The pH of cheese is determined by the amount of lactose fermented and the buffering capacity of the cheese. The buffering capacity of cheese is largely determined by the protein contents of milk and ...cheese and the amount of insoluble calcium phosphate in the curd, which is related to the rate of acidification. The objective of this study was to standardize both the lactose and casein contents of milk to better control final pH and prevent the development of excessive acidity in Cheddar cheese. This approach involved the use of low-concentration factor ultrafiltration of milk to increase the casein content (∼5%), followed by the addition of water, ultrafiltration permeate, or both to the retentate to adjust the lactose content. We evaluated milks with 4 different lactose-to-casein ratios (L:CN): 1.8 (control milk), 1.4, 1.1, and 0.9. All cheesemilks had similar total casein (2.3%) and fat (3.4%) contents. These milks were used to make milled-curd Cheddar cheese, and we evaluated cheese composition, texture, functionality, and sensory properties over 9 mo of ripening. Cheeses made from milks with varying levels of L:CN had similar moisture, protein, fat, and salt contents, due to slight modifications during manufacture (i.e., cutting the gel at a smaller size than control) as well as control of acid development at critical steps (i.e., cutting the gel, whey drainage, salting). As expected, decreasing the L:CN led to cheeses with lower lactic acid, residual lactose, and insoluble Ca contents, as well as a substantial pH increase during cheese ripening in cheeses. The L:CN ratio had no significant effect on the levels of primary and secondary proteolysis. Texture profile analysis showed no significant differences in hardness values during ripening. Maximum loss tangent, an index of cheese meltability, was lower until 45 d for the L:CN 1.4 and 0.9 treatments, but after 45 d, all reduced L:CN cheeses had higher maximum loss tangent values than the control cheese (L:CN 1.8). Sensory analyses showed that cheeses made from milks with reduced L:CN contents had lower acidity, sourness, sulfury notes, and chewdown cohesiveness. Standardization of milk to a specific L:CN ratio, while maintaining a constant casein level in the milk, would allow Cheddar cheese manufacturers to have tighter control of pH and acidity.
A DNA sequencing-based strategy was applied to study the microbiology of Continental-type cheeses with a pink discoloration defect. The basis for this phenomenon has remained elusive, despite decades ...of research. The bacterial composition of cheese containing the defect was compared to that of control cheese using 16S rRNA gene and shotgun metagenomic sequencing as well as quantitative PCR (qPCR). Throughout, it was apparent that
, a carotenoid-producing genus, was present at higher levels in defect-associated cheeses than in control cheeses. Prompted by this finding and data confirming the pink discoloration to be associated with the presence of a carotenoid, a culture-based approach was employed, and
was successfully cultured from defect-containing cheeses. The link between
and the pinking phenomenon was then established through the cheese defect equivalent of Koch's postulates when the defect was recreated by the reintroduction of a
isolate to a test cheese during the manufacturing process.
Pink discoloration in cheese is a defect affecting many cheeses throughout the world, leading to significant financial loss for the dairy industry. Despite decades of research, the cause of this defect has remained elusive. The advent of high-throughput, next-generation sequencing has revolutionized the field of food microbiology and, with respect to this study, provided a means of testing a possible microbial basis for this defect. In this study, a combined 16S rRNA, whole-genome sequencing, and quantitative PCR approach was taken. This resulted in the identification of
, a carotenoid-producing thermophile, in defect-associated cheeses and the recreation of the problem in cheeses to which
was added. This finding has the potential to lead to new strategies to eliminate this defect, and our method represents an approach that can be employed to investigate the role of microbes in other food defects of unknown origin.
Nonstarter lactic acid bacteria are commonly implicated in undesirable gas formation in several varieties, including Cheddar, Dutch-, and Swiss-type cheeses, primarily due to their ability to ferment ...a wide variety of substrates. This effect can be magnified due to factors that detrimentally affect the composition or activity of starter bacteria, resulting in the presence of greater than normal amounts of fermentable carbohydrates and citrate. The objective of this study was to determine the potential for a facultatively heterofermentative Lactobacillus (Lactobacillus casei DPC6987) isolated from a cheese plant environment to promote gas defects in the event of compromised starter activity. A Swiss-type cheese was manufactured, at pilot scale and in triplicate, containing a typical starter culture (Streptococcus thermophilus and Lactobacillus helveticus) together with propionic acid bacteria. Lactobacillus helveticus populations were omitted in certain vats to mimic starter failure. Lactobacillus casei DPC6987 was added to each experimental vat at 4 log cfu/g. Cheese compositional analysis and X-ray computed tomography revealed that the failure of starter bacteria, in this case L. helveticus, coupled with the presence of a faculatively heterofermentative Lactobacillus (L. casei) led to excessive eye formation during ripening. The availability of excess amounts of lactose, galactose, and citrate during the initial ripening stages likely provided the heterofermentative L. casei with sufficient substrates for gas formation. The accrual of these fermentable substrates was notable in cheeses lacking the L. helveticus starter population. The results of this study are commercially relevant, as they demonstrate the importance of viability of starter populations and the control of specific nonstarter lactic acid bacteria to ensure appropriate eye formation in Swiss-type cheese.
