• The ultra-rapid chilling of lamb carcasses

      McGeehin, Brian; Sheridan, James J.; Department of Agriculture, Food and the Marine (Teagasc, 1999-01)
      The practice in Irish commercial abattoirs is to chill lamb carcasses for a period of approximately 16 hours at 2 - 4°C, at which stage the core temperature of the carcass has reached 7°C. Chilling in this manner is considered necessary because it is generally held that faster chilling leads to toughening of the meat. The objective of this work was to develop a continuous ultra-rapid chilling system for lambs which would reduce carcass chilling time without adversely affecting the quality of the meat.
    • Up-grading of low value meats and by-products for use in consumer foods.

      Kenny, Tony; Desmond, Eoin; Ward, Patrick (Teagasc, 1999-02-01)
      The investigation was concerned with the up-grading of: (i) connective tissue material in the form of beef membrane, pig rind and turkey skin; (ii) muscle material from low-value cuts and from offals such as beef heart; (iii) heart muscle, by extrusion processing; (i) An emulsified material from beef membrane and beef replaced up to 5% of lean meat in corn beef and up to 10% in beefburgers without impairing cooked yield and eating quality. A collagen emulsion paste (CEP) from pig rind replaced up to 5% of lean meat in ham prepared from diced meat, and between 2 and 5% in ham prepared from whole muscles without reduction in cooked yield, texture, appearance and eating quality. Turkey skin was minced, chopped and incorporated at 10, 15 and 20% levels in a mix with turkey leg meat, which was used to make battered and breaded re-formed steaklets. Steaks containing up to 20% of emulsified skin were similar to control samples in flavour, juiciness and overall acceptability. An antioxidant may be required to prevent rancidity during frozen storage. (ii) Yields of surimi-like material, prepared by water-extraction, sieving and centrifuging, were 16% from lean of topside of beef (used as control for comparison), 39% from beef heart, 17% from pork mechanically recovered meat, 11% from beef weasand and less than 5% from beef cheek meat. The beef heart surimi was studied for its gelation properties and for its performance as an ingredient replacing lean meat in frankfurters and in beefburgers at levels between 3 and 15%. In frankfurters the addition of the surimi reduced cook loss and increased tenderness. For overall eating quality the frankfurters with 7 or 10% of surimi were preferable, and those with 15% equal, to those with none. In beefburgers cook loss was decreased from 32 to 25% by the addition of 15% surimi. Other results were similar to those for frankfurters, showing that the surimi could be added at 10 to 15% level without impairing texture or flavour. (iii) Cold extrusion processing of beef heart muscle with the aim of increasing its functionality showed that gelation properties of the material were not improved by extrusion compared to bowl chopping; moreover, the extruded product had a strong odour and dark colour.
    • Upgrading the cold chain for consumer food products

      Gormley, Ronan T.; Brennan, Martine H.; Butler, Francis (Teagasc, 2000-12)
      The prepared consumer foods sector in Ireland is undergoing sustained dynamic growth. Products that are distributed chilled or frozen require a cold chain and there is potential to increase product quality by optimising the cold chain. This potential prompted the current study.
    • Use of Bacteriocins to Improve Cheese Quality and Safety

      Ross, R Paul; Hill, Colin; Ryan, Maire; Cunniffe, Alan; McAuliffe, Olivia; Murray, Deirdre; O'Keefe, Triona; Rea, Mary C. (Teagasc, 1998-09-01)
      The objectives of this project were to generate, characterise and exploit a range of novel bacteriocin producing starter cultures to improve both the safety and the quality of fermented dairy foods. The main conclusions were as follows: Lacticin 3147 is a broad spectrum bacteriocin which inhibits a wide range of Gram-positive bacteria including lactobacilli, clostridia and Listeria. The bacteriocin has been purified by chromatographic procedures and has been shown to be composed of two peptides, both of which are required for biological activity. The mechanism of action of lacticin 3147 has been elucidated. The entire plasmid encoding lacticin 3147 has been sequenced and the bacteriocin in distinct from any previously characterised lactococcal bacteriocin. The Food Grade introduction of the bacteriocin genes into cheese starters was carried out. Lacticin 3147 producing starters have been used to control the pathogen Listeria monocytogenes on the surface of mould ripened cheese. Lacticin 3147 producing starters have been used to control the non-starter lactic acid bacteria complement in Cheddar cheese during the ripening process. A novel starter system using a bacteriocin (lactococcin)- producing adjunct has been designed which gives increased cell lysis during Cheddar cheese manufacture while ensuring that efficient acid production is not compromised. In summary these studies have found that naturally occurring antimicrobials such as bacteriocins have a wide range of applications in the food industry for improving both the quality and safety of fermented dairy products.
    • The use of Cold Setting Whey Proteins to enhance the Gelation Properties of Foods.

      Keogh, Kieran; O'Kennedy, Brendan; Twomey, Myra (Teagasc, 1999-06-01)
      The 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.
    • Using ultrasound to measure beef tenderness and fat content

      Allen, Paul; Dwyer, Catherine; Mullen, Anne Maria; Buckin, Vitaly; Smyth, Cormac; Morrissey, Siobhan (Teagasc, 2001-04)
      A new acoustical technique was developed for the quantitative analysis of the texture and composition of meat and meat products. This new approach exploits the fact that the acoustical velocity and attenuation of waves propagated through meat are affected by its mechanical properties, thus allowing characterisation in terms of its composition and eating quality. The method is based on a new high-resolution ultrasonic resonator. This technique is rapid and uses small samples. Procedures for the acoustical analysis of meat were developed and the results were correlated with taste panel and shear force measurements of meat tenderness.
    • Variation in the quality of meat from Irish steers at the time of slaughter.

