Mature Cheddar Cheese Research Articles

Ion-exchange HPLC analysis of a broad spectrum of organic acids from matured Cheddar cheese and assessment of extraction methods

An ion-exclusion HPLC technique was used to separate a total of 16 organic acids from matured Cheddar cheese. Three extraction methods, reported in the literature for the purpose of extracting organic acids from cheese, were evaluated by determining the percentage recovery of the organic acids from the selected cheese. All three extraction methods evaluated yielded high recovery rates for all compounds analyzed. The method using 0.009 N H 2SO 4 gave best recoveries for 11 of the 16 detected compounds while the barium hydroxide/zinc sulphate extraction method yielded best recoveries for oxalic and malic acids. The buffer-acetonitrile extraction method showed the highest recovery percentages for propionic, isovaleric and n-valeric acids. In addition, the method using 0.009 N H 2SO 4 exhibited improved retention of minor peaks. With the exception of oxalic acid, organic acid concentrations determined for the mature Cheddar cheese corresponded well with values in the literature. On the basis of amount of analytes separated, resolution and ease of analysis, the 0.009 N H 2SO 4 extraction method and proposed ion-exchange HPLC protocol was well suited for the quantification of a broad spectrum of major and minor organic acids from Cheddar cheese. However, rapid sample pre-treatment techniques to eliminate contaminating biochemical species, require investigation. ©

Development of a probiotic cheddar cheese containing human-derived Lactobacillus paracasei strains.

Cheddar cheese was manufactured with either Lactobacillus salivarius NFBC 310, NFBC 321, or NFBC 348 or L. paracasei NFBC 338 or NFBC 364 as the dairy starter adjunct. These five strains had previously been isolated from the human small intestine and have been characterized extensively with respect to their probiotic potential. Enumeration of these strains in mature Cheddar cheese, however, was complicated by the presence of high numbers (>10(7) CFU/g of cheese) of nonstarter lactic acid bacteria, principally composed of lactobacilli which proliferate as the cheese ripens. Attempts to differentiate the adjunct lactobacilli from the nonstarter lactobacilli based on bile tolerance and growth temperature were unsuccessful. In contrast, the randomly amplified polymorphic DNA method allowed the generation of discrete DNA fingerprints for each strain which were clearly distinguishable from those generated from the natural flora of the cheeses. Using this approach, it was found that both L. paracasei strains grew and sustained high viability in cheese during ripening, while each of the L. salivarius species declined over the ripening period. These data demonstrate that Cheddar cheese can be an effective vehicle for delivery of some probiotic organisms to the consumer.

Aminopeptidase Activities of Starter and Non-Starter Lactic Acid Bacteria under Simulated Cheddar Cheese Ripening Conditions

Abstract The effects of pH, NaCl and CaCl2 concentration on aminopeptidase activities of lactic acid bacteria were investigated in order to assess the potential role of these enzymes on proteolysis during cheese ripening. A NaCl concentration of around 4% and a CaCl2 concentration of around 125 mM were selected for study to approximate concentrations present in the moisture phase of ripening Cheddar cheese. At pH 5.2, the pH of mature Cheddar cheese, aminopeptidase activities were partially inhibited in comparison to activities at physiological pH (7.5). However, most of the hydrolysis activities at the lower pH could be either partially or fully restored by the addition of NaCl and/or CaCl2 at concentrations found in the moisture phase of ripening Cheddar cheese. There was a major difference between the Lys p-NA hydrolysis activity of lactococci and lactobacilli in that the activity of lactococci was stimulated in the presence of salts while the activity of the lactobacilli was inhibited. These results indicate that variations in salt concentration are important parameters in cheese ripening and flavour development due to their effect on peptidase activities. A decrease in the concentration of NaCl, for instance, while perhaps increasing the risk of growth of contaminating microflora, may reduce bitter flavour development through increased PepN activity of selected non-starter lactobacilli if used as adjuncts.

