Random or systematic sampling to detect a localised microbial contamination within a batch of food

Pathogenic microorganisms are known to be distributed heterogeneously in food products that are solid, semi-solid or powdered, like for instance peanut butter, cereals, or powdered milk. This complicates effective detection of the pathogens by sampling. Two-class sampling plans, which are deployed when the health hazard is severe and direct, specify how many samples have to be drawn. In order to take a representative sample, the sampling strategy is important, especially when the microorganisms are distributed heterogeneously or localised.This theoretical study shows the impact of random versus systematic sampling on the probability to detect localised microbial contamination in a batch of food. A statistical model was used to compare these sampling strategies. The microbial contamination was modelled as being present in one specific localised fraction of the batch in which the cells were randomly distributed, while no cells were present in the remaining part of the batch.The probability that the entire sampling scheme contains at least one cell was calculated for various numbers of samples drawn either randomly or systematically and was shown to depend on the size of the contaminated fraction, the microbial concentrations, and the number of samples drawn. The probability of detection was either equal or higher for systematic sampling as compared to random sampling. The maximal improvement in probability of detection was 0.37, when the sampling interval was equal to the size of the contaminated fraction, meaning that exactly one systematic sample hits the contaminated fraction. In those cases where the size of the contaminated fraction can be estimated, this study may assist in selecting the sampling strategy that is most optimal regarding probability of detection.     

Application of Bayesian Networks in the development of herbs and spices sampling monitoring system

Knowing which products and hazards to monitor along the food supply chain is crucial for ensuring food safety. In this study, we developed a model to predict which types of herbs and spices products and food safety hazards should preferentially be monitored at each level of the supply chain (suppliers, border inspection points, market and consumers). A Bayesian Network method was used to develop a model based on notifications reported in the Rapid Alert System for Food and Feed and the database of the Dutch national monitoring program for chemical contaminants in food and feed over the period 2005–2014. The model was constructed by randomly selecting ca. 80% of the 3126 data records and validated using the remaining ca. 20% of the records. Model validation showed that the prediction accuracy was higher than 85%. Results showed that the sampling plan is closely related to the place where the products are checked along the supply chain, the products and the country of origin. Our approach of integrating different data sources and considering the entire supply chain can support industry and authorities at border inspection points and at all control points along the herbs and spices supply chain in setting priorities for their monitoring program.     

Quantity-based microbiological sampling plans and quality after inspection

Sampling inspection plans are principally used to determine whether a batch of food is contaminated or not. In this theoretical research, we study the effect of increasing the analytical unit amount on the performance of microbiological sampling plans, and on the resulting quality after inspection. We discuss several scenarios of homogeneous and inhomogeneous contamination for assessing the consumer's risk. Several statistical approaches to describe the effect of an increase in analytical amount are studied. We provided a procedure for designing of the sampling plan for a given consumer's risk and according to different dispersion parameters and contamination levels.     

Environmental and food safety of spices and herbs along global food chains

Spices and herbs, which are consumed in small quantities, but used in a wide range of foods and food products, represent a unique segment within the food sector. Moreover, being distributed as mostly in their dried, low water activity formats and associated with very complex distribution product chains, specific concerns as regards food safety apply to these particular commodities. To promote the capability of the food sector and the society to detect, respond to and prevent bio-threats, data generated from the EU FP7 project “Securing the spices and herbs commodity chains in Europe against deliberate, accidental or natural biological and chemical contamination” (SPICED) are presented thematically including: general considerations, issues of sampling, chemical and microbial contamination, and food chain and societal aspects.     

Public and private standards for dried culinary herbs and spices—Part I: Standards defining the physical and chemical product quality and safety

Dried spices and culinary herbs are vulnerable products, which are used for their aroma (and colour). They are important ingredients in many processed foods, e.g. meat products, dairy products, and bakery products, and in most of our dishes. Food processors and consumers have high expectations regarding the organoleptic quality of culinary herbs and spices. Moreover, although used at relatively low amounts, herbs and spices can represent a health threat to the consumer, e.g. when contaminated with mycotoxins or adulterated with harmful colourants. The current review provides an overview from a European perspective on product standards covering (i) general physical and chemical specifications important for product quality and (ii) chemical characteristics concerning the safety of culinary herbs and spices. Focus is given to standards addressing dried culinary herbs and spices on global and European Union (EU) level. At some points, additional information on fresh herbs and on some national standards of non-EU member states is provided.General specifications for individual herbs and spices based on international agreements are developed by the International Organisation for Standardisation (ISO) and are currently under development by the Codex Alimentarius Commission. Besides global standards, the review outlines product specifications for dried culinary herbs and spices that are defined by national bodies and industry associations. To reduce potential chemical hazards, specific maximum and action levels are laid down for culinary herbs and spices. In EU law, these address besides residues of pesticides certain mycotoxins, heavy metals, persistent organic pollutants, and additives as described in the following.     

