Rice Dreg Protein as an Alternative to Soy Protein Isolate: Comparison of Nutritional Properties

Figures & data

Table 1 Proximate composition of RDP and RPI

	Protein	Moisture	Fat	Ash	Fiber	Carbohydrate
RDP	62.62 ± 0.96^b	6.05 ± 0.05^a	10.47 ± 0.36^a	7.71 ± 0.07^a	4.10 ± 0.08^a	9.37 ± 0.04^a
RPI	87.38 ± 0.31^a	3.24 ± 0.02^b	0.78 ± 0.13^b	4.33 ± 0.39^b	0.40 ± 0.12^b	2.25 ± 0.20^b

^ab Mean ± SD (n = 3) in the same column indicate significant difference at p ≤ 0.05.

Table 2 Onset temperature (T_o), denaturation temperature (T_p), end temperature (T_e), and denaturation enthalpy (ΔH) of RPI and SPI

Proteins	To (°C)	Tp (°C)	Te (°C)	ΔH (J/g protein)
RPI	43.4 ± 0.30	47.4 ± 0.08	50.1 ± 0.01	1.61 ± 0.15
	76.5 ± 0.07	97.2 ± 0.00	113.9 ± 0.01	72.49 ± 0.65
SPI	79.5 ± 0.12	91.4 ± 0.00	103.3 ± 0.09	26.23 ± 1.48

Figure 1 DSC curves of RPI and SPI.

Table 3 Amino acid composition^a and the FAO/WHO suggested essential amino acid requirements (g/100 g of protein)

				FAO/WHO (1985)
Parameters	RDP	RPI	SPI	Child	Adult
Essential amino acids
Thr	3.79	3.27	3.54	3.40	0.90
Val	5.49	6.04	5.40	3.50	1.30
Ile	4.19	4.62	3.70	2.80	1.30
Leu	8.51	8.62	7.38	6.60	1.90
Lys	3.18	3.17	3.46	5.80	1.60
Trp	0.85	1.33	1.21	1.10	0.50
His	2.56	2.48	2.33	1.90	1.60
Met+Cys	3.88	2.35	4.31	2.50	1.70
Phe+Tyr	7.52	10.33	8.72	6.30	1.90
Non-essential amino acids
Asp	8.86	9.12	10.24
Ser	4.91	5.12	4.93
Glu	17.16	18.56	16.82
Gly	4.80	5.35	4.90
Ala	5.90	5.25	6.02
Arg	8.18	9.73	8.02
Pro	10.22	4.67	9.04
Hydrophobic^b	46.97	42.64	45.26
Uncharged-polar^c	13.09	14.31	13.89
Basic^d	13.92	15.38	13.81
Acidic^e	26.02	27.68	27.06

^aThe values of amino acid composition reported represent the average of three determinations.

^bAla, Val, Ile, Leu, Phe, Trp, Pro, Gly, and Met.

^cCys, Thr, Tyr, and Ser.

^dArg, His, and Lys.

^eAsp and Glu.

Table 4 Nutritional evaluation of RDP, RPI and SPI ^a according to FAO/WHO (1973).^[24]b,c

Parameters	RDP	RPI	SPI
AAS
Ile	104.8	115.5	92.5
Leu	121.6	123.1	105.4
Lys	57.8*	57.6*	62.9*
Met+Cys	110.9	67.1**	123.1
Phe+Tyr	125.3	172.2	145.3
Thr	94.8	81.8	88.5**
Trp	85.0**	133.0	121
Val	109.8	120.8	108
CS
Ile	77.6	85.6	68.5**
Leu	99.0	100.2	85.8
Lys	45.4*	45.3**	49.4*
Met+Cys	68.1	41.2*	75.6
Phe+Tyr	80.9	111.1	93.8
Thr	80.6	69.6	75.3
Trp	50.0**	78.2	71.2
Val	83.2	91.5	81.8
E/T, %	39.97	42.21	40.05
BV	77.29	34.76	55.86
EAAI	0.710	0.721	0.740
PER
I	2.72	3.03	2.26
II	3.14	2.87	2.55
III	3.90	1.11	2.32

^a:*First limiting amino acid; **second limiting amino acid.

^bEssential amino acids of the standard protein: Ile 4.00, Leu 7.00, Lys 5.50, Met+Cys 3.50, Phe+Tyr 6.00, Thr 4.00, Trp 1.00 and Val 5.00.

^cEssential amino acids of the whole egg protein: Ile 5.40, Leu 8.60, Lys 7.00, Met+Cys 5.70, Phe+Tyr 9.30, Thr 4.70, Trp 1.70 and Val 6.60.

Figure 2 Reduced and unreduced SDS-PAGE profiles of RPI and SPI digested with sequential pepsin and pancreatin.

Figure 3 The nitrogen release (%) of RPI and SPI during sequential pepsin and pancreatin digestion. The error bars indicate the standard deviations of duplicate measurements.

FAO/WHO. Energy and protein requirements. Report of FAO Nutritional Meeting Series, Number 52. FAO: Rome, Italy. 1973.

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