RICE AND HUMAN NUTRITION - GENERAL DESCRIPTION

The following terms listed are an introduction to give an idea of what is meant by nutritional components of our organism.

GLUCIDES: These cover starches, cellulose and sugars (fructose, glucose etc.) and are of vegetable origin, being synthesized from plants. Their function is essentially one of nourishment and energy for our organism’s cells.

LIPIDS: These are represented by the various types of fats, both animal and vegetable, (triglycerides, phospholipids, cholesterol, etc.) which are responsible for the functioning of the membranes of the body cells.

PROTEIN: These consist of a series of smaller molecules called aminoacids. There are about 20 diverse aminoacids in existence which, by joining together into various structures, give rise to the various proteins present in our organism. They are basic to life in that they form part of the cell structure and are employed in its reproduction; further more they are involved in numerous biological processes that take place.

VITAMINS: Although only present in minute quantities they are extremely important for the role they play in many biological processes; some vitamins have to be introduced with food as they can not be synthesized by us. They are divided into liposoluble (Vitamins A, D, E, K) and watersoluble (Vitamins C. B, P etc.) according to whether they are dissolved in a fat or water; it is important to have a varied diet to ensure the correct amount of these essential substances every day.

MINERALS: These are classed as macroelements (calcium, potassium, magnesium, phosphorus, sodium, chlorine),which are necessary in relatively large quantities, and trace elements (copper, cobalt, magnesium, zinc, iron, etc.) that although only present in minute quantities in both food and body tissue are however essential for health; and, as for vitamins, are introduced through a well balanced diet. .
Every food contains these principal nutrients in quantities that can vary to the complete absence of some of them; in the case of rice, glucides are present in a higher quantity in respect to proteins and lipids, while the vitamin and mineral content varies according to the degree of processing undergone by the rice (see table).

THE GLUCIDES: The glueides in rice are separated into non-cellulose and starch: the first forms part of the external protection of the grain and is removed during the milling process; the starch however constitutes the most inner part, i.e. the endosperm, and is exposed during husking process.
Starch is formed from molecules of glucose which when combining, give to linear chains (amylose) and branching chains (amylopectin).
The starch granule consists of amylose and amylpectin and these take part in the modifications and transformations that occur during cooking. The size of the starch granule varies in each food considered and whereas the starch granules in potatoes are large, those present in rice are very small; an important characteristic that improves digestibility because the area of contact for the gastric juices is greater and therefore more efficient.
At this stage it is important to introduce the concept of gelatinization. Leaving rice to soak for a certain length of time will cause an absorption of water and the movement of some of the components found in the outer layers and germ towards the centre;  on contact with water the starch granules swell slightly but if heat is applied they become a dense sticky mass. This process is called gelatinization.
During the parboiling process the external layers generally gelatinize whereas some substances, minerals and vitamins move towards the

endosperm.

Even though not highly representative, the presence of protein is of a highly biological value. To understand the significance of this is it must be known that eight of the aminoacids used to form protein can not be made by the human organism and have to be introduced through food: these are
called “essential". The higher the proportion of these essential aminoacids present in a food the higher is its biological value. Rice contains these
essential amino-acids in the correct proportions but as the quantity is very small it needs to be combined with other more proteinic foods to give a proper nourishment.

This concept of “essentiality“  needs also to be considered for the lipids as these are very scarce in rice; we are unable to synthesize some of the polyunsaturated fats which are. however, called “essential acid fats”. The quality of fats is high but totally insufficient "compounded by losses during milling" and it is advisable to supply an adequate lipid ratio. and therefore a balanced food, by the use of other foods.
Rice is quite a good source of vitamins, especially groups B and P. but unfortunately the needs of preservation and milling cause a massive loss of these substances. A good part of these can be saved (circa 80%)

by treating the paddy as the Orientals used to, soaking and heating it before letting it dry. A process they used to facilitate the removal of the glumes, little knowing that in this way many of the principal nutrients essential to good
health were retained; a process we know of as “parboiling”. Also the minerals, of which we have iron, potassium, phosphorous, magnesium and manganese in good quanties, roughly follow the same path as the vitamins, the major part being retained in parboiled rice.But even white rice is a commendable product for its low sodium content relative to potassium; numerous studies made on this seem to attribute much importance to a low sodium content in the prevention of some illnesses such as high-blood pressure, an attribute applicable to rice in general.
In some countries "enriched" rice is commercially available: this consists of rice to which previously treated grains are added. They can be enriched with vitamins, minerals and sometimes aminoacids.

This type of rice is not available in Italy, considering it better to do something to safeguard the nutrients in their rice. Many people do not know, for example, that washing raw rice causes a massive reduction of the vitamin and mineral content. For such it would be better not to wash it before cooking. The loss will be even more drastic if the rice is boiled in an excess of water: the loss of vitamins such as B and P can be higher than 50%. Steam cooking or the typically oriental method where the water is totally absorbed retains many more of the principal nutrients.
It is therefore advisable to avoid unnecessary loss of precious substances from a food already debilitated, trying not only to prepare tasty and appetizing dishes but also to raise the nutritive qualities.