Know Your Grains
A whole grain comprises of three different components – Bran, Endosperm and Germ as shown in the image below.
Parts of a Whole Grain Seed
(Representative of whole kernels like that of corn, wheat, rice, oats, barley, rye,etc.)
Nutritional content of different parts of a whole grain
a) Bran – It is the outer covering of the grain that protects the delicate inner parts of the grain from wear and tear. It is majorly composed of insoluble dietry fiber. Only whole grain flour (chakki milled/stone-ground) has this part of the grain.
b) Endosperm – It is the most carbohydrate rich part of the grain and forms majority of the grain weight (eg. 83% of wheat grain weight is endosperm). If you buy refined flour eg white flour or maida, then it is the part of the grain that you are eating because while making refined flour the bran and germ is removed from the grain. Endosperm is carbohydrates and proteins rich.
c) Germ – It is the embryo or the sprouting section of the seed and forms a very small part of the entire grain (eg. only 2.5% by weight of wheat grain is the germ). It is very rich in nutrients like B-complex vitamins and trace minerals, and also has small quantities of high quality protein and fats in it. Only whole grain flour has this part of the grain as it is removed from refined grains to improve shelf life (fat present in germ spoils the flour sooner).
Flour Processing Techniques
a) Stone (Chakki) Grinding – It is a grain grinding process based on crushing grains between two rotating stones. It has been used since ancient times in India to make flour at home. In this technique the whole kernel(grain) – including germ and bran, is ground to flour(atta).
b) Roller milling – In this technique the grain is broken down into smaller parts – the bran and germ is separated from the endosperm and then the endosperm alone is milled to flour. The flour produced by this technique is whitish in color as bran and germ have been removed, as a result it is much less nutritious than stone-ground flour.
c) Garhaat Grinding– Garhaat (also called Girhaat or Panchakki) is the traditional Indian water powered stone grinding method used in hilly regions of Himachal Pradesh and Uttarakhand states of India, to produce flour. Since the speed to rotation of the stones is slow, lesser heat is generated and hence the flour is considered very nutritious. However the process is very slow so flour costs are much higher