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Consumer Poultry Freezing and Thawing: A New Zealand Survey

Study of the practice of freezing, and thawing poultry in New Zealand households, and its impact on pathogens such as Campylobacteriosis.

Year of Publication2008

Introduction: Campylobacteriosis is the most frequently reported gastrointestinal illness in New Zealand, with more than 50% of cases attributed to chicken consumption. Given the pathogen’s sensitivity to freezing, it has been argued that all fresh poultry should be temporarily withdrawn and replaced with frozen/processed alternatives. A previous survey identified that New Zealand consumers prefer to purchase fresh poultry but 66% then freeze more than 50% of fresh poultry in the home. This consumer practice was further investigated by collecting baseline information on: (i) domestic freezer types commonly in use; (ii) typical domestic freezer temperatures; and (iii) freezing and thawing temperature profiles for chicken portions. Methods: A preliminary email survey using ESR staff was conducted to analyse the prevalence of different freezer types in New Zealand. A questionnaire, two chicken portions (skin-on and skin-off) with attached data loggers and an air logger were then distributed to 41 urban Christchurch households to collect consumer poultry freezing and thawing data. Results: Freezer compartment air temperatures ranged between -11.5 and -23.3°C (mean - 16.6°C) with bottom-loading fridge-freezers the most frequently reported freezer type (43%). Freezer air temperature was significantly affected by data logger location and freezer loading. Freezer type, loading and sample location were also found to significantly influence sample freezing rates over a defined temperature range (from 0 to -5°C). The presence of skin did not have a statistically significant impact on freezing rates, and external and internal freezing rates were identical. Chicken samples thawed at room temperature (+19 to 28°C) took on average 11.4 hours to reach ambient temperature, while refrigerated thawing (-0.9 to +3.5°C) took considerably longer (18 to 72 hours). Discussion: Only 28% of surveyed domestic freezers operated at -18°C or below. Thawing overnight at room temperature, a common consumer practice in New Zealand, exposed poultry to only limited periods where pathogens (excluding Campylobacter) could potentially grow. Conversely the extended duration and inconvenience of thawing under recommended thawing conditions (+2 to 4°C) likely contributes to the consumer practice of room temperature thawing. These data should be taken into consideration when designing experimental work to determine the impact of poultry freezing as a food safety intervention.

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freezingcampylobacter
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Supporting the development of the national rural economy.

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