Reporting of traceability and food safety data in the culinary herb and spice chains

Reporting of information is crucial to enable backward and forward tracing of food along the chain, which is of main importance in case of non-compliance with legal obligations on food safety. Thus, food business operators in the European Union (EU) must enable tracing of any foodstuff one step forward and one step back. However, flux of information relevant for traceability and food safety can be a challenge in the supply chains of dried culinary herbs and spices.Results of a survey among herb/spice businesses – either located within the EU or exporting dried herbs/spices to the EU – showed the widespread use of electronic systems for recording and processing of traceability/food safety data. However, automated capture of transaction data and automated read-out/processing of reported data were rare. The survey indicates that besides electronic documents, typed paper documents are often exchanged between businesses. For data delivery along the chain, paper documents filled in by hand are still used – even in the EU or upon import to the EU. The document type as well as the forms varied, particularly in case of incoming herbs/spices. The forms used for reporting by the survey participants or by their suppliers covered mostly individual/company-specific forms. Standardised forms provided by herb/spice associations were rarely shared between these businesses. The extent of reporting of traceability data upon import to the EU and within the EU appears to be sufficient. Some additional traceability data that promote product tracing, such as the country of harvest, were frequently reported. Same was true for information on food safety hazards.     

Isolation,identification and antimicrobial resistance of Cronobacter spp. isolated from various foods in China

Cronobacter spp. are important foodborne pathogens that can cause severe diseases such as meningitis, sepsis, and necrotizing enterocolitis in neonates. In this study, 195 food samples, including cereals, cereal products, powdered infant formula (PIF), infant food formula, herbs, spices, vegetables, and fruits, were analyzed for the presence of Cronobacter spp. by culture-based method. The presumptive isolates were further confirmed by targeting the 16S rDNA gene using PCR. Out of 195 samples, 13 samples (6.7%) were positive for Cronobacter species. 12 of 85 cereal and cereal products (14.1%), and 1 of 22 herbs and spices (4.5%) were contaminated. In contrast, no Cronobacter was detected in commercial powdered infant formula, infant food formula, vegetables, or fruits. Alignment of 16S rRNA gene sequences showed that 13 isolates was most closely related to the genus Cronobacter. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis revealed that Cronobacter sakazakii was the only Cronobacter species isolated from various food samples. The antimicrobial susceptibility of 13 Cronobacter isolates was determined by the standard disk diffusion method. All isolated strains, except one resistant to ampicillin, were sensitive or displayed intermediate susceptibility to the 10 antimicrobial agents investigated. No multiple drug resistance was observed.     

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.     

The food safety impact of the Codex sampling plans for Listeria monocytogenes in ready-to-eat foods: An empirical case study applying the FAO/WHO sampling plan tool

Sampling plans are specified by the Codex Alimentarius Commission microbiological criteria for Listeria monocytogenes in ready-to-eat foods. This case study evaluates the direct food safety impact of the Codex sampling plans as estimated by the FAO/WHO web-based microbiological sampling plan analysis tool under different assumptions about the pathogen distribution, test procedures, and the fraction of lots tested. The case study uses L. monocytogenes concentration data available for deli-type salads to empirically illustrate application of the sampling tool. The results indicate that the estimated impact of the sampling plans is dependent on the partitioning of total observed variance into its within- and between-lot components. The presence-absence based sampling plan is relatively insensitive to the substantial uncertainty and variability of the sensitivity of the reference method for detection of L. monocytogenes. The analytical sample size for enumeration impacts the ability of the concentration-based sampling plan to discriminate between compliant and non-compliant lots. Reducing the frequency of lot testing dramatically changes the statistical properties of the sampling schemes. Skip-lot sampling places greater importance on compliance assurance than on the direct, curative impact of lot acceptance sampling.     

