Parboiling to improve milling quality of Selam rice variety, grown in Ethiopia

Figures & data

Figure 1. Working principle of a rubber roll husker (source (Dhankhar & Hissar, 2014).

Table 1. Effects of soaking temperatures on milling qualities of parboiled rice

SkTp (^oC)	Husking (%)	Broken rice(%)	Milling Recovery (%)	Head Rice Yield (%)
40	85.37^b ± 1.52	5.98^b ± 1.76	87.55^a ± 1.52	81.57^c ± 0.95
60	85.93^a ± 1.94	2.81^c ± 1.15	84.87^c ± 1.96	82.11^b ± 1.66
80	85.44^b ± 2.48	2.86^c ± 1.49	85.97^b ± 1.94	83.21^a ± 2.62
Control	75.00^c ± 3.61	41.73^a ± 1.94	79.30^d ± 2.95	58.02^d ± 2.94
CV (%)	0.47	8.01	0.79	0.8
LSD	0.22	0.17	0.37	0.37

Note: SkTp: Soaking Temperature, means with the same letters are not significantly different, values are in mean ± SD.

Table 2. Effects of soaking time on milling qualities of parboiled rice

SkTm (hours)	Husking (%)	Broken (%)	MR (%)	HRY (%)
6	85.00^c ± 2.24	4.79^b ± 2.32	86.24^b ± 2.28	81.59^b ± 1.65
12	85.74^b ± 1.97	3.88^c ± 1.98	86.65^a ± 1.87	82.70^a ± 2.03
24	86.00^a ± 1.73	2.97^d ± 1.56	85.52^c ± 2.07	82.60^a ± 2.08
Control	75.00^d ± 3.61	41.73^a ± 1.94	79.30^d ± 2.95	58.02^c ± 2.94
CV (%)	0.47	8.01	0.79	0.8
LSD0.05	0.22	0.17	0.37	0.36

Note: SkTm: soaking time, MR: milling recovery, HRY: head rice yield, values are in mean±SD.

Table 3. Effects of steaming time on milling qualities on parboiled rice

SmTm (min)	Husking (%)	Broken (%)	MR (%)	HRY (%)
15	84.07^c ± 1.24	5.22^b ± 2.38	86.31^b ± 2.25	81.15^c ± 1.08
25	85.48^b ± 1.93	3.61^c ± 1.53	85.37^c ± 1.89	81.89^b ± 1.28
35	87.18^a ± 1.47	2.82^d ± 1.54	86.72^a ± 2.01	83.85^a ± 2.26
Control	75.00^d ± 3.61	41.73^a ± 1.94	79.30^d ± 2.95	58.02^d ± 2.94
CV (%)	0.47	8.01	0.79	0.8
LSD0.05	0.22	0.17	0.37	0.36

Note: SmTm: steaming time, MR: milling recovery, HRY: head rice yield, values are in mean±SD.

Table 4. Effects of soaking temperature and soaking time on milling quality parameters

SkTp	SkTm	Husking (%)	MR (%)	Broken (%)	HRY (%)
40	6	84.22^e ± 1.39	88.44^a ± 1.72	6.97^b ± 1.84	81.47^cde ± 0.90
	12	85.44^c ± 1.33	87.56^b ± 1.24	6.24^c ± 1.56	81.32^de ± 0.81
	24	86.44^a ± 1.01	86.65^c ± 1.09	4.72^d ± 1.14	81.94^cd ± 0.37
60	6	86.00^b ± 2.45	84.40^e ± 1.56	3.13^f ± 1.62	81.29^e ± 1.21
	12	85.78^bc ± 2.167	86.18^cd ± 1.81	3.19^f ± 0.49	82.98^b ± 2.08
	24	86.00^b ± 1.22	84.04^e ± 1.98	2.11^g ± 0.77	82.05^c ± 1.23
80	6	84.78^d ± 2.54	85.87^d ± 1.50	4.29^e ± 1.69	82.01^c ± 2.51
	12	86.00^b ± 2.45	86.21^cd ± 2.26	2.22^g ± 0.36	83.81^a ± 2.19
	24	85.56^c ± 2.60	85.86^d ± 2.18	2.08^g ± 0.93	83.82^a ± 2.97
Control		75.00^f ± 3.61	79.30^f ± 2.95	41.73^a ± 1.94	58.02^f ± 2.94
CV (%)		0.47	0.79	8.01	0.8
LSD0.05		0.38	0.64	0.29	0.62

Note: SkTp: soaking temperature (^oC), SkTm: soaking time (hr), MR: milling recovery, HRY: head rice yield, values are in mean±SD, means represented by the same letter are not significant.

