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Maria Rosaria Corbo - One of the best experts on this subject based on the ideXlab platform.
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spore inactivation and dpa release in Alicyclobacillus acidoterrestris under different stress conditions
Food Microbiology, 2015Co-Authors: Antonio Bevilacqua, Milena Sinigaglia, Emanuela Ciuffreda, Maria Rosaria CorboAbstract:This paper reports on the inactivation of spores of 5 strains of Alicyclobacillus acidoterrestris under different stress conditions (acidic and alkaline pH, high temperature, addition of lysozyme, hydrogen peroxide and p-coumaric acid). The research was divided into two different steps; first, each stress was studied alone, thus pointing out a partial uncoupling between spore inactivation and DPA release, as H2O2 reduced spore level below the detection but it did not cause the release of DPA. A partial correlation was found only for acidic and alkaline pH. 2nd step was focused on the combination of pH, temperature and H2O2 through a factorial design; experiments were performed on both fresh and 4 month-old spores and pinpointed a different trend for DPA release as a function of spore age.
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effects of lysozyme on Alicyclobacillus acidoterrestris under laboratory conditions
International Journal of Food Science and Technology, 2014Co-Authors: Antonio Bevilacqua, Milena Sinigaglia, Emanuela Ciuffreda, Maria Rosaria CorboAbstract:Summary This research was aimed at investigating the bioactivity of lysozyme towards Alicyclobacillus acidoterrestris. Lysozyme (0.1–20 ppm) was tested towards five different strains; the experiments were performed on both spores and vegetative cells using a microdilution approach to assess the minimal inhibitory concentration (MIC). Thereafter, spore viability of two selected strains was evaluated through the traditional plate count. Finally, an experiment was run to assess the role of lysozyme on the complex phenomenon of spore germination. The MIC of lysozyme towards vegetative cells varied from 0.1 to 6 ppm, while for the spores, it was from 0.1 to 3 ppm. Concerning spore viability, the effect of lysozyme relied upon its amount on the broth, as at MIC it caused a slight reduction in spores (approximately 1 log cfu ml−1) after 24 h; otherwise, higher concentrations caused a decrease in spore level below the detection limit. Concerning spore germination, lysozyme exerted a promoting effect on this phenomenon and reduced the optical density by 66%.
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control of Alicyclobacillus acidoterrestris in apple juice by citrus extracts and a mild heat treatment
Food Control, 2013Co-Authors: Antonio Bevilacqua, Milena Sinigaglia, Daniela Campaniello, Barbara Speranza, Maria Rosaria CorboAbstract:Abstract This paper reports on the use of different citrus extracts (biocitro, lemon extract and neroli) for the inhibition of the spores of two strains of Alicyclobacillus acidoterrestris; the research included 3 steps. First, the bioactivity of citrus extracts was assessed under in vitro conditions using a modified micro-dilution method; the concentration of extracts was from 20 to 500 ppm. Then, biocitro and lemon extract (0–80 ppm) were combined with two different thermal treatments (at 70 and 80 °C for 3–6 min) through a fractional factorial design and finally a treatment at 80 °C for 6 min was combined with either biocitro (80 ppm) or lemon extract (80 ppm) and tested in apple juice. Biocitro and lemon extract showed MIC values (Minimal Inhibitory Concentration) from 160 to 500 ppm; their effect could be enhanced by a thermal treatment at 80 °C for 3–6 min, both under in vitro conditions and in apple juice. Finally, biocitro or lemon extract could be added before and after the thermal treatment without any significant loss of their bioactivity.