European alerting and monitoring data as inputs for the risk assessment of microbiological and chemical hazards in spices and herbs

Food chains are susceptible to contaminations from food-borne hazards, including pathogens and chemical contaminants. An assessment of the potential product-hazard combinations can be supported by using multiple data sources. The objective of this study was to identify the main trends of food safety hazards in the European spice and herb chain, and then, evaluate how the data sources can be used during each step of a microbiological and a toxicological risk assessment. Thereafter, the possibilities and limitations of the selected data sources for the risk assessment of certain hazards in spices and herbs are examined. European governmental alerting and monitoring data and legislation were examined and evaluated for particular product-hazard combinations. Pathogenic microorganisms, particularly Salmonella spp. and pathogenic Bacillus spp., were identified as a potential concern in black pepper and dried herbs, while mycotoxins like aflatoxin (B₁) and ochratoxin A were a probable concern in chilies (including chili powder and cayenne), paprika, and nutmeg. Evaluating multiple, accessible, data sources can support several steps during the risk assessment process as seen for the hazard identification step. Therefore, identifying the potential spice and herb food safety hazards in the chain and other specific data can support risk assessors in compiling a comprehensive risk assessment.     

Implementation of a food safety management system according to ISO 22000 in the food supplement industry: A case study

This work aims to present a methodology to carry out hazard and control measures assessments to properly establish operational prerequisite programmes (oPRPs) and the HACCP plan in the food supplement industry according to the ISO 22000 standard. This study focused on the manufacture of propolis, royal jelly and vitamin C ampoules, sold as energy boosters. Seven of the 13 hazards identified in this study were significant: two hazards were in the reception step (residues of pesticides, antibiotics and/or heavy metals (code 2) and contamination by pathogens (code 3)), two in the ingredients weighing step (cross-contamination by metabisulphite (code 9) and contamination by pathogens (code 10)), one in the mixture preparation step (contamination by pathogens and/or proliferation of microorganisms (code 11)) and two in the ampoule-filling and -sealing step (cross-contamination by metabisulphite (code 12) and contamination by pathogens (code 13)). After assessing the control measures, critical control points (CCPs) were determined in the hazards with codes 2, 9 and 12, which could be managed by an HACCP plan. The remaining hazards were managed by establishing oPRPs. Implementation of the ISO 22000 standard in the food supplement industry guarantees food safety and helps improve their competitiveness in the global market.     

Environmental sampling for Listeria monocytogenes control in food processing facilities reveals three contamination scenarios

Listeria monocytogenes enters the food processing facility via environment, or contaminated raw materials. To increase the understanding of L. monocytogenes environmental contamination in the meat and dairy food sector, six European scientific institutions sampled twelve food processing environments (FPEs) in a harmonized methodological approach. The selection of six previously assumed uncontaminated (UC) FPEs and six contaminated (C) FPEs was based on the L. monocytogenes occurrence information originating from the time prior to the current study. An aim of the study was to highlight, that FPEs regarded for years as uncontaminated, may also become L. monocytogenes contaminated and repeated environmental sampling could help to identify the potential sources of contamination.From a total of 2242 FPE samples, L. monocytogenes was present in 32% and 8.8% of meat and dairy processing environments, respectively. In the actual study, each FPE was contaminated with L. monocytogenes on at least one sampling occasion. Three contamination scenarios could be observed: (i) sporadic contamination in the interface of raw material reception and hygienic areas, (ii) hotspot contamination in the hygienic processing areas (iii), and widely disseminated contamination in the entirely FPE. These data demonstrate that L. monocytogenes are common colonizers of FPEs in the European processing facilities sampled and that a consistent cross-contamination risk exists. To avoid food contamination, a risk assessment approach should assign risk levels to critical control areas (CCAs) and identify those where cross-contamination should be essentially excluded.     