      Moloney, Aidan P; Mullen, Anne Maria; Maher, S.C.; Buckley, D.J.; Kerry, Joseph P. (Teagasc, 01/01/2004)
      There is no information on the variation in quality, in particular tenderness, that exists in Irish Beef nor is there information on the variation that would remain if optimum practices were imposed at all stages of the beef production chain. Evaluation of the success of measures to improve beef consistency requires information on existing variation and the minimum variation achievable.The objectives of this project were (i) to establish the variation that exists in the quality of meat from Irish cattle, (ii) to quantify the minimum variation in meat quality that can be achieved in a practical beef production system, (iii) to determine the effects and mechanisms of additional sources of variation. The conclusions from this project are: • The M. longissimus dorsi (loin) was found to be more variable than the M. semimembranosus (topside) for most quality attributes examined (tenderness, sarcomere length and pH). The scale of variation within the loin was similar to that reported by the other research groups within the EU and US. Heifers were more variable than steers for most attributes, while there was no consistent classification effect on the variability of meat quality attributes. • Tenderness was equally variable in meat from genetically similar steers, managed similarly, compared to commercial steers randomly selected from a factory lairage but matched for weight and grade.This was likely a result of both groups being crossbred beef cattle of similar age, fat score, carcass weight and managed identically post-mortem. However, variation in tenderness of both groups was less than that observed in a survey of commercial throughput (experiment 1). This decrease is attributed to better pre-and-post-slaughter handling practices. • The data suggest that selection of sires (within a breed) with better than average conformation has no deleterious effect on the eating quality of beef of their progeny.A more comprehensive comparison of sires within a breed and between breeds is required to confirm the generality of this conclusion. • In a comparison of genotypes, gender and slaughter weights, there was no evidence that variation around the mean value for tenderness differed between breeds or liveweights after 14 days ageing. Bulls were more variable than steers for some quality traits but the variation in tenderness was similar for bulls and steers after 14 days ageing. • While optimising the management of animals during the pre and post-slaughter period reduced variation in tenderness, some residual variation remained. A large percentage of the residual variation in tenderness (Warner Bratzler shear force) after 2 and 7 days post-mortem was explained by proteolysis (breakdown of myofibrillar proteins).Variation in tenderness (Warner Bratzler shear force) after 2 days post-mortem was largely explained by phosphates (energy) and proteolysis, while sensory tenderness was largely explained by phosphates and glycolytic potential. • Further work is required to reduce residual variation in Irish beef and to determine the causes of this variation.
    • Very fast chilling in beef

      Troy, Declan J.; Joseph, Robin; European Union; AIR-CT94-1881 (Teagasc, 2001-07)
      Very fast chilling (VFC) of beef reduces the temperature to -1ºC after 5 hours post mortem throughout its mass. The process has many potential benefits (Joseph,1996) including the production of tender meat and greater process efficiency in the meat plant.
    • The virulence of E. coli 0157:H7 isolated from Irish sheep and pigs to humans

      Lenahan, Mary; Sheridan, James J.; O'Brien, Stephen (Teagasc, 2008-02)
      Investigations were carried out at five sheep and five pig export abattoirs situated in the Republic of Ireland to determine the prevalence of E. coli O157:H7 in these animals at slaughter. This is the first study for the presence of E. coli O157:H7 on sheep and pigs to be carried out in Ireland. Faeces and pre- and post-chill carcass swabs were collected from pigs over a one year period between January and December 2004. Samples were collected from sheep over a 13-month period between February 2005 and February 2006. The pig study recovered E. coli O157:H7 from 0.24 % (n=4) of 1680 porcine samples while the sheep study isolated the pathogen from 2.1 % (n=33) of 1600 ovine samples. PCR analysis of E. coli O157:H7 isolates determined that they carried the virulence genes vt1, vt2, eaeA and hlyA typically associated with clinical illness in humans. The results presented indicate that Irish sheep and pigs are reservoirs for E. coli O157:H7 which may be potentially harmful to humans.
    • Wheat flour properties and end product quality

      Dwyer, Elizabeth; O'Halloran, Grainne R.; Department of Agriculture, Food and the Marine (Teagasc, 1999-01)
      For pizza production, the flour quality values identified for the wheat cultivars, Promessa, Quintus (spring), and Soissons (winter) should be used as guidelines in selecting new cultivars and in the development of flour specifications. Similarly for biscuit production, compositional and rheological data for the cultivars, Riband,Woodstock (soft-milling) and Brigadier (hardmilling) should be used for identifying biscuit flours. The rheological properties of dough (as measured by the alveograph, extensograph and farinograph) did not relate to the baking quality for some wheat cultivars. However the rheological properties of the gel protein prepared from these flours explained their baking quality. The very high elastic moduli of these gels explained the basis of shrinkage of pizza bases produced from Baldus and Lavett flours and biscuits produced from Ritmo flour.
    • β-Lactoglobulin: A Whey Protein Fraction with Enhanced Functionality

      Mehra, Raj; Raggett, Elaine; O'Kennedy, Brendan; Kelly, Philip M.; Rawle, Donal (Teagasc, 2001-08-01)
      Infant 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.