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characterization of a wild strain of Alicyclobacillus acidoterrestris heat resistance and implications for tomato juice
Journal of Food Science, 2011Co-Authors: Antonio Bevilacqua, Maria Rosaria CorboAbstract:UNLABELLED This article reports the characterization of a wild strain of Alicyclobacillus acidoterrestris and describes the implications of the heat resistance of this microorganism in tomato juice. The strain (labeled as A. acidoterrestrisγ4) showed pH and temperature ranges for growth typical of the species (3.0 to 6.0 for the pH and 35 to 60 °C for the temperature); heat resistance in tomato juice was as follows: D(T) values of 40.65, 9.47, and 1.5 min (at 85, 90, and 95 °C, respectively) and z-value of 7 °C. A treatment at 70 °C for 15 min was found to be optimal for spore activation, whereas Malt Extract Agar, acidified to pH 4.5, showed good results for spore recovery. Concerning the implications of heat resistance of A. acidoterrestris on tomato juice, high temperatures required for spore inactivation determined a general decrease of the antioxidant activity (increase of the redox potential and reduction of the chain-breaking activity), but not the formation of brown compounds (namely, hydroxymethylfurfural), thus suggesting an effect on the secondary antioxidants (carotenoids and ascorbic acid) rather than on lycopene. PRACTICAL APPLICATION Alicyclobacillus acidoterrestris is an emerging spore-forming microorganism, capable of causing spoilage in tomato juice. Due to their high thermal resistance, spores could be used as targets for the optimization of heat processing; this article reports on the assessment of thermal resistance of a wild strain of A. acidoterrestris, then focusing on the effect of the thermal treatment necessary to inactivate spores on the quality of tomato juice.
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combining eugenol and cinnamaldehyde to control the growth of Alicyclobacillus acidoterrestris
Food Control, 2010Co-Authors: Antonio Bevilacqua, Maria Rosaria Corbo, Milena SinigagliaAbstract:Abstract This paper proposes the use of a combination of cinnamaldehyde and eugenol to control spore germination of Alicyclobacillus acidoterrestris. In the 1st phase a three variables-five levels Central Composite Design was used to study the individual and additive effects of cinnamaldehyde (0–80 ppm), eugenol (0–160 ppm) and pH (3.5–5.5). The assays were carried out in a laboratory medium (Malt Extract Broth). Cinnamaldehyde appeared as the most effective antimicrobial; otherwise, eugenol acted as a strengthening element and allowed a reduction of cinnamaldehyde amount in the system. Then, the experiments were performed in a commercial apple juice, thus highlighting that spore germination could be inhibited through the use of 80 ppm of eugenol and 40 ppm of cinnamaldehyde or alternatively through the combination of 40 ppm of eugenol with 20 ppm of cinnamaldehyde.
Antonio Bevilacqua - One of the best experts on this subject based on the ideXlab platform.
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spore inactivation and dpa release in Alicyclobacillus acidoterrestris under different stress conditions
Food Microbiology, 2015Co-Authors: Antonio Bevilacqua, Milena Sinigaglia, Emanuela Ciuffreda, Maria Rosaria CorboAbstract:This paper reports on the inactivation of spores of 5 strains of Alicyclobacillus acidoterrestris under different stress conditions (acidic and alkaline pH, high temperature, addition of lysozyme, hydrogen peroxide and p-coumaric acid). The research was divided into two different steps; first, each stress was studied alone, thus pointing out a partial uncoupling between spore inactivation and DPA release, as H2O2 reduced spore level below the detection but it did not cause the release of DPA. A partial correlation was found only for acidic and alkaline pH. 2nd step was focused on the combination of pH, temperature and H2O2 through a factorial design; experiments were performed on both fresh and 4 month-old spores and pinpointed a different trend for DPA release as a function of spore age.
