scholarly journals Theoretical and Experimental Investigation of the Thermal Inactivation of Thermoanaerobacterium Thermosaccharolyticum and Geobacillus Stearothermophilus in Different Canned Food Matrices

2021 ◽  
Vol 46 (341) ◽  
pp. 97-104
Author(s):  
Evalds Raits ◽  
Svetlana Raita ◽  
Asnate Kirse-Ozolina ◽  
Sandra Muizniece-Brasava
Keyword(s):  
Thermal Processing ◽  
Thermal Inactivation ◽  
Thermophilic Bacteria ◽  
Food Samples ◽  
Geobacillus Stearothermophilus ◽  
Thermoanaerobacterium Thermosaccharolyticum ◽  
Practical Evaluation ◽  
Destruction Kinetics ◽  
Food Sterilization ◽  
Canning Industry

Abstract In the canning industry, thermal preservation processes typically are designed based on Clostridium botulinum thermal destruction kinetics. However, some bacteria can still survive, necessitating implementation of stricter timetemperature regimen for sterilization process. The aim of this study was to compare processing effectiveness at F0 (sterilization value) 8 ±1 min from the perspective of the vegetable-based product canning facility, while analyzing the inactivation, viability, and recovery of thermophilic bacteria. Four commercial products [tomato soup and rassolnik soup - acidified food (AF), and mushroom soup and pea porridge - low-acid food (LACF)] with different heat transfer characteristics (convection and conduction) were inoculated with 6.6 log10 spores/ml Geobacillus stearothermophilus LMKK 244 (reported as DSM 6790 and ATCC 10149 in other collections) and 4.810 log spores/ml Thermoanaerobacterium thermosaccharolyticum DSM 571 spore suspensions. Food samples contaminated with bacterial spores were processed in a steam-air retort at 118 °C for 75 min. G. stearothermophilus and T. thermosaccharolyticum growth was not detected in AF samples (pH = 4.4 and 4.5), but was observed in LACF samples (pH = 5.1 and 5.8). Practical evaluation showed that T. thermosaccharolyticum did not survive thermal processing, which was verified using a presence/absence test after incubation at 55 °C. G. stearothermophilus did not survive thermal processing, but recovered in pea porridge (pH = 5.8) during incubation. Our observations showed that food pH is a crucial factor determining microorganism survival during heat treatment and may be used by the vegetable-based product canning facilities to improve the food sterilization conditions.

scholarly journals Cadmium Ion Biosorption by the Thermophilic Bacteria Geobacillus stearothermophilus and G. thermocatenulatus

2006 ◽  
Vol 72 (6) ◽  
pp. 4020-4027 ◽  
Author(s):  
Adrian Hetzer ◽  
Christopher J. Daughney ◽  
Hugh W. Morgan
Keyword(s):  
Metal Ion ◽  
Functional Group ◽  
Thermophilic Bacteria ◽  
Toxicity Tests ◽  
Ion Adsorption ◽  
Geobacillus Stearothermophilus ◽  
Cadmium Ion ◽  
Thermophilic Microorganisms ◽  
Gram Positive Bacteria ◽  
Metal Ion Adsorption

ABSTRACT This study reports surface complexation models (SCMs) for quantifying metal ion adsorption by thermophilic microorganisms. In initial cadmium ion toxicity tests, members of the genus Geobacillus displayed the highest tolerance to CdCl2 (as high as 400 to 3,200 μM). The thermophilic, gram-positive bacteria Geobacillus stearothermophilus and G. thermocatenulatus were selected for further electrophoretic mobility, potentiometric titration, and Cd2+ adsorption experiments to characterize Cd2+ complexation by functional groups within and on the cell wall. Distinct one-site SCMs described the extent of cadmium ion adsorption by both studied Geobacillus sp. strains over a range of pH values and metal/bacteria concentration ratios. The results indicate that a functional group with a deprotonation constant pK value of approximately 3.8 accounts for 66% and 80% of all titratable sites for G. thermocatenulatus and G. stearothermophilus, respectively, and is dominant in Cd2+ adsorption reactions. The results suggest a different type of functional group may be involved in cadmium biosorption for both thermophilic strains investigated here, compared to previous reports for mesophilic bacteria.

