abstract
This study evaluated hyperbaric inactivation (HI) at 150, 200 and 250 MPa, up to 24 h (at ambient temperatures,18-23 degrees C) to inactivate Alicyclobacillus acidoterrestris (ACB) spores in apple juice. The effects of pretreatments on spores by thermal pasteurization (90 degrees C, 30 s), high pressure processing (600 MPa, 3 min, HPP), pulsed electric field (30 kV, 80 mu s, 1400 Hz, PEF), and ultrasound (67 W, 20 kHz, 5 min, US) prior to HI was evaluated. The results were fitted to non-linear inactivation kinetic models, including Biphasic, Log-logistic, and Weibull. Without a previous pre-treatment, ACB spores were reduced approximate to 4.56 log units by HI after 24 h, regardless of the pressure level (initial load around 6 log CFU/mL). The pre-treatments did not affect ACB spores during HI (approximate to 4-5 log units' inactivation after 24 h under pressure), except for PEF that resulted in a lower inactivation (approximate to 3.5 log units after 24 h under pressure). Phase contrast microscopy revealed that the spores were unable to form a vegetative cell during HI. HI at 5 degrees C resulted in a lower inactivation level, with 3.86, 2.54 and 1.77 log units of inactivation, respectively, at 150, 200 and 250 MPa after 96 h. Industrial relevance: The results of this work point to the possibility of using HI, before or after conventional thermal pasteurization and other nonthermal technologies (HPP, PEF, and US) to process apple juice, to inactivate ACB spores at room temperature and also under refrigeration. This methodology should be further studied in the context of ACB spores' high thermal stability and its industrial relevance.
keywords
BACILLUS-SUBTILIS SPORES; PULSED ELECTRIC-FIELDS; HIGH-PRESSURE; ORANGE JUICE; APPLE JUICE; GERMINATION; PASTEURIZATION; ENDOSPORES; RESISTANCE; ULTRASOUND
subject category
Food Science & Technology
authors
Pinto, CA; Ganjeh, AM; Martins, AP; Lopes, R; Martínez-Terol, S; Barba, FJ; Alegria, MJ; Saraiva, JA
Groups
acknowledgements
This work received financial support from FCT/MCTES (LA/P/0008/2020 DOI 10.54499/LA/P/0008/2020, UIDP/50006/2020 DOI 10.54499/UIDP/50006/2020 and UIDB/50006/2020 DOI 10.54499/UIDB/50006/2020) through national funds. This study was also funded by the PRR - Plano de Recuperacao e Resiliencia and by the NextGenerationEU funds at Universidade de Aveiro, through the scope of the Agenda for Business Innovation "Plataforma de Valorizacao, Industrializacao e Inovacao comercial para o AgroAlimentar (VIIAFOOD)" (Project no. 37 AAC n.o 02/C05-i01/2022 with the application C644929456-00000040). Thanks are also due to FCT/MCTES for financing the PhD grant of Carlos A. Pinto (SFRH/BD/137036/2018 and COVID/BD/153220/2023), Alireza Mousakhani Ganjeh (2022.12558.BD), Ana P. Martins (SFRH/BD/146369/2019) and Rafaela Lopes (UI/BD/151276/2021).