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effects of lysozyme on Alicyclobacillus acidoterrestris under laboratory conditions
International Journal of Food Science and Technology, 2014Co-Authors: Antonio Bevilacqua, Milena Sinigaglia, Emanuela Ciuffreda, Maria Rosaria CorboAbstract:Summary This research was aimed at investigating the bioactivity of lysozyme towards Alicyclobacillus acidoterrestris. Lysozyme (0.1–20 ppm) was tested towards five different strains; the experiments were performed on both spores and vegetative cells using a microdilution approach to assess the minimal inhibitory concentration (MIC). Thereafter, spore viability of two selected strains was evaluated through the traditional plate count. Finally, an experiment was run to assess the role of lysozyme on the complex phenomenon of spore germination. The MIC of lysozyme towards vegetative cells varied from 0.1 to 6 ppm, while for the spores, it was from 0.1 to 3 ppm. Concerning spore viability, the effect of lysozyme relied upon its amount on the broth, as at MIC it caused a slight reduction in spores (approximately 1 log cfu ml−1) after 24 h; otherwise, higher concentrations caused a decrease in spore level below the detection limit. Concerning spore germination, lysozyme exerted a promoting effect on this phenomenon and reduced the optical density by 66%.
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control of Alicyclobacillus acidoterrestris in apple juice by citrus extracts and a mild heat treatment
Food Control, 2013Co-Authors: Antonio Bevilacqua, Milena Sinigaglia, Daniela Campaniello, Barbara Speranza, Maria Rosaria CorboAbstract:Abstract This paper reports on the use of different citrus extracts (biocitro, lemon extract and neroli) for the inhibition of the spores of two strains of Alicyclobacillus acidoterrestris; the research included 3 steps. First, the bioactivity of citrus extracts was assessed under in vitro conditions using a modified micro-dilution method; the concentration of extracts was from 20 to 500 ppm. Then, biocitro and lemon extract (0–80 ppm) were combined with two different thermal treatments (at 70 and 80 °C for 3–6 min) through a fractional factorial design and finally a treatment at 80 °C for 6 min was combined with either biocitro (80 ppm) or lemon extract (80 ppm) and tested in apple juice. Biocitro and lemon extract showed MIC values (Minimal Inhibitory Concentration) from 160 to 500 ppm; their effect could be enhanced by a thermal treatment at 80 °C for 3–6 min, both under in vitro conditions and in apple juice. Finally, biocitro or lemon extract could be added before and after the thermal treatment without any significant loss of their bioactivity.
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characterization of a wild strain of Alicyclobacillus acidoterrestris heat resistance and implications for tomato juice
Journal of Food Science, 2011Co-Authors: Antonio Bevilacqua, Maria Rosaria CorboAbstract:UNLABELLED This article reports the characterization of a wild strain of Alicyclobacillus acidoterrestris and describes the implications of the heat resistance of this microorganism in tomato juice. The strain (labeled as A. acidoterrestrisγ4) showed pH and temperature ranges for growth typical of the species (3.0 to 6.0 for the pH and 35 to 60 °C for the temperature); heat resistance in tomato juice was as follows: D(T) values of 40.65, 9.47, and 1.5 min (at 85, 90, and 95 °C, respectively) and z-value of 7 °C. A treatment at 70 °C for 15 min was found to be optimal for spore activation, whereas Malt Extract Agar, acidified to pH 4.5, showed good results for spore recovery. Concerning the implications of heat resistance of A. acidoterrestris on tomato juice, high temperatures required for spore inactivation determined a general decrease of the antioxidant activity (increase of the redox potential and reduction of the chain-breaking activity), but not the formation of brown compounds (namely, hydroxymethylfurfural), thus suggesting an effect on the secondary antioxidants (carotenoids and ascorbic acid) rather than on lycopene. PRACTICAL APPLICATION Alicyclobacillus acidoterrestris is an emerging spore-forming microorganism, capable of causing spoilage in tomato juice. Due to their high thermal resistance, spores could be used as targets for the optimization of heat processing; this article reports on the assessment of thermal resistance of a wild strain of A. acidoterrestris, then focusing on the effect of the thermal treatment necessary to inactivate spores on the quality of tomato juice.
