ABSTRACT:
In the present study, microparticles of the combination between Lactobacillus acidophilus probiotics and tomato paste using polymers of sodium alginate and CaCl2 are made. The purpose of the study is to discover the effects of sodium alginate concentration to physical characteristics, viability, and the microparticle antioxidant activity of the combination of probiotics and tomato paste. The microparticles are made by extrusion method. The extrusion conditions prepared included the stirring speed of 1000 rpm, the stirring duration of 2 hours, the distance of 8 cm between nozzle and crosslinking solution, and the pressure of 40 psi. Further, the microparticles are made by using CaCl2 concentration of 1.5 M and sodium alginate concentation of 2.5% as FI, 3% as FII, and 3.5% as FIII. Results of the study show that the forms of microparticles obtained are not spherical. The sizes of FI, FII, and FIII microparticles are 34,60 µm, 34,69 µm, and 80,53 µm. The particle sizes increase along with the increase of sodium alginate concentration. Besides, the moisture content of FI, FII, and FIII is 16,05 ± 0,41; 13,34 ± 0,23; and 12,65 ± 0,32. In this case, the highest viability of Lactobacillus acidophilus is FIII by 95.64 ± 1.84. However, after FIII goes through a statistical test, it has no significant difference with FII (p>0,05). Then, the antioxidant activity by using DPPH obtains the highest IC25 value on FIII; that is 5906,50 ppm. Besides, results of statistical test indicate that FIII has no significant difference with FII (p>0,05), but it has a significant difference with FI (p<0,05). Those results indicate that the increasing sodium alginate concentration from 2.5% to 3% can increase the antioxidant activity of probiotic-tomato paste microparticles. Nevertheless, the increase of antioxidant activity is not significant if the use difference of alginate concentration is narrow.