• Application of Probiotic Bacteria to Functional Foods

      STANTON, CATHERINE; Ross, R Paul; Fitzgerald, Gerald F; Collins, K.; McBrearty, S.; Gardiner, Gillian E.; Desmond, C.; Kelly, J.; Bouchier, Paul J.; Lawless, Fergal; et al. (Teagasc, 2001-05-01)
      Probiotic cultures are described as live microbial feed supplements that improve intestinal microbial balance and are intended for maintenance of health or prevention, rather than the curing of disease. The demand for probiotic foods is increasing in Europe, Japan and the U.S. reflecting the heightened awareness among the public of the relationship between diet and health. Traditionally, the most popular food delivery systems for these cultures have been freshly fermented dairy foods, such as yogurts and fermented milks, as well as unfermented milks with cultures added. However, in the development of functional foods, the technological suitability of probiotic strains poses a serious challenge since their survival and viability may be adversely affected by processing conditions as well as by the product environment and storage conditions. This is a particular concern, given that high levels (at least 107 per gram or ml) of live micro-organisms are recommended for probiotic products. In previous studies (see DPRC No. 29) the successful manufacture of probiotic Cheddar cheese harbouring high levels (>108 cfu/g) of the probiotic Lactobacillus paracasei NFBC 338 strain was reported. Hence, the overall objective of these studies was to continue the development and evaluation of Functional Foods containing high levels of viable probiotic bacteria, with particular emphasis on overcoming the technological barriers and the identification of strains suited to particular applications, such as incorporation into Cheddar cheese and spray-dried powders.
    • Assessment and Control of Foodborne Pathogens in Ireland

      Ross, R Paul; Hill, Colin; Murphy, P.; Jordan, Kieran; Arendt, Elke; van Sinderen, Douwe; Morgan, S.M.; Hickey, Rita M.; Maher, M.J.; Kelly, J.; et al. (Teagasc, 2001-05-01)
      Consumers are increasingly demanding food that is free from pathogens, but with less preservatives and additives. As a response to these conflicting demands, current trends in the food industry include minimal processing, and the investigation of alternative inhibitors for use in foods. Additionally, the manufacture of an increasing range of novel foods, and the inclusion of non-dairy ingredients into dairy products, and vice versa, poses additional dangers with respect to safety. Furthermore, the dramatic increase in incidence of food-borne illness internationally, as a result of contamination with food-borne pathogens such as Listeria monocytogenes, is a cause of considerable consumer concern. Bacteriocins are inhibitory peptides produced by a number of Lactic Acid Bacteria which are capable of killing other bacteria. These natural inhibitors have widespread applications in the preservation of foods, since they can kill a number of pathogenic and spoilage bacteria. The broad spectrum bacteriocin Lacticin 3147 (discovered in a previous project and patented - see DPRC No. 3) is produced by Lactococcus lactis subsp. lactis DPC3147, a food-grade strain, similar to strains used for commercial cheese manufacture. Lacticin 3147 is effective in the inhibition of all Gram positive bacteria tested including the food pathogens Listeria monocytogenes and Staphylococcus aureus and food spoilage bacteria such as Clostridia and Bacillus species. As part of this project the bacteriocin Lacticin 3147 was assessed as a food preservative for improving food safety via inhibition of pathogenic organisms. Thus the project plan followed a "twin-track" approach to assessing and controlling the food safety aspects of Irish food. The first of these was designed to investigate the current safety status of Irish dairy products. The second approach involved an attempt to exploit natural antimicrobial substances, including Lacticin 3147, to protect foods from pathogenic bacteria.
    • Ingredient Dehydration of Fermented and Flavour-Sensitive Products.

      Kelly, Philip; Keogh, M.K.; Kelly, J.; Kennedy, B. (Teagasc, 2001-08-01)
      Traditionally, yoghurt is produced in a hydrated form and, thus, possesses a limited shelf-life even when refrigerated. Consumption within a short time of production is advisable, particularly if advantage is to be taken of the putative benefits associated with the ingestion of live yoghurt cultures. The production of an instant yoghurt powder would, thus, provide benefits of shelf-life extension and convenience of preparation and storage. However, the drying of such products is difficult due to low pH, which causes stickiness in drier chambers and makes powder recovery difficult. Furthermore, key flavour components formed by fermentation such as acetaldehyde and diacetyl which contribute to the unique flavour of natural yoghurt are sensitive to heat and easily lost during spray-drying. Hence, a major challenge of this project was to investigate the processing technologies and conditions necessary for the minimisation of flavour losses during the spray-drying of acidified/fermented milk bases, to monitor the effects on drier performance such as powder adhesion to drier walls, and to develop functional forms of the spray-dried ingredients. The main aims of the project were to: - improve yoghurt powder spray-drying efficiency through optimisation of concentrate solids, - investigate the effect of spray-drying conditions on flavour losses of sensitive products such as dehydrated yoghurt and fermented creams,- apply technological approaches for the reduction of flavour losses: a) ingredient formulation, b) modification of fermentation conditions, - investigate the production of agglomerated forms of spray-dried yoghurt powders, - study factors affecting the physical properties such as rheological characteristics and powder bulk density, and - adapt technology to ensure greater viability of culture cell numbers at the end of the drying process.
    • 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.
    • Nutritional Studies on Dried Functional Food Ingredients Containing omega-3 Polyunsaturated Fatty-Acids.

      Kelly, Philip; Keogh, M.K.; Kelly, J.; O'Kennedy, Brendan; Murray, C.A. (Teagasc, 2000-10-01)
      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.