Effect of Different Processing Methods on Microorganisms in Food

A special issue of Foods (ISSN 2304-8158). This special issue belongs to the section "Food Microbiology".

Deadline for manuscript submissions: closed (31 October 2022) | Viewed by 8658

Special Issue Editors

Centro Interdipartimentale di Ricerca Industriale Agroalimentare, Università degli Studi di Bologna, Sede di Cesena, Via Quinto Bucci 336, 47521 Cesena (FC), Italy
Interests: food microbiology; fermented foods; food safety; lactic acid bacteria; foodborne pathogens; bioprotective cultures; natural antimicrobials; flow cytometry; thermal treatments
Dipartimento di Scienze degli Alimenti e del Farmaco, Università di Parma, Parma, Italy
Interests: food microbiology; lactic acid bacteria; fermented foods; molecular microbiology; real-time qPCR; functional genomics; microbiome analysis; toxin–antitoxin systems

Special Issue Information

Dear Colleagues,

The behavior of microorganisms in food is affected by many variables, including biotic and abiotic factors that can be modulated to drive microbial development in foods. In the perspective of food processing, modification of manufacturing parameters (treatments applied, presence of antimicrobials, environmental parameters) as well as the handling of microbial sources when used as starter or bioprotective cultures can influence the development of microorganisms in food matrices. As a consequence, processing methods can strongly influence microbial performances or, concerning pathogens or spoilage microflora, their resistance to the adopted treatments and, therefore, their ability to recover and affect product stability and safety.

This Special Issue aims to collect articles or reviews dealing with the effect of food processing factors on microbial performances in fermented foods. In particular, papers focusing on the effect of processing conditions on microbial viability, recovery, gene expression; research on the effect of various treatments on specific microbial groups or on the entire microbiota; and papers presenting novel approaches for the preparation of starter, adjunct or bioprotective cultures are welcome.

Dr. Chiara Montanari
Dr. Alessia Levante
Guest Editors

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Keywords

  • fermentation
  • microbial performances
  • starter, adjunct, and bioprotective cultures
  • food safety
  • technological processes
  • nonthermal technologies
  • strain selection

Published Papers (4 papers)

