Category Archives: Bacillus cereus

Research – Modeling the inactivation of Bacillus cereus by infrared radiation in paprika powder (Capsicum annuum)

Wiley Online 

Infrared (IR) irradiation, a novel technology for modeling of decontamination of Bacillus cereus in paprika powder was evaluated and the effect on temperature profiles and total phenolic content was determined. The highest reduction in B. cereus count (2.3 log CFU/g) was achieved after a holding time of 1 min at 200 W IR power and 5 cm distance. The rapid rise in temperature was observed in surface paprika powder and the highest temperature at 200 W IR power and 5 cm distance reaching to 127.8°C. An increase in IR power and a decrease in sample distance of the IR lamp caused a significant decrease in the total phenolic content. The Double Weibull model closely predicted the inactivation of B. cereus in paprika powder by IR irradiation.

Research – Decontamination of Bacillus cereus in cardamom (Elettaria cardamomum) seeds by infrared radiation and modeling of microbial inactivation through experimental models

Wiley Online

In this work, infrared (IR) irradiation was used for inactivation of Bacillus cereus in cardamom seeds. The effect of IR power (100, 200, and 300 W), sample distance from radiation source (5, 10, and 15 cm) and holding times (0–11 min) was investigated on B. cereus count, as well as cardamom seeds color and temperature profiles. Inactivation of B. cereus on cardamom seeds during IR processing was demonstrated by experimental models. The highest reduction of B. cereus count (5.11 Log CFU/g) was achieved after 8 min IR irradiation at 300 W power and 15 cm distance. Measurement of temperature profiles revealed that there was a significant difference (p < .05) between surface and center temperatures of the cardamom seeds. The green color (a* value) of cardamom seeds was slightly affected and the highest color change was observed at 200 W IR, 10 cm distance and 10 min irradiation that resulted in an increase of a* from −3.05 ± 0.96 to −0.05 ± 0.44. In conclusion, IR irradiation could be successful for decontamination of cardamom seeds without severe alteration of its quality. Among the experimental models for microbial inactivation during IR processing, the Double Weibull model had the highest coefficient value of determination (R2 = 0.9966).

Research – A Study on Prevalence and Characterization of Bacillus cereus in Ready-to-Eat Foods in China

Frontiers in Microbiology

Bacillus cereus is widely distributed in different food products and can cause a variety of symptoms associated with food poisoning. Since ready-to-eat (RTE) foods are not commonly sterilized by heat treatment before consumption, B. cereus contamination may cause severe food safety problems. In this study, we investigated the prevalence of B. cereus in RTE food samples from different regions of China and evaluated the levels of bacterial contamination, antibiotic resistance, virulence gene distribution, and genetic polymorphisms of these isolates. Of the tested retail RTE foods, 35% were positive for B. cereus, with 39 and 83% of the isolated strains harboring the enterotoxin-encoding hblACD and nheABC gene clusters, respectively. The entFM gene was detected in all Bcereus strains. The cytK gene was present in 68% of isolates, but only 7% harbored the emetic toxin-encoding gene cesB. Antimicrobial susceptibility testing revealed that the majority of the isolates were resistant not only to most β-lactam antibiotics, but also to rifamycin. Multilocus sequence typing (MLST) revealed that the 368 isolates belonged to 192 different sequence types (STs) including 93 new STs, the most prevalent of which was ST26. Collectively, our study indicates the prevalence, bacterial contamination levels, and biological characteristics of B. cereus isolated from RTE foods in China and demonstrates the potential hazards of B. cereus in RTE foods.

Research -Inactivation of Bacillus cereus Spores on Stainless Steel by Combined Superheated Steam and UV-C Irradiation Treatment

Journal of Food Protection

ABSTRACT

Bacillus cereus spore contamination on food contact surfaces is of great concern in the food industry. Thus, in the present study, superheated steam (SHS) was used alone or combined with UV-C irradiation for inactivation of B. cereus spores inoculated on stainless steel coupons. Temperatures higher than 250°C were needed to effectively inactivate B. cereus spores by SHS treatment alone, while a synergistic bactericidal effect resulted from the sequential treatment of SHS before or after UV-C irradiation. The increased dipicolinic acid ratio obtained by the combined treatment had a significant role in the synergistic bactericidal effect. Therefore, the combined treatment of SHS and UV-C could be used effectively to inactivate B. cereus on stainless steel. It is recommended to use hurdle technology with reduced energy consumption to ensure microbiological safety on food contact surfaces.

HIGHLIGHTS
  • Inactivation of Bacillus cereus spores on stainless steel was identified in this study.

