Denaturation of porcine pepsin during Cheddar cheese manufacture

1977 ◽  
Vol 44 (2) ◽  
pp. 335-343 ◽  
Author(s):  
A. M. O'Keeffe ◽  
P. F. Fox ◽  
C. Daly

SummaryPorcine pepsin was rapidly denatured in phosphate buffers, pH 6·4–6·7, in the temperature range 31–39 °C and was only slightly more stable in milk under similar conditions. However, the enzyme was considerably more stable in Cheddar cheese curd in which the extent of denaturation was very markedly influenced by the pH of the milk at setting. Under normal cheese-making conditions, porcine pepsin was about equally stable with chymosin. Two modifications of the cheesemanufacturing procedure were developed which permit the manufacture of cheese almost free of coagulant and suitable for the assessment of the contribution of starter proteinases to proteolysis during cheese ripening.

1975 ◽  
Vol 42 (2) ◽  
pp. 313-326 ◽  
Author(s):  
H.-E. Pettersson ◽  
G. Sjöström

SummaryA method is outlined for accelerating ripening in Swedish semihard cheese by increasing the number of lactic starter bacteria present in the cheese without impairing characteristic texture and flavour. In addition to the normal starter inoculum, suitable lactic starter bacteria whose lactic-acid-producing activity had been greatly reduced by previous sublethal heat treatment, were added to the cheesemilk. When suspensions of streptococci and lactobacilli cultivated at a constant pH were heated at 59 and 69°C respectively acid production was retarded by 5–10 h, which was found to be sufficient for the cheese-making. Proteolysis was lowered only 10–30% by these heating temperatures. Bacterial cell suspensions, prepared by the methods outlined and added to the cheesemilk, were incorporated in cheese curd to extents depending on the amount added and the type of starter. The number in the final cheese could be increased to a maximum of 4–5 times that of control cheese. No adverse effect of the extra starter bacteria on pH, fat content and water content of cheeses 24-h old was observed. Proteolysis, measured as the increase in trichloroacetic acid and phosphotungstic acid (PTA)-soluble N, increased with increasing number of cells in the cheese. Organoleptic judgements showed a positive correlation (r= 0·81) between taste and PTA-soluble N, which in turn was influenced by the number of cells in the final cheeses.


1976 ◽  
Vol 43 (1) ◽  
pp. 113-115 ◽  
Author(s):  
M. F. Eino ◽  
D. A. Biggs ◽  
D. M. Irvine ◽  
D. W. Stanley

SummaryCalf rennet, bovine pepsin, and porcine pepsin were used to produce cheese curd, using the same milk and lactic culture for each. Specimens were prepared for scanning electron microscope examination by a modified critical-point drying technique.From examination of the micrographs, the curd made with bovine and porcine pepsin were similar in structure and in orientation of the coagulated protein, whereas the curd produced with rennet was different, having a more compact and organized structure.


1972 ◽  
Vol 39 (2) ◽  
pp. 261-273 ◽  
Author(s):  
Margaret L. Green

SummaryThree enzymes were assessed as rennet substitutes for cheese-making. The bovine and chicken pepsins used were relatively crude extracts of bovine stomach mucosa and chicken proventriculae respectively; the swine pepsin was a partially purified commercial product. The ratios of milk-clotting activity to general proteolytic activity were high for rennet and bovine pepsin and low for swine and chicken pepsins. Both bovine mucosa and chicken stomach gave low milk-clotting activities compared with calf stomach. For all the enzymes the chemical reactions causing milk clotting appeared to be the same. The milk-clotting activity showed a decrease with increase in substrate pH for all the enzymes, although they were all still active at pH 6·81.Duplicate cheeses were made from each of the swine, bovine and chicken pepsins, with rennet as a standard in each trial. The cheese-making process was similar with each enzyme, but differences appeared during ripening. The chicken-pepsin cheeses had poor body and weak Cheddar-cheese flavour, with many and intense off-flavours. The cheeses made with bovine and swine pepsins were only slightly inferior in quality and intensity of Cheddar-cheese flavour to the rennet cheeses. From a simulated cheese-making experiment it was concluded that 30–40 % of the added rennet, bovine pepsin and chicken pepsin was probably inactivated during the cheese-making process and that most or all of the swine pepsin was lost. These results provide an explanation for the variations observed in cheese ripening.It was concluded that chicken pepsin would not prove a suitable rennet substitute for making Cheddar cheese because of the quality of the cheese produced, and that bovine pepsin would not prove suitable because of the cost of preparing a suitable extract. Swine pepsin would appear to be suitable if the ripening time were to be lengthened or if another enzyme were to be added to assist ripening; it is cheaper than rennet and other rennet substitutes.


