Refined grains




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



  • Flour

  • Whole-wheat flour



References




  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



  • The History of Bread, UK Bakers Federation, 2002









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