Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Subject: search.filters.subject.Cheddar cheese

Search Results

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    An attempt to manufacture Cheddar cheese containing only one type of organism : thesis for the degree of M. Agr. Sc. (in Dairy Science) at the University of New Zealand, by Ascend
    (Massey University, 1931) Neil, William C.; Ascend
    There have been many investigations on the effect of various bacteria on the ripening of hard rennet varieties of cheese. Hucker (1922) in a review of the bacteriological aspects of cheese ripening summaries the position as follows: "As it stands to-day the investigations have closely demonstrated that the breaking down of the insoluble casein compounds is due to enzymes, either natural or bacterial; while characteristic flavors are produced by the action of certain groups of bacteria. (Bacterium casei or coccus group), which depend on the products of B. lactis acidi present in large numbers during the manufature and early ripening stages." The effect of lactic acid bacteria upon the flavour of Cheddar cheese has been studied by Hastings, Evans and Hart (1912), Evans, Hastings and Hart (1914), Evans (1918). Leitch (1923) and Hucker and Marquardt (1926). [From Introduction]
  • Thumbnail Image
    Item
    Modelling primary proteolysis in cheddar cheese in commercial cool stores : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Bioprocess Engineering at Massey University
    (Massey University, 2000) Edmonds, Richard
    One issue identified as a possible problem during the manufacture of cheddar cheese is the possibility of producing a non-uniform product. It was proposed that a pallet of cheese experiencing different time-temperature histories, depending on the position within the pallet, could cause the heterogeneity. This work involved the investigation of that issue. The level of primary proteolysis observed in cheese was measured over time in cheeses of different compositions, stored at different temperatures. The remaining intact αₛ₁casein was measured using reverse phase high performance liquid chromatography. Several trends were observed during maturation. High temperatures caused a faster rate of disappearance of αₛ₁casein. The temperature relationship followed Arrhenius law. High moisture content caused a faster rate of the disappearance of αₛ₁casein. The level of rennet added to the milk during production had a directly proportional effect on the rate of the disappearance of αₛ₁casein. Salt had no observable effect in the range investigated here. From the data a kinetic model was developed that described the rate of disappearance of αₛ₁casein in terms of the temperature, the moisture content, and the level of rennet in the cheese. The heat transfer occurring in the commercial pallet of cheese was mathematically modelled and solved numerically. The heat transfer model was then applied to produce data describing the time-temperature profile throughout a pallet of cheese for a variety of possible industrial storage conditions. The kinetic model developed was then used to predict the extent of proteolysis in each case. It was found that there would be significantly different levels of proteolysis within a pallet of cheese that had undergone chilling. A 10% difference in the level of proteolysis between the surface and the centre was observed after chilling for 40 days. During freezing the difference in the level of proteolysis after freezing was complete ranged from 10-25%. It was found that the heterogeneity was reduced during the thawing process and that the greatest reduction in non-uniformity was observed when thawed at lower temperatures.
