Residual amount of water in a draining curd of camembert cheese and physicochemical characteristics of the drained curd as modified by the pH at renneting, the casein concentration and the ionic strength of milk

Abstract

International audienceCamembert soft cheeses were prepared from cheese milk modified using membrane technologies to obtain different casein contents (27-37 g$\cdot$kg$^{-1}$) and different ionic strengths estimated from the dilution factor of milk with a lactose solution (0.6 compared to 1.0 in normal milk). Renneting was performed at pH 6.0 or 6.4. The amount of water remaining in the draining curds, expressed as the water to casein ratio, R (g$\cdot$g$^{-1}$), was calculated from the whey drainage kinetics data. A kinetics of variation of R during drainage was obtained in each of the experimental conditions and was characterised by fitting with a descriptive mathematical model involving 2 relaxation processes and 5 parameters: R (g water$\cdot$g$^{-1}$ casein) = R1 exp(-t/$\tau$1) + R2 exp(-t/$\tau$2) + R3. The R values at the end of drainage, obtained from the model for t = 1 000 min, fitted well with the water amounts determined in the drained curds by chemical analysis. The values of the equation parameters, obtained by fitting the equation to experimental data, were correlated to the levels of factors which were varied in the experiments. This allowed a mean value for each parameter to be obtained, and values for the effects of factors. The amount of water remaining in drained curd at the end of drainage was dependent on the milk casein content and pH at renneting factors through a negative effect. Prediction of final values of R by calculation from this data was possible. However, the correlation with experimental values was low. In addition, the drained curd composition and rheological properties were determined and the effects of the factors on these curd characteristics were quantified. A positive effect of the pH at renneting on the dry matter and ash contents of drained curd was observed. Incidentally, these factors also modified its rheological properties.Étude de l'évolution de la teneur en eau du caillé au cours de l'égouttage, de la composition et des propriétés rhéologiques du caillé égoutté, en relation avec le pH à l'emprésurage, la teneur en caséine du lait et sa force ionique. Des fromages à pâte molle de type Camembert ont été préparés à partir de laits modifiés par des technologies à membranes pour obtenir différentes teneurs en caséine (27-37 g$\cdot$kg$^{-1}$) et différentes forces ioniques estimées d'après le taux de dilution par une solution de lactose (0,6 par comparaison à 1,0 dans le lait non modifié). L'emprésurage était réalisé à pH 6,0 ou 6,4. La quantité d'eau résiduelle dans le caillé en cours d'égouttage, exprimée par le rapport de la quantité d'eau du caillé à la quantité de caséine du lait initial, R (g$\cdot$g-1) était calculée à partir des données de l'égouttage. Une cinétique de R était obtenue pour chaque expérience d'égouttage. Un ajustement de ces cinétiques à un modèle mathématique a été réalisé en utilisant une équation à 3 étapes, R (g eau$\cdot$g$^{-1}$ caséine) = R1 exp(-t/$\tau$1) + R2 exp(-t/$\tau$2) + R3. R3 était une mesure de l'humidité du caillé en fin d'égou...

Whey drainage during soft cheese manufacture and properties of drained curd as modified by casein concentration, whey protein to casein ratio, and pasteurisation of milk

“…Biochemical analyses were performed on milk (m), whey (w) and drained curd (c), according to Daviau et al [15]. They included the determination of total nitrogen matter (TN) from Kjeldahl determination of N (N × 6.38), and of the non-casein nitrogen matter (NCN) fractionated according to the Rowland procedure [40], dry matter (DM), fat, ash, total calcium (Ca) and pH.…”

Using near infrared spectroscopy for the determination of total solids and protein content in cheese curd

“…Total solids in the data set do correspond to published values (Munro and van Til 1988;Lee et al 1997) and to the available literature on the amount of expelled whey (e.g. van Dijk et al 1979;Marshall 1982;Pearse et al 1984;Emmons 1990;Daviau et al 2000;Emmons et al 2003;Kammerlehner 2003) as, based on the distribution of the solids in curd grains and whey, a solid content of 165 g/kg refers to a relative whey drainage of 55%, which is typical for soft cheese production. On the other hand, a whey to curd ratio of 0.86 : 0.14 corresponds to 360 g/kg solids in the curd, which is usually achieved in the production of hard cheese.…”

“…Despite the fact that structural changes occur during pressing, salting or ripening, curd formation followed by curd cutting is considered to be the most essential step in cheese manufacture (Lee et al . 1997; Daviau et al . 2000).…”

“…Because of the upward trend towards automation in food processing there is considerable interest in methods with a high potential for the in-line or online analysis of composition or processing variables. Despite the fact that structural changes occur during pressing, salting or ripening, curd formation followed by curd cutting is considered to be the most essential step in cheese manufacture (Lee et al 1997;Daviau et al 2000). Due to the technical progress there is a continuing trend away from mechanical devices for, e.g.…”

An optical method to monitor casein particle size distribution in whey

“…Various variables affect the drainage rate of the curd, such as milk composition (fat, casein concentration and acidity) and rennet or inoculum concentration [7,9,10,13]. Factors associated with the cheesemaking procedure also affect the extent of syneresis.…”