1936 ◽  
Vol 7 (2) ◽  
pp. 156-175 ◽  
Author(s):  
F. H. McDowall ◽  
R. M. Dolby

1. Determinations have been made of lactose and lactic acid in whey, curd and curd juice throughout the cheese-making process.2. The effect of adding salt to curd at various stages of the process on the concentration of lactose and lactic acid in the whey has been investigated.3. The rate of penetration of salt into curd has been determined, and it has been shown that by the time the cheese is normally hooped but little salt has reached the centre of each curd strip. Within 12 hours after hooping the distribution of salt is substantially uniform.4. It has been shown that the conversion of lactose to lactic acid by starter bacteria in the cheese vat is almost quantitative.5. Evidence has been brought forward indicating the presence of bound water in cheese curd.6. It has been shown that a Donnan equilibrium controls the partition of electrolytes between curd and whey.


1956 ◽  
Vol 23 (3) ◽  
pp. 355-360 ◽  
Author(s):  
H. R. Whitehead ◽  
D. J. Lane

The addition of penicillin to cheese milk had the effect of delaying acid production by starter in the cheese curd; any effect on cheese quality could be traced to the delay in acid production and to a high final pH in the cheese. There was no indication of any direct effect of penicillin on the ripening process.A concentration of 0·10 unit/ml. of penicillin in the cheese milk was a borderline amount with the particular starters which were used. Cheese quality was sometimes adversely affected. A smaller concentration (0·05 unit/ml.) delayed the cheese-making process slightly but had no adverse effect in final cheese quality. Higher concentrations regularly resulted in poor quality cheese.Penicillinase added to cheese milk neutralized any penicillin present but with a short time of contact of about 30 min., a large excess of penicillinase had to be used.


1981 ◽  
Vol 48 (2) ◽  
pp. 333-341 ◽  
Author(s):  
Margaret L. Green ◽  
Frank A. Glover ◽  
Elizabeth M. W. Scurlock ◽  
Richard J. Marshall ◽  
David S. Hatfield

SummaryMilks were prepared at 1·7- to 4-fold the initial concentration by combining skim-milk concentrated by ultrafiltration with cream, and used for Cheddar cheese-making. Starter growth was unaffected, but the increased buffering capacity in the more concentrated milks resulted in a slower decline in pH and a higher pH value in the cheese. Curd formation was faster despite the use of reduced amounts of rennet. With milk concentrated more than 2-fold, large amounts of fat were lost in the whey, so that the cheeses had less fat than normally. Fat losses may be partly related to the lower degree of aggregation of the casein micelles when the curd was cut. As the concentration factor of the milk increased, the rate of casein breakdown, the intensity of Cheddar flavour, and the levels of H2S and methanethiol in the cheese decreased. These factors may relate to the reduced concentration of active rennet retained in the curd at pressing.


1995 ◽  
Vol 58 (1) ◽  
pp. 62-69 ◽  
Author(s):  
K. ANJAN REDDY ◽  
ELMER H. MARTH

Three different split lots of Cheddar cheese curd were prepared with added sodium chloride (NaCl) potassium chloride (KCl) or mixtures of NaCl/KCl (2:1 1:1 1:2 and 3:4 all on wt/wt basis) to achieve a final salt concentration of 1.5 or 1.75%. At intervals during ripening at 3±1°C samples were plated with All-Purpose Tween (APT) and Lactobacillus Selection (LBS) agar. Isolates were obtained of bacteria that predominated on the agar media. In the first trial (Lactococcus lactis subsp. lactis plus L. lactis subsp. cremoris served as starter cultures) L. lactis subsp.lactis Lactobacillus casei and other lactobacilli were the predominant bacteria regardless of the salting treatment Received by the cheese. In the second trial (L. lactis subsp. lactis served as the starter culture) unclassified lactococci L. lactis subsp. lactis unclassified lactobacilli and L. casei predominated regardless of the salting treatment given the cheese. In the third trial (L. lactis subsp. cremoris served as the starter culture) unclassified lactococci unclassified lactobacilli L. casei and Pediococcus cerevisiae predominated regardless of the salting treatment applied to the cheese Thus use of KCl to replace some of the NaCl for salting cheese had no detectable effect on the kinds of lactic acid bacteria that developed in ripening Cheddar cheese.


Foods ◽  
2013 ◽  
Vol 2 (1) ◽  
pp. 100-119 ◽  
Author(s):  
Alice Nongonierma ◽  
Magdalena Abrlova ◽  
Kieran Kilcawley

2000 ◽  
Vol 35 (5) ◽  
pp. 483-495 ◽  
Author(s):  
Ehab E. Kheadr ◽  
Jean-Christophe Vuillemard ◽  
Samy A. El Deeb

1931 ◽  
Vol 2 (2) ◽  
pp. 176-178 ◽  
Author(s):  
George M. Moir

The preceding investigation left a little doubt as to the effect produced by pasteurisation of clean milk upon the flavour of the mature cheese. For although the cheese made from milk, flash-pasteurised at 165° F., appeared to develop a desirable flavour more rapidly than the raw control throughout the greater part of the ripening period, yet at the end this was spoilt by a very slight bitterness.


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