Effect of grinded flaxseed on physicochemical, microbiological and sensory properties of yoghurt

In this research, physicochemical, microbiological and sensory properties of ground flaxseed added yoghurt samples at different rations (0.25%, 0.50%, 0.75% ve1%) were examined during a 28 day storage time. Dry matter, acidity, pH, syneresis, viscosity (50 ve100 rpm) (p<0.01) and fat (p<0.05) values of yoghurt samples were affected by addition of ground flaxseed, whereas ash values were not affected (p>0,05). The storage period had a significant effect on acidity, pH, syneresis veviscosity (50 ve100 rpm) values (p<0.01), but its effect was not significant on fat, dry matter and ash values (p>0.05). Flaxseed ratio had significantly effect on L*, a*, b* and C* (p<0.01), while H° values was not statistically affected (p>0.05). The L*, b*, H*, C (p<0.01) and a* (p<0.05) values were affected by storage period. The effect of storage period was significant on L. bulgaricus and S. thermophilus counts of ground flaxseed added yoghurt samples (p<0.01), the effect of flaxseed ratio was not significant (p>0.05). Yeast-mould counts were found as <2 log CFU/g in all of yoghurt samples during storage. The flaxseed ratio had statistically significant on all sensory properties (p<0.01). The color and apparence, body and texture, acidity, gas formation (p<0.01), syneresis and mouth feel (p<0.05) scores were affected by storage period, whereas storage period did not have significantly effect on taste and odor, flavour and general acceptability scores (p>0.05). Generally, the sample containing 0.25% ground flaxseed (KT2) and control sample had higher scores compared to other samples in terms of all sensory properties, but the scores lowered depending on storage period. As a result, The ground flaxseed had significantly effect physicochemical, colorimeteric, viscosity and sensory properties of yoghurt samples. All properties of yoghurt samples was negatively affected by storage time. The low ground flaxseed added yoghurt was increased all sensory scores given by panelist, but the addition of ground flaxseed at the high ratio in yoghurt was not desired by panelist. The appreciate of panelist decreased as sensory depending on increment of grinded flaxseed ratio in yoghurt samples. It is recommended that ground flaxseed uses at 0.25% and 0.50% in yoghurt production. But ground flaxeed ratio should not be too much 0.75%.