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Madison, United Kingdom

Johnson M.E.,Wisconsin Center for Dairy Research
Microbiology Spectrum

Most cheese varieties require acidification of milk by a select group of bacteria called starters. They ferment lactose to lactic acid and in so doing aid the cheesemaker in developing the desired texture as well as acidity of the cheese. However, while other microorganisms play the major role in flavor development of cheese, it is the starter that sets the stage for quality cheese manufacture. Starters were traditionally derived from the native microflora of the milk, but this practice is almost unheard of today. With the advent of better hygienic milking practices and industrialized cheesemaking, there was a need for more uniformity and reliable sources of the starter culture. Today's starters are produced by companies specializing in their production as well as in the development of new strains for cheesemakers. The choice of starter for the manufacture of a specific cheese is dictated by the cheesemaking protocol, but it is also governed by the need to produce cheese with desired physical attributes. The properties of the starter that make it possible to do so help drive innovation in developing new potential choices in starter cultures. Indeed, the demands for predictable and reliable rates and extent of acidification of milk for cheesemaking and flavor development are as key for successful cheesemaking today with artisanal cheesemakers as they are for larger, more industrialscale cheesemakers. © 2013 American Society for Microbiology. Source

Arunkumar A.,University of Wisconsin - Madison | Molitor M.S.,Wisconsin Center for Dairy Research | Etzel M.R.,University of Wisconsin - Madison
International Dairy Journal

This work compared laboratory-scale flat-sheet and pilot plant-scale spiral-wound wide-pore, negatively-charged ultrafiltration membranes for concentration of whey proteins. By placing a negative charge on the surface of ultrafiltration membranes, a wider pore size could be used to concentrate whey proteins because negatively-charged proteins were rejected by electrostatic repulsion and not simply sized-based sieving. Negatively-charged 100 kDa regenerated cellulose membranes had an 85% higher flux than unmodified 10 kDa membranes, and equivalent protein retention. The pilot plant-scale spiral-wound membranes had 70-fold more area, and a different membrane geometry than the laboratory-scale flat-sheet membranes, yet both membranes were successful in retaining >98% of the whey protein. © 2016 Elsevier Ltd. Source

Shirashoji N.,Morinaga Milk Industry Co | Shirashoji N.,University of Wisconsin - Madison | Jaeggi J.J.,Wisconsin Center for Dairy Research | Lucey J.A.,University of Wisconsin - Madison
Journal of Dairy Science

Sodium hexametaphosphate (SHMP) is commonly used as an emulsifying salt (ES) in process cheese, although rarely as the sole ES. It appears that no published studies exist on the effect of SHMP concentration on the properties of process cheese when pH is kept constant; pH is well known to affect process cheese functionality. The detailed interactions between the added phosphate, casein (CN), and indigenous Ca phosphate are poorly understood. We studied the effect of the concentration of SHMP (0.25-2.75%) and holding time (0-20. min) on the textural and rheological properties of pasteurized process Cheddar cheese using a central composite rotatable design. All cheeses were adjusted to pH 5.6. The meltability of process cheese (as indicated by the decrease in loss tangent parameter from small amplitude oscillatory rheology, degree of flow, and melt area from the Schreiber test) decreased with an increase in the concentration of SHMP. Holding time also led to a slight reduction in meltability. Hardness of process cheese increased as the concentration of SHMP increased. Acid-base titration curves indicated that the buffering peak at pH 4.8, which is attributable to residual colloidal Ca phosphate, was shifted to lower pH values with increasing concentration of SHMP. The insoluble Ca and total and insoluble P contents increased as concentration of SHMP increased. The proportion of insoluble P as a percentage of total (indigenous and added) P decreased with an increase in ES concentration because of some of the (added) SHMP formed soluble salts. The results of this study suggest that SHMP chelated the residual colloidal Ca phosphate content and dispersed CN; the newly formed Ca-phosphate complex remained trapped within the process cheese matrix, probably by cross-linking CN. Increasing the concentration of SHMP helped to improve fat emulsification and CN dispersion during cooking, both of which probably helped to reinforce the structure of process cheese. © 2010 American Dairy Science Association. Source

