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Buffers stabilize the pH in foods. They are also used to neutralize foods which are too acidic. By using the salt of the acid already present, acidity is reduced without adding neutralization flavors. Many buffers are present naturally in foods. Animal products are usually buffered by amino acids, proteins, and phosphate salts. In plants, organic acids (such as citric, malic, oxalic, and tartaric) in conjunction with phosphate salts are the primary buffers. Table 1.2 shows the pHs of some common foods. Notice that most foods are buffered in the acidic range (pH < 7).

Table 1.2 Approximate pH values for some common foods^a.

Food	pH	Food	pH
Lime juice	2.0	Yogurt	4.0–4.5
Lemon juice	2.2	Cheddar cheese	5.1–5.5
Vinegar	2.6	Beef, fresh	5.5–5.0
Rhubarb	3.0	Pork, fresh	5.6–6.9
Grape juice	3.1–3.2	Turkey, fresh	5.7–6.1
Wines	2.9–3.9	Tuna	6.0
Apple juice	3.5–3.9	Carrots, fresh	5.7–6.1
Strawberries	3.2–3.4	Potatoes, fresh	6.1
Peaches	3.8	Green beans, fresh	6.5–6.7
Pears	3.9	Milk, fresh	6.6
Grapefruit juice	4.0	Sweet corn, fresh	6.7
Orange juice	4.2	Egg yolk	6.0–6.9
Tomato juice	3.8–4.7	Egg white (pH increases as egg ages)	7.6–9.2

^a Modified from [3] and [4].

See Appendix III or your chemistry and biochemistry textbooks for a review of acid and base chemistry.