Effect of Cold Storage on Viability of Probiotic Bacteria in Carrot Fortified Milk

Abstract

The growing interest in new functional drinks has resulted in the development of healthy nutritional probiotic drinks. Since dairy-based products are good carriers for probiotics, the suitability of a milk/carrot juice drink for the production of a non-fermented probiotic drink was studied. Survival of Lactobacillus acidophilus LA5, L. plantarum, L. rhamnosus GG and Bifidobacterium lactis BB12 was evaluated in the milk/carrot juice drink during storage at 4 +or- 2 degrees C for up to 20 days. Drink samples were evaluated at 5 day intervals for cell number, pH and acidity. L. acidophilus LA5 seemed more stable than the other strains, with >98% viability during storage compared to 88-92% viability for the other strains. pH and acidity changes (6.43-6.66 and 0.13-0.15%, respectively) brought about by L. acidophilus LA5, L. plantarum and B. lactis BB12 during storage were small and varied according to strain, but not significantly. The L. rhamnosus GG and control (non-probiotic) samples showed more variation in pH and acidity. Changes in pH and acidity caused by L. rhamnosus were significant (5.33- 6.47 and 0.13-0.31%, respectively). pH decreased from 6.48 to 5.85 and acidity increased from 0.13 to 0.28% in the control sample. It is thus concluded that milk/carrot juice drink could serve as a probiotic drink after refrigerated storage for 20 days.