Proceedings of the IDF Seminar held in Cork (Ireland), in April 1993
The Proceedings start with an overview of the Irish cheese industry. The programme of the Seminar was divided into 11 topics.
Topic 1: Transfer of milk components to cheese: scientific considerations
The first paper in this section discusses mainly the transfer of protein (casein) to cheese. Some attention is given to the problem of correctly calculating the protein or casein content in milk and cheese. The relation between casein content and paracasein content is then discussed. The second paper investigates the impact of whey pH at draining on the transfer of calcium to Mozzarella cheese.
Topic 2: Definition and expression of cheese yield
The transformation of casein in milk into the paracasein structure of cheese and its relation to non-casein milk components is investigated. A model to calculate the amount and composition of the cheese from processing parameters and related to 1 kg casein is developed for Gouda cheese.
Topic 3: Factors that affect yield over which the milk producer has control
This section covers factors affecting cheese yield such as: the influence of mastitis; the importance and effects on technology of physical, chemical and microbiological properties of vat milk in the Parmigiano-Reggiano cheese zone; regional and seasonal variations of nitrogen fractions in cheese milk in Quebec; genetic and environmental factors affecting milk composition; effects of low temperature storage of milk; the effect of seasonal and regional variation in milk compositions. Finally, an evaluation of an automated, rapid method for measurement of rennet coagulation time with a view to controlling processing quality of herd milks during late lactation is presented.
Topic 4: Genetic variants of milk proteins and cheese yield
The effect of genetic polymorphisms of milk proteins on milk properties relevant to cheesemaking, for example, protein content, casein number, rennet coagulation properties and cheese yielding capacity of milk, is demonstrated. This is followed by the results of an extensive study on properties related to the genetic variants of k-casein and ß-lactoglobulin in relation to milk composition and cheesemaking properties; the effect of k- casein genotype on the composition of whole casein and rennet coagulation of bovine milk; chemical composition and coagulation properties of milk from Reggiana breed dairy cows with different casein ß- and k- genotypes; genetic variants of milk proteins and cheese yield; influence of milk protein polymorphism on cheese producing ability in the milk of Manchega ewes breed; effect of genetic variants of casein on the recovery of milk proteins in fresh and soft cheeses obtained by ultra- or microfiltration from goat’s milk; effect of genetic variants of milk proteins on the yield of Cheddar cheese; genetic variants of milk proteins in the Moorepark research herds.
Topic 5: Measurement of casein and other analytical methods
Six papers covering: reference and routine methods for the measurement of nitrogen fractions in milk and whey; a rapid determination of casein in milk and factors affecting casein proportion in milk protein; analysis of cheese and cheese products for moisture; on-line analysis of dairy products by near-infrared spectroscopy; near-infrared spectroscopic analysis of bovine milk for fat, protein and lactose; does the addition of components of cheese equal 100% ?
Topic 6: Factors that affect yield over which the cheese plant has control
Twelve papers covering: factors that affect yield over which the cheese plant has control; cheese yield performance of various coagulants; a nearinfrared system that may enhance cheese yield and process control; coagulation properties, proteolytic activities of milk-clotting enzymes and their effect on cheese yield; effects of compositional modifications and addition of microbial protease on the qualities of experimental cheese; influence of milk microfluidization on Cheddar cheese composition, quality and yields; variability of moisture content in Cheddar cheese; the effect of carbonation of milk on the yield and quality of Cheddar cheese; rennet-clotting properties, starter activity and cheese yield of milk acidified with carbon dioxide; effects of losses to whey and effluent on Cheddar cheese yield; low concentration factor ultrafiltration for the standardization of milk for Cheddar cheese production; assessment of the Amelung-Coagulometer, Formagraph and hot wire technique for measurement of rennet clotting time.
Topic 7: Systems in cheese plants for control of yield
Four papers covering: a spreadsheet system for evaluation and improvement of cheese yield performance; the concept of double-loop standardization; the use of statistical methods to optimize yield in Cheddar cheese plants; control the standardization of the cheese milk – the key to future improvement of cheese quality and profit in cheese production.
Topic 8: Inclusion of whey proteins in cheese, as the process influences yield
Nine papers covering: the inclusion of whey proteins in cheese – an overview; incorporation of whey proteins into Dutch-type cheese; measuring cheese yield increases obtained by ultrafiltration; on-farm thermalization of milk to improve cheese yield; consistency and yield of fresh cheeses obtained by ultrafiltration of coagulated milk; yield of cheese-base material produced by application of continuous Ricotta processing technology; composition of Cheddar cheese made from high-heat treated milk; effect of Simplesse® 100 on the manufacture of low fat Cheddar cheese; methods for improving the rennet coagulation properties of heated milk.
Topic 9: Conduct, design and execution of experiments
Four papers covering: methodology in pilot-scale cheese yield measurement; the use of a pilot plant to study milk processing techniques for cooked body cheese; critical factors in pilot-scale cheese yield studies; experimental design, milk-clotting enzymes and cheese yield.
Topic 10: Other topics
Five papers including: effect of homogenization on the properties of low-fat Mozzarella cheese; analysis of proteolysis in cheese using ionexchange and reverse phase chromatography; dynamic mechanical spectroscopy of Cheddar cheese; development of processed cheese spread from cow’s milk using enzymes and additives; approaches to detecting mislabelled cheeses.
Topic 11: Maximize yield, quality or profit ?
One paper considering the factors influencing yield, quality and profitability.