Structural properties of high-protein, low glycaemic index (GI) rice flour

Figures & data

Figure 1. Protein contents of untreated and treated rice flour samples. Results are expressed as mean ± standard deviation.

Figure 2. Hydrolysis pattern of untreated and treated (high-protein, low GI) rice flour.

Table 1. Equilibrium concentration (C_∞), kinetic constant (k), hydrolysis index (HI) and estimated GI of untreated rice flour, treated rice flour and white bread.

Sample	C∞*	k*	HI**	GI***
Untreated rice flour	70.5 ± 1.8^a	0.02 ± 0.00^c	87.6 ± 0.2^e	88 ± 0.2 ^g
Treated rice flour	12 ± 0.5^b	0.01 ± 0.00^d	11.6 ± 0.7^f	46.1 ± 0.2^h
White bread	75.9 ± 0.02	0.03 ± 0.00	100	-

*parameters of the kinetic equation C = C_∞ (1–e^–kt)

**HI was calculated as (AUC_sample/AUC_{white bread}) × 100

***GI was calculated from the equation proposed by Goni et al. (1997), GI = 39.71 + 0.549HI

Results are expressed as mean ± standard deviation

Values with different superscripts (within columns) differ significantly (p< 0.05)

Table 2. Thermal behavior of samples.

Sample	To (°C)	Tp (°C)	Te (°C)	EPW = Te–Tp (°C)	ΔHg (J/g)	DG%	R	PHI (J/g/°C)
Untreated rice flour	90.70 ± 0.02^a	104.3 ± 0.02^c	138.8 ± 0.02^e	34.5 ± 0.005^g	10.8 ± 0.04^i	80 ± 0.3	27.3 ± 0.07^k	0.8 ± 0.00^m
Treated rice flour	73.8 ± 0.03^b	76.9 ± 0.03^d	80.3 ± 0.02^f	3.4 ± 0.01^h	2.16 ± 0.03^j	-	6.2 ± 0.1^l	0.7 ± 0.02^n

Values are expressed as mean±standard deviation and values with different superscripts (within columns) differ significantly (p < 0.05).

T_o = onset temperature; T_p = peak temperature; T_e = End-set temperature; EPW = Endothermic peak width; ΔH_g = enthalpy of gelatinization; R = gelatinization temperature range; PHI = peak height index

Figure 3. Differential Scanning Calorimetry thermograms of untreated (A) and treated rice flour (B).

Figure 4. FT-IR spectra of untreated (A) and treated (high-protein, low GI) (B) rice flour.

Table 3. Rheological modeling parameters.

	Untreated rice flour				Treated rice flour
	Power law model	Herschel–Bulkley model	Bingham model	Casson model	Power Law model	Herschel–Bulkley model	Bingham model	Casson model
n		0.505		2	0.1	0.180		2
R^2	0.833	0.984	0.984	0.982	0.988	0.999	0.722	0.910

Figure 5. Frequency sweep of rice flour. 5A: Storage modulus versus angular frequency; 5B: Loss modulus versus angular frequency, 5C: Damping factor (tanδ) versus angular frequency (ω).