Fortification of yoghurt with calcium salts and its effect on starter microorganisms and yoghurt quality

Abstract

Yoghurt samples were prepared after fortification of pasteurized milk by addition of the suitable level of calcium lactate (CaL) or calcium gluconate (CaG), which were determined by a preliminary study. A combination of CaL and CaG (CaL + CaG), providing approximately the same level of calcium as the dosage in the case of individual salts was also included in the study. Fortification of yoghurt with CaL or CaG at the levels tested significantly affected the titratable acidity and the pH of yoghurt (P < 0.05). However, there was no significant difference between the acidity values of the control and CaL + CaG fortified yoghurts. CaL fortification increased the numbers of lactobacilli. Statistical analysis revealed significant differences in the ratios of cocci to rods only between CaL- and CaG-fortified yoghurt during storage (P < 0.05). Fortification with CaG increased the ratios of cocci to rods in yoghurt. The highest overall sensory scores among the fortified yoghurts were obtained with the CaL fortified one at the 1st storage day. CaG-fortified yoghurt had lower sensory scores than CaL- or CaL + CaG-fortified yoghurts. The results of this study indicate that yoghurt is a suitable vehicle for fortification with calcium salts. Calcium content of the fortified yoghurts could be increased with about 34.3, 37.6, and 39.4% by addition of CaL, CaG and CaL + CaG, respectively. It is concluded that CaL and its appropriate combination with CaG may be preferred for fortification of yoghurt.