Evaluation of the Effects of Hydrothermal Treatment on Rice Flour and Its Related Starch

Figures & data

TABLE 1 Chemical composition of rice flour (RF) and rice starch (RS) extracted from the same flour

Chemical composition (%)	Rice flour	Rice starch
Moisture	9.60 ± 0.40^a	9.36 ± 0.20^a
Protein	7.76 ± 0.05^a	0.68 ± 0.01^b
Lipid	0.89 ± 0.09^a	0.48 ± 0.17^b
Ash	0.74 ± 0.01^a	0.30 ± 0.01^b
Total carbohydrate content	81.01 ± 0.20^b	89.18 ± 0.17^a

Values are the average of triplicates ± standard deviation. Averages followed by different superscripts in the same row are statistically different (p < 0.05).

FIGURE 1 Micrographs of A: rice flour (RF); B: hydrothermaled rice flour for 3 h (HTRF3); C: hydrothermaled rice flour for 5 h (HTRF5); D: rice starch (RS); E: hydrothermaled rice starch for 3 h (HTRS3); and F: hydrothermaled rice starch for 5 h (HTRS5). Bars on the images are 20 µm. S: starch granules; P: protein.

FIGURE 2 Water solubility of the rice flour (RF), hydrothermaled rice flour for 3 h (HTRF3), hydrothermaled rice flour for 5 h (HTRF5), rice starch (RS), hydrothermaled rice starch for 3 h (HTRS3), and hydrothermaled rice starch for 5 h (HTRS5). Values are the average of triplicates ± standard deviation. Bars with different letters are statistically different (p < 0.05).

FIGURE 3 Water absorption of the rice flour (RF), hydrothermaled rice flour for 3 h (HTRF3), hydrothermaled rice flour for 5 h (HTRF5), rice starch (RS), hydrothermaled rice starch for 3 h (HTRS3), and hydrothermaled rice starch for 5 h (HTRS5). Values are the average of triplicates ± standard deviation. Bars with different letters are statistically different (p < 0.05).

TABLE 2 Pasting properties of rice flour (RF), hydrothermaled rice flour for 3 h (HTRF3), hydrothermaled rice flour for 5 h (HTRF5), rice starch (RS), hydrothermaled rice starch for 3 h (HTRS3) and hydrothermaled rice starch for 5 h (HTRS5)

RVA parameters	RF	HTRF3	HTRF5	RS	HTRS3	HTRS5
Peak vis^1 (cP)	5106^b	4820^c	4733^d	7873^a	3151^e	2664^f
Pasting temp °C)	78.1^c	78.4^c	84.4^a	77.7^d	78.9^c	80.4^b
Trough vis (cP)	2342^b	2305^b	2162^c	2759^a	2334^b	1996^d
Final vis (cP)	5156^f	5852^d	6013^c	7094^a	6769^b	5459^e
Setback (cP)	4751^a	4464^b	3297^e	2396^f	3517^d	4017^c

Values are the average of triplicates ± standard deviation. Averages followed by different superscript in the same row are statistically different (p < 0.05).

¹Vis: viscosity.

TABLE 3 Textural properties of rice flour (RF), hydrothermaled rice flour for 3 h (HTRF3), hydrothermaled rice flour for 5 h (HTRF5), rice starch (RS), hydrothermaled rice starch for 3 h (HTRS3), and hydrothermaled rice starch for 5 h (HTRS5)

Parameters	RF	HTRF3	HTRF5	RS	HTRS3	HTRS5
Hardness (kg)	0.031 ± 0.002^e	0.133 ± 0.007^b	0.148 ± 0.008^a	0.041 ± 0.007^d	0.079 ± 0.006^c	0.071 ± 0.014^c
Elasticity	0.855 ± 0.031^c	0.946 ± 0.007^b	0.954 ± 0.028^ab	0.911 ± 0.032^b	0.945 ± 0.016^b	0.972 ± 0.013^a
Cohesiveness	0.759 ± 0.011^b	0.704 ± 0.014^c	0.707 ± 0.013^c	0.880 ± 0.022^a	0.887 ± 0.028^a	0.908 ± 0.020^a

Values are the average of triplicates ± standard deviation. Averages followed by different superscript in the same row are statistically different (p < 0.05).