The use of Cold Setting Whey Proteins to enhance the Gelation Properties of Foods.

End of Project ReportThe main objective of this project was to produce dried, denatured, whey protein-based powders, which on reconstitution in food formulations show an increased ability to bind water in the presence of added salts, especially in the ambient temperature range. To achieve this, a number of secondary objectives were set to observe the behaviour of the whey protein system. These included the effects of salt on increases in viscosity during the heating process, the requirement for pH adjustment during processing and the ability of the pre-treated whey protein to interact with fat. The main conclusions were as follows: * It was shown that, compared to a commercial 75% whey protein concentrate, a preheated whey protein ingredient (cold-setting whey protein) improved the consistency of surimi and a cold-set dessert system. * For cold-setting applications, the whey proteins need to withstand heating without gel formation. For example, as the protein concentration was increased, the salt concentration had to be decreased and pH increased to prevent the initiation of gelling during processing. When the salt concentration was increased, a lower heat treatment was needed to prevent viscosity increase. However, lower heat treatment resulted in a lower degree of protein unfolding and weaker cold-set gels. This example implies that only certain whey sources are suitable starting materials for cold-set applications. * Model oil-in-water emulsions were studied using whey proteins pre-treated at different homogenisation and heating conditions to evaluate the potential of cold-setting whey proteins in yoghurt, mayonnaise and sauces. It was found that with these pretreatments, emulsion viscosity increases were observed at very low whey protein concentration (< 1%), when salt was added after emulsion formation, indicating that cold-set whey proteins are much more effective gelling agents than normal whey protein ingredients. For this reason, they have potential in acidified dairy products such as yoghurt. * Pre-heated whey protein dispersions are also capable of binding and stabilising calcium phosphate. This property can be exploited in the stabilisation of calcium-fortified milkbased beverages. * The commercial production of cold-setting whey protein ingredients will depend on the ability to retain whey protein solubility during processing. A number of mechanisms exist to achieve this but, in all cases, very exact control of the process is required. * Because low salt levels prevent the aggregation and gelling of denatured whey proteins, whey protein isolate is an ideal starting material for the production of these ingredients, but due to the high cost, de-mineralised whey was chosen instead as the starting material. Careful consideration has also to be given to the processing equipment and the economics involved. * The development of whey protein ingredients especially for cold-set end uses is a product specific exercise. General guidelines were developed in the current work, but further work with industry partners will be necessary before commercial success is achieved.Department of Agriculture, Food and the Marin

Novel Milk Protein Ingredients.

End of Project ReportThe manufacture of casein/caseinates containing whey protein is immediately attractive due to its potential to enhance product yield. However, some technologies capable of producing these products are ineligible for manufacturing subsidy because of restrictions pertaining to relevant EU regulations. Other emerging technologies require refinement and process design before implementation at industrial level. Furthermore, the implications of incorporating virtually the entire complement of whey protein in what is essentially a caseinate ingredient needs to be investigated carefully in terms of the versatility of use in a wide range of food formulations. The development is significant in the context of U.S. market changes - traditionally, an important outlet for Irish casein exports amounting to 20,000 - 27,000 t per annum. Ireland accounts for ~ 30% of EU casein/caseinate production with the greater proportion in Rennet form (27,000 t) and the remainder (18,000 t) as Acid casein. In recent years, a new market for a related casein ingredient - milk protein concentrate (MPC) opened up in the US, and accounted for total imports of 40,000 t in 1998, 10,000 t of which were exported from Ireland. However, this market is more restricted due to regulatory changes introduced in response to the perceived threat of MPC imports to the US dairy industry. Since casein, or its derivative products such as milk proteinate (EU Annex III compliant), are not perceived to be in competition with local milk supplies and dairy ingredients, it is now hoped that Irish casein manufacturers may be able to reclaim recently lost markets through the introduction of an innovative proteinate ingredient which is expected to command a premium in nutrition applications e.g. in sports, infant formula and nutraceutical products. With a choice of emerging new technologies for the production of novel casein-related ingredients, the dairy industry has an opportunity to decide on what is appropriate for the defence of its market share and at the same time benefit from simultaneous compliance with relevant regulatory supports (EU) and market access rules (USA). Hence the main aims of this project were: * To investigate new technologies for the isolation of casein and casein/whey protein combinations in the course of developing new milk protein ingredients, and * To compare the performance in selected food formulations of novel milk protein ingredients namely milk proteinates, milk protein concentrates, native phosphocasein and classical Annex III casein products.Department of Agriculture, Food and the Marin