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combining eugenol and cinnamaldehyde to control the growth of Alicyclobacillus acidoterrestris
Food Control, 2010Co-Authors: Antonio Bevilacqua, Maria Rosaria Corbo, Milena SinigagliaAbstract:Abstract This paper proposes the use of a combination of cinnamaldehyde and eugenol to control spore germination of Alicyclobacillus acidoterrestris. In the 1st phase a three variables-five levels Central Composite Design was used to study the individual and additive effects of cinnamaldehyde (0–80 ppm), eugenol (0–160 ppm) and pH (3.5–5.5). The assays were carried out in a laboratory medium (Malt Extract Broth). Cinnamaldehyde appeared as the most effective antimicrobial; otherwise, eugenol acted as a strengthening element and allowed a reduction of cinnamaldehyde amount in the system. Then, the experiments were performed in a commercial apple juice, thus highlighting that spore germination could be inhibited through the use of 80 ppm of eugenol and 40 ppm of cinnamaldehyde or alternatively through the combination of 40 ppm of eugenol with 20 ppm of cinnamaldehyde.
Cristina L M Silva - One of the best experts on this subject based on the ideXlab platform.
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modelling Alicyclobacillus acidoterrestris inactivation in apple juice using thermosonication treatments
Lwt - Food Science and Technology, 2019Co-Authors: Andreia Tremarin, Teresa R S Brandao, Emine Asik Canbaz, Cristina L M SilvaAbstract:Abstract A spore-forming bacterium, Alicyclobacillus acidoterrestris, is often responsible for fruit juices quality degradation. The objective was to study the influence of ultrasounds and combinations with temperature (thermosonication) on A. acidoterrestris spores inactivation in apple juices. Commercially available juice was artificially inoculated with the bacterium (∼105 CFU/mL). Sonication was carried out in an ultrasonic bath (35 kHz; 120–480 W) at room temperature and at 70, 80, 85, 90 and 95 °C for different times. Thermal treatments at the same temperatures were performed as a control. Sonication had no significant effect on A. acidoterrestris spores inactivation. However, when applied at 70 and 80 °C, it allowed 1 log-cycle more of inactivation when compared to thermal treatments and at the end of the processes. Ultrasounds at higher temperatures required approximately half of the treatment time to attain the same inactivation that occurred when the thermal processes were applied alone. In thermosonicated juices, spores decreased by 4.8, 4.7 and 5.5 log-cycles (at 85, 90 and 95 °C, respectively) after 90, 60 and 20 min. The Weibull model satisfactorily fitted inactivation data of thermosonicated juices. Thermosonication is efficient for A. acidoterrestris spores inactivation, with a drastic impact on spores’ loads when high temperatures are used.
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application of ultraviolet radiation and ultrasound treatments for Alicyclobacillus acidoterrestris spores inactivation in apple juice
Lwt - Food Science and Technology, 2017Co-Authors: Andreia Tremarin, Teresa R S Brandao, Cristina L M SilvaAbstract:Abstract Alicyclobacillus acidoterrestris is a spore-forming bacterium, which is responsible for quality degradation of fruit juices. Non-thermal treatments, such as ultraviolet-C radiation (UV-C) and ultrasound (US), are promising methods for microbial inactivation. The main objective was to study the influence of UV-C, ultrasound and combinations of both treatments on A. acidoterrestris spores inactivation in apple juices. A thermal treatment at 95 °C was used as control. Commercial juices artificially inoculated with the bacterium were exposed to the treatments. Results showed that ultrasound had the lowest impact on A. acidoterrestris inactivation. When UV-C radiation was applied, the number of spores decreased drastically after 8 min, being more effective than a 95 °C thermal treatment. In terms of final microbial loads, combination of US and UV-C did not result in synergetic effects. However, inactivation rates of the combined treatments were significantly different from the ones obtained when the treatments were applied individually.
