Nutritional implications of rice milling

In rice milling, the bran layers and germ removed during polishing are high in fibre, vitamins and minerals as well as protein. Their removal results in loss of nutrients, especially in substantial losses of B vitamins (Table 1). Polishing rice reduces the thiamin content of rice by over 80%.

Parboiling results in gelatinisation of the starch and disintegration of the protein in the endosperm resulting in inward shift of water-soluble vitamins to the endosperm. Parboiled rice is therefore higher in B vitamins than raw milled rice.

Table 1. Nutrient content of rice

mg/100 g

Paddy rice

Brown rice

Polished rice

Parboiled rice

Thiamin

0.4

0.34

0.07

0.44

Riboflavin

0.05

0.05

0.03

0.03

Niacin

5.5

4.7

1.6

3.5

Iron

2.8

1.9

0.5

3.1

Magnesium

118

187

13

143

Garrow JS et al (ed) Human Nutrition and Dietetics. 2000:Harcourt Publishers; London.

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