Characterization and ranking of commercial vanilla flavoured set yoghurt marketed in Sri Lanka

Abstract

Vanilla flavoured sweetened set yoghurt manufactured by few commercial scale processors dominates the yoghurt market in Sri Lanka. Despite the comparable production technologies, the quality of the final product differs widely in several aspects. Therefore, the present study was conducted to characterize and to rank the most preferred vanilla flavoured commercial set yoghurt brand marketed in Sri Lanka. Yoghurts from six popular commercial brands (Y1, Y2, Y3, Y4, Y5, and Y6) were purchased from two supermarkets. Compositional (total solid %, fat %, protein %, ash %, carbohydrate %), physicochemical (pH, titratable acidity) and physical (water-holding capacity, spontaneous whey syneresis, instrumental color and texture) properties were tested using standard procedures. Sensory properties (flavor, color and appearance, body & texture, acidity, over-all acceptability) were evaluated with 30 untrained panel of judges. Data were analyzed using SPSS (ver.20) except sensory data. Fuzzy toolbox from MATLAB computer software was used to analyze sensory data. Significant (p<0.05) variations were observed in the composition, physicochemical, physical and sensory parameters of different yoghurt brands. Highest water holding capacity and the lowest instrumental hardness value were reported by Y3 and were observed to be significantly (p>0.05) different from other 5 brands. Spontaneous whey syneresis was negligible in all the commercial yoghurt brands. Significant (p<0.05) variations were observed in instrumental colour parameters of yoghurts and no relationship was observed with the preference. Brand Y3 had the highest sensory acceptability, rated under the ‘good’ category whereas the lowest acceptability by Y5 which was classified under ‘satisfactory’ category. Proximate composition of the most preferred yoghurt brand was observed to be 22.80±0.10% TS, 3.25±0.06% fat, 4.06±0.09% protein, 0.77±0.10% ash and 14.72±0.46 total carbohydrates with acceptable pH (4.09±0.06) and acidity (1.16±0.01% lactic acid). Overall sensory score of yoghurt samples has a significant (p<0.05) negative correlation with instrumental hardness (R2 = 0.513) and storage period (R2 = 0.791). The ranking of the yoghurts according to the overall sensory score were Y3 > Y1 > Y6 > Y2 > Y4 > Y5.