Determination of specific heat capacity of raspberry puree

Specifični toplinski kapacitet (cp) predstavlja svojstvo materijala koje ovisi o sastavu i temperaturi. U radu je određivan specifični toplinski kapacitet kaše od malina modificiranom metodom miješanja u ovisnosti o temperaturi. Kako ne postoje standardne metode određivanja specifičnog toplinskog kapaciteta za hranu tako je konstruiran uređaj (kalorimetar) za određivanje spečificnog toplinskog kapaciteta (B. Šeruga i S. Budžaki, 2003.). Uređaj se temelji na standardnoj metodi za određivanje cp materijala poput metala, različitih konstrukcijskih i ambalažnih materijala. Kalorimetar je modificiran u smislu smjera prijenosa topline između materijala kojem se određuje specifični toplinski kapacitet i medija koji služi kao izvor topline. Metoda određivanja cp kaše od malina sastoji se od uranjanja uzorka, vakumiranog u PVC foliju, u vodu određene temperature i mjerenja te temperature sve do uspostave toplinske ravnoteže. Temperatura uzorka niža je u odnosu na temperaturu vode u kalorimetru. Specifični toplinski kapacitet kaše od malina određen je u temperaturnom intervalu od 35 do 95 °C. Vrijednosti za specifični toplinski kapacitet kaše od malina pokazuju linearan porast s porastom temperature u promatranom temperaturnom intervalu i kreće se u rasponu od 3,22 do 3,94 kJ/kg°C.Specific heat capacity (cp) is a property of materials that depends upon temperature and composition. The specific heat capacity of raspberries puree was determined as a function of temperature. The standard methods for determination of specific heat for food are not known and because of that the calorimeter for determination of specific heat capacity was constructed (B.Šeruga i S.Budžaki, 2003.). The calorimeter is based on standard methods for determination of materials such as metals, and different construction and packaging materials. The apparatus is modified in way of heat transfer between food materials (which is subjected to specific heat determination) and substances for heat exchange. The method for determination of cp of raspberries puree were consist of immersing the sample, which was vacuuming in PVC bags, into water (substance for heat exchange) specified temperature. The temperature of water was measured until the thermal equilibrium between water and sample was reached. The temperature of samples (before the measuring) was lower in comparation to temperature of water. Specific heat capacity of raspberries puree was determined thought temperatures interval from 35 to 95°C. The values of specific heat capacity of the raspberries puree are in linear correlation with the temperature increase in investigated temperature range and were in range from 3.22 do 3.94 kJ/kg°C