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Food Protection Trends
Abstracts - May 2006
Effect of Added Citric Acid and Acetic Acid on the Survival of Staphylococcus aureus and Listeria monocytogenes in a Mayonnaise-based Salad
New England Home Gardeners’ Food Safety Knowledge of Fresh Fruits and Vegetables
Top Ten Food Safety Problems in the United States Food Processing Industry
Effect of Added Citric Acid and Acetic Acid on the Survival of Staphylococcus aureus and Listeria monocytogenes in a Mayonnaise-based Salad
Vanessa L. Bornemeier-1, Julie A. Albrecht-1, and Susan S. Sumner-2
1-Department of Nutritional Science & Dietetics, University of Nebraska, Lincoln, NE 68583-0807, USA
2-Department of Food Science, Virginia Polytechnical Institute and State University, Blacksburg, VA 24061, USA
SUMMARY
The study objective was to determine the effect of two concentrations (5% and 10%) of citric acid and
acetic acid on the survival of S. aureus and L. monocytogenes in a mayonnaise-based surimi salad. The pH of a
mayonnaise-based surimi salad (control, pH 5.45) was adjusted to approximately 5.0 and 4.6 with 5% and
10% citric acid or acetic acid. Duplicate samples of each salad were inoculated with 108 CFU/g S. aureus (FRI
100 SEA) or 107 CFU/g L. monocytogenes (ATCC 49594). Listeria monocytogenes-inoculated samples were held
at 4°C (refrigeration) for 28 days and 10°C (temperature abuse) for 8 days. Samples inoculated with S. aureus were held for 8 days at 10°C. Population samples were analyzed at predetermined intervals. Three replications
of the experiment were conducted. At 4°C, a 2 log reduction of L. monocytogenes was obtained for the noacid
control sample and the 5% citric acid sample by day 28. A 2.5 log reduction in L. monocytogenes was
observed for the 5% acetic acid and 10% citric acid sample, and a 3 log reduction was observed for the 10%
acetic acid sample. At 10°C, a 1 log reduction of L. monocytogenes was observed in the 5% citric acid sample
and a 1.5 log reduction in the no-acid control and 10% citric acid samples by day 8. The 5% and 10% acetic
acid samples decreased L. monocytogenes populations by approximately 2 log at 10°C. For salads inoculated
with S. aureus at 10°C, a slight reduction in S. aureus populations was observed in the no-acid control and the
5% citric acid samples by day 8. A 1.5 log reduction of S. aureus occurred in the 5% acetic acid sample, and a
2 log reduction in the 10% citric acid and 10% acetic acid samples. The overall effectiveness of added acidulants
on the inactivation of S. aureus and L. monocytogenes in a mayonnaise-based surimi crab salad were 10% acetic
acid > 5% acetic acid > 10% citric acid > 5% citric acid > no acid. However, the addition of acid should not be
a replacement for proper temperature control or proper food handling practices.
New England Home Gardeners’ Food Safety Knowledge of Fresh Fruits and Vegetables
Lori F. Pivarnik-1, Martha S. Patnoad-1, Nicole Leydon-1, and Robert K. Gable-2
1-University of Rhode Island, Nutrition and Food Sciences Department, 530 Liberty Lane, West Kingston, RI 02892,
USA
2-Educational Psychology, University of Connecticut, Educational Leadership Doctoral Program,
Johnson and Wales University, 26 Quail Run Road, Storrs, CT 06268, USA
SUMMARY
The objective of this research was to assess the knowledge of
and attitudes toward Good Agricultural Practices of home gardeners
in New England (NE). A survey was designed to measure food safety
knowledge and attitudes regarding growing and handling of produce
by home gardeners. By use of a professionally generated mailing list,
a questionnaire was distributed to 5,000 randomly selected
households of gardeners in 5 NE states. Respondents answered
questions on food safety topics for all aspects of gardening and postharvest
handling. “Agree,” “disagree” and “don’t know,” as well as
Likert scale response formats, were used. Content validity and
reliability were determined. Fifty-six knowledge questions for 762
respondents were assessed at item level and by use of five categories
of gardening timeline (e.g., soil preparation, planting) and four
categories of content (e.g., sanitation water quality). Mean percent
correct ranged from 61 to 71 for timeline and from 59 to 74 for
content areas, with the lowest scores for prior to planting/soil
preparation and water quality. With 80% taken as subject mastery
standard, respondents met the standard for only 23 of 56 items (41%).
Topics scoring low concerned use of fresh manure /compost, safety
of organically grown produce, cleaning produce, water safety and
home canning. Responses to attitudinal questions, alpha reliability
score of 0.75, were generally supportive of proper home gardening
practices; however, the relationship between attitude and knowledge
was lower than expected (r = .23). Significantly higher levels of
knowledge (P < .01) for timeline and/or content categories were
found for respondents with higher number of income, higher number
of gardening years or Master Gardener certification.
Top Ten Food Safety Problems in the United States Food Processing Industry
Aylin Sertkaya-1, Ayesha Berlind-1, Rachel Lange-1, and Donald L. Zink-2
1-Eastern Research Group, Inc. (ERG), 110 Hartwell Ave., Lexington, MA 02421, USA
2-FDA,
Center for Food Safety and Applied Nutrition (CFSAN), 5100 Paint Branch Pkwy., College Park, MD 20740, USA
SUMMARY
The preventive controls are less rigorous at some food processing
facilities than at others, potentially increasing the risk of
microbiological, chemical, and physical food safety hazards. We used
a modified three-round Delphi technique to generate expert opinion
on the ten food safety problems that are of top concern for the food
processing industry today, and the preventive controls needed to
address them. The expert panel members evaluated the frequency
and severity of the food safety risk posed for five food processing
industry sectors (baked, dairy, frozen, refrigerated, and shelf-stable
goods, excluding meat and poultry products) and three plant sizes
for each of the ten most important problems identified. The experts
collectively ranked “deficient employee training” as the top problem
facing food processors today, followed by “poor plant and equipment
sanitation” and “contamination of raw materials.” Other problems
included “poor plant design and construction,” “post-process
contamination,” “difficult-to-clean equipment,” and “incorrect labeling
and packaging.” The expert panel also made recommendations on
the types of preventive controls needed to address these problems.
Some of the main recommendations with broad applicability across
all food sectors included ongoing and targeted training of employees,
management, and suppliers; periodic audits of facility and raw material
suppliers; improved recordkeeping; and validation/evaluation of
activities such as employee training and cleaning procedures.
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