Optimisation of Ingredient Formulation in Processed Meat Products.

End of Project ReportReformed and restructured meat are two major categories of processed meat products. Reformed meat products require intact meat pieces to bind together while restructured meat products are extensively minced prior to restructuring. Salts such as sodium chloride and phosphates together with mechanical treatment and heat, have been used to bind meat pieces together. In the process the proteins in muscle become soluble, bind large amounts of water and gel on heating. While heat-induced gelation of soluble meat protein provides binding in reformed meat products and reduces cook losses in restructured meat products, no binding occurs in raw meat systems. Non-meat proteins, especially soya protein, are routinely used in processed meat products, often in conjunction with salts, to increase water and fat binding during the cooking process. However, such proteins do not bind intact meat pieces in either the raw or cooked state. Transglutaminase (TGase) is a food-grade commercially available enzyme which can crosslink suitable proteins leading to the formation of a protein matrix (gel) and immobilisation of large quantities of water. This property could improve the water-binding properties of non-meat proteins in restructured meat products. The prospect of crosslinking native meat proteins and non-meat proteins or native meat proteins on adjacent meat pieces would make salt-free reformed meat products a realistic objective. Hence, the main objective of this project was to study protein-protein interactions in reformed and restructured meats, especially between meat proteins and added non-meat proteins in the absence of salts but in the presence of a protein crosslinking enzyme.Department of Agriculture, Food and the Marin

Improving the Quality of Low Fat Cheddar Cheese

End of Project ReportThe aims of this study were to elucidate the contribution of fat to cheese biochemistry and texture and to improve the texture and flavour of half-fat Cheddar cheese by modifications in make procedure, the addition of a fat mimetic, and/or the use of novel starter cultures/bacterial culture adjuncts. The main conclusions were as follows: A 'Moorepark Process' has been established for the production of half-fat Cheddar cheese with improved sensory acceptability. The flavour and texture of half-fat (17% w/w) Cheddar was improved by modification of the cheesemaking procedure and/or ripening conditions and through the use of novel starter cultures and/or bacterial culture adjuncts. Extensive databases have been compiled on: the effects of fat on the compositional, microbiological, biochemical, rheological and sensory properties of, and the yield of, Cheddar cheese. the compositional, biochemical and sensory characteristics of commercial Cheddar cheeses of different fat levels, available on the Irish and UK markets. Reduction in the fat level of Cheddar cheese resulted in a marked deterioration both in texture and flavour due to: increases in cheese hardness and fracture stress, indicating that the cheese became more elastic, tough and less amenable to mastication. a higher ratio of secondary-to-primary proteolysis a reduction in the level of primary proteolysis and an increase in the concentration of hydrophobic peptides which are conducive to bitterness.Department of Agriculture, Food and the Marin

Nutritional Studies on Dried Functional Food Ingredients Containing omega-3 Polyunsaturated Fatty-Acids.