Application of a mass spectrometry sequencing technique for identifying peptides present in Cheddar cheese

Peptides were isolated from a water-soluble fraction of a commercial mature Cheddar cheese by reversed phase-high performance liquid chromatography. Characterisation of 16 peptides was performed using a matrix assisted laser desorption/ionisation time-of-flight mass spectrometer, by determining their masses and applying N-terminal sequencing using a volatile degradation reagent, trifluoroethylisothiocyanate. The experimental approach allowed the sequencing of overlapping peptide mixtures. Of the 16 peptides identified, eight came from αs1-casein, seven from β-casein and one from αs2-casein.

Cheddar cheese flavour and chemical indices: changes during maturation.

In many ways, Cheddar cheese is like wine. Its final character is determined not only by the initial composition of the product but also by the biochemical and chemical changes which occur during maturation. The cheese technologist is faced with the problem of harnessing these complex reactions to produce cheese which has a clear identity. That is, a Cheddar cheese should be quite different from a Jarlsberg. Moreover, the product must be consistent or the consumer will be confused. For example, mature Cheddar cheese should always have a flavour level and balance which meets the customer’s expectations.

Relations between cheese flavour and chemical composition

Abstract Five Australian groups have attempted to correlate various compounds with the development of Cheddar flavour. Perret (1978) used vacuum distillation of grated mature Cheddar cheese followed by gas chromatography and mass spectrometry to reveal more than 150 components, including acids, alcohols, esters, aldehydes, ketones, sulphur compounds and lactones. He determined H2S, thiols and disulphides chemically to obtain the actual concentrations of sulphur compounds in the cheese rather than in the headspace. Commercial cheeses with flavour defects described as soapy, eggy, oniony and fruity were found to contain ‘out of balance’ concentrations of fatty acids, hydrogen sulphide, methane thiol and ethyl esters, respectively. Aston (1981, M. Appl. Sc. thesis, Queensland Institute of Technology, Brisbane, Queensland) compared normal Cheddar cheeses with cheeses manufactured using (a) mutant starters, (b) higher initial ripening temperature and (c) a combination of (a) and (b) to accelerate ripening. The cheeses were analysed at 1, 3, 6 and 9 months for (1) flavour, (2) volatile sulphur compounds (by GC/FPD of the headspace), (3) amino acids (phosphotungstic acid-soluble nitrogen) and (4) free amino acids and trichloracetic acid-soluble peptides (TCA-soluble tyrosine). Only (3) and (4) correlated well enough with flavour to be considered useful as repening indicators. Barlow et al. (1989a, b, Aust. J. Dairy Technol., 44, 7–18) examined 54 batches of Cheddar cheese over the period of maturation. At each sampling time the cheeses were submitted to a taste panel and analysed for H2S, methane thiol, dimethyl sulphide, free fatty acids from acetic to hexanoic acids, d - and l -lactic acid, water soluble amino-nitrogen (WSN), and volatiles in the headspace over grated Cheddar cheese. The best Cheddar flavour was associated with 45–50 mg/kg butyric and 20–25 mg/kg hexanoic acids. WSN, lactic acid and H2S correlated highly with Cheddar flavour. A reasonable prediction of flavour at 12 months could be made from flavour at 3 months plus H2S plus WSN. Wood (1989, M. Appl. Sc. thesis, Queensland Institute of Technology, Brisbane, Queensland) developed a method for analysis of the volatile headspace components from cheese using cryogenic sample collection. In a 20-month old cheese, methanol, ethanol, acetone, propyl formate, carbon disulphide, propan-1-ol, butanone, butan-2-ol, 3-methyl-butanal, pentan-2-one, pentanal, dimethyl disulphide, toluene, diethyl carbonate, hexanal, ethyl butyrate, ethyl benzene, o-, m- and p-xylene, α-pinene and an α-pinene isomer, dimethyl trisulphide, β-pinene were identified. The effect of, (1) addition of neutrase, (2) use of mutant starter, (3) increased storage temperature, and various combinations of these on accelerating maturation and on the profile of headspace volatiles during maturation were examined. Dimos (1992, M.Sc. thesis, Latrobe University, Bundoora, Victoria) compared the volatiles from full-fat and low-fat (7%) Cheddar cheeses, manufactured on 4 separate occasions at the CSIRO pilot plant, over a 26-week maturation period and found a significant straight-line relationship between actual flavour and fitted flavour calculated from: y = b0 + b1x1 + b2x2 + b3x3 + b4x4 + b5x5 where y is the fitted flavour, b0–b5 are constants and x15 are the logs of the concentrations of H2S, heptan-2-one, butanone, δ-decalactone and propan-2-ol. This relationship held for both the full-fat and the low-fat cheese. Increases in butanone and butan-2-ol with maturation are widely reported, although high quality, mature Cheddar does not necessarily contain these compounds. Sulphur compounds, particularly CH3SH, have been shown to be essential to Cheddar flavour but are likely to be breakdown products of a highly unstable Cheddar flavour compound or compounds.

