Structure development in a soft cheese curd model during manufacture in relation to its biochemical characteristics

• Published in: Journal of dairy research 2002-11, Vol.69 (4), p.605-618
• Main Authors: BOUTROU, RACHEL, FAMELART, MARIE-HELENE, GAUCHERON, FREDERIC, GRAET, YVON LE, GASSI, JEAN-YVES, PIOT, MICHEL, LEONIL, JOELLE
• Format: Article
• Language: English
• Subjects: Animals; Biochemistry; Biological and medical sciences; Calcium phosphates; Caseins - chemistry; Caseins - ultrastructure; Cheese - analysis; Chemical Phenomena; Chemistry, Physical; Dairy products; drainage; Food and Nutrition; Food engineering; Food Handling - methods; Food industries; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Life Sciences; Micelles; Microscopy, Electron, Scanning; Milk and cheese industries. Ice creams; Milk Proteins - chemistry; Milk Proteins - ultrastructure; minerals; Original article; Particle Size; proteolysis; Rheology; soft cheese; Solubility; Structure
• ISSN: 0022-0299; 1469-7629
• DOI: 10.1017/S0022029902005836

The structure development of a soft cheese curd model has been studied in relationship to its rheological properties and its biochemical characteristics (pH, amount and partition of minerals, casein proteolysis) at different technical steps including cutting, drawing, three turns and demoulding. Scanning electron microscopy was used to observe structural changes during the drainage of a fat-free soft cheese. The micrographs provided visual evidence of changes in the casein matrix from casein particles aggregated in clusters to uniform strands observed at the demoulding. The initial increase of loss tangent and of the exponent of the power law between G′ and G′′ and frequency (that were maximal at the second turn) was related to the solubilization of micellar calcium phosphate, while intact caseins and large casein fragments accumulated in the curd. After the second turn, the strength, Youngs' and loss moduli of the curd increased greatly. The hydrolysis of αs1-casein into αs1-I-CN f(24–199) may facilitate the rearrangement of casein particles within the curd. The pH-induced solubilization of calcium phosphate continued throughout the manufacture process but was unexpectedly incomplete at the end of the drainage. Combination of electron microscopic observations with dynamic rheological measurements and chemical and biochemical assessments provided increased knowledge about the structure of soft cheese during drainage, an important but poorly understood cheese making stage.