The effect of kappa-carrageenan and carboxy methyl cellulose hydrocolloids on the physicochemical and organoleptic properties of calcium-enriched sterile milk

With the increasing awareness of consumers regarding the health effects of calcium, the enrichment of dairy products with calcium has increased. However, adding calcium salts to sterile milk can cause milk instability and increase sedimentation. In this research, the effect of adding hydrocolloids of carbox ymethyl cellulose (0.01%), kappa carrageenan (0.02%) and a mixture of carboxy methyl cellulose and kappa carrageenan on the physicochemical and sensory properties of calcium-enriched sterile milk was investigated. The results indicated that the addition of carboxy methyl cellulose and kappa carrageenan had no significant effect on the pH, acidity, and electrical conductivity of milk samples (p˃0.05), but during the storage period, the pH of the samples decreased, and their acidity and electrical conductivity increased significantly (p<0.05). The maximum thermal stability was observed in the first treatment (0.01% carboxymethyl cellulose and 0.15% calcium citrate) and the third (0.01% carboxymethyl cellulose, 0.02% capacarrageenan and 0.15% calcium citrate), while Control samples and the second treatment (0.02% capacarrageenan and 0.15% calcium citrate) had less thermal stability.The results showed that in all the samples, the percentage of precipitation increased significantly with increasing storage time (p<0.05), but in the treatment samples and in the presence of carboxy methyl cellulose hydrocolloids and kappa carrageenan, the percentage of calcium precipitation decreased and viscosity increased significantly (p<0.05). It seems that the sediment consists of accumulations of proteins or protein particles of different sizes that are precipitated together with calcium and phosphate under the influence of gravity. Evaluation of overall acceptance determined that the control sample and the first treatment were the most acceptable among the tested treatments. It seems that the reduction of sediment in the first treatment and its lower viscosity compared to other treatments have been effective in increasing the overall acceptance score of the first treatment in terms of evaluators.