Potatoes are the major source of carbohydrates in the diet of hundreds of millions of people in developing countries .
It is a growing importance to the economy of the people living in South America, Africa, East Asia and Central Asia. In the list of foods to which the world depends for food safety, potatoes occupy third place after rice and wheat.
According to FAO estimates in Europe just over 60 % of the total of potatoes produced is intended for food uses. A 25% is used for animal feed and the rest is used for industrial purposes , to produce alcohol and starch.
The food consumption of potatoes is gradually shifting from methods of direct consumption of the product purchased fresh , the use of industrial products based on potatoes . One of the main uses is that of frozen potatoes that represent the vast majority of French fries served in restaurants and fast food. It is estimated that this type of consumption covers more than 11 million tons per year.
Another product is the industrial potato starch ( the trade name of starch potatoes); prepares subjecting the potatoes, washed and peeled, to the action of machinery that reduces to a pulp, then this is sieved, allowed to settle and the dried residue is obtained the final granular product . For drying of dense suspensions, on cylinders, are obtained with different methods, the potato flakes while from the distillation of fermented mash potato is possible obtain a brandy well known : the vodka ( alcohol content between 40 and 60%) .
Potatoes provide 85 kcal per 100 g, have a modest amount of fat and protein ( 2 % ) which, however, contain the amino acid essential lysine, in contrast to the protein content of cereals .The carbohydrate content is considerable ( about 18 %) and mostly consisting of starch and small quantities of simple sugars.
These tubers are an important source of vitamins, a medium-sized potato (150 g) provides about 25 mg of vitamin C (45% of the recommended daily dose), 850 mg of potassium (18% of recommended daily dose) , approximately 0, 2 mg of vitamin B5 (10% of recommended daily dose ) in addition to traces of thiamine , riboflavin , folate , niacin, magnesium, phosphorus , iron and zinc . In addition to vitamins , minerals and fiber, potatoes contain a variety of phytochemicals , such as carotenoids and polyphenols . The contribution of potatoes to the introduction of these important nutrients obviously depends on the amount consumed and the importance of this crop in the diet of a population.
The value of the potatoes as an important source of vitamin C is often underestimated or even ignored. However, it should be borne in mind that as long as the potatoes are kept lower the content of vitamin C ( ascorbic acid) : it was found that after nine months of harvesting the content of this vitamin in the tubers turns out to be 12.5% compared to the original one . The variety , environmental conditions , methods of cooking and preserving of potatoes affect much on the content of vitamin C. For example, the cooking of the tubers in the oven or microwave involves a greater loss of this Vitamin compared to boiling.
Importance of Vitamin C to human health
Vitamin C is a component essential to living cells and the tissues and being an antioxidant free that can damage tissues contributing to the developmentof chronic diseases and certain types of cancer
Potatoes are easily digestible and are , therefore, advantageous use for both child and geriatric nutrition . A portion of reference (QB ) potato is about 200 g in proper nutrition for a healthy individual , it is recommended to take 2 QB per week. In fact, a survey conducted in 2005 by the National Institute of Research on Food and Nutrition ( INRAN ) of Italian food consumption has emerged that the Italian population consumes a quantity of potatoes which is well below the recommended although it is , in fact , a food rich in nutrients. The study involved a sample of 3322 individuals between males and females , divided by age group , belonging to the whole country . The data obtained indicate that 73% of the total population consumes an average of 51 g / day of tubers and products.
How to Preserve the nutritional characteristics potato
Potato is one of the sources most important potassium ( about 570 mg/100 g ) , phosphorus and calcium , which in part pass into the cooking water if not you follow the precautionary boil potatoes whole and unpeeled
The biggest consumers of potatoes were teenagers, especially males (69 g / day) and the elderly ( aged 65 years), always male , with 61 g / day. In every age group shows that women consume fewer potatoes than men. This figure reflects the fact that potatoes are generally considered so as to avoid high calorie foods and weight-loss diets , which are mainly followed by women. In fact from the nutritional point of view the potatoes are known mainly for the high carbohydrate content ( approximately 25 g in a potato 150 g , ie medium-sized ) , present mainly in the form of starches. A small but significant part of these potato starch is resistant to the enzymes present in the stomach and small intestine , so as to reach the large intestine almost intact. It is believed that these starches have physiological effects equal to those of dietary fiber . In addition to the increase satiety and improve bowel function and disorders associated with it (constipation , diverticulosis ) , the introduction of fiber with food has been put in relation to the reduction in the risk for major chronic diseases , in particular tumors of the colon - rectum ( in part explained by the dilution of any carcinogenic substances and the reduction of their time of contact with the mucosa, diabetes (as it improves glucose tolerance and insulin sensitivity) and cardiovascular disease ( in part peruna reduction of blood cholesterol levels) .
Potatoes and Glycemic Index
The potatoes , given the high amount of carbohydrates ( 18-20%) , are classified as foods with a high glycemic index (GI ) and generally excluded from low-calorie diets and low carbohydrate . In fact, the GI of potatoes will change significantly depending on their variety ( red-skinned potato , white paste , etc. . ) , Their origin ( growing area ) , preparation ( cooking method , whether eaten cold or hot , mashed , chopped or whole etc. . ) and other foods with which they accompany ( sauces rich in fat or high protein content .) the glycemic index is defined as the ratio between the area of the increase in blood glucose response after ingestion of 50 g of a standard food ( white bread ) compared to that obtained by consuming a isoglucidica amount of a particular food item examination, always in the same individual .
In fact only consider the glycemic index in the formulation of a diet low carbohydrate regime can be misleading when you take into account the amount isoglucidiche necessary in the preparation of a plan for replacement of food to enable the diversification of the diet. In other words the replacement isoglucidica of 100 g of white bread ( which is IG 100 ) provides for the introduction of 760 g of carrots whose IG is 135 .
More correctly it should be taken into account not the IG of single food but overall the entire meal. As already mentioned, the ability of a food to raise your blood sugar is affected by several factors such as the chemical composition of the food itself and the various technological treatments In any case, several epidemiological studies suggest that consumption of foods with a low glycemic index, especially when taken inside of a diet rich in fiber , protect from the onset of type 2 diabetes . In addition to the control of diseases related to carbohydrate metabolism (diabetes , hyperglycemia) a meal low GI would be preferred in the case of low-calorie diet and to control the level of blood lipids .