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Research

14 pages, 8511 KiB  
Article
Assessment of Ultrasonic Stress on Survival and β-Glucosidase Activity of Encapsulated Lactiplantibacillus plantarum BCRC 10357 in Fermentation of Black Soymilk
by Hung-Chih Tseng and Chun-Yao Yang
Foods 2022, 11(9), 1234; https://doi.org/10.3390/foods11091234 - 25 Apr 2022
Cited by 6 | Viewed by 1490
Abstract
The enhanced β-glucosidase activity of encapsulated Lactiplantibacillus plantarum BCRC 10357 within calcium alginate capsules was investigated by ultrasonic stimulation to induce the stress response of the bacteria for the biotransformation of isoflavones in black soymilk. The effects of various ultrasound durations, sodium alginate [...] Read more.
The enhanced β-glucosidase activity of encapsulated Lactiplantibacillus plantarum BCRC 10357 within calcium alginate capsules was investigated by ultrasonic stimulation to induce the stress response of the bacteria for the biotransformation of isoflavones in black soymilk. The effects of various ultrasound durations, sodium alginate concentrations (% ALG), and cell suspensions on the β-glucosidase activity of encapsulated bacteria were explored. The β-glucosidase activity of encapsulated L. plantarum BCRC 10357 with ultrasonic stimulation (40 kHz/300 W) was greater than that without ultrasound. With 20 min of ultrasonic treatment, the β-glucosidase activity of encapsulated L. plantarum BCRC 10357 from 2% ALG/0.85% NaCl cell suspension was 11.47 U/mL at 12 h, then increased to 27.43 U/mL at 36 h and to 26.25 U/mL at 48 h in black soymilk at 37 °C, showing the high adaptation of encapsulated L. plantarum BCRC 10357 encountering ultrasonic stress to release high β-glucosidase until 48 h, at which point the ratio of isoflavone aglycones (daidzein and genistein) in total isoflavones (daidzin, genistin, daidzein, and genistein) was 98.65%, reflecting the effective biotransformation of isoflavone glycosides into aglycones by β-glucosidase. In this study, the survivability and β-glucosidase activity of encapsulated L. plantarum BCRC 10357 were enhanced under ultrasonic stimulation, and were favorably used in the fermentation of black soymilk. Full article
(This article belongs to the Special Issue Effect of Different Processing Methods on Microorganisms in Food)
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11 pages, 1566 KiB  
Article
Influence of Processing Parameters and Natural Antimicrobial on Alicyclobacillus acidoterrestris and Clostridium pasteurianum Using Response Surface Methodology
by Jasmine Hadj Saadoun, Alessia Levante, Martina Marrella, Valentina Bernini, Erasmo Neviani and Camilla Lazzi
Foods 2022, 11(7), 1063; https://doi.org/10.3390/foods11071063 - 06 Apr 2022
Cited by 2 | Viewed by 1705
Abstract
The food industry must ensure the stability of the products, and this is often achieved by exposing foods to heat treatments that are able to ensure the absence of pathogenic or spoilage microorganisms. These treatments are different in terms of temperature and duration [...] Read more.
The food industry must ensure the stability of the products, and this is often achieved by exposing foods to heat treatments that are able to ensure the absence of pathogenic or spoilage microorganisms. These treatments are different in terms of temperature and duration and could lead to a loss in nutritional and sensory value. Moreover, some types of microorganisms manage to survive these treatments thanks to the sporification process. The addition of antimicrobials can become necessary, but at present, consumers are more inclined toward natural products, avoiding synthetic and chemical additives. Antimicrobials from plants could be a valuable option and, in this context, a patent concerning an antimicrobial extract from fermented plant substrate was recently tested against foodborne pathogens revealing high antimicrobial activity. The objective of this study was the creation of a model for the evaluation and subsequent prediction of the combined effect of different process and product variables, including antimicrobial addition, on the inhibition and reduction of spore germination of target microorganisms, Alicyclobacillus acidoterrestris and Clostridium pasteurianum, responsible for spoilage of tomato-based products. Full article
(This article belongs to the Special Issue Effect of Different Processing Methods on Microorganisms in Food)
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12 pages, 1381 KiB  
Article
Insights into the Metabolomic Diversity of Latilactobacillus sakei
by Federica Barbieri, Luca Laghi, Chiara Montanari, Qiuyu Lan, Alessia Levante, Fausto Gardini and Giulia Tabanelli
Foods 2022, 11(3), 477; https://doi.org/10.3390/foods11030477 - 06 Feb 2022
Cited by 5 | Viewed by 1766
Abstract
Latilactobacillus sakei (L. sakei), widely used as a starter culture in fermented sausages, is a species adapted to meat environments. Its ability to survive for a long time in such products is due to the exploitation of different metabolic pathways to [...] Read more.
Latilactobacillus sakei (L. sakei), widely used as a starter culture in fermented sausages, is a species adapted to meat environments. Its ability to survive for a long time in such products is due to the exploitation of different metabolic pathways to gain energy (hexose and pentose sugar fermentation, amino acids catabolism, etc.). Since L. sakei demonstrates high phenotypic and metabolic strain biodiversity, in this work, a metabolomic approach was used to compare five strains of different origins. They were cultivated in a defined medium with glucose or ribose at two concentrations, and analyzed through nuclear magnetic resonance (1H-NMR) spectroscopy to monitor amino acid consumptions and accumulation of organic acids and aroma compounds. The results showed that all the strains were able to use arginine, especially when cultivated with ribose, while serine was consumed mainly in the presence of glucose. Aroma compounds (i.e., diacetyl and acetoin) were mainly accumulated in samples with ribose. These aspects are relevant for starter cultures selection, to confer specific features to fermented sausages, and to optimize the fermentations. Moreover, the use of 1H-NMR allowed the fast identification of different classes of compounds (without derivatization or extraction procedures), providing a powerful tool to increase the knowledge of the metabolic diversity of L. sakei. Full article
(This article belongs to the Special Issue Effect of Different Processing Methods on Microorganisms in Food)
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13 pages, 962 KiB  
Article
Survival of Escherichia coli O157:H7 during Moderate Temperature Dehydration of Plant-Based Foods
by Yadwinder Singh Rana, Philip M. Eberly, Quincy J. Suehr, Ian M. Hildebrandt, Bradley P. Marks and Abigail B. Snyder
Foods 2021, 10(9), 2162; https://doi.org/10.3390/foods10092162 - 13 Sep 2021
Cited by 4 | Viewed by 2698
Abstract
The effect of moderate-temperature (≤60 °C) dehydration of plant-based foods on pathogen inactivation is unknown. Here, we model the reduction of E. coli O157:H7 as a function of product-matrix, aw, and temperature under isothermal conditions. Apple, kale, and tofu were each [...] Read more.
The effect of moderate-temperature (≤60 °C) dehydration of plant-based foods on pathogen inactivation is unknown. Here, we model the reduction of E. coli O157:H7 as a function of product-matrix, aw, and temperature under isothermal conditions. Apple, kale, and tofu were each adjusted to aw 0.90, 0.95, or 0.99 and inoculated with an E. coli O157:H7 cocktail, followed by isothermal treatment at 49, 54.5, or 60.0 °C. The decimal reduction time, or D-value, is the time required at a given temperature to achieve a 1 log reduction in the target microorganism. Modified Bigelow-type models were developed to determine D-values which varied by product type and aw level, ranging from 3.0–6.7, 19.3–55.3, and 45.9–257.4 min. The relative impact of aw was product dependent and appeared to have a non-linear impact on D-values. The root mean squared errors of the isothermal-based models ranged from 0.75 to 1.54 log CFU/g. Second, we performed dynamic drying experiments. While the isothermal results suggested significant microbial inactivation might be achieved, the dehydrator studies showed that the combination of low product temperature and decreasing aw in the pilot-scale system provided minimal inactivation. Pilot-scale drying at 60 °C only achieved reductions of 3.1 ± 0.8 log in kale and 0.67 ± 0.66 log in apple after 8 h, and 0.69 ± 0.67 log in tofu after 24 h. This illustrates the potential limitations of dehydration at ≤60 °C as a microbial kill step. Full article
(This article belongs to the Special Issue Effect of Different Processing Methods on Microorganisms in Food)
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