Effect of Calcium on the Physical Properties of Stirred Probiotic Yogurt

Calcium ion concentration of milk samples as a function of added ionic calcium (▴), citrate (■), and ion exchange resin, Amberlite IR-120 plus, Sigma-Aldrich Ltd., Castle Hill, Australia (●): a) calcium and citrate added before heat treatment of milk, b) calcium and citrate added after heat treatment of milk, c) ion exchange resin added before heat treatment of milk. Data points represent averages of 3 experiments.

pH of milk samples measured immediately before heat treatment as a function of added ionic calcium (▴), citrate (■), and ion exchange resin addition (●) before heat treatment of milk.

Nodulation in yogurt (nodules greater than 0.5mm diameter in 1g of yogurt) as a function of added ionic calcium, citrate, non-ionic calcium (Gadocal-K, Gadot Biochemical Industries Ltd., Haifa Bay, Israel), and ion exchange resin (Amberlite IR-120 plus, Sigma-Aldrich Ltd., Castle Hill, Australia): a) ionic calcium and citrate added before heat treatment, b) ionic calcium and citrate added after heat treatment, c) non-ionic calcium added before heat treatment, d) ion exchange resin added before heat treatment of milk. ▴= ionic calcium; ■ = citrate; ♦ = non-ionic calcium; ● = ion exchange resin. Error bars represent pooled standard error. Data points represent averages of 3 experiments.

Firmness of yogurt samples as a function of addition of ionic calcium, citrate, non-ionic calcium (Gadocal-K, Gadot Biochemical Industries Ltd., Haifa Bay, Israel), and ion exchange resin (Amberlite IR-120 plus, Sigma-Aldrich Ltd., Castle Hill, Australia): a) ionic calcium and citrate added before heat treatment, b) ionic calcium and citrate added after heat treatment, c) non-ionic calcium added before heat treatment, d) ion exchange resin added before heat treatment of milk. ▴ = ionic calcium; ■ = citrate; ♦ = non-ionic calcium; ● = ion exchange resin. Error bars represent pooled standard error. Data points represent averages of 3 experiments.

Viscosity of yogurt samples as a function of added ionic calcium, citrate, non-ionic calcium (Gadocal-K, Gadot Biochemical Industries Ltd., Haifa Bay, Israel), and ion exchange resin (Amberlite IR-120 plus, Sigma-Aldrich Ltd., Castle Hill, Australia): a) ionic calcium and citrate added before heat treatment, b) ionic calcium and citrate added after heat treatment, c) non-ionic calcium added before heat treatment, d) ion exchange resin added before heat treatment of milk. ▴ = ionic calcium; ■ = citrate; ♦ = non-ionic calcium; ● = ion exchange resin. Error bars represent pooled standard error. Data points represent averages of 3 experiments.