Effects of Water Activity (Aw) and Degree of Acidity_(pH) on Food Properties Many degradative activities in foods, such as microbial growth and certain enzymatic activities are directly related to the water content, more specifically the water activity (Aw) and the degree of acidity (pH) of the food. Water activity is defined as the amount of available free water in foods. The Aw and pH of various foods and their impact on shelf stability are presented in the table below: Food Lemons Fresh Tomatoes Grapes Raisins Aw 0.9 0.9 pH 2.2 4.0 3.2 6.5 Shelf Stability (weeks) 3.0 0.4 0.7 8.0 0.9 0.5 1. Which food is more shelf-stable and why? Raisins are more shelf-stable because of their high pH and their extremely low water activity 2. Describe the relationships between Aw, pH and Shelf Stability of the food products. 3. Based on the data, which of the two properties (Aw and pH) is more effective in controlling food degradation? Experiment 2- Effects of Water Activity (Aw) and Degree of Acidity_(pH) on Food Properties Many degradative activities in foods, such as microbial growth and certain enzymatic activities are directly related to the water content, more specifically the water activity (Aw) and the degree of acidity (pH) of the food. Water activity is defined as the amount of available free water in foods. The Aw and pH of various foods and their impact on shelf stability are presented in the table below: Food Lemons Fresh Tomatoes Grapes Raisins Aw 0.9 0.9 pH 2.2 4.0 3.2 6.5 Shelf Stability (weeks) 3.0 0.4 0.7 8.0 0.9 0.5 1. Which food is more shelf-stable and why? Raisins are more shelf-stable because of their high pH and their extremely low water activity 2. Describe the relationships between Aw, pH and Shelf Stability of the food products. 3. Based on the data, which of the two properties (Aw and pH) is more effective in controlling food degradation?