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inactivation kinetics of Alicyclobacillus acidoterrestris in apple juice submitted to ultraviolet radiation
Food Control, 2017Co-Authors: Andreia Tremarin, Teresa R S Brandao, Cristina L M SilvaAbstract:Abstract Ultraviolet-C radiation (UV-C) is widely used as an alternative strategy to control microorganism in food products. Alicyclobacillus acidoterrestris is a thermo-acidophilic, non-pathogenic and spore-forming bacterium, able to grow at low pH and high temperatures. It is a concern, particularly in apple juice thermal pasteurization, because it is responsible for quality degradation. The main objective of this work was to study the influence of UV-C radiation treatments with seven different intensities (0.34, 0.86, 2.59, 5.59, 8.45, 11.50 and 13.44 W/m2) on A. acidoterrestris inactivation in apple juices. Treatments were carried out in a camera (75 × 70 × 45 cm3) with four germicidal UV lamps with peak emission at 254 nm. Commercial juices were artificially inoculated with bacterium, with initial loads around 107 CFU/mL and then exposed to UV-C radiation and the treatment impact on microbial loads was assessed throughout exposure times. The UV transmittance at 254 nm of the juice was 58%. Results showed that the log-survival of A. acidoterrestris decreased linearly with treatment time, for all intensities tested. When the most severe intensity was used, the number of spores decreased drastically (around 5-log reduction) after 8 min of treatment. Overall it can be concluded that UV-C radiation is a promising treatment with a drastic impact on the loads of A. acidoterrestris in apple juices, especially when high intensities are used.
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thermal inactivation of Alicyclobacillus acidoterrestris spores under different temperature soluble solids and ph conditions for the design of fruit processes
International Journal of Food Microbiology, 1999Co-Authors: Filipa V.m. Silva, Paul Gibbs, Margarida C Vieira, Cristina L M SilvaAbstract:Abstract Alicyclobacillus acidoterrestris, a thermoacidophilic, non-pathogenic and spore-forming bacterium has been detected in several spoiled commercial pasteurised fruit juices. A. acidoterrestris spores, besides being resistant to the pasteurisation treatment conditions normally applied to acidic fruit products, can germinate and grow causing spoilage. Therefore, this microorganism was suggested as the target to be used in the design of adequate pasteurisation processes. The objectives of this work were to investigate the influence of temperature (T: 85–97°C), total soluble solids (SS: 5–60°Brix or % by weight) and pH (2.5–6.0) on D-values (decimal reduction time) of Alicyclobacillus acidoterrestris (type strain, NCIMB 13137) spores, and to fit a model using response surface methodology. A central composite face-centred experimental design was used, and the response, D-value determined in malt extract broth, ranged between 0.498±0.045 and 94.9±6.7 min. Within the factor ranges studied, temperature was the parameter that most affected the D-value. Following this was the SS and, lastly, the pH value. A linear decrease in D-value was observed with decreasing SS and pH, and a non-linear decrease in D-value was noticed with increasing temperature. A second order polynomial was successfully fitted to the data (R2=0.98). In general, D-values measured in real fruit systems, such as orange, apple and grape juices, blackcurrant concentrates, cupuacu (exotic fruit) extract and orange juice drink, were higher than those predicted by the malt extract broth model. This result emphasises the importance of experimental validation of any model-derived process.
Milena Sinigaglia - One of the best experts on this subject based on the ideXlab platform.
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spore inactivation and dpa release in Alicyclobacillus acidoterrestris under different stress conditions
Food Microbiology, 2015Co-Authors: Antonio Bevilacqua, Milena Sinigaglia, Emanuela Ciuffreda, Maria Rosaria CorboAbstract:This paper reports on the inactivation of spores of 5 strains of Alicyclobacillus acidoterrestris under different stress conditions (acidic and alkaline pH, high temperature, addition of lysozyme, hydrogen peroxide and p-coumaric acid). The research was divided into two different steps; first, each stress was studied alone, thus pointing out a partial uncoupling between spore inactivation and DPA release, as H2O2 reduced spore level below the detection but it did not cause the release of DPA. A partial correlation was found only for acidic and alkaline pH. 2nd step was focused on the combination of pH, temperature and H2O2 through a factorial design; experiments were performed on both fresh and 4 month-old spores and pinpointed a different trend for DPA release as a function of spore age.
