Fruit juice is important in human nutrition for beyond its use as a refreshing source of liquid. Many fruits contain a variety of minor ingredients, particularly vitamins and minerals, as well as carbohydrates which are the predominant solid component.
Although fruit contains small amounts of protein and fat, these are not important ingredients of juices.
Nutrients frequently consumed in sub-optimal concentrations by humans are protein, calcium, iron, vitamin A, thiamin (vitamin B1), riboflavin (vitamin B2) an ascorbic acid (vitamin C).
Some of these nutrients occur in higher concentrations in fruit juices than in other foods.
There is experimental evidence that indicates that ascorbic acid of natural origin is apparently superior to that of synthetic origin.
It has been established that the above phenomenon is caused by the presence of certain flavonoids compounds in fruit juice that influence blood circulation, increasing the permeability and elasticity of capillaries.
This action is known as vitamin P activity, but the flavonoids showing this property are not classified as vitamins, because there several substances with is activity and no serious deficiency diseases occur if they are not consumed.
There are indications that these flavonoids have a useful protective action, in particular against some respiratory diseases, but they are readily decomposed in the body, and it is impossible to maintain an effective concentration.
Apart from the more obvious benefits of fruit juice, such as being a source of potassium, it contains other substances that have or are claimed to have useful pharmacological activity. Sorbitol, which occurs in many fruit juices, has a laxative effect.
Several components with antioxidant activity are found in fruit juices. These are including ascorbic acid, tocopherols (vitamin E), beta carotene and flavonoids.
Whatever the nutritional interest, it should be noted that changes occur during storage, particularly to the minor components of juices and particularly under adverse conditions (e.g., light, increasing temperature, time).
Important nutrients in fruit juice