Observations on the microscopic crystalline inclusions in Cheddar cheese

SummaryIn ripening and mature Cheddar cheese, 2 distinct types of birefringent microscopic crystalline inclusions are found. One of these is an irregularly shaped large aggregate of needle-like crystals (LAC). The histochemical demonstration of Ca in the LAC together with their total absence from cheese made with δ-gluconic acid lactone (GAL) instead of starter bacteria suggests that they are composed of Ca lactate.The other type of inclusion is a smaller aggregate of crystals (SAC). They are more numerous than the LAC and are concentrated in areas which probably correspond to the lines of curd particle fusion. The SAC appear in cheese immediately after pressing and increase in number until the cheese is about 1 month old. They can be detected in unsalted, milled curd after 1 d and are present in large numbers in cheese made with GAL. These observations together with histochemical evidence that they may contain phosphate groups suggest that the SAC are probably composed of Ca phosphate. Their location in spaces between the fat and casein phases of the cheese indicates that they crystallize from pockets of residual whey. Each SAC is composed of a large number of very long (maximum length 4·5 μm), thin (maximum diam. 25 nm) crystals each of which is covered by a thin layer of electron-dense material tentatively identified as casein.

Some volatile compounds in New Zealand Cheddar cheese and their possible significance in flavour formation: IV. The addition of flavour compounds to cheese curd to simulate Cheddar flavour

On the basis of the experimental data provided by Harvey & Walker (1960) and Peterson, Johnson & Price (1949) various mixtures of methyl ketones (mixture K1) and fatty acids (mixture FA) were made up in proportions corresponding approximately to those found in a mature Cheddar cheese (9–10 months old). Only those carbonyl compounds which showed a significant increase in concentration as the cheese matured were included since it was assumed, for these experiments, that these ketones were the key flavour-producing compounds. It was visualized that there might be differences in the uptake of the various ketones by the curd so three additional ketone mixtures (K2, K3, K4), in which the balance of the various constituents had been altered, were also prepared.

Some volatile compounds in New Zealand Cheddar cheese and their possible significance in flavour formation: I. Identification of the volatile carbonyl fraction

Flavour concentrates from mature New Zealand Cheddar cheese were prepared by steam distillation methods. Using 2:4-dinitrophenylhydrazine reagent the presence of carbonyl compounds in the distillate was established. By means of paper chromatography, and other methods, the following compounds were identified in the distillate: acetoin, diacetyl, acetaldehyde, acetone, 2-butanone, 2-pentanone, 2-heptanone, 2-nonanone and 2-undecanone, and their approximate concentrations in New Zealand Cheddar cheese were determined. The possible role of these compounds in the formation of Cheddar cheese flavour is discussed.The authors gratefully acknowledge the helpful advice and criticism of Dr H. R. Whitehead and Dr W. A. McGillivray, and the technical assistance of Mr P. L. McLaughlin.

217. The white particles in mature Cheddar cheese

The white specks appearing in mature Cheddar cheese have been shown by analysis to be calcium lactate.