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effects of lysozyme on Alicyclobacillus acidoterrestris under laboratory conditions
International Journal of Food Science and Technology, 2014Co-Authors: Antonio Bevilacqua, Milena Sinigaglia, Emanuela Ciuffreda, Maria Rosaria CorboAbstract:Summary This research was aimed at investigating the bioactivity of lysozyme towards Alicyclobacillus acidoterrestris. Lysozyme (0.1–20 ppm) was tested towards five different strains; the experiments were performed on both spores and vegetative cells using a microdilution approach to assess the minimal inhibitory concentration (MIC). Thereafter, spore viability of two selected strains was evaluated through the traditional plate count. Finally, an experiment was run to assess the role of lysozyme on the complex phenomenon of spore germination. The MIC of lysozyme towards vegetative cells varied from 0.1 to 6 ppm, while for the spores, it was from 0.1 to 3 ppm. Concerning spore viability, the effect of lysozyme relied upon its amount on the broth, as at MIC it caused a slight reduction in spores (approximately 1 log cfu ml−1) after 24 h; otherwise, higher concentrations caused a decrease in spore level below the detection limit. Concerning spore germination, lysozyme exerted a promoting effect on this phenomenon and reduced the optical density by 66%.
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control of Alicyclobacillus acidoterrestris in apple juice by citrus extracts and a mild heat treatment
Food Control, 2013Co-Authors: Antonio Bevilacqua, Milena Sinigaglia, Daniela Campaniello, Barbara Speranza, Maria Rosaria CorboAbstract:Abstract This paper reports on the use of different citrus extracts (biocitro, lemon extract and neroli) for the inhibition of the spores of two strains of Alicyclobacillus acidoterrestris; the research included 3 steps. First, the bioactivity of citrus extracts was assessed under in vitro conditions using a modified micro-dilution method; the concentration of extracts was from 20 to 500 ppm. Then, biocitro and lemon extract (0–80 ppm) were combined with two different thermal treatments (at 70 and 80 °C for 3–6 min) through a fractional factorial design and finally a treatment at 80 °C for 6 min was combined with either biocitro (80 ppm) or lemon extract (80 ppm) and tested in apple juice. Biocitro and lemon extract showed MIC values (Minimal Inhibitory Concentration) from 160 to 500 ppm; their effect could be enhanced by a thermal treatment at 80 °C for 3–6 min, both under in vitro conditions and in apple juice. Finally, biocitro or lemon extract could be added before and after the thermal treatment without any significant loss of their bioactivity.
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combining eugenol and cinnamaldehyde to control the growth of Alicyclobacillus acidoterrestris
Food Control, 2010Co-Authors: Antonio Bevilacqua, Maria Rosaria Corbo, Milena SinigagliaAbstract:Abstract This paper proposes the use of a combination of cinnamaldehyde and eugenol to control spore germination of Alicyclobacillus acidoterrestris. In the 1st phase a three variables-five levels Central Composite Design was used to study the individual and additive effects of cinnamaldehyde (0–80 ppm), eugenol (0–160 ppm) and pH (3.5–5.5). The assays were carried out in a laboratory medium (Malt Extract Broth). Cinnamaldehyde appeared as the most effective antimicrobial; otherwise, eugenol acted as a strengthening element and allowed a reduction of cinnamaldehyde amount in the system. Then, the experiments were performed in a commercial apple juice, thus highlighting that spore germination could be inhibited through the use of 80 ppm of eugenol and 40 ppm of cinnamaldehyde or alternatively through the combination of 40 ppm of eugenol with 20 ppm of cinnamaldehyde.