Table 5. Effect of soaking temperature and steaming time on milling quality parameters

SkTp	SmTm	Husking (%)	MR (%)	Broken (%)	HRY (%)
	15	84.89^d ± 1.27	88.93^a ± 1.37	7.87^a ± 1.44	81.06^d ± 0.75
40	25	84.89^d ± 1.45	86.52^d ± 1.14	5.28^b ± 1.14	81.24^d ± 0.57
	35	86.33^c ± 0.50	87.20^c ± 0.91	4.77^c ± 0.72	82.43^bc ± 0.90
	15	83.78^e ± 1.20	85.33^e ± 1.22	3.93^d ± 1.01	81.39^d ± 1.46
60	25	87.00^b ± 1.22	84.47^g ± 2.24	2.52^f ± 0.82	82.15^c ± 1.31
	35	87.00^b ± 1.22	84.84^efg ± 2.36	1.97^g ± 0.56	82.79^b ± 1.99
	15	83.56^e ± 0.88	84.67^fg ± 1.14	3.85^d ± 1.86	80.99^d ± 0.99
80	25	84.56^d ± 2.13	85.13^ef ± 1.66	3.03^e ± 0.91	82.30^bc ± 1.58
	35	88.22^a ± 1.09	88.13^b ± 0.44	1.72^g ± 0.63	86.34^a ± 1.15
Control		75.00^f ± 3.61	79.30^f ± 2.95	41.73^a ± 1.94	58.02^f ± 2.94
CV (%)		0.47	0.79	8.01	0.8
LSD0.05		0.38	0.64	0.29	0.62

Note: SkTp: soaking temperature (^oC), SmTm: steaming time (minutes), Milling R: milling ratio (mm/mm), HRY: head rice yield, values are in mean±SD.

Table 6. Interaction effect of soaking time with steaming time on milling quality parameters

Soaking Time (hr)	Steaming Time (min)	Husking (%)	Milling Recovery (%)	Broken (%)	Head rice yield (%)
	15	83.56^f ± 1.13	87.16^ab ± 2.50	6.94^b ± 1.84	80.46^f ± 0.86
6	25	84.89^e ± 2.57	85.56^e ± 1.50	4.23^d ± 1.73	81.55^cd ± 0.97
	35	86.56^b ± 1.81	86.00^de ± 2.64	3.22^e ± 1.69	82.76^b ± .06
	15	83.56^f ± 0.88	85.44^e ± 2.74	4.59^c ± 2.74	80.85^ef ± 0.50
12	25	86.00^c ± 1.22	86.90^bc ± 0.72	3.98^d ± 1.43	82.82^b ± 1.55
	35	87.67^a ± 0.86	87.61^a ± 0.72	3.06^e ± 1.36	84.44^a ± 1.86
	15	85.11^e ± 1.05	86.34^cd ± 1.03	4.11^d ± 1.53	82.14^c ± 1.04
24	25	85.56^d ± 1.81	83.65^f ± 1.67	2.62^f ± 0.97	81.31^de ± 0.67
	35	87.33^a ± 0.50	86.56^bcd ± 2.03	2.18^g ± 1.52	84.36^a ± 2.63
Control		75.00^g ± 3.61	79.30^g ± 2.95	41.73^a ± 1.94	58.02^g ± 2.94
CV (%)		0.47	0.79	8.01	0.8
LSD0.05		0.38	0.64	0.29	0.62

Note: means represented by the same letter are not significant; values are in mean±SD.

