CHEMICAL AND MICROBIOLOGICAL STUDIES ON STORED, SALTED BUTTER

Abstract

Salted butter from two Canadian plants was stored in parchment wrappers and in cans at −1.1°, 10.1°, 21.1°, and 32.2 °C. (30°, 50°, 70°, and 90° F.). Deterioration of the stored samples was followed by assessment of flavor, and by determination of: total acidity, free acidity, amino acid, pH, and fluorescence of the butter serum; peroxide oxygen, free fatty acids, and fluorescence of the butterfat; acidity of the whole butter; the number of viable, proteolytic, lipolytic, and oxidase positive organisms; and yeast and mold counts.Butter in cans deteriorated less rapidly than print samples although differences were less pronounced at 70° and 90° F. than at 30° and 50° F. Canned samples did not change appreciably in quality during 45 weeks' storage at 30° F. In general, decomposition of the serum and flavor deterioration became evident before changes occurred in the fat fraction. Stability of the serum was the limiting factor in keeping quality. The formation of amino acids and intermediate products of protein decomposition contributed largely to flavor changes.Flavor scores were more closely related to chemical objective test values than to microbiological counts. Storage temperature showed a marked influence on the correlation of objective test values with flavor score. Of the objective tests studied, total serum acidity (amino acidity plus free serum acidity) pH and serum fluorescence were most closely associated with flavor score.