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effects of ph cinnamaldehyde and heat treatment time on spore viability of Alicyclobacillus acidoterrestris
International Journal of Food Science and Technology, 2009Co-Authors: Antonio Bevilacqua, Milena Sinigaglia, Maria Rosaria CorboAbstract:Summary A three variables–five levels central composite design was used to study the effects of pH (3.5, 4.0, 4.5, 5.0 and 5.5), cinnamaldehyde (0, 40, 80, 120 and 160 ppm) and heating temperature (80, 84, 88, 92 and 96 °C) on the spores of Alicyclobacillus acidoterrestris in malt extract broth (MEB). The heat shock resulted in a slight decrease of spore number from 3.2 to 2.5 log CFU mL−1 and occurred at 80–85 °C depending on the pH of the medium. Otherwise, cinnamaldehyde acted as an additional hurdle within the storage time; the critical amounts to be used were included in the range 41.35–44.42 ppm of cinnamaldehyde and were related positively to the pH, i.e. the critical amount of active compound decreased with the decreasing of the pH.
Zhouli Wang - One of the best experts on this subject based on the ideXlab platform.
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antibacterial activity and mechanism of thymol against Alicyclobacillus acidoterrestris vegetative cells and spores
Lwt - Food Science and Technology, 2019Co-Authors: Mingquan Zhang, Yahong Yuan, Yifei Yang, Zhouli WangAbstract:Abstract Alicyclobacillus acidoterrestris has received much attention due to its unique thermo-acidophilic property and implication in the spoilage of pasteurized juices. The aim of this study was to investigate the antibacterial characteristics and mechanisms of thymol against A. acidoterrestris vegetative cells and spores. Minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) of thymol against vegetative cells were both 0.25 mg/mL. MIC of thymol against spores was 0.5 mg/mL, and the MBC was greater than 1.0 mg/mL. Thymol could effectively inhibit A. acidoterrestris growth, spore germination and guaiacol production. When treated by thymol, the leakage of nucleic acids and proteins from A. acidoterrestris cells and spores increased significantly. SDS-PAGE investigation of bacterial proteins showed that the loss of soluble proteins was obvious as well. Scanning electron microscopy observation exhibited that A. acidoterrestris cells or spores treated with thymol had a severe morphological damage. These results demonstrated that thymol exerted its good antibacterial activities by destroying the integrity of the cell and spore. This study provides a new method for the inactivation of A. acidoterrestris in fruit juice.
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antibacterial activity and mechanism of thymol against Alicyclobacillus acidoterrestris vegetative cells and spores
Lwt - Food Science and Technology, 2019Co-Authors: Mingquan Zhang, Yahong Yuan, Yifei Yang, Zhouli WangAbstract:Abstract Alicyclobacillus acidoterrestris has received much attention due to its unique thermo-acidophilic property and implication in the spoilage of pasteurized juices. The aim of this study was to investigate the antibacterial characteristics and mechanisms of thymol against A. acidoterrestris vegetative cells and spores. Minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) of thymol against vegetative cells were both 0.25 mg/mL. MIC of thymol against spores was 0.5 mg/mL, and the MBC was greater than 1.0 mg/mL. Thymol could effectively inhibit A. acidoterrestris growth, spore germination and guaiacol production. When treated by thymol, the leakage of nucleic acids and proteins from A. acidoterrestris cells and spores increased significantly. SDS-PAGE investigation of bacterial proteins showed that the loss of soluble proteins was obvious as well. Scanning electron microscopy observation exhibited that A. acidoterrestris cells or spores treated with thymol had a severe morphological damage. These results demonstrated that thymol exerted its good antibacterial activities by destroying the integrity of the cell and spore. This study provides a new method for the inactivation of A. acidoterrestris in fruit juice.
