Every type of fruit has a particular taste and while some fruits taste sweet, other fruits taste sour. This depends on the compounds contained within each fruit. Compounds of fructose, acid, vitamins, proteins, cellulose and starch are found in varying proportions within each type of fruit, giving it a characteristic taste that is either sweet or sour.
Guavas, grapes, apples, mangoes and pears are some of the fruits that you will find to be sweet in taste. These fruits contain a greater amount of fructose than sour fruits. Fructose is a natural form of sugar, which is why fruits with large amounts of fructose taste sweet. Sweet fruits contain more calories because of their higher fructose sugar content, and can increase you blood sugar levels higher than sour fruits. Eating sweet food can lead to weight gain. If you are trying to put on weight, you can eat sweet fruit, while if you are attempting to lose weight, you may prefer to eat sour fruit. You will still benefit from the vitamins contained in fruit, without the excess sugar.
Fruits that contain more acid taste sour. Citrus fruits like lemons and limes have a large amount of acid, which accounts for their sour and at times bitter taste. Other sour fruits include kiwifruit, blackcurrants and raspberries. Generally, fruits that are less ripe contain more acid and less fructose. During the ripening process, a series of chemical changes take place inside the fruit. Through ripening, the amount of acid in the fruit decreases while the fructose content increases, making it sweeter. Fruits with a very large amount of acid, like lemons, don't become sweet even after ripening.
Sour and Sweet
Not all fruits are either sweet or sour. Some fruit, such as oranges, contain almost equal amounts of acids and fructose, which gives them both a sweet and sour taste. In addition, different varieties of the same type of fruit can result in a fruit that can be either sweet or sour. For example, granny smith apples are more sour than the pink lady apple variety. Other factors can change the sweetness of the fruit, such as the growing climate, and the soil, water or techniques used to grow the fruit. This changes the proportions of the compounds within the fruit, which changes the taste.
According to Chinese traditional medicine, foods with a sweet flavor affect the stomach and spleen while foods with a sour flavor affect the liver and gall bladder. According to Chinese belief, sweet fruit such as watermelon can neutralize the toxicity of other foods when eaten in accompaniment with other food. The Chinese categorize sweet and sour fruits in terms of the affect they have on your body, rather than their initial taste. Sour foods can stop excessive perspiration and diarrhea. Some fruits are included in both the sweet and sour categories, as they are believed to contain both sweet and sour flavor properties.