  • Thumbnail Image
    Item
    A study of some aspects of the quality and yield of cheddar cheese made from milk concentrated by ultraflitration : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in the Department of Food Technology at Massey University
    (Massey University, 1986) Iyer, Mani
    Ultrafiltration (UF) is a concentration and separation process which operates at the molecular level. It has been successfully applied to certain soft cheese varieties with the primary advantage of increased yields. When applied to Cheddar, which is a hard variety, problems are encountered. These are lack of flavour and texture development, lack of economically viable yield increase and practical problems in handling of UF curd. An investigation was undertaken to study the application of UF technology to the manufacture of Cheddar cheese. The emphasis was on the biochemical and biophysical problems in UF Cheddar and the possible yield advantages in making the product. Results suggest that UF per se does not contribute to problems in the quality of UF Cheddar. No major problems were encountered in the cheese making process or in final cheese quality when cheese was made from 2:1 UF retentate using conventional method and equipment. There were, however, no yield advantages. When 3:1 and 5:1 retentates were used, some modification in the method of manufacture, particularly in the cutting time and cutting device, was necessary. The quality of cheese obtained from 3 : 1 retentate was found to be inferior while that from 5:1 retentate was comparable with respect to the control cheeses. The biochemical and biophysical problems associated with the quality of UF Cheddar could be overcome to a large extent by adjusting the amount of starter and rennet added on the basis of quantity of milk prior to UF. This yields Cheddar of normal one-day pH but with residual rennet concentration much higher than that in the conventional product. The higher level is probably required to over come the 'dilution' effect of the extra whey proteins present in the UF product. This 'dilution 'effect may be partly due to the difficulty of rennet diffusion in UF Cheddar and partly a result of a decrease in concentration of flavour compounds due to the presence of extra whey proteins. The results show that subs tanti a l savings i n rennet are not possible in cheesemaking from 5:1 UF retentate. The results also suggest that it is possible to make UF Cheddar with a required residual rennet concentration by regulating the amount of rennet added to the retentate and draining the whey at a predetermined pH. The yield advantage in cheesemaking from 5:1 retentate (if UF Cheddar is made to normal MNFS of 53.5%) was limited to 4% largely because only one third of the whey proteins of UF milk was retained in the cheese. Theoretical analysis of mass balance data indicated that this yield advantage could be improved to about 6% by reducing 'fines' losses and to about 8% by decreasing fatlosses as compared with the conventional process. Given the current state of UF cheesemaking technology, it is possible that reductions in losses in conventional cheese-making plants may prove to be a more profitable method of increasing yields of Cheddar cheese than the use of UF cheesemaking methods.
  • Thumbnail Image
    Item
    The biosynthesis of methyl ketones with special reference to their presence in Cheddar cheese : being a thesis presented for the degree of Doctor of Philosophy of the Massey University of Manawatu
    (Massey University, 1964) Lawrence, R C
    The similarity of the pattern of methyl ketones obtained from the steam distillates at atmospheric pressure of cheeses made under controlled aseptic conditions, despite the wide differences in bacterial flora, led to the suspicion that the methyl ketones were being formed as artifacts. This was confirmed by steam distilling cheeses from 1 day to 13 months old when the qualitative patterns and quantitative amounts differed little with the age of the cheese. Evidence was produced to show that the greater part of these methyl ketones must be formed during the heat treatment of milk fat. The maximum quantities of methyl ketones obtainable from cheese and from milk fat, determined by exhaustive steam distillation at atmospheric pressure, averaged from 14 p.p.m. for 2-undecanone to 46 p.p.m. for 2-pentadecanone. Some artifact formation of methyl ketones also occurred, although to a greatly reduced extent, when dairy products containing milk fat were steam distilled under reduced pressure at 40°. As methyl ketones in low concentrations could be extracted from mature cheese at room temperature by solvents or by flushing cheese suspension with nitrogen, milk fat appears to contain precursors which break down to methyl ketones slowly during cheese ripening, this breakdown being accelerated at higher temperatures. Two possible modes of formation of the methyl ketones with an odd number of carbon atoms, found in limiting quantity in the steam distillates of Cheddar cheese, were considered:- (a) From precursors, probably β-keto acids, bound in milk fat. (b) The β-oxidation of free fatty