• Genetic Variants of Milk Proteins - Relevance to Milk Composition and Cheese Production.

      Fitzgerald, Richard J.; Walsh, Daniel; Guinee, Timothy P.; Murphy, J.J.; Mehra, Raj; Harrington, D.; Connolly, J.F. (Teagasc, 1999-07-01)
      Objectives: (i) to develop rapid screening procedures for the determination of milk protein polymorphism (genetic variants) (ii) to determine the frequency distribution of milk protein genetic variants in a large population of Irish Holstein-Friesians and to determine if there was an association between κ-casein variant and milk yield and composition in this group of animals, and (iii) to make Cheddar and low-moisture part-skim Mozzarella cheese from different κ-casein genetic variant milks and to assess any effect on cheese yield, composition and functional characteristics. Conclusions:Analysis of 6,007 individual Irish Holstein-Friesian milks showed that the phenotype distribution of the κ-casein BB variant was very low at 1.98% compared to 53.07% for κ-casein AA and 44.95% for κ-casein AB. While no statistically significant associations were observed between κ-casein variant and milk yield and composition, κ-casein BB variant milks had superior rennet coagulation properties to that of the AA or AB variants. Generally, κ-casein variant had little effect on compositional attributes of cheese apart from FDM (fat in dry matter) which was significantly higher in cheeses from κ-casein BB milk than in those from κ-casein AA milk. Generally, κ-casein variant had no significant effects on either primary or secondary proteolysis, or on the sensory and/or textural characteristics of Cheddar or Mozzarella cheese throughout ripening; or on the functional characteristics (e.g. flow and stretch) of baked Mozzarella on storage for 90 days at 4°C. However, κ-casein BB variant milk gave significantly higher actual, and moisture adjusted yields of Cheddar and Mozzarella cheese than either κ-casein AB or AA variant milks. For example, the moisture adjusted Cheddar yield from κ-casein BB milk was 8.2% higher than from κ-casein AA milk. In the case of Mozzarella, the moisture adjusted yield was 12% higher. Based on the results, it is estimated that the actual yield of cheese in a plant producing 20,000 tonnes per year from κ-casein AA milk would increase to approximately 21,180 tonnes of Cheddar, or 21,780 tonnes of Mozzarella if made from κ-casein BB milk. Where κ-casein AB milk is used instead of κ-casein BB milk, the estimated yield of Mozzarella would increase to 21,580 tonnes.
    • Ingredient Development using a Pilot-Scale Tall-Form Spray Drier

      Kelly, Philip; Kelly, J.; Harrington, D. (Teagasc, 1998-02-01)
      The main objectives of the project were to establish relationships between process variables and product physicochemical/functional characteristics in the course of processing and drying new dairy-based ingredients such as high-fat and protein-rich products in regular and agglomerated forms. By establishing processing protocols, R&D users of the ingredient drying facilities of Moorepark Technology Ltd may be able to predict the process variables necessary for desired end-product specifications to be achieved, and thus make experimentation more efficient and cost effective, as well as facilitate small scale production runs and sample preparation for market development purposes. Particular emphasis was placed on the development of high fat cream and fat-filled powders, flavour-delivery systems and protein-enriched ingredients. The major achievement of this project is that it is now possible to confidently select the appropriate processing conditions during the spray drying of ingredients in order to attain desired end-product specifications. Based on the use of the newly-installed Tall-form drier, the project succeeded in correlating the effects of process parameters of this technicallyadvanced pilot plant with the physicochemical properties of powders containing varying fat (20-80%) and protein contents. In general, the physicochemical characteristics of fat-filled and cream-filled powders with similar fat contents were similar except for higher solubility index values (range 0.1-0.6) in the case of the former particularly in the range 26-28% fat. Furthermore, the free fat content of powders may now be controlled much more precisely using an appropriate combination of total fat, atomiser nozzle selection and post-drying blending.