Alicyclobacillus acidoterrestris is a cause of major concern for the orange juice industry due to its thermal and chemical resistance, as well as its spoilage potential. A. acidoterrestris spoilage of orange juice is due to off-flavor taints from guaiacol production and some halophenols. The present study aimed to evaluate the effectiveness of antimicrobial Photodynamic Treatment (aPDT) as an emerging technology to inactivate the spores of A. acidoterrestris. The aPDT efficiency towards A. acidoterrestris was evaluated using as photosensitizers the tetracationic porphyrin (Tetra-Py⁺-Me) and the phenothiazinium dye new methylene blue (NMB) in combination with white light-emitting diode (LED; 400–740 nm; 65–140 mW/cm²). The spores of A. acidoterrestris were cultured on YSG agar plates (pH 3.7 ± 0.1) at 45 °C for 28 days and submitted to the aPDT with Tetra-Py⁺-Me and NMB at 10 μM in phosphate-buffered saline (PBS) in combination with white light (140 mW/cm²). The use of Tetra-Py⁺-Me at 10 μM resulted in a 7.3 ± 0.04 log reduction of the viability of A. acidoterrestris spores. No reductions in the viability of this bacterium were observed with NMB at 10 μM. Then, the aPDT with Tetra-Py⁺-Me and NMB at 10 μM in orange juice (UHT; pH 3.9; 11°Brix) alone and combined with potassium iodide (KI) was evaluated. The presence of KI was able to potentiate the aPDT process in orange juice, promoting the inactivation of 5 log CFU/mL of A. acidoterrestris spores after 10 h of white light exposition (140 mW/cm²). However, in the absence of KI, both photosensitizers did not promote a significant reduction in the spore viability. The inactivation of A. acidoterrestris spores artificially inoculated in orange peels (10⁵ spores/mL) was also assessed using Tetra-Py⁺-Me at 10 and 50 μM in the presence and absence of KI in combination with white light (65 mW/cm²). No significant reductions were observed (p < .05) when Tetra-Py⁺-Me was used at 10 μM, however at the highest concentration (50 μM) a significant spore reduction (≈ 2.8 log CFU/mL reductions) in orange peels was observed after 6 h of sunlight exposition (65 mW/cm²). Although the color, total phenolic content (TPC), and antioxidant capacity of orange juice and peel (only color evaluation) seem to have been affected by light exposition, the impact on the visual and nutritional characteristics of the products remains inconclusive so far. Besides that, the results found suggest that aPDT can be a potential method for the reduction of A. acidoterrestris spores on orange groves.

酸热脂环酸杆菌由于其耐热和耐化学性以及其变质的潜力而成为引起橙汁工业主要关注的原因。A.耐热菌橙汁的变质是由于从愈创木酚的生产和一些卤代异味污点。本研究旨在评估抗菌光动力治疗（aPDT）作为灭活嗜酸曲霉孢子的新兴技术的有效性。朝向APDT效率A.耐热菌使用光敏剂的tetracationic卟啉（TETRA-PY评价⁺ -Me），并在用白色发光二极管（LED组合的吩噻嗪染料新亚甲蓝（NMB）; 400-740纳米; 65 –140毫瓦/厘米²）。酸曲霉孢子在YSG琼脂平板（pH 3.7±0.1）上于45°C培养28天，并在磷酸盐缓冲液（PBS）中与10μMTetra-Py ⁺ -Me和NMB一起进入aPDT。结合白光（140 mW / cm ²）。使用10μM的Tetra-Py ⁺ -Me会导致嗜酸曲霉孢子活力降低7.3±0.04 log 。用10μM的NMB未观察到该细菌活力的降低。然后，使用Tetra-Py ⁺的aPDT评估了橙汁（UHT; pH 3.9; 11°Brix）中10μM的-Me和NMB以及与碘化钾（KI）的结合情况。KI的存在能够增强橙汁中的aPDT过程，在白光暴露10 h（140 mW / cm ²）后促进5 log CFU / mL嗜酸曲霉孢子的失活。然而，在没有KI的情况下，两种光敏剂均不能促进孢子活力的显着降低。在存在和不存在KI的情况下，在10和50μM的Tetra-Py ⁺ -Me联合白光（65 mW / m）的条件下，还评估了人工接种到橙皮中的酸曲霉孢子（10 ⁵孢子/ mL）的失活。厘米²）。 当使用10μMTetra-Py ⁺ -Me时，未观察到明显的减少（p <.05），但是在最高浓度（50μM）下，橙皮中的孢子明显减少（≈2.8 log CFU / mL减少）。在阳光照射6 h（65 mW / cm ²）后观察到。尽管橙汁和果皮的颜色，总酚含量（TPC）和抗氧化能力（仅通过颜色评估）似乎已受到光暴露的影响，但到目前为止，对产品的视觉和营养特性的影响仍然不确定。除此之外，发现的结果表明，aPDT可能是减少橙树林中酸曲霉孢子孢子的一种潜在方法。