Physicochemical properties of waxy rice varieties with contrasting hardening rates

Figures & data

Table 1. The hardness levels of cooked rice grains at different storage (4°C) times.

Time	zhenzhunuo (g)	zaonuo5 (g)	zhennuo29 (g)	yj98 (g)
0 h	86.31 ± 0.40^Ba	130.55 ± 11.30^Ae	83.20 ± 18.31^Bb	82.09 ± 3.43^Bd
12 h	124.84 ± 10.94^Ca	168.18 ± 3.01^Bd	86.26 ± 7.97^Db	249.53 ± 33.83^Ac
24 h	118.31 ± 30.21^Ba	401.01 ± 9.85^Ac	90.37 ± 17.20^Bb	552.21 ± 75.09^Ab
36 h	128.88 ± 43.34^Ca	469.31 ± 13.20^Bb	116.85 ± 5.91^Ca	780.91 ± 32.70^Aa
48 h	126.09 ± 9.56^Ba	583.55 ± 18.77^Aa	133.71 ± 8.45^Ba	/

Values followed by different lowercase letters in the same column are significantly different between storage time (P < .05); Values followed by different uppercase letters in the same row are significantly different between varieties at(P < .05);/indicates the value is beyond the instrument`s detection limit.

Table 2. Gelatinisation properties of waxy rice flours.

Variety	To (°C)	Tp (°C)	Tc (°C)	ΔT (°C)	ΔHgel (J/g)
zhenzhunuo	61.80 ± 0.00^d	67.25 ± 0.35d	74.30 ± 0.71^c	12.50 ± 0.71^a	8.64 ± 0.07^b
zaonuo5	67.80 ± 0.00^b	73.55 ± 0.07b	76.95 ± 0.21^b	9.15 ± 0.21^b	9.15 ± 0.04^a
zhennuo29	63.30 ± 0.14^c	69.00 ± 0.00c	73.30 ± 0.99^c	10.00 ± 0.85^b	7.65 ± 0.21^c
yj98	73.05 ± 0.07^a	78.60 ± 0.28a	82.65 ± 0.07^a	9.60 ± 0.14^b	8.57 ± 0.49^b

To, onset temperature; Tp, peak temperature; Tc, final temperature; ΔT, gelatinisation temperature range. ΔH_gel, gelatinisation enthalpy; Values followed by different letters in the same column are significantly different (P <0.05).

Figure 1. Changes in retrogradation enthalpy (∆H_ret) of retrograded waxy rice gel stored at 4°C.

Figure 2. Pasting viscosity profiles of rice flour.

Table 3. Pasting properties of waxy rice flours.

Variety	Pasting temperature (℃)	Peak viscosity (cP)	Trough viscosity (cP)	Final viscosity (cP)	Breakdown (cP)	Setback (cP)
zhenzhunuo	72.0 ± 0.5b	3355 ± 22a	1720 ± 15a	1997 ± 37a	1635 ± 18a	277 ± 5b
zaonuo5	79.9 ± 0.2a	1994 ± 39d	1292 ± 24c	1591 ± 26c	702 ± 13c	299 ± 10ab
zhennuo29	72.8 ± 0.3b	2481 ± 13c	1233 ± 17c	1458 ± 10d	1248 ± 26b	225 ± 15c
yj98	8.7 ± 0.2a	2825 ± 35b	1526 ± 43b	1864 ± 25b	1299 ± 21b	337 ± 38a

Values followed by different letters in the same column are significantly different (P < .05).

Figure 3. Scanning electron microscopy of cooked rice grains. a) zhenzhunuo gelatinised rice before storage. b) zhenzhunuo gelatinised rice stored at 4°C for 24 h. c) zaonuo5 gelatinised rice before storage. d) zaonuo5 gelatinized rice stored at 4°C for 24 h. e) zhennuo29 gelatinized rice before storage. f) zhennuo29 gelatinised rice stored at 4°C for 24 h. g) yj98 gelatinised rice before storage. h) yj98 gelatinised rice stored at 4°C for 24 h. Arrow indicates the cavity. Scale bar = 15 μm.

Figure 4. Amylopectin branch chain length distribution of waxy rice starches..

Table 4. Amylopectin chain length distribution of rice starches.

Variety	Average chain length (DP)	Amylopectin branch chain length distribution (%)
		6≤DP≤12	13≤DP≤24	25≤DP≤36	37≤DP≤100
Zhenzhunuo	20.49 ± 0.10^c	29.25 ± 0.20^a	47.80 ± 0.07^a	10.15 ± 0.08^b	12.79 ± 0.19^c
zaonuo5	22.12 ± 0.45^b	26.25 ± 0.60^b	46.76 ± 0.37^b	11.24 ± 0.14^a	15.75 ± 0.83^b
zhennuo29	22.11 ± 0.35^b	25.04 ± 0.40^b	47.65 ± 0.13^a	11.52 ± 0.50^a	15.79 ± 0.67^b
yj98	23.02 ± 0.29^a	22.95 ± 0.85^c	48.13 ± 0.30^a	11.38 ± 0.43^a	17.53 ± 0.51^a

DP, degree of polymerization. Values followed by different letters in the same column are significantly different (P < .05).