The influence of sterilized cow\u27s and goat\u27s milk and their mixture on yoghurt fermentation

Suvremen način života koji teži potrošnji sve zdravije hrane zahtijeva od mliječnih prerađivačkih industrija izradu sve većeg broja fermentiranih proizvoda. Jedan od njih je i jogurt od kozjeg mlijeka. Kozje je mlijeko slično kravljem, ali sadrži nešto veći udjel lakše probavljivih bjelančevina i masti, nešto više topivog kalcija, neorganskog fosfora, magnezija, kalija, više vitamina (osobito vitamina A), te ima jače izražene baktericidne i imunološke odlike. Stoga je svrha ovoga rada bila proučiti utjecaj kozjeg mlijeka na tijek fermentacije jogurta u usporedbi s kravljim mlijekom. Proizveden je jogurt od steriliziranog kravljeg i kozjeg mlijeka sa 3,2% mliječne masti, te njihove mješavine u omjeru 1:1. Fermentacija mlijeka vođena je pri 4CPC i bila je najkraća za jogurt od kozjeg mlijeka (2 sata i 33 minute), dok je za jogurt od kravljeg mlijeka bila sporija (2 sata i 50 minuta). U inokulumu je odnos laktobacila i streptokoka bio 1:0,63, dok je krajem fermentacije u jogurtu taj odnos bio 1:1,12 kravlje, 1:1,38 kozje i 1:2,14 jogurt od mješavine (1:1) mlijeka. Ukupan broj laktobacila i streptokoka povećanje tijekom fermentacije od 9,5x107/ml do 7,1x108/ml (kravlje mlijeko), 6,2x108/ml (kozje mlijeko) i 6,9x107/ml (mješavina mlijeka).Modern way of life which strives for consumption of health food forced the dairy industry to produce new kind of fermented products. One of them is the yogurt from goat\u27s milk. The main composition of goat\u27s and cow\u27s milk is similar but quantities due to higher digestibility proteins and fats, as well as soluble calcium, inorganic phosphorous, magnesium, potassium and vitamins (specially vitamin A) are greater and the bacterial and immunological properties strongly expressed in goat\u27s milk. The aim of this work was to compare the fermentation of goat\u27s and cow\u27s milk during the yoghurt production. The yogurt was produced from sterilized cow\u27s and goat\u27s milk with 3.2% of fat and from the mixture of both milks in proportion 1:1. The fermentation at 4CP C was faster in goat\u27s (2 hours 33 minutes), than in cow\u27s milk (2 hours 50 minutes). The proportion of lactobacilli and streptococci varied from 1:0,63 at the beginning of the fermentation to 1:1.12 (cow\u27s milk), 1:1.38 (goat\u27s milk), and 1:2.14 (mixed milk) at the end of the fermentation. Total count of lactobacilli and streptococci increased during the fermentation from 9.5x107/ml to 7.1x108/ml (cow\u27s milk), 6.2x108/ml (goat\u27s milk) and 6.9x107/ml (mixed milk)