Electrophoretic Characterization and Functional Properties of Rice Proteins from Indian Rice Cultivars

Figures & data

Table 1  Chemical properties of milled rice

Cultivar	Moisture (g/100 g sample)*	Ash (g/100 g sample)	Fat (g/100 g sample)*	Starch (g/100 g sample)*
Jaya	12.55 ± 0.08	0.31 ± 0.04^a	0.82 ± 0.07	70.24 ± 1.22
HKR120	12.15 ± 0.04	0.40 ± 0.05^a	0.78 ± 0.08	69.43 ± 1.47
P-44	12.72 ± 0.05	0.67 ± 0.05^b	0.72 ± 0.04	70.10 ± 0.69
Sharbati	11.64 ± 0.06	0.41 ± 0.04^a	0.66 ± 0.08	69.88 ± 1.32
Bas-370	11.85 ± 0.05	0.44 ± 0.06^a	0.65 ± 0.08	68.73 ± 0.71
HBC-19	11.90 ± 0.03	0.67 ± 0.05^b	0.54 ± 0.06	69.25 ± 1.21
The values are mean ± SD of three independent determinations at 5% level of significance. Values with similar superscripts in column do not differ significantly (p < 0.05).
*Non-significant differences.

Table 2  Protein contents of various fractions extracted from milled rice

Cultivar	Albumin (g/100 g sample)	Globulin (g/100 g sample)	Prolamin (g/100 g sample)	Glutelin (g/100 g sample)	Net protein extracted	Protein content (g/100 g sample)
Jaya	0.34 ± 0.01^b	0.57 ± 0.01^b	0.20 ± 0.02^b	3.03 ± 0.03^b	4.14	5.46 ± 0.23^a
	(8.2)	(13.8)	(4.8)	(73.2)
HKR-120	0.36 ± 0.02^b	0.58 ± 0.01^b	0.20 ± 0.01^b	3.17 ± 0.02^c	4.31	5.59 ± 0.12^a
	(8.3)	(13.4)	(4.6)	(73.5)
P-44	0.47 ± 0.01^d	0.60 ± 0.02^b	0.19 ± 0.02^b	3.15 ± 0.02^c	4.41	6.26 ± 0.27^b
	(10.6)	(13.6)	(4.3)	(71.4)
Sharbati	0.30 ± 0.01^a	0.50 ± 0.01^a	0.15 ± 0.01^a	3.54 ± 0.04^d	4.49	6.52 ± 0.12^bc
	(6.7)	(11.1)	(3.3)	(78.8)
Bas-370	0.40 ± 0.01^c	0.53 ± 0.01^a	0.17 ± 0.01^ab	3.15 ± 0.01^c	4.25	7.02 ± 0.16^c
	(9.4)	(12.5)	(4.0)	(74.1)
HBC-19	0.49 ± 0.02^d	0.59 ± 0.01^b	0.20 ± 0.01^b	2.88 ± 0.04^a	4.16	6.94 ± 0.14^c
	(11.7)	(14.2)	(4.8)	(69.2)
Values expressed in parentheses indicate relative percentage of protein fraction. The values are mean ± SD of three independent determinations. Values with similar superscripts in column do not differ significantly (p < 0.05).

Figure 1 Electrophoretic patterns of total protein, glutelin, albumin, globulin, and prolamin fractions from different rice cultivars (M: molecular marker; Lane 1: Jaya; Lane 2: HKR-120; Lane 3: P-44; Lane 4: Sharbati; Lane 5: Bas-370; Lane 6: HBC-19).

Table 3  Functional properties of rice endosperm protein isolates

Cultivar	WAC (ml/g)	OAC (ml/g)	EC*	FC (%)	FS (%) (after 30 min)
Jaya	1.95 ± 0.03^a	1.51 ± 0.04^d	89 ± 0.58^bc	35 ± 1.73^a	40 ± 1.16^a
HKR-120	2.45 ± 0.04^b	1.23 ± 0.03^c	85 ± 1.16^a	39 ± 1.16^b	45 ± 0.58^bc
P-44	2.51 ± 0.05^b	0.95 ± 0.06^b	88 ± 1.73^ab	45 ± 0.29^c	44 ± 1.73^b
Sharbati	2.95 ± 0.02^d	0.86 ± 0.02^ab	92 ± 0.58^c	42 ± 0.5^bc	50 ± 0.87^c
Bas-370	2.70 ± 0.04^c	0.88 ± 0.01^ab	86 ± 0.29^ab	47 ± 1.72^cd	48 ± 0.57^c
HBC-19	2.97 ± 0.02^d	0.80 ± 0.03^a	88 ± 0.87^ab	50 ± 1.44^d	50 ± 1.44^c
*Milliliters of oil emulsified per g of sample.
WAC: water absorption capacity; OAC: oil absorption capacity; EC: emulsifying capacity; FC: foaming capacity; FS: foam stability.

Figure 2 Emulsifying (a) and foaming (b) capacities of isolated rice proteins as a function of pH.

Table 4  Pearson correlation coefficients of functional properties with total protein content and protein fractions

Protein fraction	WAC	OAC	EC	FC
Albumin	0.257	−0.444	−0.371	0.738
Globulin	−0.352	0.249	−0.485	0.066
Prolamin	−0.524	0.509	−0.551	−0.158
Glutelin	0.269	−0.192	0.515	−0.233
Total protein	0.829*	−0.914*	0.090	0.917**
WAC: water absorption capacity; OAC: oil absorption capacity; EC: emulsification capacity; FC: foaming capacity.
*p < 0.05; **p < 0.01.

Table 5  Pearson correlation coefficients of cooking and textural properties of rice grains with total protein content and protein fractions

Properties	Albumin	Globulin	Prolamin	Glutelin	Total protein
Hardness	0.587	−0.140	−0.368	−0.033	0.966**
Cohesiveness	−0.342	0.319	0.464	−0.140	−0.900*
Adhesiveness	−0.264	0.432	0.455	0.023	−0.935**
Springiness	−0.097	−0.430	−0.728	0.760	0.352
Gumminess	0.658	−0.025	−0.329	−0.013	0.893*
Cooking time	0.573	−0.126	−0.283	−0.131	0.956**
Water uptake	0.568	−0.125	−0.241	−0.246	0.942**
Solid loss	−0.451	0.293	0.465	−0.022	−0.987**
Elongation ratio	0.442	−0.290	−0.395	−0.076	0.983**
*p < 0.05; **p < 0.01.