Determination of water activity in the cheese with cryoscopic method

U radu je opisana krioskopska metoda mjerenja aktivnosti vode u sirevima. Budući da se svaki mikroorganizam, može razvijati samo u određenim granicama aktivnosti vode, pristupačne metode mjerenja aktivnosti vode s dostupnim uređajima vrijedne su pažnje. Osnovni element uređaja za mjerenje aktivnosti vode tom metodom je diferencijalni termopar Fe-Ko. Jedan kraj termopara uboden je u sir kojem se mjeri aktivnost vode, a drugi u smjesu voda-led. Termopar je priključen na linijski kompenzacijski uređaj za mjerenje i registraciju fizikalnih veličina koje se mogu prikazati kao standardni strujni signal u mA. Opisanom metodom određivana je aktivnost vode u sirevima proizvedenim iz iste sirovine uz različiti sadržaj vode i m,asti u siru, određivan je utjecaj soli za topljenje na vrijednost aktivnosti vode u siru i dr. Krioskopska metoda mjerenja aktivnosti vode pokazala se kao dobra metoda kontrole koja uspješno prati proizvodnju.In this paper the cryoscopic method of measuring the water activity in cheeses is described. Since every microorganism can become developed in only fixed limits of water activity, accessible methods of measuring the water activity (i.e. measuring with accessible devices) are worthy of one\u27s attention. Basic element of device for measuring the water activity by this method is differential thermo-pair Fe-Ko. One end of the thermo-pair is sticked into the cheese in which the water activity is to be measured; the other end is sticked in water-ice mixture. Thermo-pair is connected on the line compensation device for measuring and registration of the physical values which can be presented as standard electric signal in mA. By this method the water activity in cheeses which are produced from the same raw material but with different water and fat amount is determined, as well as the influence of melting salt on the water activity value in cheese. The cryoscopic method of measuring the water activity appeared to be the control method which successfully follows the production