Influence of the hot-fill water-spray-cooling process after continuous pasteurization on the number of decimal reductions and on Alicyclobacillus acidoterrestris CRA 7152 growth in orange juice stored at 35 °C

In this study, the influence of the hot-fill water-spray-cooling process after continuous pasteurization on the number of decimal reductions (γ) and growth parameters (lag time; λ, ratio Nf/No; κ, maximum growth rate; μ) of Alicyclobacillus acidoterrestris CRA 7152 in orange juice stored at 35 °C were investigated. Two different inoculum levels of A. acidoterrestris CRA 7152 (102 and 103 spores/mL) in orange juice (110Brix, pH 3.7) and a Microthermics UHT-HTST pilot plant were used to simulate industrial conditions. Results have shown that regardless of the inoculum level (102 or 103 spores/mL), the pasteurization processes were unable to cause even 1 γ. Predictive modeling using the Baranyi model showed that only κ and time to reach 104spores/mL (t104 — time to juice spoilage) were affected by the spore inoculum used (p < 0.05). It has been concluded that A. acidoterrestris was able to survive the hot-fill process and to grow and spoil orange juice in 5–6 days when the final storage temperature was 35 °C.