Porcellato D.,Norwegian University of Life Sciences | Johnson M.E.,Wisconsin Center for Dairy Research | Houck K.,Wisconsin Center for Dairy Research | Skeie S.B.,Norwegian University of Life Sciences | And 3 more authors.
Food Microbiology

Defects in Cheddar cheese resulting from undesired gas production are a sporadic problem that results in significant financial losses in the cheese industry. In this study, we evaluate the potential of a facultatively heterofermentative lactobacilli, Lactobacillus curvatus LFC1, to produce slits, a gas related defect in Cheddar cheese. The addition of Lb. curvatus LFC1 to cheese milk at log 3CFU/ml resulted in the development of small slits during the first month of ripening. Chemical analyses indicated that the LFC1 containing cheeses had less galactose and higher levels of lactate and acetate than the control cheeses. The composition the cheese microbiota was examined through a combination of two culture independent approaches, 16S rRNA marker gene sequencing and automated ribosomal intergenic spacer analysis; the results indicated that no known gas producers were present and that high levels of LFC1 was the only significant difference between the cheese microbiotas. A ripening cheese model system was utilized to examine the metabolism of LFC1 under conditions similar to those present in cheeses that exhibited the slit defect. The combined cheese and model system results indicate that when Lb. curvatus LFC1 was added to the cheese milk at log 3CFU/ml it metabolized galactose to lactate, acetate, and CO2. For production of sufficient CO2 to result in the formation of slits there needs to be sufficient galactose and Lb. curvatus LFC1 present in the cheese matrix. To our knowledge, facultatively heterofermentative lactobacilli have not previously been demonstrated to result in gas-related cheese defects. © 2015. Source

Stankey J.A.,University of Wisconsin - Madison | Johnson M.E.,Wisconsin Center for Dairy Research | Lucey J.A.,University of Wisconsin - Madison | Lucey J.A.,Wisconsin Center for Dairy Research
Journal of Dairy Science

Three Hofmeister salts (HS; sodium sulfate, sodium thiocyanate, and sodium chloride) were evaluated for their effect on the textural and rheological properties of nonfat cheese. Nonfat cheese, made by direct acidification, were sliced into discs (diameter=50mm, thickness=2mm) and incubated with agitation (6h at 22°C) in 50mL of a synthetic Cheddar cheese aqueous phase buffer (pH 5.4). The 3 HS were added at 5 concentrations (0.1, 0.25, 0.5, 0.75, and 1.0M) to the buffer. Post-incubation, cheese slices were air dried and equilibrated in air-tight bags for 18h at 5°C before analysis. Small amplitude oscillatory rheology properties, including the dynamic moduli and loss tangent, were measured during heating from 5 to 85°C. Hardness was determined by texture profile analysis. Acid-base buffering was performed to observe changes in the indigenous insoluble (colloidal) calcium phosphate (CCP). Moisture content decreased with increasing HS concentration. Cheeses incubated in high concentrations of SCN - softened earlier (i.e., loss tangent=1) compared with other HS treatments. Higher melting temperature values were observed for cheeses incubated in high concentrations of SO 4 2-. Hardness decreased in cheeses incubated in buffers with high concentrations of SCN -. The indigenous CCP profile of nonfat cheese was not greatly affected by incubation in Cl - or SCN -, whereas buffers with high concentrations of SO 4 2- reduced the acid-base buffering contributed by CCP. The use of high concentrations (1.0M) of SCN - for incubation of cheeses resulted in a softer protein matrix at high temperatures due to the chaotropic effect of SCN -, which weakened hydrophobic interactions between CN. Cheese samples incubated in 1.0M SO 4 2- buffers exhibited a stiffer protein matrix at high temperatures due to the kosmotropic effect of SO 4 2-, which helped to strengthen hydrophobic interactions in the proteins during the heating step. This study showed that HS influenced the texture and rheology of nonfat cheese probably by altering the strength of hydrophobic interactions between CN. © 2011 American Dairy Science Association. Source

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