Table 7. Three-way interaction effects of parboiling factors on milling qualities

SkTp	SkTm	SmTm	Husking	Milling Recovery	Broken rice	Head rice yield
40	6	15	84.33^f ± 1.53	90.40^a ± 0.58	9.3^b ± 0.49	81.10^cde ± 1.05
	6	25	83.67^g ± 1.53	87.31^def ± 0.96	6.19^d ± 0.52	81.11^cde ± 0.44
	6	35	84.67^ef ± 1.53	87.61^cde ± 1.36	5.41^e ± 0.51	82.20^bcde ± 0.85
	12	15	84.33^f ± 0.58	89.02^b ± 0.16	8.17^c ± 0.51	80.84^cde ± 0.47
	12	25	85.00^e ± 1.00	86.74^efg ± 1.07	5.77^de ± 0.51	80.97^cde ± 0.64
	12	35	87.00^c ± 0.00	86.93^ef ± 0.46	4.78^fg ± 0.43	82.14^bcde ± 0.69
	24	15	86.00^d ± 1.00	87.38^de ± 0.59	6.15^d ± 0.30	81.24^bcde ± 0.89
	24	25	86.00^d ± 1.00	85.50^hij ± 0.74	3.87^hij ± 0.16	81.63^bcde ± 0.60
	24	35	87.33^c ± 0.58	87.08^def ± 0.92	4.13^hi ± 0.64	82.94^abcde ± 1.21
60	6	15	83.00^h ± 0.58	85.70^ghi ± 0.81	5.25^ef ± 0.08	80.45^de ± 0.77
	6	25	88.00^b ± 1.00	84.89^ijk ± 0.90	2.27^mno ± 0.25	82.623^bcde ± 0.93
	6	35	87.000^c ± 1.00	82.66^no ± 0.90	1.86^nop ± 0.43	80.80^cde ± 0.53
	12	15	83.33^gh ± 0.58	84.05^klm ± 0.87	3.43^jk ± 0.17	80.62^cde ± 0.71
	12	25	86.00^d ± 1.00	86.71^efg ± 0.76	3.54^ijk ± 0.28	83.17^abcde ± 0.66
	12	35	88.00^b ± 1.00	87.77^cde ± 0.85	2.59^lm ± 0.23	85.18^abcd ± 0.89
	24	15	85.00^e ± 1.00	86.23^fgh ± 0.78	3.11^kl ± 0.09	83.12^abcde ± 0.88
	24	25	87.00^c ± 1.00	81.79°±0.49	1.76^op ± 0.11	80.64^cde ± 0.48
	24	35	86.00^d ± 1.00	84.08^klm ± 0.17	1.46^pq ± 0.12	82.40^bcde ± 0.44
80	6	15	83.33^gh ± 0.58	85.38^hij ± 0.55	6.28^d ± 0.06	79.84^e ± 0.17
	6	25	83.00^h ± 1.00	84.49^jkl ± 0.53	4.21^gh ± 0.19	80.91^cde ± 0.28
	6	35	88.00^b ± 1.00	87.73^cde ± 0.19	2.39^mn ± 0.06	85.28^abc ± 0.37
	12	15	83.00^h ± 1.00	83.25^mn ± 0.09	2.19^mno ± 0.04	81.08^cde ± 0.35
	12	25	87.00^c ± 1.00	87.25^def ± 0.23	2.64^lm ± 0.10	84.34^abcde ± 0.10
	12	35	88.00^b ± 1.00	88.13^bcd ± 0.14	1.82^nop ± 0.07	86.00^ab ± 0.51
	24	15	84.33^f ± 0.58	85.40^hij ± 0.54	3.07^kl ± 0.06	82.06^bcde ± 0.23
	24	25	83.67^g ± .53	83.65^lmn ± 0.37	2.22^mno ± 0.11	81.64^bcde ± 0.48
	24	35	88.67^a ± 1.53	88.52^bc ± 0.51	0.95^q ± 0.07	87.75^a ± 0.27
Control			75.00^i ± 3.61	79.30^p ± 2.95	41.73^a ± 1.94	58.02^f ± 2.94
CV (%)			0.47	0.79	8.01	0.8
LSD0.05			0.66	1.11	0.51	1.07

Note: SkTp: soaking temperature (^oC), SkTm: soaking time (hours), SmTm: steaming time (minutes), means represented by the same letter are not significant, values are in mean±SD.

Dhankhar, P., & Hissar, T. (2014). Rice milling. IOSR Journal of Engineering, 4(5), 34–42. https://doi.org/10.9790/3021-04543442

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