Textural properties of alginate–pectin beads and survivability of entrapped Lb. casei in simulated gastrointestinal conditions and in yoghurt

Lactobacillus casei was entrapped in beads made with sodium alginate (A), amidated low-methoxyl pectin (P), and blends of A–P (1:2, 1:4, 1:6 ratios) by the extrusion technique. Diameter, sphericity and textural properties of the beads and the survivability of entrapped Lb. casei in yoghurt and in simulated gastrointestinal conditions were determined. Entrapment efficiency of Lb. casei and diameter increased as the proportion of P and the total biopolymers concentration increased. Principal Component Analysis showed that the survivability of Lb. casei in yoghurt, and in simulated gastric juice, was positively correlated with the diameter and all the textural properties of the beads, while survivability after exposure to simulated gastric juice and bile salts was positively correlated with the sphericity of the beads. The beads made with A–P blends in 1:4 and 1:6 ratios provided a significant better protection to the entrapped Lb. casei under all conditions studied.