EAL

MHFS: Food Safety (2012-2013)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The purpose of this study was to determine the effect of different food-handling practices on the number of bacteria present in the prepared salad
Furthermore, the effect of incorrectly applying food safety measures on several critical control points (CCPs) on the contamination level of the salad was investigated for C. jejuni and L. casei.

Inclusion Criteria:

Not described.

Exclusion Criteria:

Not described.

Description of Study Protocol:

Recruitment

Participants were recruited by placing advertisements in the local newspapers in Wageningen (a university and agricultural town in the Netherlands) and the surrounding area and in Utrecht
Participants received a gift voucher of $18 and were thanked for their cooperation.

Design

Cross-sectional study.

Statistical Analysis

Not described.

Data Collection Summary:

Timing of Measurements

First, an interview was conducted to determine what consumers know about food preparation in relation to safety. A qualitative, exploratory approach was used to obtain information.
Second, observational data was collected to identify how consumers actually prepared food.
Third, to determine how hazardous the consumer behavior actually is the number of bacteria that survive was determined by inoculating a chicken fillet with high levels of L. casei. Participants were then asked to prepare a recipe of chicken curry salad and all ingredients were provided by the researchers.

Dependent Variables

Food-handling practices

Participants were told that they would be part of a study on the quality of a prepared meal and they were asked to prepare a chicken salad curry using a recipe provided by the researcher
Consumers were asked to use their own pots and cutlery; and the chicken breast fillet introduced risks of cross-contamination and risk of undercooking. The recipe was provided as a listed sequence of actions which was designed to include several opportunities for cross-contamination.
Participants were videotaped by one of the researchers using a small hand-held digital video camera
After the meal was prepared by the respondent, it was immediately placed in a cooling box containing ice-packs to be transported to the laboratory for microbial analysis
The study then continued with an interview. Participants were given ample opportunity to ask the researchers questions and received an information leaflet with the researchers' contact details.

Independent Variables

Consumer food safety knowledge.

Description of Actual Data Sample:

Initial N: 16 participants from Wageningen and nine from Utrecht (22 female participants and three male participants)
Attrition (final N): 16 participants from Wageningen and nine from Utrecht (22 female participants and three male participants)
Age: Average age is 40 years (minimum, 19 years; maximum, 61 years)
Ethnicity: Not reported
Other relevant demographics: Educational level varied from vocational school to university degree
Anthropometrics: Not reported
Location: Wageningen and Utrecht, The Netherlands.

Summary of Results:

Key Findings

While most consumers are knowledgeable about the importance of cross-contamination and heating in preventing the occurrence of foodborne illness, this knowledge is not necessarily translated into behavior
The adoption of habitual cooking practices may also be important
Potentially risky behaviors were observed in the domestic preparation environment: 18 of the participants made errors in food preparation that could potentially result in cross-contamination and seven participants allowed raw meat juices to come into contact with the final meal
13 of 25 participants implicitly or explicitly stated that they found it difficult to recall meal preparation practices because they cooked by habit or experience
14 of 25 participants mentioned Salmonella when asked to tell the interviewer what they knew about bacteria
Many participants indicated that hygiene is important in the control of bacterial contamination. Several participants also indicated that thorough heating can be a mixed blessing since overcooking may destroy the taste of vegetables.
When considering the question of domestic hygiene, we found that consumers considered cleaning and cross-contamination highly relevant
A mean meat cooking time of 13 minutes (SD=9'36") was observed and the shortest cooking time was 2'44" and the longest 41'30"
In total, over all the participants, 98 occurrences of hand-washing were recorded, of which only 14 were completed correctly
On average, participants washed their hands 3.9 times during the course of recipe preparation
Four consumers placed the unpeeled fruits (apple or orange) on the cutting board with the raw chicken
The most common mistake was rinsing the cutting board (24% of participants) or the cutlery (12% of participants) without detergent or with only cold water
42% of the variance in log reductions in the finished salad could be explained by observed cross-contamination practices. Adding the procedural safety knowledge measure, constructed from remarks in the open-ended interview, accounted for another 12%
Using a tracer micro-organism, the log reduction as a result of consumer preparation was estimated at an average of log 4.1cfu per salad. It was found that cross-contamination errors were a good predictor for log reduction.
Procedural food safety knowledge (knowledge proffered after general open questions) was a better predictor of efficacious bacterial reduction than declarative food safety knowledge (knowledge proffered after formal questioning).

Author Conclusion:

The transdisciplinary approach adopted in this research facilitated identification of potential problems in domestic food hygiene preparation practices, as well as psychological factors that might explain why certain risky behaviors are adopted
By integrating interview data on food safety knowledge, observations of consumer food-handling practices and data on microbiological quality of the prepared meal, exposure can be better estimated and barriers to developing effective interventions identified
Combination of observational, interview and microbial sampling data permitted explanation of a greater proportion of the variance in obtained meal safety between consumers than could have been achieved using each approach independently
This suggests that motivation to prepare safe food was a better indicator of actual behavior than knowledge about food safety, per se.

Funding Source:

Government:

Dutch Ministry of Public Health

Not-for-profit

The Netherlands Organization for Health Research and Development

Other non-profit:

Other:

Nutrition, Health, Safety and Sustainability program of ZonMW

Reviewer Comments:

Inclusion and exclusion criteria and statistical analysis were not described
The authors noted that the intensive level of data collection and use of qualitative methods resulted in the use of a small sample, which of course does not represent the overall population of the Netherlands.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	N/A
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	N/A

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		No
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	No
	2.2.	Were criteria applied equally to all study groups?	N/A
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	No
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	Yes
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	Yes
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	Yes
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	Yes
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		N/A
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	N/A
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	Yes
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	Yes
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	Yes
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		No
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	No
	8.2.	Were correct statistical tests used and assumptions of test not violated?	No
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	No
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	N/A
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	No
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes