Journal Article

Milk Fat Thermal Properties and Solid Fat Content in Emmental Cheese: A Differential Scanning Calorimetry Study

Gassi, J.-Y, Camier, B, Lopez, C, Briard-Bion, V

2006

Overview

The experiments reported in this study give deeper insight into the crystallization of milk fat in Emmental cheese, which is the most widely consumed hard cheese in France. Differential scanning calorimetry (DSC) was used to monitor the thermal properties of milk fat after the main stages involved during manufacture of Emmental cheese. By heating the samples to 60°C to eliminate their thermal history and cooling them at 2°C/min, the liquid → solid phase transition of fat was investigated. Confocal laser scanning microscopy was used to characterize in situ the supramolecular organization of milk fat dispersed in the casein matrix. The destabilization of fat globules by aggregation or coalescence and the formation of free fat during the manufacture altered the thermal properties of milk fat by increasing the initial temperature of crystallization and by the formation of 2 overlapping exotherms. The melting properties of the crystalline structures formed by fat at the temperatures used for ripening (12, 21, and 4°C) were examined. Differential scanning calorimetry was used to determine the ratio of solid to liquid fat; that is, the amount of fat that is crystallized, by dividing the partial enthalpy of melting of the fat for ripening temperature by the total enthalpy of melting of the same fat extracted from cheese. This study shows, for the first time, that milk fat is partially crystallized in Emmental cheese: about 55.7±3.5% of fat is solid at 4°C at the end of ripening. Polymorphic phase transitions of milk fat are also suggested during ripening of Emmental cheese.

• Publisher: Elsevier Inc,American Dairy Science Association,Am Dairy Sci Assoc
• Subject: ambient temperature / analysis / Animal productions / Animals / Biological and medical sciences / Calorimetry / Calorimetry, Differential Scanning / Cheese / Cheese - analysis / cheese ripening / chemistry / confocal laser scanning microscopy / confocal scanning laser microscopy / Crystallization / Emmental cheese / Esters / Esters - analysis / fat crystal / Fats / Fats - analysis / Fats - chemistry / Fatty Acids / Fatty Acids - analysis / Food Handling / Food Handling - methods / Food industries / France / Fundamental and applied biological sciences. Psychology / Hot Temperature / melting / methods / Methylation / Microscopy, Confocal / Milk / Milk - chemistry / Milk and cheese industries. Ice creams / milk fat / Particle Size / Phase Transition / polymorphism / Terrestrial animal productions / Thermal properties / Thermodynamics / triacylglycerol / triacylglycerols / Vertebrates