Thermal Sensitivity of Neosartorya fischeri Ascospores in Regular and Reduced-Sugar Grape Jelly

1997 ◽  
Vol 60 (12) ◽  
pp. 1577-1579 ◽  
Author(s):  
LARRY R. BEUCHAT ◽  
GERALD D. KUHN
Keyword(s):  
Thermal Processing ◽  
Thermal Inactivation ◽  
Thermal Sensitivity ◽  
Neosartorya Fischeri ◽  
Concord Grape ◽  
Grape Jelly ◽  
Made In ◽  
Product Formulas

A study was conducted to determine the thermal sensitivity of Neosartorya fischeri ascospores in regular (standard) and reduced-sugar formulas of Concord grape jelly. Ascospores were inactivated more rapidly by heating in the reduced-sugar formula than in the regular formula. Protection against inactivation in the regular formula may be due to its having a higher pH (3.27) than the pH (3.14) of the reduced-sugar formula. The lower aw (0.78) of the regular jelly formula compared to that of the reduced-sugar formula (aw, 0.82) would also protect against thermal inactivation. These results demonstrate the need to consider the efficacy of thermal processing schemes in achieving desired levels of sterility when changes are made in product formulas.

scholarly journals Predicting the Quality of Pasteurized Vegetables Using Kinetic Models: A Review

2013 ◽  
Vol 2013 ◽  
pp. 1-29 ◽  
Author(s):  
Muhammad Aamir ◽  
Mahmoudreza Ovissipour ◽  
Shyam S. Sablani ◽  
Barbara Rasco
Keyword(s):  
Thermal Processing ◽  
Pathogenic Bacteria ◽  
Microbial Growth ◽  
Thermal Inactivation ◽  
New Technologies ◽  
Preventive Measures ◽  
Concomitant Reduction ◽  
Natural Foods ◽  
Thermal Pasteurization

A resurgence in interest examining thermal pasteurization technologies has been driven by demands for “cleaner” labeling and the need of organic and natural foods markets for suitable preventive measures to impede microbial growth and extend shelf life of minimally processed foods and ready-to-eat foods with a concomitant reduction in the use of chemical preservatives. This review describes the effects of thermal pasteurization on vegetable quality attributes including altering flavor and texture to improve consumer acceptability, stabilizing color, improving digestibility, palatability and retaining bioavailability of important nutrients, and bioactive compounds. Here, we provide kinetic parameters for inactivation of viral and bacterial pathogens and their surrogates and marker enzymes used to monitor process effectiveness in a variety of plant food items. Data on thermal processing protocols leading to higher retention and bioactivity are also presented. Thermal inactivation of foodborne viruses and pathogenic bacteria, specifically at lower pasteurization temperatures or via new technologies such as dielectric heating, can lead to greater retention of “fresh-like” properties.

Optimizing Thermal Processing of Broccoli: Model Development, Numerical Simulation, Experimental Validation

2019 ◽  
Vol 15 (11-12) ◽  
Author(s):  
Milad Pero ◽  
Hossein Kiani ◽  
Torstein Skåra ◽  
Dagbjørn Skipnes ◽  
Gholamreze Askari
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Thermal Processing ◽  
Experimental Validation ◽  
Thermal Inactivation ◽  
Arrhenius Equation ◽  
Model Development ◽  
Process Time ◽  
Cold Spot ◽  
Conductive Heat

AbstractKinetic models describing the thermal inactivation of peroxidase and degradation of broccoli (Brassica Oleracea var. Italica) color were coupled with heat transfer equation (2D conductive heat transfer in cylindrical packed broccoli samples), and their simultaneous numerical simulation followed by experimental validation was carried out. Obtained results revealed that modeling the rate constants of the reactions with log logistic equation provides a better prediction in comparison with the most popular Arrhenius equation. It was observed that processing at temperatures lower than 80 °C is not recommended for processing of broccoli due to its adverse effect on the color of samples and considerable longer process time needed for assuring sufficient inactivation of enzyme at the cold spot. Temperatures above 80 °C were suitable for this purpose because the process time needed for inactivating peroxidase at the cold spot of sample not only affected the green color of samples negatively, but oppositely it resulted in a higher greenness than the original value.

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