Processing and intrinsic factors affecting the occurrence of calcium lactate crystals in cheddar cheese

Shantanu Agarwal

doi:10.7273/000005621

Calcium lactate crystals (CLC) in hard cheeses are a continual expense to the cheese industry. Appearance of a white haze on cheese is unappealing to consumers, who may refrain from buying, resulting in lost revenue to manufacturers. Improved sanitation and better cheese manufacturing practices reduced the occurrence of D( - )-lactate crystals in cheese, but in recent years there increased occurrence of L(+)-lactate crystals in Cheddar cheese. We believe that there are correlations among total lactic acid in cheese, cheese pH and concentration of calcium ions with formation of CLC. Objective one was to determine whether gas flushing of Cheddar cheese contributes to the occurrence of calcium lactate crystals (CLC). Two different cheese milk compositions were used: Standard (lactose:protein=1.47, protein:fat=0.90, lactose=4.8%) and Ultrafiltered (UF) (lactose:protein=1.23, protein:fat=0.84, lactose=4.8%), with or without adjunct Lb.curvatus. After aging at 7.2o C for 6 mo, cheeses were cubed and either vacuum packaged or gas flushed. High intensity of crystals were observed on surfaces of cubed cheeses that were gas flushed, but not on cheeses that were vacuum packaged. Cheeses made without Lb. curvatus exhibited L(+)- CLC on surfaces, while cheeses made with Lb. curvatus exhibited racemic mixtures of L(+)/D( - )-CLC throughout the cheese matrix. Gas flushing, milk composition and presence of nonstarter lactic acid bacteria (NSLAB) contribute to the development of CLC on cheese surfaces. These findings stress the importance of packaging to cheese quality. Objective two was to investigate the effect of concentrating milk (using UF) or increasing solids with nonfat dry milk (NFDM), and cheese pH, upon formation of CLC. In cheeses made from skim milk supplemented with UF (CSM2) and NFDM (CSM3), total calcium was 26% greater than in cheeses made from skim milk (SM2). As the pH of cheeses made from SM2 decreased from 5.4 to 5.1, the concentration of soluble calcium increased by 61.6%. In cheeses made from CSM2 and CSM3, the concentration of soluble calcium increased by 41.4% and 45.5%, respectively. CLC were observed in cheeses made from SM2 at and pH 5.1, while CLC were observed in cheeses from CSM2 and CSM3 at pH 5.3 and lower. Increased concentrations of soluble calcium can increase the potential for development of CLC in cheese manufactured with increased concentrations of milk solids, particularly at and less than pH 5.1. Objective three was to determine the effect of salt and starter bacteria on the cheese pH and occurrence of CLC. A commercial starter was selected based on its sensitivity for salt-tomoisture (S/M) smaller than and greater than 4.0. Cheddar cheese was made using either whole milk (3.25% protein, 3.85% fat) or whole milk supplemented with ultrafiltered milk and cream (4.5% protein, 5.3% fat). Calculated amounts of salt were added at milling (pH 5.40 0.02) to obtain low S/M whole milk cheese (LSWMC), low S/M concentrated milk cheese (LSCMC) with 3.5 S/M and high S/M whole milk cheese (HSWMC), high S/M concentrated milk cheese (HSCMC) with 4.5 S/M. The cheeses were either vacuum packaged or gas flushed with N2 and aged at 7.2o C for 15 weeks. Soluble calcium was 41 to 35% higher in LSWMC and LSCMC compared to HSWMC and HSCMC. Concentration of lactic acid in high S/M cheeses was double of smaller S/M cheeses at end of 15 weeks of aging. CLC were observed in smaller S/M cheeses but greater intensity of CLC were observed in cheeses made with milk with high protein concentration and gas flushed packaging. Cheese manufacturers must be careful about the salt tolerance of the starter culture used in their cheese plant and should make sure adequate salt is added to inhibit the metabolism of starter bacteria. The results from the three studies confirm that occurrence of CLC is dependent on cheese milk concentration an

Processing and intrinsic factors affecting the occurrence of calcium lactate crystals in cheddar cheese

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