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antibacterial activity and mechanism of cinnamic acid and chlorogenic acid against Alicyclobacillus acidoterrestris vegetative cells in apple juice
International Journal of Food Science and Technology, 2019Co-Authors: Rui Cai, Zhouli Wang, Tianli Yue, Miao Miao, Yijun Zhang, Lu Cui, Yahong YuanAbstract:The aim of this study was to investigate the antibacterial activity and mechanism of cinnamic acid and chlorogenic acid against Alicyclobacillus acidoterrestris. Minimum inhibitory concentrations of cinnamic acid and chlorogenic acid were 0.375 and 2.0 mg mL⁻¹, and the minimum bactericidal concentrations were 0.50 and 4.0 mg mL⁻¹, respectively. The apple juice ingredients had little influence on the inactivation of A. acidoterrestris. After treatment with cinnamic acid and chlorogenic acid, the morphology of A. acidoterrestris cells were severely destroyed; the leakage of nucleic acids and proteins increased significantly. SDS‐PAGE investigation of bacterial proteins proved that the loss of soluble proteins was obvious as well. These results demonstrated that cinnamic acid and chlorogenic acid exerted their antibacterial activity mainly by an action mode of membrane disruption. This study provides an alternative method for the control of A. acidoterrestris‐related spoilage in the fruit juice/beverage industry.
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precursors and metabolic pathway for guaiacol production by Alicyclobacillus acidoterrestris
International Journal of Food Microbiology, 2015Co-Authors: Rui Cai, Yahong Yuan, Zhouli Wang, Chunfeng Guo, Bin Liu, Laping Liu, Yutang Wang, Tianli YueAbstract:Alicyclobacillus acidoterrestris has recently received much attention due to its implication in the spoilage of pasteurized fruit juices, which was manifested by the production of guaiacol. Vanillic acid and vanillin have been accepted as the biochemical precursors of guaiacol in fruit juices. The purpose of this study was to try to find other precursors and elucidate details about the conversion of vanillic acid and vanillin to guaiacol by A. acidoterrestris. Four potential substrates including ferulic acid, catechol, phenylalanine and tyrosine were analyzed, but they could not be metabolized to guaiacol by all the thirty A. acidoterrestris strains tested. Resting cell studies and enzyme assays demonstrated that vanillin was reduced to vanillyl alcohol by NADPH-dependent vanillin reductase and oxidized to vanillic acid by NAD(P)(+)-dependent vanillin dehydrogenases in A. acidoterrestris DSM 3923. Vanillic acid underwent a nonoxidative decarboxylation to guaiacol. The reversible vanillic acid decarboxylase involved was oxygen insensitive and pyridine nucleotide-independent.
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effects of preservatives on Alicyclobacillus acidoterrestris growth and guaiacol production
International Journal of Food Microbiology, 2015Co-Authors: Rui Cai, Yahong Yuan, Zhouli Wang, Chunfeng Guo, Bin Liu, Laping Liu, Chunqing Pan, Tianli YueAbstract:Alicyclobacillus acidoterrestris can survive the pasteurization process, multiply in pasteurized juices and produce guaiacol which causes medicinal or antiseptic off-flavors. Chemical preservatives have the potential to suppress outgrowth of surviving populations during subsequent storage of fruit juices. In the present study, the individual effects of potassium sorbate, sodium benzoate, potassium metabisulfite, dehydroacetic acid, ethyl 4-hydroxybenzoate, cinnamic acid and e-polylysine on A. acidoterrestris growth and guaiacol production were firstly evaluated in a laboratory medium. Of the seven preservatives investigated, only dehydroacetic acid, cinnamic acid and e-polylysine were effective both in controlling growth and guaiacol formation by A. acidoterrestris. Then, these three antimicrobials were applied to apple juice. Through the addition of 270 mg/L dehydroacetic acid, 108 mg/L cinnamic acid or 100 mg/L e-polylysine, the A. acidoterrestris counts were reduced by 3.43, 3.17 and 4.78 log colony forming unit(CFU)/mL, respectively, and no guaiacol was detected after 14 days of storage. Sensory evaluation revealed that the addition of these three preservatives did not affect the organoleptic properties of the apple juice. Results obtained in this paper could be very useful for a better control of A. acidoterrestris-related spoilage in the fruit juice/beverage industry.