Chapter 7. Determination of acidity
Chapter 7. Determination of acidity
Section 1. General
Section 1. General
1. Concept of acidity • 1. Total acidity • 2. Effective acidity • 3. Volatile acid • 4. Acidity of milk
1. Concept of acidity • 1. Total acidity • 2. Effective acidity • 3. Volatile acid • 4. Acidity of milk
2. Significance of acidity • Organic acid affects color, aroma, taste and stability of foods. • Quality of foods can be judged by acidity. • Mature degree of some fruits can be judged by acidity
2. Significance of acidity • Organic acid affects color, aroma, taste and stability of foods. • Quality of foods can be judged by acidity. • Mature degree of some fruits can be judged by acidity
3. Organic acid kinds and distribution of foods • There are organic acid and inorganic acid in foods, and mainly organic acid. • Familiar organic acids in foods: citric acid, malic acid, tartaric acid, oxalic acid, lactic acid and acetic acid
3. Organic acid kinds and distribution of foods • There are organic acid and inorganic acid in foods, and mainly organic acid. • Familiar organic acids in foods: citric acid, malic acid, tartaric acid, oxalic acid, lactic acid and acetic acid
Section 2. Determination of acidity
Section 2. Determination of acidity
1. Determination of total acidity • 1.1 Principle : RCOOH + NaOH = RCOONa + H2O Indicator: phenolphthalein, PH8.2 • 1.2 Applying range : Foods of slight color
1. Determination of total acidity • 1.1 Principle : RCOOH + NaOH = RCOONa + H2O Indicator: phenolphthalein, PH8.2 • 1.2 Applying range : Foods of slight color
2. Determination of pH • pH test paper • pH meter
2. Determination of pH • pH test paper • pH meter
pH meter
pH meter
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