Open AccessThermal resistance and high-performance microwave decontamination assessment of Bacillus endospores isolated from food-grade herbal extracts
Author(s) -
Armin Tarrah,
Shadi Pakroo,
Milena Carlot,
Camilla Nesto,
Antonella Cirillo,
Angiolella Lombardi,
Viviana Corich,
Alessio Giacomini
Publication year - 2021
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0261988
Subject(s) - endospore , bacillus pumilus , spore , bacillus subtilis , food science , human decontamination , bacillus (shape) , microbiology and biotechnology , biology , chemistry , bacteria , medicine , genetics , pathology
Generally, endospore contamination can occur from different sources during product manufacturing in many industries and therefore lower its quality by affecting physicochemical properties and shelf-life. Bacterial endospores can germinate inside the product and produce several enzymes, which can cause several undesirable changes. This study assessed the spores thermal resistance and applied a microwave decontamination technique toward herbal extracts ( Tilia tomentosa and Centella asiatica ) containing ethanol or glycerol. Based on 16S rRNA analysis, the detected contaminant endospores belonged to different Bacillus species, namely B . subtilis , B . zhangzhouensis , and B . pumilus . The thermal resistance assessment using inoculated endospores in the actual products revealed B . pumilus T2 as the most resistant endospore to the heat treatments tested in both T . tomentosa and C . asiatica extracts. Finally, a high-performance microwave technique was used to decontaminate T . tomentosa extract against the mixture of Bacillus spores. Results from the microwave technique indicate that the increase of temperature from 100°C to 105°C not only decontaminated the product but also could dramatically decrease the effective thermal treatment time (10 times), which can benefit the product quality. The results provided in this study considerably contribute to improving an original decontamination method for products containing glycerol and ethanol with the most negligible effect on product quality.