End of Project ReportTeagasc acknowledges with gratitude grant aid under the EU Framework Programme (EU FAIR contract No. CT-95-0085).The nutritional benefits of fish oils are generally attributed to their content of long chain omega-3 polyunsaturated fatty acids (PUFAs). Diets rich in these fatty acids are known to reduce the risk of coronary thrombosis, and are recommended to those who are susceptible to atherosclerosis. In addition, some of these long chain PUFAs play an important role in early infant nutrition, in the development of vital human organs such as the neural tube. However, practical difficulties arise in achieving an adequate daily intake of fish oils to obtain these physiological benefits. Per capita fish consumption is low in many countries, especially of oily fish with high levels of omega-3 PUFAs. Fish oil, while available as a dietary supplement, is not universally appealing in that form. Attempts to incorporate fish oil into food formulations have had limited success mainly because of fishy flavours coming through in the consumer products. Fish oil is particularly susceptible to oxidation, which results in fishy, painty and metallic flavours. Hence the main aim of this study was the development of a dried ingredient in which the formulation and related processing conditions were optimised to protect the fish oil from oxidation. Protection of any sensitive oil may be achieved by means of microencapsulation, whereby oil is dispersed as very fine droplets in emulsions. During subsequent spray drying the droplets are effectively sealed inside a protective coating of protein surrounded by carbohydrate. The objective was, therefore, to evaluate microencapsulation as a means of extending the shelf-life of fish oil in powder form thus increasing its versatility as a nutritional ingredient in food formulations.European Unio

β-Lactoglobulin: A Whey Protein Fraction with Enhanced Functionality

End of Project ReportInfant formula manufacturers are progressively moving towards the development of the next generation of infant milk formula based on the inclusion of α-lactalbumin-enriched ingredients in order to further ‘humanise’ baby milk, as well as to reduce the allergenicity associated with the presence of β-lactoglobulin ( β-lg). Since α-lactalbumin represents one of the two major whey protein fractions in bovine milk, the viability of new fractionation processes currently under development will depend inter alia on the functional value that will attach to the remaining fraction, namely β-lg. Since this protein fraction influences whey protein functionality for the most part, it is to be expected that its availability in an enriched form should lead to further enhancement of its key functional properties, and stimulate further market opportunities. It is therefore imperative that attention is given to the processes and functionality of β-lg produced by different processing approaches. Hence, the overall objective of the project was: - To source and/or produce sufficient quantities of β-lg-enriched ingredients obtained through whey protein fractionation using different technologies, and to evaluate their functionality in model and food systems. - To investigate the influence of thermal treatments and ionic environment on the molecular structure of purified β-lg in order to understand their effect on protein functionality (gelation). - To improve the water-holding capacity of β-lg-enriched fraction so that it could compete more favourably with carbohydrate hydrocolloids in food applications. Downstream processing of β-lg was manipulated to influence the composition, and hence the functional properties of β-lg-enriched fractions. * β-Lg-enriched fractions had enhanced functional properties compared to WPC 75 and WPI. * β-Lg-enriched fraction has clear advantages over conventional whey protein products (WPC, WPI), in that it can be tailor-made to have specific functional properties desired in particular food products. * Water-binding properties of β-lg-enriched fraction could be improved by multi-stage heating.Department of Agriculture, Food and the Marin

Development of a Range of Encapsulated Milk Fat Products

End of Project ReportThe aims of this research were to determine the effects of milk composition (fat, whey protein, lactose and salts) and process (homogenisation) factors on the formation of emulsions and microencapsulated powder particles and to relate these to the properties of the powder, especially susceptibility to fat oxidation. The effect of composition, using sodium caseinate and lactose on the production of high fat powders was also studied. Finally, new developments in microencapsulated milk powders were undertaken in collaboration with industry using sodium caseinate and lactose. Overall, the microencapsulation process should provide a technique to extend the shelf-life of sensitive fats and flavours and to produce high fat powders for a range of end-uses. The major components of the emulsions used to make the microencapsulated powders influenced fat globule diameter and stability, but the minor salt components also affected globule size and stability. Free flowing high fat (70%) powders with sodium caseinate and lactose as encapsulants were manufactured using a tall-form Niro spray dryer with fluidised beds. A flavoured ingredient using a by-product flavoured fat as the flavour agent was made using the same encapsulants. Microencapsulated powders were incorporated into baked goods as multi-functional ingredients. They increased loaf volumes and improved handling and processability of the dough, thereby extending the product range for fat and other dairy ingredients used for baking. Microencapsulated 80% fat blends were manufactured for biscuit formulations to overcome the handling problems associated with bulk fats. This sub-project also gave rise to a leading role in a EU FAIR project on the microencapsulation of fish oil for use in functional foods using milk components as the sole encapsulants.Department of Agriculture, Food and the Marin

