Soft goat cheeses at different ripening stages: cheese structure, composition and non solvent water

Abstract

-Soft goat cheeses of the Sainte-Maure variety were studied at different ripening stages to characterise their microstructure in relation to their composition and water content. The intemalliquid phase of the cheeses was extracted by hydraulic pressure and analysed. Non solvent water (NSW) in cheese was calculated according to the method of van Boekel and Walstra from the concentration of sorne completely dissolved components such as potassium (K), sodium (Na) or 13-lactoglobulin (I3-Lg) in the liquid fraction compared to that in the whole cheese. The values obtained for NSW in the 7-d-old cheeses were 1.1, 0.8, 2.1 ss:' casein (CN) for K, Na and I3-Lg, respectively. A reduction in NSW values was observed during ripening, down to 0.6 gg " CN for K and Na and 1.3 ss:' CN for I3-Lg in the 58-d-old cheese. Total water content of cheese decreased during ripening from 4.7 to 1.9 g.g-I CN, so that the relative proportion of NSW to total water increased during ripening. Very different cheese microstructures were observed at the beginning and end of the ripening period. In the early stage of ripening the structure of cheese was loose, characterised by accelerated enzymatic reactions which developed in the aqueous phase as a result of proteolysis. A rapid decrease in the water content occurred due to evaporation at the cheese surface, facilitated by the easy movement of water from the inner part of cheese to the surface through the open and porous structure. During these early stages of ripening, pressing of the cheese led to high flow rates of Iiquid. When cheese total solids reached 600-650 g·kg-1 , which occurred after -43 d of ripening, the cheese microstructure became more compact. The residual water had a slower diffusion rate in the structure, as indicated by the lower variation in the cheese water content with time. Residual water was mainly non solvent. The proteolytic rate in the cheeses decreased, probably due to the lower content in solvent water. The kinetics of the pressing at this stage was characterised by a low flow rate. © InraJElsevier, Paris. Résumé -Caractérisation du fromage de chèvre à différents stades de maturation: structure du fromage, composition et détermination de l'eau non solvante. Des fromages de chèvre de type Sainte-Maure ayant des durées d'affinage de 7 à 58 j ont été caractérisés par leur microstructure, leur composition et leur teneur en eau afin de déterminer l'évolution se produisant au cours de l'affinage. La fraction liquide des fromages a été extraite par pressage hydraulique et analysée pour connaître la concentration des constituants se trouvant en solution dans les fromages. La comparaison de la concentration des solutés dans la fraction liquide et dans le fromage a permis de calculer la quantité d'eau non solvante du fromage relativement à deux types de constituants se trouvant entiè-rement à l'état soluble, des cations, le potassium (K) et le sodium (Na), et une protéine, la~-Iactoglobuline (~-Lg). L'eau non sol vante pour le K et le Na était respectivement de l,le...

Changes in water binding during ripening of cheeses made from raw, pasteurized or high-pressure-treated goat milk

“…Additionally, the microstructure of a high moisture cheese (e.g. at the beginning of ripening) has high porosity, so that the liquid phase could be forced out easily by the diffusion gradient produced by the water evaporation [16]. As cheese water content decreases, cheese microstructure becomes more compact [17].…”

Évaluation des méthodes d'appréciation des propriétés fonctionnelles des fromages d'emmental de l'Ouest de la France

“…Il faut noter également que la quantité de jus est très variable pour différents échantillons d'un même type de fromage [12]. Selon des études récentes, la quantité de jus serait le reflet des propriétés du fromage, comme les propriétés fonctionnelles [12] ou son degré d'affinage [31]. Les extraits secs sont comparables aux études précédentes (entre 125 et 173 g .…”

Investigation at the molecular level of soft cheese quality and ripening by infrared and fluorescence spectroscopies and chemometrics—relationships with rheology properties

“…Cheese structure is heterogeneous with several of its constituents present as a solid matrix (paracasein), some as a liquid phase, and others such as fat either solid or liquid, according to cheese technology and temperature (Pierre, Michel, Le Grae¨t, & Berrier, 1999). The chemical and physical changes occurring during ripening cause the body of the freshly made cheese to lose its firm, tough and curdy texture and to become soft.…”