Modelling the interaction of storage temperature,pH, and water activity on the growth behaviour of Listeria monocytogenes in raw and pasteurised semi-soft rind washed milk cheese during storage following ripening

The objective of this study was to investigate the growth of Listeria monocytogenes in semi-soft rind washed cheese made from raw and pasteurised milk at different storage temperatures (4, 10 and 15 °C) over a 28 day period simulating storage following ripening. Changes in water activity (a_w) and pH in cheeses were also monitored during storage. Response surface models were used to model the interaction of storage temperature and time on a_w, pH and L. monocytogenes population. Growth curves were fitted using Baranyi, modified Gompertz and Logistic models at all storage temperatures for both cheeses, and model parameters were statistically analysed. In raw and pasteurised milk cheeses, all models showed a significant (P < 0.05) increase in the specific growth rate (SGR, Day⁻¹) of L. monocytogenes with an increase in storage temperature. A higher SGR was observed for L. monocytogenes in pasteurised milk cheese (0.18–0.85 Day⁻¹) compared to raw milk cheese (0.05–0.37 Day⁻¹) at all storage temperatures studied. Response surface models indicated an increase in the L. monocytogenes population and pH with an increase in storage temperature. However, a decreasing trend in a_w for both cheese types was observed. The predicted regression model parameters for both the raw and pasteurised milk cheese showed a high correlation coefficient R² > 0.87. Overall, the L. monocytogenes population increased up to 3 log₁₀ cfu⁻g⁻¹ for both cheeses during storage following ripening. The fitted models confirmed different L. monocytogenes growth behaviour between raw and pasteurised milk cheeses, which could support the Food Business Operator in predicting growth during storage following ripening.     

Culture-independent quantification of pathogenic bacteria in spices and herbs using real-time polymerase chain reaction

A culture-independent method was developed for quantification of pathogenic bacteria in spices and herbs. The method is based on DNA extraction using cetyltrimethylammonium bromide (CTAB) and on real-time polymerase chain reaction (PCR). When evaluated with spices (black pepper, paprika) and herbs (oregano, parsley) artificially contaminated with Staphylococcus aureus, Salmonella enterica or Escherichia coli, the method demonstrated quantitative response with linear calibration lines and quantification limits of 10²–10⁴ CFU/g. The developed method is suitable for rapid microbiological analysis of spices and herbs, taking 8–9 h.     

Sporeforming bacteria in beer: Occurrence,diversity, presence of hop resistance genes and fate in alcohol-free and lager beers

The aim of this study was to assess the occurrence of sporeforming bacteria in different types of beers (n = 163) and to assess the presence of hor genes in the isolates. Additionally, the study aimed to evaluate the fate of five representative sporeforming bacteria harboring horA and horC genes in alcohol-free and lager beers. Two hundred and sixty (n = 260) sporeforming bacteria belonging to eight different genera were isolated from beers, i.e., Bacillus (n = 118), Paenibacillus (n = 89) and Brevibacillus (n = 41), Lysinbacillus (n = 6), Cohnella (n = 3), Rummeliibacillus (n = 1), Alicyclobacillus (n = 1), and Anoxybacillus (n = 1), respectively. A predominance of members within the Bacillus cereus sensu lato (n = 72; 27.1%), followed by B. megaterium (n = 18; 7%), P. validus (n = 16; 6.1%), P. humicus (n = 13; 5%), P. alginolyticus (n = 13; 5%) and Br. brevis (n = 13; 5%) was observed in beer samples analyzed. Only 5% (n = 14) out of 260 sporeforming bacterial isolates recovered from beers harbored one or both horA and horC genes. Only one (0.3%) isolate, i.e., Bacillus cereus sensu lato (identified as B. thuringiensis LMQA 206) presented both horA and horC genes. None of the five bacterial sporeforming strains harboring horA or horC genes inoculated was able to grow in the beers throughout the storage period studied, and no spoilage was detected. The results of this study indicated a widespread occurrence of sporeforming bacteria in several types of beers from different brands, highlighting that measures should be taken to reduce the occurrence of sporeforming bacteria considering stability and safety concerns.     

A survey on the occurrence of aflatoxin M1 in raw milk produced in Adana province of Turkey

During 2012, a total of 176 samples of raw milk obtained from dairy plants of Adana province of Turkey were analysed for the presence of aflatoxin M₁ (AFM₁). Aflatoxin M₁ analysis was carried out by centrifugation, liquid–liquid extraction, immunoaffinity column clean-up and high performance liquid chromatography with fluorescence detection (HPLC-FD). The limits of detection (LOD) and quantification (LOQ) of the analytical method were 0.021 μg kg⁻¹ and 0.025 μg kg⁻¹. Accuracy of the method obtained from bias ranged from 2.94 to 8.70. Aflatoxin M₁ was detected in 53 out of 176 samples analysed (30.1%). The ranges for positive samples were 0.042–0.552, 0.033–1.01, 0.047–0.150 and 0.025–0.102 μg kg⁻¹ in autumn, winter, spring and summer seasons, respectively. Thirty samples of raw milk (17%) were above the legal limits of Turkey and EU regulations.     

Knowledge,attitudes and practices of food handlers on food safety in food service operations at the Universiti Kebangsaan Malaysia

This study was conducted to determine the level of knowledge, attitudes and practices of food handlers in food service operation at the main campus of Universiti Kebangsaan Malaysia (UKM) regarding food safety. Data were collected from 112 food handlers through questionnaires which consisted of questions about knowledge, attitudes and practices. The results showed that there was significantly positive correlation among the three levels and respondents possess good scores for knowledge (19.68 ± 3.87) about personal hygiene, foodborne diseases and temperature control of food; for attitudes (89.26 ± 8.66) on safe food handling, and for practices (90.02 ± 8.23), specifically for appropriate hand washing, use of gloves in food preparation and prevention of food hazards. About 73.2% of respondents never attend any training related to food safety and majority show poor knowledge of pathogens associated with disease-causing agents as well as critical temperatures for storage of ready-to-eat foods. Therefore, effective and ongoing training on food safety and hygiene must be given to all food service employees to ensure the safety of food provided.     

Evaluation of food safety and sanitary practices among food vendors at car parks in Ile Ife,southwestern Nigeria

Globally, the street food business has expanded rapidly and provides access to a diversity of inexpensive, ready-to-eat variety of food for customers. Street Food vendors (SFVs) operate where numerous customers exist and their operations are poorly regulated in Nigeria. Globally, SFVs were implicated in several outbreaks of foodborne diseases. This study therefore evaluates the behavioural characteristics and hygiene practices of SFVs in car parks in Ile Ife, southwestern Nigeria.The study was cross sectional in design and utilized interviewer-administered questionnaire on 160 randomly selected SFVs, targeting demography, food and personal hygiene practices and knowledge of foodborne diseases.Most respondents were <40 years (134, 83.7%); females (147, 91.9%); married (125, 78.1%); had at least secondary education (144, 90%); and vend whole meals (151, 94.3%), respectively. In addition, only 27 (16.9%) ‘always’ wash hands after using the toilet; 100 (62.5%) ‘rarely’ keep finger nails short while only 6 (3.8%) SFVs ‘always’ refrigerate leftover cooked food, though experiences power outages that compromise refrigeration temperatures. About ⅔ (61.9%) of the SFVs had no formal training and their medical status is unknown. Hence, inception and refreshers trainings should be mandatory and enforced by appropriate authorities. In addition, supportive monitoring, supervision, among others are necessary to promote compliance.