An Objective Method and a Device for Determining the End Point of Cooking of Dhal and Rice

Figures & data

Figure 1 The Cooked Dhal Pressing Device (CDPD). A: Lever; B: Loading Platform; C: Spring; D: Ram; E: Cooked Sample; F: Glass Plates; G: Shed Housing; H: Fulcrum Link; and I: Wooden Base.

Table 1 Subjective cooking time, UTM values, spread area and spread area ratio of the Dhals/Rice

Sample	^aSubjective Cooking time (SCT) min.	^bSpread area (SA) at SCT (sq.mm)	Spread area ratio (SAR) at SCT	^cUTM Hardness (N) at SCT
Green gram dhal	18 ± 1	27.6 ± 4.05	3.60	7.3 ± 0.65
Horse gram dhal	40 ± 2	26.1 ± 5.55	5.30	8.5 ± 0.15
Red gram dhal	28 ± 2	62.1 ± 5.09	2.60	3.0 ± 0.32
Lentil dhal	18 ± 1	33.7 ± 6.34	2.16	8.8 ± 0.20
Raw rice	20 ± 1	123.9 ± 27.10	15.40	1.1 ± 0.18
Hybrid raw rice	18 ± 1	153.4 ± 15.43	11.90	3.2 ± 0.74
Parboiled rice	27 ± 2	111.6 ± 11.60	7.54	5.8 ± 0.65
(a) n = 3; (b) n = 20; and (c) n = 10. Mean ± SD.

Figure 2 The slides showing ‘Area of Raw,’ ‘Spread Area’ of middle CT, and end CT of Dhals / Rice. 1: raw; 2: middle of cooking; and 3: end of cooking.

Figure 3 Spread area of Dhals and Rice using 500 g load.

Table 2 Comparison of various methods tested for determining cooking times of different grains

	Cooking time, min.
Sample	SCT*	UTM**	CDPD***
Green gram dhal	18 ± 1	19.0 ± 1.4	20.0 ± 1.0
Horse gram dhal	40 ± 2	42.5 ± 3.5	42.0 ± 2.0
Red gram dhal	28 ± 2	29.0 ± 1.4	31.0 ± 3.6
Lentil dhal	18 ± 1	19.0 ± 1.4	17.8 ± 1.9
Raw rice	20 ± 1	16.5 ± 2.1	18.6 ± 1.5
Hybrid raw rice	18 ± 1	19 ± 1.4	18.5 ± 1.4
Parboiled rice	27 ± 2	27.0 ± 1.4	27.5 ± 0.70
*SCT (n = 3)—Subjective Cooking Time; **UTM (n = 10)—Cooking time expressed when relative hardness attains a steady value using UTM; ***CDPD (n = 20)—Cooking time expressed when the spread area curve attains steady value /change of slope; and (p<0.05) for CT determined by SCT,UTM, and CDPD.

Table 3 Relative Hardness (HR) and Spread Area Ratio (SAR) of Dhals/Rice during progressive cooking

	Green gram		Horse gram		Red gram		Lentil		Raw rice		Hybrid raw rice		Parboiled rice
SCT(min)	HR	SAR	HR	SAR	HR	SAR	HR	SAR	HR	SAR	HR	SAR	HR	SAR
Raw	1	1	1	1	1	1	1	1	1	1	1	1	1	1
1h soaked only	0.066	1.76	0.119	1.8	0.145	1.82	0.136	1.55	0.214	1.06	0.364	1.26	0.172	1.27
5	0.111	2.21	0.111	1.99	0.223	1.91	0.131	1.91	0.040	3.69	0.077	3.09	0.247	2.25
10	0.103	2.98	0.101	2.06	0.162	2.01	0.104	2.01	0.023	7.66	0.051	4.38	0.148	3.27
15	0.087	3.42	0.099	–	0.114	2.11	0.094	2.07	0.017	10.8	0.044	10.44	0.093	3.78
18	0.070	4.00	–	–	–	–	0.088	2.16	0.016	12.2	0.035	11.99	–	–
20	0.069	4.11	0.082	2.06	0.054	2.36	0.088	2.18	0.010	12.7	0.034	12.03	0.078	5.61
22	–	4.40	–	–	–	–	–	2.13	0.010	16.9	0.026	13.93	–	–
25	0.062	4.3	0.064	–	0.041	2.46	0.086	–	0.008	18.6	0.027	16.11	0.053	6.32
28	–	–	–	–	0.015	2.6	–	–	–	–	–	–	0.027	7.54
30	–	–	0.060	2.13	0.015	2.6	–	2.29	0.007	18.6	0.026	18.14	0.027	9.21
32	–	–	–	–	–	–	–	–	–	–	–	–	–	–
35	–	–	0.050	–	0.015	2.62	–	–	–	–	–	–	0.021	9.2
40	–	–	0.036	2.30	–	–	–	–	–	–	–	–	–	–
45	–	–	0.033	2.31	–	–	–	–	–	–	–	–	–	–
SD	0.33	1.47	0.25	1.09	0.25	1.18	0.25	1.06	0.26	7.47	0.26	6.83	0.25	3.51
Std err	0.08	0.38	0.06	0.28	0.07	0.30	0.06	0.27	0.07	1.93	0.07	1.76	0.07	0.91
r	–0.798		–0.992		–0.983		–0.975		–0.632		–0.661		–0.698

Figure 4 Changes in Hardness (N) by UTM during cooking of Dhals/Rice.

Figure 5 Effect of soaking on hardness of Dhals/Rice. Gg: green gram; Hg: horse gram; Rg: red gram; Lentil: lentil dhal; R. rice: raw rice; H. rice: hybrid raw rice; and P. rice: parboiled rice.