Structure and Functional Properties of Acetylated Sorghum Starch

Figures & data

Table 1 Acetyl (%) and DS of acetylated starches^a

Acetic anhydride(% w/w)	Acetyl (%)	DS
Native	0	0
1.25	1.31 ^a	0.050 ^a
2.5	1.44 ^a	0.055^ab
3.75	1.59 ^a	0.061^b
5.0	1.81^bc	0.069^c
6.25	2.10^c	0.081^d
^aValues with similar superscripts in column do not differ significantly (p < 0.05).

Table 2 Physicochemical properties of native and acetylated starches ^a

Acetic anhydride (% w/w)	Amylose content (%)	Swelling power (g/g)	Solubility (%)
Native	18.7 ^a	6.2 ^a	11.9 ^a
1.25	18.9 ^a	8.7^b	12.2 ^a
2.5	19.0 ^a	11.2^c	12.5 ^a
3.75	19.2 ^a ^bc	14.5^d	13.2^b
5.0	19.3^bc	15.7^e	13.8^b
6.25	19.5^c	16.9^e	14.7^c
^aValues with similar superscripts in column do not differ significantly (p < 0.05).

Table 3 Gelatinization properties of native and acetylated starches^a

Acetic anhydride (w/w)	To (°C)	Tp (°C)	Tc (°C)	ΔHgel (J/g)
Native	68.40^d	72.10^e	76.16^e	11.47^b
1.25	67.90^d	71.25^d	74.81^c	11.32^b
2.5	66.40^c	69.98^b	73.93^b	9.61 ^a
3.75	65.40^b	70.61^c	75.51^d	9.45 ^a
5.0	65.30^b	69.40^b	74.11^b	9.40 ^a
6.25	63.30 ^a	67.60 ^a	72.30 ^a	9.35 ^a
To = Onset temperature, Tp = Peak temperature, Tc = Conclusion temperature, ΔHgel = Enthalpy of gelatinization (dwb, based on starch weight).
^aValues with similar superscripts in column do not differ significantly (p < 0.05).

Table 4 Pasting properties of native and acetylated starches ^a

Acetic anhydride (% w/w)	PV (cP)	HPV (cP)	BD (cP)	CPV (cP)	SB (cP)	PT (°C)
Native	4072^f	2396^f	1676^c	4120^f	1724 ^a	77.40^d
1.25	3378^e	2134^e	1244^b	3819^e	1685 ^a	77.55^d
2.5	2939^d	1724^d	1215^b	3516^d	1792 ^a	76.71^cd
3.75	2638^c	1463^c	1175 ^a	3326^c	1863^b	75.95^bc
5.0	2489^b	1257^b	1232^b	3117^b	1860^b	74.25 ^a
6.25	2204 ^a	1017 ^a	1187 ^a	2752 ^a	1735 ^a	75.85^bc
PV = Peak viscosity, HPV = Hot paste viscosity, BD = Breakdown viscosity, CPV = Cool paste viscosity, SB = Setback viscosity, PT = Pasting temperature.
^aValues with similar superscripts in a column do not differ significantly (p < 0.05).

Figure 1 FT-IR spectra of native and acetylated starches (A. native; B. acetylated) (color figure available online).

Figure 2 Scanning electron micrographs (SEM) of native and acetylated starches (A. native; B. 1.25% Ac₂O; C. 6.25% Ac₂O).

Figure 3 X-ray diffractograms of native and acetylated starches (A. native; B. 1.25% Ac₂O; C. 2.5% Ac₂O; D. 3.75% Ac₂O; E. 5.0% Ac₂O; F 6.25% Ac₂O).

Table 5 Textural properties of gels of native and acetylated starches^a

Acetic anhydride (% w/w)	Hardness (g)	Cohesiveness	Springiness	Gumminess (g)	Chewiness (g)
Native	49.3^e	0.301 ^a	0.94^b	14.84^c	13.95^d
1.25	37.7^d	0.381 ^a	0.92^b	14.36^c	13.21^d
2.5	25.6^c	0.432^b	0.94^b	11.06^b	10.40^c
3.75	20.1^b	0.511^c	0.87 ^a	10.27^b	8.94^bc
5.0	16.6^b	0.552^c	0.88 ^a	9.16^b	8.06^ab
6.25	12.8 ^a	0.544^c	0.95^b	6.96 ^a	6.62 ^a
^aValues with similar superscripts in column do not differ significantly (p < 0.05).

Table 6 Syneresis (%) of native and acetylated starches^a

	Storage duration (h)
Acetic anhydride(% w/w)	24	72	120
Native	26.21^b	31.23^c	37.91^c
1.25	3.15 ^a	5.87^b	7.21^b
2.5	1.32z ^a	2.89 ^a	5.44^b
3.75	1.18 ^a	1.78 ^a	2.08 ^a
5.0	1.03 ^a	1.12 ^a	1.15 ^a
6.25	0.95 ^a	1.01 ^a	1.03 ^a
^aValues with similar superscripts in column do not differ significantly (p < 0.05).