Why fruits need to be grouped?

Fruits are classified into the following groups:

Alkaline Fruits--Apples, Persimmons, Thompson Grapes (Seedless), Muscat Grapes, All Sweet Grapes, Fresh Figs, Dates, Figs, Raisins, Prunes, Apricots, Peaches, Bananas, Cherries, Lychees, Carob, All Dried Fruit

Subacidic Fruits--Sweet Apples (Delicious), Sweet Peaches, Sweet Nectarines, Pears, Sweet Cherries, Some Grapes (Neither sweet nor sour), Papayas, Mangoes, Apricots, Fresh Lychees, Sweet Plums, Blueberries, Raspberries, Blackberries, Mulberries, Huckleberries, Cherimoyas

Acidic Fruits--Oranges, Grapefruit, PineApples, Strawberries, Pomegranates, Lemons, Kiwi Fruit, Kumquats, Loquats, Carambolas, Loganberries, Gooseberries, Cranberries, Limes, Sour Apples, Sour Grapes, Sour Peaches, Sour Nectarines, Sour Plums, Sour Cherries, Tomatoes

Melons--Watermelon, Honeydew Melon, Honey Balls, Cantaloupe, Muskmelon, Casaba Melon, Crenshaw Melon, Pie Melon, Banana Melon, Persian Melon, Christmas Melon, Nutmeg Melon