Refined grains

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Refined grains, in contrast to whole grains, refers to grain products consisting of grains or grain flours that have been significantly modified from their natural composition. The modification process generally involves the mechanical removal of bran and germ,[1] either through grinding or selective sifting. Further refining includes mixing, bleaching, and brominating; additionally, thiamin, riboflavin, niacin, and iron are often added back in to nutritionally enrich the product. Because the added nutrients represent a fraction of the nutrients removed, refined grains are considered nutritionally inferior to whole grains.[2] However, for some grains the removal of fiber coupled with fine grinding results in a slightly higher availability of grain energy for use by the body.[3] Furthermore, in the special case of maize, the process of nixtamalization (a chemical form of refinement) yields a considerable improvement in the bioavailability of niacin, thereby preventing pellagra in diets consisting largely of maize products.[citation needed]

Nutritional effects of refining or enriching wheat and rice[4]
Wheat Rice
Whole Refined Enriched Whole Refined Enriched
Food energy 100% 107% 107% 100% 99% 99%
Carbohydrates 100% 105% 105% 100% 104% 104%
Fiber 100% 22% 22% 100% 37% 37%
Protein 100% 75% 75% 100% 90% 90%
Thiamin (B1) 100% 27% 176% 100% 17% 144%
Riboflavin (B2) 100% 19% 230% 100% 53% 53%
Niacin (B3) 100% 20% 93% 100% 31% 82%
Pantothenic Acid (B5) 100% 43% 43% 100% 68% 68%
Pyridoxine (B6) 100% 13% 13% 100% 32% 32%
Folate (B9) 100% 59% 350% 100% 40% 1155%
Vitamin E 100% 5% 5% 100% 18% 18%
Calcium 100% 44% 44% 100% 100% 100%
Iron 100% 30% 120% 100% 54% 293%
Magnesium 100% 16% 16% 100% 17% 17%
Phosphorus 100% 31% 31% 100% 35% 35%
Potassium 100% 26% 26% 100% 52% 52%
Sodium 100% 40% 40% 100% 71% 71%
Zinc 100% 24% 24% 100% 29% 29%
Copper 100% 38% 38% 100% 79% 79%
Manganese 100% 18% 18% 100% 29% 29%
Selenium 100% 48% 48% 100% 65% 65%

See also[edit]

References[edit]

  1. ^ FDA Provides Guidance on "Whole Grain" for Manufacturers
  2. ^ Campbell, Hauser & Hill, Nutritional Characteristics of Organic, Freshly Stone-Ground, Sourdough & Conventional Breads, McGill University, 1991
  3. ^ Goodband, Tokach & Nelssen, The Effects of Diet Particle Size on Animal Performance, Kansas State University, 1995
  4. ^ USDA Standard Reference 17 Food Nutrient Database

External links[edit]