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Testing Cream for Acidity THE acid test tells when the cream is "ripe" or sour enough to churn. This device should be used with the Minnetonna Home Creamery. It is simple. Anyone can quickly learn to use it. We will explain the Nafis acidity-testing outfit here. We believe it to be the best outfit made for home creamery use because of its simplicity and small cost. You can procure it from the Minnetonna Company. It is listed in their dairy supply catalog. The idea of the test is simply this: The acid in the cream when mixed with an alkali becomes neutral that is, it changes into a substance that is known among chemists as a salt. (There are different kinds of salts. Table salt or the salt used for seasoning food is only one of the many kinds of salts.) The alkali which we use to neutralize the acid in sour cream we call neutralizer. The amount of neutralizer it takes to neutralize the acid in a given quantity of sour cream gives us a basis for figuring the percentage of acidity in the cream we are testing. "But can you tell when the acid in sour cream has become neutralized?" you ask. We put a few drops of a solution called indicator into the sample of sour cream we are testing. Then, when enough neutralizer has been added to the sour cream to neutralize the acid, the cream will turnpink. If you know how much neutralizer you have added to the cream before it turned pink you can easily figure the percentage of acidity of the cream. Here's where the necessity for the acidity-testing outfit comes in. You must have the instruments for making accurate measures of both the sour cream to be tested for acidity and the neutralizer used. The value of the test depends absolutely upon theaccuracy of the measures taken. Such a small amount of cream is used that if a m...