Effects of pomegranate and pomegranate–apple blend juices on the growth characteristics of Alicyclobacillus acidoterrestris DSM 3922 type strain vegetative cells and spores

• Survival of A. acidoterrestris in pomegranate and blend juices was evaluated.
• Pomegranate and blend juices (40% and 80%) inhibited vegetative cell growth.
• The inhibitory effect against spores was sporulation medium dependent.
• Phenolics in pomegranate juice might prevent spore germination/outgrowth.

The present study examined the growth characteristics of Alicyclobacillus acidoterrestris DSM 3922 vegetative cells and spores after inoculation into apple, pomegranate and pomegranate–apple blend juices (10, 20, 40 and 80%, v/v). Also, the effect of sporulation medium was tested using mineral [Bacillus acidoterrestris agar (BATA) and Bacillus acidocaldarius agar (BAA)] and non-mineral containing media [potato dextrose agar (PDA) and malt extract agar (MEA)]. The juice samples were inoculated separately with approximately 105 CFU/mL cells or spores from different sporulation media and then incubated at 37 °C for 336 h. The number of cells decreased significantly with increasing pomegranate juice concentration in the blend juices and storage time (p < 0.001). Based on the results, 3.17, 3.53, and 3.72 log cell reductions were observed in 40%, 80% blend and pomegranate juices, respectively while the cell counts attained approximately 7.17 log CFU/mL in apple juice after 336 h. On the other hand, the cell growth was inhibited for a certain time, and then the numbers started to increase after 72 and 144 h in 10% and 20% blend juices, respectively. After 336 h, total population among spores produced on PDA, BATA, BAA and MEA indicated 1.49, 1.65, 1.67, and 1.28 log reductions in pomegranate juice; and 1.51, 1.38, 1.40 and 1.16 log reductions in 80% blend juice, respectively. The inhibitory effects of 10%, 20% and 40% blend juices varied depending on the sporulation media used. The results obtained in this study suggested that pomegranate and pomegranate–apple blend juices could inhibit the growth of A. acidoterrestris DSM 3922 vegetative cells and spores.