This slide shows some studies about improving of probiotic viability. From reviews, we found that types of protective agents, bacteria strains, and testing conditions play an important role in cell viability. The table shows effects of plant extracts on cell viability when they were exposed in acid and bile conditions. For example, wheat, barley, and malt extracts could increase the cell number of L. acidophilus, L. plantarum, and L. reuteri when they were under bile condition. Another study found that at pH 2, soybean extracts was the most protective compound improving viability of L. plantarum, compared to sesame and job’s tears but when the cell was incubated under bile conditions, job tear extract provided better protective effect than other extracts. And chestnut extract could maintain population level of LGG in both acid and bile conditions.