acids, formed by the lipolysis of milk triglycerides, and subsequent decarboxylation of the β-keto acids formed. The use of radioactive milk fat from a lactating cow which had been injected intravenously with carboxy-14C acetate allowed a direct comparison to be made between the labelling patterns of fatty acids and the corresponding methyl ketones from the same milk source. The similarity of the labelling patterns suggests that the C6 to C16 β-keto acids and the corresponding fatty acids have a common precursor (or that one is the precursor of the other) and are together incorporated into the triglycerides. Only butyric acid of the C4 to C16 fatty acids in all 3 milkings had a higher specific activity than the corresponding methyl ketone. This suggests that the acetone found in steam distillates of milk fat is formed from a compound (probably D-β-hydroxybutyrate), derived almost entirely from a precursor other than acetate. The finding that the saturated C18 acid in all 3 samples of radioactive milk fat had an extremely low activity was in agreement with the fact that no C17 methyl ketone was detected in any of the numerous steam distillates from milk fat or cheese. This supports the generally accepted view that, in the biosynthesis of milk fat, the fatty acids up to c16 acid are synthesised from an acetate pool, whereas C18 acids and above are obtained from the blood triglycerides. The possibility that methyl ketones were being formed in Cheddar cheese from the β-oxidation of free fatty acids, as well as from a slow breakdown of bound β-keto acids in milk fat, was shown to be improbable. Triglycerides of acids (undecanoic, nonanoic, and heptanoic), which occur normally only in traces in milk fat, were synthesised and incorporated in Cheddar cheeses. On steam distillation of these cheeses when mature, no methyl ketones corresponding to the acids in the added triglycerides were obtained, although the normal range of methyl ketones with an odd number of carbon atoms was found in the distillates. A detailed study of the metabolism of fatty acids and synthetic triglycerides by spores and mycelium of Penicillium roqueforti was undertaken, this fungus being chosen as a general representative of lipolytic organisms that might be of importance in producing Cheddar flavour. The effect of the growth medium, pH of solution, concentration of acid and inorganic ions on both oxygen uptake and methyl ketone formation was determined. The rate of methyl ketone formation suggested the synthesis of adaptive β-keto acid decarboxylases after a lag period of 1 to 2 hours. An hypothesis based upon the possible toxicity of the C6 to C12 β-keto acids can explain a number of the experimental results: (1) Only one methyl ketone was formed (2) The most toxic acids were those which gave the least amount of methyl ketone (3) Concentrations of the C8 to C12 fatty acids that markedly inhibited the respiration of mycelium were nevertheless oxidised to considerable quantities of the corresponding methyl ketone. The relationship between the toxic action of fatty acids and chain length was found to be dependent upon pH. The chain length of the most toxic acid increased with pH, being C10 acid at pH 2.5 and C12 at pH's 5.2 and 6.0. At pH 6.8 none of the acids from C4 to C18 inhibited oxygen uptake but C14 acid was the most toxic acid at pH 8.0. There appeared to be no sharp dividing line between the metabolic activity, with respect to fatty acids, of spores and mycelium. Mycelium oxidised fatty acids rapidly giving varying amounts of methyl ketone but considerably more CO2 than spores. In general spores formed higher amounts of methyl ketones than mycelium but showed also a slight but definite ability to form CO2 from octanoic acid. Evidence for a β-oxidation mechanism in the fungal metabolism of fatty acids was obtained by the use of 1-C14 and 2-C14 octanoic acids. A relatively slow movement of intermediates through the T.C.A. cycle was also indicated. High concentrations of triglycerides were oxidised slowly by spores to methyl ketones when equivalent concentrations of the free acid (up to 66 μmoles/ml) inhibited methyl ketone formation. It seems probable that the very slow rate of formation of methyl ketones is due to the inhibitory effect of the ketones themselves on the lipases. Methyl carbinols were not detected in significant amounts as products of the metabolism of methyl ketones, evidence being obtained on the contrary that the carbinols were possibly precursors of the ketones during the oxidation of fatty acids by spores. Cell free extracts obtained from mycelium were able to oxidise low concentrations of octanoic acid (0.5 μ-moles/ml or less) after a lag of up to 3 hours. The supplementation of the extracts with several coenzymes, known to be associated with fatty acid oxidation, or with T.C.A. cycle intermediates were unable, however, to decrease the lag before oxidation started. No methyl ketones were detected after the oxidation of fatty acids by cell-free extracts but were formed when cell debris from the Hughes Press was used. This suggests that the β-keto acid decarboxylases were tightly bound to the cell walls.