TY - JOUR
T1 - Antimicrobial photodynamic treatment as an alternative approach for Alicyclobacillus acidoterrestris inactivation
AU - do Prado-Silva, Leonardo
AU - Gomes, Ana T.P.C.
AU - Mesquita, Mariana Q.
AU - Neri-Numa, Iramaia A.
AU - Pastore, Glaucia M.
AU - Neves, Maria G.P.M.S.
AU - Faustino, Maria A.F.
AU - Almeida, Adelaide
AU - Braga, Gilberto Ú.L.
AU - Sant'Ana, Anderson S.
N1 - Funding Information:
This work was supported by: Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq; Grants: #140092/2017-0 , #302763/2014-7 , and #305804/2017-0 ); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) - Finance Code 001 for the financial support. Thanks are due for the financial support to CESAM Research Unit ( UID/AMB/50017/2019 and UIDB/50017/2020+UIDP/50017/2020 ), QOPNA Research Unit (FCT UID/QUI/00062/2019 ) and LAQV-REQUIMTE Research Unit ( UIDB/50006/2020 ), to FCT/MCTES through national funds, and the co-funding by the FEDER , within the PT2020 Partnership Agreement and Compete 2020.
Funding Information:
This work was supported by: Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq; Grants: #140092/2017-0, #302763/2014-7, and #305804/2017-0); Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) - Finance Code 001 for the financial support. Thanks are due for the financial support to CESAM Research Unit (UID/AMB/50017/2019 and UIDB/50017/2020+UIDP/50017/2020), QOPNA Research Unit (FCT UID/QUI/00062/2019) and LAQV-REQUIMTE Research Unit (UIDB/50006/2020), to FCT/MCTES through national funds, and the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020.
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/11/16
Y1 - 2020/11/16
N2 - 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.
AB - 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.
KW - aPDT
KW - Decontamination
KW - Emerging technologies
KW - Food spoilage
KW - Orange juice
KW - Sporeforming bacteria
UR - http://www.scopus.com/inward/record.url?scp=85089336686&partnerID=8YFLogxK
U2 - 10.1016/j.ijfoodmicro.2020.108803
DO - 10.1016/j.ijfoodmicro.2020.108803
M3 - Article
C2 - 32798958
AN - SCOPUS:85089336686
SN - 0168-1605
VL - 333
JO - International Journal of Food Microbiology
JF - International Journal of Food Microbiology
M1 - 108803
ER -