The effect of fermentation temperature on the functional dairy product quality

APTEFF, 42, 1-288 (2011) DOI: 10.2298/APT1142063K UDC: 637.146:663.88]:663.14.039.3 BIBLID: 1450-7188 (2011) 42, 63-70 Original scientific paper THE EFFECT OF FERMENTATION TEMPERATURE ON THE FUNCTIONAL DAIRY PRODUCT QUALITY Katarina G. Kanurića, Dajana V. Hrnjeza, Marjan I. Ranogajeca, Spasenija D. Milanovića, Mirela D. Iliĉića, Vladimir R. Vukića and Maja Lj. Milanovićb a University of Novi Sad, Faculty of Technology, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia b University of Novi Sad, Faculty of Medicine, Hajduk Veljkova 3, 21000 Novi Sad, Serbia The aim of this study was to examine the possibility of fermented dairy beverage production by the application of kombucha cultivated on thyme tea in combination with a probiotic starter and to evaluate the quality of the new functional product. Fermented dairy beverages are produced from milk with 1.6% milk fat at three fermentation temperatures: 37°C, 40ºC and 43ºC.Chemical quality, rheological properties and products of added starter cultures metabolism were determined in the fermented dairy beverages after production and after10 days of storage. Produced fermented dairy beverages have reduced milk fat content and good textural characteristics. Besides the highly valuable milk components, they contain numerous compounds which have pronounced therapeutic properties. These products could be used as functional food in the diet of different populations for health improvement. KEY WORDS: milk, kombucha, probiotics, fermented dairy product, functional food INTRODUCTION Nowadays, new food products have the potential to improve human health and also reduce the risk of disease. Functional food is positioned above the traditional food. A product is considered functional food if in addition to the nutritional value it contains components that have a positive effect on health, physical and mental condition of the human body. The most famous examples of functional foods are fermented milk products, especially those containing probiotic bacteria and prebiotics. Fermented dairy products contain a number of micronutritive components that, either individually or in combination with other such components, may influence the maintenance or even improvement of human health (1-3). Fermented milk products, as well as milk, contain all the basic ingredients needed for growth, development, reproduction, maintenance and energy of a human body. These ingredients are lactose, lactic acid, protein, fat, minerals and vitamins. During the fer* Corresponding author: Katarina G. Kanuriš, University of Novi Sad, Faculty of Technology, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia, e-mail: 63 APTEFF, 42, 1-288 (2011) DOI: 10.2298/APT1142063K UDC: 637.146:663.88]:663.14.039.3 BIBLID: 1450-7188 (2011) 42, 63-70 Original scientific paper mentation, there is a change of some constituents of the milk and with creating of new constituents, fermented product get new features compared to milk (3, 4). Metabolic activity of starter cultures causes numerous changes during the milk fermentation. Lactose content decreases up to 20-30%, transforming to lactic acid. The lactic acid content in mild acid yoghurt is around 0.85 - 0.95%, and 0.95 - 1.2% in more acidic yoghurt. Enzymes of lactic acid bacteria hydrolyse milk protein and induce better digestibility of casein. People with the problems such as lactose intolerance and milk protein allergy, can consume yoghurt to maintain the microflora balance in gastrointestinal tract. The fermentation process has a little effect on the content of minerals in yoghurt. Fermented milk products are rich in calcium and phosphorus, citric and other organic acids, but poor in the iron and iodine contents. During milk fermentation, there are no significant changes in vitamin A and D concentrations. Dramatic increase in folic acid and a decrease in vitamin B12 have been reported. Levels of thiamin, riboflavin, nicotinic acid, pantothenic acid and biotin are generally similar or higher compared to the average values of the starting milk (2, 5, 6). New generation of the fermented dairy products, so called bio-yoghurts, shows a multifunctional effect on the human health comparing to traditional yoghurt because the probiotic microorganisms are natural inhabitants of the human intestine. Nowadays, health improvement is emphasized the implementation of functional ingredients and the fat reduction in nutrition. Recent investigations are focused on the possibilities of the kombucha (unconventional starter) application for milk fermentation with the aim to enlarge assortmentof the fermented dairy products as functional food (7, 8). Kombucha is a symbiotic association of yeast (Pichia, Zygosaccharomyces, Saccharomyces, Schizosaccharomyces, Saccharomycodes, Brettanomyces, Torulaspora and Candida) and acetic acid bacteria (Acetobacter and Gluconobacter). Kombucha is traditionally cultivated on a sweetened black and green tea. It can be cultivated on a dark beer, red vine, white vine, coca-cola, whey, lactose or some other type of tea, too (9, 10). Prophylactic and therapeutic properties of kombucha are the result of metabolic activity with the production of: acetic acid, ethanol, glycerol and others. Kombucha acts positively with tonsillitis, headaches, atherosclerosis, rheumatism, digestive difficulties, and so on. It shows beneficial effects in arthritis because of the presence of enzymes that break down and assimilate caffeine and other purine derivatives which cause arthritis. Antibiotic activity to Heliobacter pylori, Escherichia coli, Staphylococcus aureus and Agrobacterium tumefaciens has been proven by kombucha, and other activities mainly due to the production of acetic acid during fermentation. The role of kombucha in the detoxication is probably due to the ability of glucuronic acid to bind toxins and enhance their excretion from the body (11, 12). Cellulose pellicle kombucha is used for skin injuries and burns. In view of the multiple positive effects of kombucha on the human health, the aim of this study was to examine the possibility of fermented dairy beverage production by the application of kombucha cultivated on thymetea in combination with probiotic starter, and to evaluate the quality of the new functional product. 64 APTEFF, 42, 1-288 (2011) DOI: 10.2298/APT1142063K UDC: 637.146:663.88]:663.14.039.3 BIBLID: 1450-7188 (2011) 42, 63-70 Original scientific paper EXPERIMENTAL Homogenized and pasteurized cow milk with 1.6% fat was taken from AD Imlek, Division Novi Sad Dairy, for the production of kombucha fermented milk beverage. For milk fermentation, the following starters were used: kombuchacultivated on thyme tea in theconcentration of 1.25g/L sweetened with sucrose concentration of 70g/L as a source of carbon (9) and probiotic culture (ABT-7 Probio-Tek®contains BB-12®, CHR Hansen, Denmark). Production of fermented milk beverages included these operations: pasteurized milk with 1.6% milkfat was inoculated wi (...truncated)