Potential of high-throughput sequencing for broad-range detection of pathogenic bacteria in spices and herbs

A broad-range culture-independent method was developed and evaluated regarding its sensitivity of detection of pathogenic bacteria in spices and herbs, with focus on paprika powder. The method involved DNA extraction using cetyltrimethylammonium bromide (CTAB), 16S rDNA amplification using universal bacterial polymerase chain reaction, and high-throughput sequencing on Illumina MiSeq platform. The sensitivity of the method was evaluated with series of model samples contaminated at different levels with Salmonella enterica and Escherichia coli (as representatives of Gram-negative bacteria) and Staphylococcus aureus (as a representative of Gram-positive bacteria). For spices (paprika, black pepper), the method had a screening-level sensitivity with limits of detection in the range of 10⁴–10⁵ CFU/g, and a semi-quantitative response. Low sensitivity (LOD ≥10⁷ CFU/g) was observed with herbs (oregano, parsley). The developed method demonstrated a good potential for microbiological screening of spices, with a prospect of further improvement of sensitivity based on progress in high-throughput sequencing technology.     

A risk-based pesticide residue monitoring tool to prioritize the sampling of fresh produce

Pesticide residues remain a key issue in food safety for consumers. Accordingly, pesticide residue monitoring at all stages of the food chain gains importance. In Europe, fresh produce processing and trading companies are requested to have a company-specific sampling plan that covers all on-site food safety risk issues. In settings where the prevalence of contamination is known and there are a limited number of suppliers, statistical sampling plans are easily designed based on theoretical calculations. Unfortunately, this is not the case in the current setting of fresh produce. In order to provide a workable alternative, empirical guidelines for the design of a risk-based sampling plan, applicable in a broad range of realistic scenarios, are established. These guidelines are based on the opinions of experts regarding the relative importance with respect to risk regarding five criteria related to products and suppliers. These criteria are: supplier guarantee, country of origin, cross-contamination, and processing and product risk. The opinions of the experts are aggregated in order to yield a weighted-sum-based risk indicator. This can facilitate the risk assessment of new scenarios and sample size calculations. While these guidelines for the design of a risk-based sampling plan do not provide guarantees for a statistically demonstrated level of safety, the plan has been proven to be a useable tool during validation. Finally, the use of this tool is demonstrated in a case study.     

National seasoning practices and factors affecting the herb and spice consumption habits in Europe

This study aimed to recognize herb and spice consumption habits as well as to explore certain factors having an influence on it in seven (Austria, Germany, Hungary, Ireland, Latvia, Slovakia, the Netherlands) member states of the European Union. A self-administered questionnaire survey was conducted in each country, comprising of 1731 European adults regularly preparing food at home. Pepper and paprika, as well as parsley and basil were found to be the most frequently consumed spices and herbs, respectively. Validation of the ‘spice consumption’ model indicated that knowledge regarding health issues of herbs and spices was of high importance, which may have had favourable effects on the consumption habits. In conclusion, this study suggests that emphasising of health issues − directly or as incorporated into gastronomic elements − can be a useful tool for the expansion of herb and spice consumption, as well as globalizing of national cuisines and the consumption of typical national spices and country specific characteristics which can be still identified in Europe.     

Characterisation of within-batch and between-batch variability in microbial counts in foods using Poisson-gamma and Poisson-lognormal regression models

In modelling risk management strategies (i.e., acceptance sampling plans, statistical process control), two basic assumptions have been normally made: that the true concentration of microorganisms are log-normally distributed within a batch, and that the variance of the samples is the same for a little or highly contaminated lot. Within a heterogeneous Poisson theoretical framework, these two assumptions have been evaluated by characterising the between-batch and within-batch variability in microbial counts. To this effect, three variants of regressions (random effects for within-batch means only, correlated and uncorrelated random effects for within-batch means and spread measures) based on the Poisson-gamma (m,1/k) and the Poisson-lognormal (μ,σ) models were fitted to six microbial data sets of TVC, coliforms and Escherichia coli on pre-chill and post-chill beef carcasses sampled from different production batches. For the high counts data sets, the Poisson-lognormal regression with random effects for within-batch means (μ) provided a better model for the estimation of the within-batch and between-batch standard deviation; whereas for the low counts data sets, the Poisson-gamma regressions were superior for the characterisation of within-batch and between-batch variability. However, the selection of a complex Poisson-gamma model with correlated (m,1/k) random effects against a simple Poisson-gamma with variable means (m) depended on the extent of between-batch heterogeneity in the dispersion factor 1/k. The need to introduce the between-batch variability notion in risk management was further highlighted by assessing the real effectiveness of a hypothetical sampling plan operating under the best-fit correlated random effects Poisson-gamma approach, whereby the within-batch dispersion factor was variable and conditional on the within-batch mean.     