Dairy Ingredients in Chocolate

End of Project ReportThe main objective was to assess and control the contribution of various ingredient components to chocolate behaviour and to optimise ingredients for specific chocolate applications. A key aim, therefore, was to understand the role of composition and particle structure and to produce spray dried powders with a functionality in chocolate as close as possible to roller dried powders. By demonstrating how the powder properties affect chocolate, it should be possible to control the functional properties of the powders to meet any powder or chocolate specification. Novel powder compositions indicated by this work should also be useful to chocolate makers. The ability to make chocolate under test conditions and to assess the role of milk powders or other ingredients has been put in place for the first time in Ireland. Previous knowledge of milk seasonality and of powder technology has provided a basis for understanding variations in milk powder functionality in chocolate. Spray dried powders with mean free fat values of 50 to 94%, particle sizes of 30 to 65 mm and vacuole volumes of 0.0 to 3.9 ml/100g were produced from milks of varying composition but under the same processing conditions. Advances were made in analysing powder structure through microscopy, particle size and occluded air measurement. Valuable new information has been generated on the changes in free fat, solid fat content, particle size and occluded air in powders. Explanations were provided for the first time for the complex effects of these properties on chocolate viscosity and yield value. This information will also make a positive contribution to other projects in the milk powder area. Good contacts have been established with multinational manufacturers and with producers of milk powder for chocolate.Department of Agriculture, Food and the Marin

Development and Evaluation of Caseins/Caseinates for use as Ingredients in Food Products

End of Project ReportThe overall objective of this project was to investigate the effects of key processing steps in the industrial production of acid casein on the characteristics and functionality of sodium caseinate with particular emphasis on analytical/functionality testing and seasonal/lactational effects on the original milk. The main conclusions were as follows: The most significant result indicates that drying and concentration after washing of the acid casein curd are responsible for alterations in the structure of casein, which result in sodium caseinates with different properties. This was confirmed in the case of two acid casein plants investigated which showed similar results even though using different washing and drying technologies. This difference due to the drying step may be further amplified depending upon whether commercial sodium caseinate is manufactured from acid casein in the dried or wet curd state. The analytical and functional testing methodology adapted in our laboratory proved effective in predicting the effects of processing steps on the functionality of sodium caseinate. In particular, the ability to detect the presence of aggregate formation was particularly important. The database generated subsequently helped an acid casein manufacturer in modifying its process(es) to manufacture experimental sodium caseinate for specific food end-uses. Progress was greatly facilitated by the collaboration of individual manufacturers in the sourcing of problem samples from previously manufactured codes, and facilitating access to process plant during production. In a commercial application of the database, confidential work was undertaken on behalf of a client. Experimentally-produced sodium caseinate ingredients were evaluated using our adapted functionality testing methods and based on the results, the company was able to modify its process(es) to produce sodium caseinates with functionality for specific food end-users. It was concluded that while processing parameters in the production of acid casein can have a significant effect on the functional behaviour of the resultant sodium caseinate, the ability to assess this change in functional behaviour, through relevant functional testing, was equally important.Department of Agriculture, Food and the Marin

Dairy Ingredients for Chocolate and Confectionery Products.

End of Project ReportHigh free-fat, spray-dried powders were successfully produced at a lower fat content (40% rather than 56%) using ultrafiltration. Chocolates made from these powders had improved flow properties and superior quality. The stability, viscosity and firmness of toffees were improved by optimising the casein, whey protein and lactose levels of skim milk powders used in their manufacture.Department of Agriculture, Food and the Marin