Effect of phosphoric acid treatment on physicochemical, functional, and structural properties of starch extracted from yam (Dioscorea rotundata)

Figures & data

Table 1. Swelling behavior and yield of native and modified starch.

H3PO4 (%)	Yield (%)	Swelling Power (g/g)	Gelation Studies (v/g)	WHC (T%)	Paste Clarity
0	20 (100)	3.84	-viscous gel	1.0	10
5	18.61 (93.05)	1.42	+firm gel	0.8	25
10	18.20 (91.00)	1.40	+firm gel	0.7	36
15	17.84 (89.20)	1.38	+firm gel	0.5	59
20	17.42 (87.10)	1.15	+firm gel	0.5	69
25	17.12 (85.60)	0.96	+firm gel	0.5	75

Table 2. Blue value, amylose, and amylopectin content of native and modified starch.

H3PO4%	Absorbance (λ = 600 nm)	Amylose content (%)	Amylopectin (%)	Blue value
0	0.66	26.56	73.44	0.53
5	0.57	21.20	78.8	0.45
10	0.49	16.44	83.56	0.39
15	0.38	9.89	90.11	0.30
20	0.33	6.92	93.08	0.26
25	0.27	3.35	96.65	0.22
30	0.17	0.22	99.78	0.14
35	0.09	0.22	99.78	0.072
40	0.02	0.21	99.79	0.02
45	–0.07	0.20	99.80	–0.06

Figure 1. Calibration curve for various amylose ratios of standard samples.

Figure 2. Photomicrograph of native yam starch.

Figure 3. Photomicrograph of phosphoric acid modified yam starch.

Table 3. Effect of modification on absorption bands of yam starch.

Wavenumber (cm^−Citation1)
Assignments	Native starch	Acid modified starch
O-H stretch	3177	—
C-H stretch	2923, 2854	2953-2884
H2O absorbed (Amorphous region)	1643.49	—
-CH bend	1462, 1377	1462, 1377
CH2OH	1253	—
C-O, C-C stretch	1155,	1146
C-O-H bending	1078	1017
C-O-C	982, 931	—
C (1)−H, CH2 deformation	860
Glucose pyranose ring	758, 720.00	656

Figure 4. FTIR spectrum of native yam (Dioscorea rotundata).

Figure 5. FTIR spectrum of modified yam (Dioscorea rotundata).

Baah, F.D.; Maziya-Dixon, B.; Asiedu, R.; Oduro I.; Ellis W.O. Nutritional and Biochemical Composition of D. Alata (Dioscorea spp.) Tubers. Journal of Food, Agriculture and Environment 2009, 7(2), 373–378.

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