Monitoring proteolysis and cheese juice composition during ripening of Cheddar cheese made from microfiltered milk

Abstract

Summary -Cheddar cheeses were made from three types of cheese milks: HTST pasteurized milk (Past), thermized milk (TH) and MF milk, a mixture of skimmilk treated according to the Bactocatchf process and pasteurized cream. Bacterial flora development of MF and TH cheeses during ripening was similar with a high growth of species belonging to the Lb casei group and an increase of Lactococci enumeration. On the contrary, Le counts in Past cheeses decreased by 3 log. As expected, the mesophilic spore count was much lower in MF cheeses than in the others. Proteolysis of the three categories of cheese was followed by analysis of peptidic fragments contained in cheese water extracts and in internaI cheese juice obtained by pressing and by electrophoregrams of non-degraded caseins. TCA 12% soluble nitrogen contents were very similar for ail cheeses except for a significant difference, at 6 months of ripening, between Past and MF cheeses. This difference was not found in the data obtained from cheese juices. On the other hand, comparison of chee se water extracts and juices showed that juices had always higher nitrogen content than extracts. I3-Casein proteolysis was significantly more pronounced in MF cheeses than in the two other cheese types, maybe, because the plasmin-plasminogene system is activated by filtration treatment. Ali cheeses were graded in c1ass 1 but slight better organoleptic qualities were found for MF cheeses (typical Cheddar cheese flavor).Cheddar cheese / pasteurized milks / thermization / microfiltration / proteolysis / cheese juice / NSLAB / sensorial analysis Résumé -Suivi de la protéolyse et de la composition du jus de fromage au cours de l'affinage de fromage cheddar, obtenu à partir de lait microfiltré. Des fabrications de fromages cheddar ont été réalisées à partir de trois types de laits de fabrication: lait pasteurisé HTST (LP), lait * Correspondence and reprints 522 D Roy et al thermisé (LT) et mélanges de lait écrémé microfiltré selon le procédé Bactocatch'" et de crème pasteurisée (MF). L'évolution de la flore bactérienne des fromages MF et LT était similaire, avec un fort développement des espèces appartenant au groupe Lb case; et une croissance de la population dénom-brée en Le (au contraire des fromages LP, où cette dernière flore décroissait de près de 3 log). Comme attendu, la teneur en spores mésophiles des fromages MF était très inférieure à celle des autres fromages. La protéolyse des trois catégories de fromages a été suivie à la fois par analyse des fragments peptidiques contenus dans l'extrait aqueux et dans le jus interne obtenu par pressage et par le suivi électrophorétique des caséines non dégradées. Les teneurs en fractions azotées solubles dans le TCA 12% étaient très similaires, avec toutefois une différence significative, à 6 mois d'affinage, entre fromages LP et fromages MF. Cette différence n'était pas retrouvée lors de l'analyse des composants azotés des jus. Sur un autre plan, la comparaison des extraits aqueux et des jus montrait que ces derniers contenaient systéma...

Microstructure, physicochemistry, microbial populations and aroma compounds of ripened Cantal cheeses

“…There is no good relationship between Na content determined in Cantal cheeses (7.8 and 7.5 g·kg -1 ) and the value calculated from juices (8.7 and 9.2 g·kg -1 ) but the observed difference is much less than in the same comparison made from the results of Roy et al [57] for Cheddar: 6.1 g·kg -1 in the direct determination in cheese and 4.0 g·kg -1 for the calculation from juice. As said by Mermet [49], it is likely that the cheese matrix induces more inaccuracy in the ICP (Inductively Coupled Plasma) analytical method used by Roy et al [57] than in the AAS (Atomic Absorption Spectrometry) method used in this study. The molar ratio (Na + K)/Cl in the Cantal cheeses and juices was close to 1 as it was in Cheddar (Tab.…”

“…Total calcium content appeared to be greatly different in the two Cantal cheeses but the soluble Ca content in both juices was similar (7.6 and 7.8 g per 1000 g of water). From the data of Tables I and II, it can be calculated that the ratio Ca S /Ca T (values expressed per 1000 g of water) which is established in the ripened cheese, by (i) the couple kinetics of curd acidification -kinetics of curd drainage, (ii) the salting of the curd and (iii) the caseino-phosphopeptide solubilisation from the cheese matrix during ripening [33], reaches 42% in Cantal A, 41% in Cantal B, 42% and 50.4% in Cheddar according, respectively, to Hassan et al [33] and Roy et al [57] and only 33% in Emmental [62]. The molar Ca T /P T ratio in Cantal cheeses A and B are, respectively, 1.5 and 1.8 versus 1.2 in Cheddar and 1.07 in Emmental [42].…”

Pre-treatment of cheese milk: principles and developments

“…MF results in reduced cheese NSLAB counts, with reduced intensity of cheese flavour and aroma, secondary proteolysis and levels of short-chain volatile acids in Swiss-type cheeses [13] and lower populations of heterofermentative lactobacilli, propionic acid bacteria and enterococci than from raw milk or from pasteurised milk with added MF retentate. However, Roy et al [120] reported similar counts of Lactobacillus casei and lactococci in both MF and thermised milks but with a lower mesophillic spore count in the latter. Beuvier et al [13] reported that MF treatment of milk resulted in lower levels of hydrolysis of β-casein in cheeses than from pasteurised milk; however, Roy et al [120] proposed that heating of cream or skim milk during MF treatment increased hydrolysis of β-casein in Cheddar cheese, possibly due to activation of the plasminogen-plasmin activation system.…”

“…However, Roy et al [120] reported similar counts of Lactobacillus casei and lactococci in both MF and thermised milks but with a lower mesophillic spore count in the latter. Beuvier et al [13] reported that MF treatment of milk resulted in lower levels of hydrolysis of β-casein in cheeses than from pasteurised milk; however, Roy et al [120] proposed that heating of cream or skim milk during MF treatment increased hydrolysis of β-casein in Cheddar cheese, possibly due to activation of the plasminogen-plasmin activation system. Further optimization is required to achieve desirable ripening characteristics of such cheeses.…”

Influence of milk treatment and ripening conditions on quality of Raclette cheese

“…The microfiltration process for debacteriazation, marketed as the "Bactocatch" process [26,29,37] has proved to be suitable for manufacturing Grevé and Herrgårds cheese [25], Comté-type cheese [7], Swisstype cheese [6,9,10] and Cheddar cheese [28,33]. These investigations showed that the indigenous flora of milk can be significantly reduced by microfiltration, however, with the result that the overall aroma intensity of the cheeses compared to raw milk cheeses is less pronounced.…”