Pink discoloration defects in cheese manifests as the appearance of pink patches within cheese blocks and has recently been associated with Thermus thermophilus. Swiss‐type cheeses were prepared at ...pilot scale using thermophilic starter cultures, Propionibacterium freudenreichii, and one of Thermus thermophilus HB27, Thermus scotoductus SE1 or Thermus thermophilus DPC6866 or a control without Thermus. Significantly, a higher level of redness was observed in cheeses with Thermus thermophilus HB27 relative to the other cheeses and suggests that the development of the pink defect is dependent on the strain of Thermus present and on other, as yet unknown, factors that require further study.
Different Thermus Strains, Inoculation of different Thermus strains to cheesemilk. Cheese manufacture, Development of Pinking during ripening is strain dependent.
The objective of this study was to identify the carotenoids imparting the orange colour to the rind, and pale yellow color to the core, of selected smear-ripened cheeses. The cheeses investigated ...were Charloe, Ashbrook, Taleggio, and Limburger, and were sourced from artisanal markets. Samples of the rind and core were extracted using non-polar solvents, followed by saponification to hydrolyze triglycerides to remove fatty acids, and to release carotenoid esters. Extracts were tested using ultra-high pressure liquid chromatograph-diode array detector-high resolution mass spectrometry (UHPLC-DAD-MS and -MS/MS), and identities of α- and β-carotene, lycopene, and β-cryptoxanthin confirmed with authentic standards. β-Carotene was the predominant species in both the rind and core, absorbing ~80% of the signal at 450 nm in all cheese extracts tested, as well as minor quantities of β-cryptoxanthin and α-carotene. Carotenoids unique to the rind included lycopene as well as the rare bacterial carotenoids previously identified in bacterial isolates of cheeses (i.e. decaprenoxanthin, sarcinaxanthin, and echinenone). This is the first detailed characterisation of carotenoids extracted directly from smear-ripened cheeses, and reveals that smear-ripened cheese can contribute both provitamin A carotenoids as well as C50 carotenoids to the human diet.
•Carotenoids from four smear-ripened cheeses were extracted and profiled.•Provitamin A carotenoids predominated in both rind and core samples.•Lycopene and C50 bacterial carotenoids were unique to rind samples.•Similar carotenoids profiles were observed between all smear-ripened cheeses tested.
Liposome‐encapsulated ethylenediaminetetraacetic acid (EDTA) was incorporated into a model miniature Gouda‐type cheese (20 g) in order to assess its effect on rennet gelation, starter viability, pH, ...and moisture content. EDTA was encapsulated within 2 different food‐grade proliposome preparations, Pro‐Lipo Duo and Pro‐Lipo C (50% and 40% unsaturated soybean phospholipids and 50% and 60% aqueous medium, respectively), using the following high‐shear technologies: Ultra‐Turrax (5000 rpm), 2‐stage homogenization (345 bar), or microfluidization (690 bar). Liposome size distribution was affected by the high‐shear technology employed with the proportion of large vesicles (>100 nm) decreasing in the order microfluidization < 2‐stage homogenization < Ultra‐Turrax. All EDTA‐containing liposomes were stable during 28 d refrigerated storage, with no significant (P ≤ 0.05) change in size distribution or EDTA entrapment efficiency (%EE). Liposome composition affected the entrapment of EDTA, with Pro‐Lipo C having a significantly greater %EE than Pro‐Lipo Duo, 63% and 54%, respectively. For this reason, Pro‐Lipo C EDTA liposomes, with and without EDTA, were incorporated into model miniature Gouda‐type cheese. Addition of liposome‐encapsulated EDTA to milk during cheese making did not impact pH or rennet gel formation. No differences in composition or pH were evident in liposome‐treated cheeses. The results of this study show that the incorporation of liposome‐encapsulated EDTA into milk during cheese manufacture did not affect milk fermentation, moisture content, or pH, suggesting that this approach may be suitable for studying the effects of calcium equilibrium on the texture of brine‐salted cheeses.
Removal of 40–95% of native serum proteins from skimmed milk may be achieved by microfiltration (MF) to generate micellar casein concentrate (MCC). The MCC may be used to prepare cheese milk of the ...target composition and resultant cheeses of the desired quality and functionality. Herein, factors affecting the composition of MCC, different methods to preserve MCC as well as the application of MF in tailoring the composition and quality of cheese milk and resultant cheeses are reviewed.
Application of microfiltration in cheesemaking.
Lactobacilli have been used as adjunct cultures in the manufacture of different cheeses with the objective of accelerating ripening and/or improving cheese quality, but no studies have been conducted ...with strains from non-dairy origins. A miniature cheddar-type cheese model was used to screen ten dairy and non-dairy Lactobacillus plantarum, Lactobacillus paraplantarum and Lactobacillus pentosus strains for their performances as adjuncts in cheese manufacture. All strains were able to grow and survive in the cheese environment and produced only minor, although statistically significant, changes in gross cheese composition. Adjuncts affected secondary proteolysis causing differences in the levels of free amino groups, total free amino acids and reversed-phase HPLC (RP-HPLC) profiles of pH 4.6-soluble extract. Three strains were selected on the basis of differences in proteolysis pattern and used in a pilot-plant production of cheddar cheese, which was ripened for 180 days. The results confirmed that use of L. plantarum adjuncts significantly affected secondary proteolysis as measured by free amino acid production with minor impact on gross composition and primary starter performance, but the impact on RP-HPLC profiles of pH 4.6-soluble extracts was not statistically significant. The use of a strain originally isolated from olive brine fermentation, L. plantarum P1.5, resulted in significantly improved preference scores over the control.
PDF
