Sastojci arome i senzorska ocjena jogurta tijekom skladištenja

It is known that more than 100 chemical compounds have been isolated from yogurt and related milk products but only a few (acetaldehyde, ethanol, aceton, diacetyl and butanon-2) have a high impact on the desired product flavour. The concentration of these typical flavour compounds changed during storage depending on duration and temperature in depot. In this article six commercial brands of plain yogurt were stored within 10 days on two different temperatures and every two days changes in acetaldehyde, diacetyl and ethanol were established. At the same time sensory evaluation was carried out as well. Acetaldehyde and ethanol concentration was determined using aldehyde dehydrogenase and alcohol dehydrogenase method. Diacetyl was measured according to Hill\u27s modification of colorimetric method. A five member panel, performed sensory analysis using scoring system with weighted factors in the 20-points\u27 scale. Expert panel\u27s ratings were regressed against concentrations of aroma compounds for both temperature levels and linear relationship among them were determined. The most pronounced relationship expressed as correlation coefficients (r) between expert panel\u27s ratings and concentrations of individual compounds was observed with ethanol (r=0.996) in yogurt sample stored at +4°C. Coefficients of correlation were generally high (from 0.824 to -0.996) and consequently very accurately predicting equations were obtained using regression analysis.Poznato je da od stotinjak kemijskih spojeva izoliranih iz jogurta i sličnih fermentiranih proizvoda samo neki od njih (acetaldehid, etanol, diacetil i 2-butanon) znatno utječu na željeni okus proizvoda. Koncentracija tih tipičnih sastojaka arome mijenja se tijekom skladištenja ovisno o temperaturi i trajanju. U ovom radu šest uzoraka jogurta čuvano je pri dvije različite temperature tijekom 10 dana i svaka dva dana uzimani su uzorci za određivanje acetaldehida, diacetila i etanola. Istovremeno je jogurt senzorski ocijenjen. Udio acetaldehida i etanola određen je enzimnom metodom a udio diacetila modificiranom Hill-ovom kolorimetrijskom metodom. Senzorski je jogurt ocijenila skupina od 5 članova koristeći sistem 20 ponderiranih bodova. Utvrđena je kvantitativna ovisnost senzorske ocjene L svake pojedine komponente arome za obje razine temperature i izražena linearnim Jednadžbama. Najbolja povezanost, izražena koeficijentom korelacije, utvrđena Je između senzorske procjene i etanola (r = 0.996) u jednom od uzoraka čuvanom pri +4°C. Općenito svi su koeficijenti korelacije bili visoki (od 0,824 do -0,996)