Bitter Cheese Research Articles

Microbial proteinases as agents for accelerated cheese ripening

Taste panel data confirm that commercial preparations of Bacillus subtilis neutral proteinase can accelerate flavour development in Cheddar cheese without defect formation. The influence of the enzyme on the rate of ripening can be controlled by varying the cheese storage temperature. Fungal acid proteinase gives bitter cheese without enhancing typical flavour, even when used at concentrations corresponding to 5×and 25× less than the optimum neutral proteinase activity. Bacterial alkaline proteinase and broadspecificity proteinase produced bitter cheese but the latter enzyme also enhanced the intensity of typical flavour.

Cheddar Cheese Made with Chicken Pepsin

Commercial chicken pepsin was compared to calf rennet and a mixture of calf rennet and porcine pepsin as coagulating enzymes for the production of pilot plant quantities (25 kg) of Cheddar cheese. Yield data indicated that a significantly lower yield of cheese may be expected using chicken pepsin. Acid soluble nitrogen levels were considerably higher in the chicken pepsin cheese at both the 3 week and 3 month sampling periods, indicating a higher level of proteolysis with this enzyme. Instrumental and sensory texture analyses showed the chicken pepsin cheese lacked firmness compared to the other cheeses. The sensory panel also perceived a high and objectionable level of bitterness in cheese prepared with the chicken enzyme. Scanning electron microscopy revealed a more open, less compact protein network in chicken pepsin cheese that is probably responsible for its poorer texture. Electrophoresis of the respective cheese caseins showed a larger beta casein peak for calf rennet cheese. The alpha S peak was composed of four separate bands and their relative proportions were influenced by enzyme source. It is concluded that the chicken pepsin enzyme used in this study does not produce an acceptable Cheddar cheese either from quality or yield considerations. This is considered due to extensive proteolysis that led to defects in flavor and texture. A more highly purified enzyme preparation should be evaluated in the future.

Zur Entstehung bitterer Peptide in Käse und aus Casein

Whereas a slightly bitter taste is desirable in certain foods, it is an off-flavour in cheese which may even lead to unfitness for consumption. Bitter principles from cheese have been found to be peptides with molecular weights ranging from 2000 to 3000. For the purpose of further characterization, bitter peptides were isolated from enzymatic casein hydrolysates as well as from bitter cheese and purified. 30 proteases from different origins proved to be able to form peptides with bitter taste of varying intensity from casein. Present experience shows that the formation of bitter peptides during casein hydrolysis can be inhibited only to a very small measure. Bitter peptides are extrmely resistant to proteases, which is probably attributable to their high contents of hydrophobic amino acids and hydrophobic bonds. The detection of only N- or C-terminal amino acid in each of 11 different bitter peptides shows that peptide chains are present and not cyclic peptides as repeatedly assumed. It must be aimed at avoiding the cheese defect "bitter" by using appropriate starter cultures and rennet substitutes as little disposed as possible to produce bitter peptides.

Influence of Carbon Dioxide and Nitrogen on Microbial Populations and Shelf Life of Cottage Cheese and Sour Cream

Creamed Cottage cheese sealed in commercial thermoplastic containers following air evacuation and carbon dioxide or nitrogen-flushing, and stored at 4C, showed greatly repressed growth of spoilage organisms, including yeast and mold and psychrophiles, for up to 112 days. Excellent flavor and texture were maintained in gassed cheese to 45 days. Slight bitterness was apparent in Cottage cheese held under carbon dioxide for 73 and 120 days, and slight to medium bitterness in cheese held under nitrogen for a similar period. Creamed Cottage cheese stored in waxed cartons and replaceable lids, without evacuation or gassing deteriorated in flavor after 11 to 18 days and in texture after 32 to 45 days.Carbon dioxide gassing maintained the basic fresh flavor of cheese for 73 days at 4C, but gave the Cottage cheese a pleasant, slight, fizzy character.Excellent quality sour cream packaged and stored under identical experimental conditions showed no growth of spoilage organisms even in control containers for 112 days at 4C and pH 4.5. Flavor of the sour cream stored under carbon dioxide was excellent for 120 days, but some body and texture destabilization occurred in 25 days. The body and texture of sour cream stored under nitrogen was excellent for 73 days at 4C.

Effect of Combining Single-Strain Cultures as Cheese Starter on Bitterness in Cheddar Cheese at Six Months of Age

Summary Five strains of Streptococcus cremoris were used to investigate how bitterness in pasteurized-milk cheese was influenced by different combinations and proportions of paired strains in the starter. The combination of strains as starter influenced bitterness in cheese at six months of age as follows: (a) The intensity of bitterness decreased as the proportion of the nonbitter-cheese-producing strain in the starter increased; (b) the intensity of bitterness was less in cheese made with Strain ML 1 in the combination than with Strain E 8 , even though the intensities of bitterness were low in cheeses made with either ML 1 or E 8 alone; and (c) the combination of two bitter-cheese-producing strains yielded bitter cheese. The results showed that nonbitter cheese could be produced even if one strain produced bitter cheese when used alone as starter. Being able to use a bitter-cheese-producing strain as one of a pair of strains in a starter simplifies the problem of selecting strains for rotation in a phage-control program. The intensity of bitterness was higher in cheese where the average chain lengths of TCA-soluble peptides and amino acids were higher.

Effect of Strain of Starter Culture and of Manufacturing Procedure on Bitterness and Protein Breakdown in Cheddar Cheese

Summary Eleven strains of Streptococcus cremoris were examined for their effect on bitterness in Cheddar cheese at six months of age. Four strains produced non-bitter cheese. The other seven strains produced bitter cheese, the intensity varying with the strain. According to nitrogen analyses of the cheese, strains producing bitter cheese hydrolyzed bitter-tasting peptides less extensively. The relation between bitterness and pH of cheese was studied by producing sweet and acid cheese with each strain, in addition to normal cheese. For each of the seven strains producing bitter cheese, bitterness in sweet cheese was less intense than in normal cheese, although sweet cheeses were often bitter. This experiment indicates that the selection of suitable strains for starter would control bitterness more satisfactorily than raising the pH of cheese. The results reconcile apparent anomalies between bitterness related to low pH and bitterness in cheese with a high pH. Strains were associated with significant differences in pH of cheese made by the same manufacturing procedure; these differences were unrelated to the intensity of bitterness. When the manufacturing procedure was changed to give cheese with a lower pH, the cheeses at six months of age generally contained greater amounts of acid-soluble, TCA-soluble and amino nitrogen. Differences in TCA-soluble nitrogen and in amino nitrogen were associated with the different strains.

A Defect of Pimento Cheese

Summary A brief summary of the results of this work is given below: 1.Streptococcus lactis was proved not responsible for the sharply acid and bitter flavor. 2.The pimentos were not responsible for the defect. 3.Aerobic methods failed to disclose the causal organism. 4.Nine samples of sharply acid and bitter cheese were found to contain large numbers of spore-forming, gram positive, motile anaerobic bacillus which resembles Clostridium butyricum. 5.The increase in sharply acid and bitter flavor was always accompanied by a corresponding increase in volatile acidity. 6.The characteristic defect was produced experimentally by the use of a pure culture of the anaerobic bacillus. 7.Shocked spores of the anaerobic bacillus produced a more active fermentation than the unheated spores. 8.Pasteurization of raw milk is equivalent to this method of shocking the spores. 9.The associative action of the Streptococcus lactis and the anaerobic bacillus proved more effective than the anaerobe alone.