Structural and rheological properties of potato starch affected by degree of substitution by octenyl succinic anhydride

Figures & data

Table 1. Chemical composition of potato starch.

Chemical composition	Potato starch (%)
Moisture	8.34 ± 0.32
Crude protein	0.61 ± 0.12
Crude fat	0.20 ± 0.14
Crude ash	0.27 ± 0.01
Total starch	90.57 ± 0.00
Amylose	35.21 ± 0.29
Amylopectin	55.36 ± 0.29

Table 2. Degree of substitution (DS) and amylose leaching for native and octenyl succinic anhydride (OSA) modified potato starch.

OSA content (%)	DS	Amylose leaching (%)
0 (Native)	-	87.32 ± 0.11^a
1	0.0012 ± 0.0001^c	61.42 ± 0.28^b
3	0.0031 ± 0.0000^b	60.43 ± 0.17^c
5	0.0055 ± 0.0002^a	47.09 ± 0.64^d

^a-d: Values with different letters within the same column differ significantly (p < 0.05).

Figure 1. Field emission scanning electron microscopy of native and octenyl succinic anhydride modified potato starches with different degree of substitution of native (A, B), 0.0012 (C, D), 0.0031 (E, F), and 0.0055 (G, H). Micrographs of each starch sample were taken at 1,000 and 3,000 X magnifications.

Figure 2. X-ray diffraction of native and octenyl succinic anhydride modified potato starches with different degree of substitution of native (A), 0.0012 (B), 0.0031 (C), and 0.0055 (D).

Figure 3. ¹H nuclear magnetic resonance spectroscopy of native and octenyl succinic anhydride (OSA) modified potato starches with different degree of substitution of native (A), 0.0012 (B), 0.0031 (C), and 0.0055 (D).

Table 3. Effect of degree of substitution (DS) on apparent viscosity (ƞ_a,100), consistency index (K), flow behavior index (n), and Casson yield stress (σ_oc) values of native and octenyl succinic anhydride modified potato starch pastes at 25°C.

DS	Apparent viscosity ƞa,100 (Pa·s)	Consistency index K (Pa·s^n)	Flow behavior index n (-)	Yield stress σoc (Pa)
-^1	2.53 ± 0.04^a	29.24 ± 0.51^a	0.47 ± 0.01^b	108.72 ± 1.50^a
0.0012	1.64 ± 0.01^b	15.36 ± 0.45^b	0.52 ± 0.01^a	51.80 ± 0.42^b
0.0031	1.09 ± 0.03^c	9.78 ± 1.21^c	0.53 ± 0.02^a	35.40 ± 1.42^c
0.0055	0.88 ± 0.03^d	7.35 ± 0.72^d	0.54 ± 0.01^a	31.96 ± 0.12^d

^a~c: Values with different letters within the same column differ significantly (p < 0.05).

-¹: Native potato starch.

Figure 4. Plot of shear stress-shear rate for native and octenyl succinic anhydride modified potato starches with different degree of substitution of native (■), 0.0012 (∆), 0.0031 (○), and 0.0055 (+).

Table 4. Effect of degree of substitution (DS) on storage modulus (G’), loss modulus (G”), complex viscosity (η*) and tan δ at 6.28 rad s⁻¹ of native and octenyl succinic anhydride modified potato starch pastes at 25°C.

DS	G’ (Pa)	G” (Pa)	η* (Pa∙s)	tan δ
-^1	17.43 ± 0.86^a	8.50 ± 0.12^a	3.09 ± 0.13^a	0.49 ± 0.02^c
0.0012	14.54 ± 0.20^b	8.18 ± 0.08^b	2.66 ± 0.03^b	0.56 ± 0.00^b
0.0031	5.18 ± 0.36^c	3.39 ± 0.20^c	0.99 ± 0.06^c	0.65 ± 0.02^a
0.0055	5.20 ± 0.40^c	3.40 ± 0.13^c	0.99 ± 0.06^c	0.66 ± 0.03^a

^a~c: Values with different letters within the same column differ significantly (p < 0.05).

-¹: Native potato starch.

Figure 5. Plots of log G′, log G″, and log tan δ versus log ω (frequency, rad s⁻¹) for native and octenyl succinic anhydride modified potato starch pastes with different degree of substitution: native (■), 0.0012 (∆), 0.0031 (○), and 0.0055 (+) at 25°C.

Table 5. Effect of degree of substitution (DS) on slopes (n′, n″) and intercepts (K′, K″) of log (G′, G″) values versus log ω data of native and octenyl succinic anhydride modified potato starch pastes at 25°C.

DS	G′			G″
	n′	K′	R^2	n″	K″	R^2
-^1	0.26 ± 0.01^c	1.03 ± 0.03^a	1.00	0.34 ± 0.00^d	0.66 ± 0.01^a	1.00
0.0012	0.31 ± 0.01^bc	0.92 ± 0.00^b	1.00	0.39 ± 0.00^dc	0.60 ± 0.01^b	1.00
0.0031	0.37 ± 0.03^ab	0.42 ± 0.05^c	0.99	0.47 ± 0.01^b	0.15 ± 0.03^c	1.00
0.0055	0.37 ± 0.06^a	0.42 ± 0.08^c	1.00	0.49 ± 0.01^a	0.14 ± 0.02^c	1.00

^a~c: Values with different letters within the same column differ significantly (p < 0.05).

-¹: Native potato starch.