  • Superheated steam (SHS) was applied solely or combined with UV-C irradiation.

  • A synergistic effect was observed by combination treatment for spore inactivation.

  • The dipicolinic acid (DPA) release level increased significantly by combination treatment.

  • The combination treatment can be applied to sanitize food processing equipment.

Hong Kong – CFS announces food safety report for October

CFS

The Centre for Food Safety (CFS) of the Food and Environmental Hygiene Department today (November 29) released the findings of its food safety report for the last month. The results of about 16,400 food samples tested were satisfactory except for 21 samples and they were announced earlier. The overall satisfactory rate was 99.9 per cent.

A CFS spokesman said about 1,800 food samples were collected for microbiological tests, some 5,500 samples were taken for chemical tests and the remaining 9,100 (including about 8,400 taken from food imported from Japan) were collected to test radiation levels.

The microbiological tests covered pathogens and hygiene indicators, while the chemical tests included pesticides, preservatives, metallic contaminants, colouring matters, veterinary drug residues and others.

The samples comprised about 4,200 samples of vegetables and fruit and their products; 1,100 samples of cereals, grains and their products; 1,300 samples of meat and poultry and their products; 1,200 samples of milk, milk products and frozen confections; 2,000 samples of aquatic and related products; and 6,600 samples of other food commodities (including beverages, bakery products and snacks).

The 21 unsatisfactory samples comprised eight frozen confection samples detected with counts of hygiene indicator organisms exceeding the legal limits; three crab samples, one vegetable sample and one rice sample detected with excessive cadmium; two silver cod samples detected with mercury exceeding the legal limit; a fresh beef sample found to contain sulphur dioxide; a pickled green mustard sample detected with excessive preservative; a roast drumstick sample found to contain excessive Bacillus cereus; a vegetable sample detected with excessive pesticide residue; a nutmeg powder sample contaminated with aflatoxins; and a chilled chicken sample found to contain veterinary drug residue.

The CFS has taken follow-up action on the unsatisfactory samples, including informing the vendors concerned of the test results, instructing them to stop selling the affected food items and tracing the sources of the food items in question.

Since the Pesticide Residues in Food Regulation (Cap 132CM) came into effect on August 1, 2014, as of October 31 this year, the CFS has taken over 189,500 food samples at import, wholesale and retail levels for testing for pesticide residues. The overall unsatisfactory rate is less than 0.2 per cent.

The spokesman added that excessive pesticide residues in food may arise from the trade not observing Good Agricultural Practice, e.g. using excessive pesticides and/or not allowing sufficient time for pesticides to decompose before harvesting. The maximum residue limit (MRL) of pesticide residues in food is not a safety indicator. It is the maximum concentration of pesticide residues to be permitted in a food commodity under Good Agricultural Practice when applying pesticides. In this connection, consumption of food with pesticide residues higher than the MRL will not necessarily lead to any adverse health effects.

The spokesman reminded the food trade to ensure that food for sale is fit for human consumption and meets legal requirements. Consumers should patronise reliable shops when buying food and maintain a balanced diet to minimise food risks.

RASFF Alert – Bacillus cereus Enterotoxin – Pumpkin Seeds

RASFF-Logo

RASFF – Bacillus cereus enterotoxin (130000 CFU/g) in pumpkin seeds from China in the Netherlands

Research – Decontamination of Bacillus cereus in cardamom (Elettaria cardamomum) seeds by infrared radiation and modeling of microbial inactivation through experimental models

Wiley Online 

In this work, infrared (IR) irradiation was used for inactivation of Bacillus cereus in cardamom seeds. The effect of IR power (100, 200, and 300 W), sample distance from radiation source (5, 10, and 15 cm) and holding times (0–11 min) was investigated on B. cereus count, as well as cardamom seeds color and temperature profiles. Inactivation of B. cereus on cardamom seeds during IR processing was demonstrated by experimental models. The highest reduction of B. cereus count (5.11 Log CFU/g) was achieved after 8 min IR irradiation at 300 W power and 15 cm distance. Measurement of temperature profiles revealed that there was a significant difference (p < .05) between surface and center temperatures of the cardamom seeds. The green color (a* value) of cardamom seeds was slightly affected and the highest color change was observed at 200 W IR, 10 cm distance and 10 min irradiation that resulted in an increase of a* from −3.05 ± 0.96 to −0.05 ± 0.44. In conclusion, IR irradiation could be successful for decontamination of cardamom seeds without severe alteration of its quality. Among the experimental models for microbial inactivation during IR processing, the Double Weibull model had the highest coefficient value of determination (R2 = 0.9966).