A Bayesian network to optimise sample size for food allergen monitoring

Generally, sampling size is optimised considering a single specific constraint. However, for financial reasons, only one sample is usually defined and used to satisfy several objectives. It is therefore crucial to choose a sample that meets all the required objectives.This paper proposes an original method for optimising a sample plan to monitor allergen traces in products consumed by allergy sufferers. The proposed method, based on a Bayesian network, enables several different constraints to be considered within a single model and the integration of literature data on concentration levels of allergen traces in food. Moreover, the construction of a three-stage sampling plan took into account the consumption preferences of peanut allergy sufferers between products with or without labels on the presence of allergen traces, and between the categories and subcategories of products. This method was applied to data from the MIRABEL project which aims to assess risks related to peanut traces for French allergy sufferers.The results show how the model used all the available information and constraints to balance the total number of samples set at 900 for food categories/subcategories and labelling types. As required, the model favoured the most consumed product categories and subcategories. At the same time, it increased the number of samples when peanut concentration is low. This helps reduce the uncertainty on peanut concentrations in these products and consequently on risk estimation.In conclusion, the proposed method is a useful tool for public administrations, risk assessors and risk managers to improve sampling plans for monitoring allergen traces or other health hazards in food.     

Aflatoxins in spices,aromatic herbs,herb-teas and medicinal plants marketed in Italy

Twenty-seven aromatic herbs, 28 spices and 48 herbal infusions and med plants were analysed for estimation of aflatoxins by high-performance liquid chromatography (HPLC) using a post-column derivatisation procedure (Kobra cell) and a fluorescence detection. Samples were randomly collected, from 2000 to 2005, from markets, shops and bonded warehouse in Emilia Romagna Region, Italy. Of the 103 samples analysed only 7 spices resulted positives: 5 chilli-peppers, 1 nut meg and 1 cinnamon. Two samples contained the toxin at non-permissible levels. It’s interesting to note that none of the aromatic herb, herb-tea and medicinal-plant samples analysed was contaminated, even if they are from tropical countries.     

Prioritization of chemical hazards in spices and herbs for European monitoring programs

Monitoring programs are preferably risk-based, which allows focusing on the most relevant human health risks. In this study, a risk matrix was used to identify those chemical hazards that have the highest human health risk for the following spices and herbs: paprika/chilli powder, black pepper, nutmeg, basil, thyme, and parsley. Both the probability of occurrence and the severity of the hazard were assessed for 36 chemical compounds and classified into low, medium, high, and severe. Probability of occurrence was evaluated based on available monitoring data and RASFF notifications as well as possibilities for economic adulteration. Severity was assessed based on available toxicological reference values and classification of carcinogenicity. The results demonstrated that the mycotoxins aflatoxins and ochratoxin A, the pesticides chlorpyrifos and triazophos, and the dye Sudan I posed the highest human health risk for spices and herbs. These compounds should, therefore, have an increased monitoring frequency in these products.     

Occurrence and legislation of mycotoxins in food and feed from Morocco

Mycotoxins are natural food and feed contaminants, mainly produced by moulds of genera Aspergillus, Penicillium and Fusarium. The number of mycotoxins known to exert toxic effect on human and animal health is constantly increasing as well as the legislative provisions taken to control their presence in food and feed. Morocco, a North African country, surrounded by the Mediterranean Sea and Atlantic Ocean, has a climate characterized by high humidity and high temperature which favor growth of moulds. This paper gives an overview about the contamination levels and the occurrence of some mycotoxins (e.g. aflatoxins, ochratoxin A, and Fusarium toxins) in cereals, bread, milk, spices, wine, olives, poultry feeds, dried fruits and nuts; the average of contaminated samples was often above 50%. A section on mycotoxin regulations by Moroccan authorities is discussed with a comparison with international and European limits. Recent data about the contamination of foods and feed from Morocco by mycotoxins are considered in this review. Finally, the paper gives a last part with conclusions and principal prospectives and recommendations that should be undertaken by authorities and scientists during monitoring of mycotoxins in food and feed produced and/or commercialized in Morocco.