An investigation on some compounds effecting aroma and flavour of strained yoghurt produced from goat milk

Abstract

In this study, acetaldehyde, acetone, pH, titratable acidity, lactic acid, tyrosine and free fatty acids, namely butyric acid (C4), caproic acid(C6), caprylic acid (C8) and capric acid (C10) were taken into consideration affecting the variation in aroma and flavour scores (AFS) of strained yoghurt during the storage period of 60 days. AFS was negatively correlated with acetone (r=-0.832, P<0.01) and positively correlated with C4 (r=0.604, P<0.05), C8 (r=0.638, P<0.01) and C10(r=0.659, P<0.01). The results of regression analysis verified that the independent compounds explain the 91.6% of variation in AFS during the storage period, but not statistically significant (P>0.05). Stepwise regression procedure was performed to select the statistically significant compounds affecting AFS. The Stepwise procedure verified that acetaldehyde, acetone and lactic acid should be included in the regression equation (r2=0.868, P<0.01). To explore the individual direct effect of these compounds, Path analysis was applied. The results of Path analysis showed that 65.6 % of variation in AFS could be directly explained by acetone (P<0.01), which the highest effect on the variation of AFS. The results of this study illustrated that although an increment in AAL compound causes an improvement in aroma and flavour, acetone and lactic acid were responsible for defective aroma and flavour of strained yoghurt.