Multiscale Characterization of the Organization of Triglycerides and Phospholipids in Emmental Cheese: From the Microscopic to the Molecular Level

• Published in: Journal of agricultural and food chemistry 2008-04, Vol.56 (7), p.2406-2414
• Main Authors: Lopez, Christelle, Briard-Bion, Valerie, Beaucher, Eric, Ollivon, Michel
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Calorimetry, Differential Scanning; Cheese - analysis; Chemical Changes Induced by Processing/Storage; Chemical Phenomena; Chemistry, Physical; Crystallization; Emmental cheese; fat crystal; Fats - analysis; Fatty Acids - analysis; fluorescence microscopy; food analysis; food composition; Food engineering; Food industries; food matrix; Fundamental and applied biological sciences. Psychology; Life Sciences; lipid content; Microscopy, Confocal; microstructure; Milk and cheese industries. Ice creams; Milk fat globule membrane; molecular conformation; phospholipids; Phospholipids - analysis; Phospholipids - chemistry; solid fat content; triacylglycerols; Triglycerides - analysis; Triglycerides - chemistry; X-Ray Diffraction
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf0720382

The chemical composition and properties of lipids, both triglycerides and phospholipids, play a major role in the functional and nutritional properties of food products. In this study, the suprastructure of fat, solid fat content, and crystallographic properties of triglycerides were investigated in hard-type cheeses from the microscopic scale to the molecular level using the combination of relevant techniques. Two industrial cheeses with different oiling off properties were compared with experimental cheeses manufactured in the laboratory. Microstructural analysis performed using confocal laser scanning microscopy showed that milk processing led to the disruption of fat globules with the formation of nonglobular fat. For a similar fatty acid composition, oiling off was mainly related to the fat in dry matter content and to the suprastructure of fat in cheese. An exogenous fluorescent phospholipid permitted the localization of milk phospholipids in the cheese matrix, which mainly remain around fat inclusions after disruption of the milk fat globule membrane, and to show heterogeneities. We also showed using differential scanning calorimetry that the suprastructure of fat did not affect the solid fat content in cheese at 4 °C: 71.6 ± 4.9%. The organization of triglyceride molecules in fat crystals, elucidated at a molecular level using X-ray diffraction, corresponded to the coexistence of 2 lamellar structures (2L 40.5 Å and 3L 54.6 Å) with four polymorphic forms: α, two β′ and β. A schematic representation of the multiscale organization of triglycerides and phospholipids in cheese is proposed.