% oat starch suspensions during a frequency sweep (0.1–100 rad/s at 25ºC): (A) OL-9 (B) OL-10 (C) Kent (D) OS-6 (E) OS-7 (F) OS-346 (G) HFO-114 (H) PLP-1.

Table 3. Dynamic rheological properties of starches from different oat cultivars.

Cultivars	G’ (Pa)	G’’ (Pa)	Breakdown in G’	Tanδ	TG’max (°C)
OL-9	3284 ± 140^a	315 ± 20^a	421 ± 30^c	0.09 ± 0.01^a	87.6 ± 0.05^b
OL-10	3893 ± 135^bc	769 ± 18^d	806 ± 19^d	0.19 ± 0.02^b	85.1 ± 0.08^a
Kent	5744 ± 127^d	434 ± 19^b	794 ± 17^d	0.07 ± 0.02^a	87.6 ± 0.09^b
OS-6	3964 ± 136^bc	766 ± 23^d	219 ± 19^b	0.19 ± 0.01^b	87.6 ± 0.08^b
OS-7	5998 ± 149^e	498 ± 27^c	–	0.08 ± 0.03^a	87.6 ± 0.07^b
OS-346	4218 ± 137^c	957 ± 29^e	130 ± 21^a	0.22 ± 0.02^bc	87.6 ± 0.06^b
HFO-114	3777 ± 146^b	340 ± 33^a	–	0.09 ± 0.01^a	90.1 ± 0.04^c
PLP-1	4042 ± 130^bc	977 ± 37^e	444 ± 22^c	0.24 ± 0.02^c	87.6 ± 0.09^b

Values are an average of triplicate observations; ±standard deviation.

Values followed by similar superscripts in a column do not differ significantly (p < 0.05).

Table 4. Storage modulus (G’), loss modulus (G’’), complex viscosity (ƞ*), and tan δ for oat starch pastes at 6.28 rad/s at 25°C.

Cultivars	G’ (Pa)	G’’ (Pa)	tan δ	ƞ*
OL-9	3449 ± 30^g	186 ± 15^c	0.05 ± 0.01^a	549 ± 12^f
OL-10	3502 ± 20^h	464 ± 10^d	0.13 ± 0.02^b	562 ± 9^f
Kent	2119 ± 32^b	152 ± 14^b	0.07 ± 0.01^a	338 ± 14^b
OS-6	3099 ± 40^f	179 ± 17^bc	0.05 ± 0.03^a	494 ± 13^e
OS-7	646 ± 16^a	105 ± 9^a	0.16 ± 0.01^bc	104 ± 17^a
OS-346	2383 ± 42^c	209 ± 16^c	0.09 ± 0.02^ab	380 ± 20^c
HFO-114	3005 ± 32^e	147 ± 11^b	0.04 ± 0.01^a	478 ± 19^e
PLP-1	2575 ± 19^d	591 ± 12^e	0.22 ± 0.01^c	420 ± 15^d

Values are an average of triplicate observations; ± standard deviation.

Values followed by similar superscripts in a column do not differ significantly (p < 0.05).

Figure 6. (a) Principal component analysis: loading plot of first principal component (PC1) and second principal component (PC2) describing the variation among measured properties of starches from different oat cultivars. (b) Principal component analysis: score plot of PC1 and PC2 describing the overall variation among the properties of starches from different oat cultivars.