Evaluation of the manufacture of cheese from micellar casein concentrate or using novel coagulants
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Date
2022-09-23
Authors
Li, Bozhao
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Publisher
University College Cork
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Abstract
Novel materials and coagulants for cheese manufacture are currently of interest since the development of membrane filtration technology and gene recombination technology may offer opportunities for innovation in cheese manufacture. A novel dairy material – micellar casein concentrate (MCC) – is the co-product of whey protein recovery. As the main protein source in cheese is casein, MCC has the potential to be a starting material for cheese manufacture. The objective of the work presented in the first part of this thesis was to evaluate the feasibility of the manufacture of Cheddar and Quarg cheeses from micellar casein concentrate. In addition, camel chymosin has been reported to cause less proteolysis as a coagulant for cheese manufacture compared to bovine chymosin. The suitability of manufacture of Cheddar cheese using a novel camel chymosin with structural changes was also investigated.
The rennet and acid coagulation properties of micellar casein concentrate were evaluated. MCC had a higher casein in total protein content compared to low heat skim milk powder (LHSMP), and shorter rennet coagulation time and higher gel strength were found in MCC compared to that of LHSMP. A gelation pH value greater than 5 was found in MCC. MCC produced by cold microfiltration (MF) formed acid-induced gels with high strength at pH 4.6, while the gel strength of acid-induced gels formed by warm MF MCC reached the highest at a pH value of around 5 and decreased below this value due to rearrangements of the casein network. The suitability of the manufacture of Cheddar cheese from MCC was subsequently investigated; standard control milk, skim milk with cream, reconstituted MCC with cream and reconstituted LHSMP with cream were used for comparison. The use of MCC led to increased proteolysis compared to the other treatments, linked to higher plasmin and chymosin activities in the cheese. Increased springiness, cohesiveness and meltability were found in Cheddar cheese manufactured from MCC. For the manufacture of Quarg cheese, lower moisture and higher protein contents were found in cheese made from MCC compared to that made from LHSMP. Cheese made from hot MF MCC showed the highest hardness compared to that made from LHSMP or cold MF MCC. Higher glycomacropeptide (GMP) content was found in cheese whey made from MCC.
The suitability of manufacture of Cheddar cheese using a modified fermentation-produced camel chymosin (mCC) was investigated; fermentation-produced bovine chymosin (BC) and camel chymosin (CC) were used for comparison. The use of mCC led to reduced proteolysis compared with BC or CC, and higher instrumental and sensory hardness and lower meltability were found in cheeses made using CC or mCC compared to BC. Descriptive sensory analysis indicated less sulphur and barny flavour in cheese made with CC and mCC, while cheese made using mCC showed the lowest brothy flavour and bitter taste. Finally, the proteolytic specificity of the three generations of chymosin on NaCN at pH 5.2 with 5% NaCl and 6.5 and in proteolysis of Cheddar cheese made using these coagulants were investigated. Many peptides were identified through liquid chromatography-mass spectrometry (LC-MS) in both NaCN digests and Cheddar cheese made using each chymosin. Other than the majority of peptides produced by BC and CC reported in the literature, some new peptides were identified in this study as well. The proteolytic activity of mCC was relatively lower than that of BC and CC.
Overall, the results presented in this thesis will support the innovation and application of new materials for the manufacture of cheese and other dairy products and add to the understanding of the properties of three generations of chymosin when used in cheese manufacture.
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Keywords
Cheese manufacture , Camel chymosin , Cheese texture , Cheese functionaliy , Rennet coagulation , Acid coagulation , Mass spectrometry , Proteolysis , Rheology , Micellar casein concentrate , Membrane filtration retentate
Citation
Li, B. 2022. Evaluation of the manufacture of cheese from micellar casein concentrate or using novel coagulants. PhD Thesis, University College Cork.