The Use and Performance of Household Refrigerators: A Review.

The domestic refrigerator is now a common household device with very few households in the developed world not possessing 1, or more, for the storage of chilled foods. Domestic storage is the last, and in many respects the most important, link in the food chill chain. Inadequate domestic refrigeration or cooling is frequently cited as a factor in incidents of food poisoning. The authors reviewed the temperature performance of refrigerators in 2008. This new review builds on that review, covering studies that have been published since (and those that were unfortunately missed in the first review), and also seeks to put this important stage of the food cold chain in its context. It is clear from the published data that many refrigerators throughout the world are running at higher than recommended temperatures. It is also clear that, despite improvements in energy use, the temperature performance and use of refrigerators have not changed significantly in the last 40 or so years. Many householders still remain unaware of the recommended refrigeration temperature range, how to ensure that the correct refrigeration temperature range is achieved, the importance of monitoring that it is being maintained, and the potential hazards of temperature abuse.

A Critical Review of AMR Risks Arising as a Consequence of Using Biocides and Certain Metals in Food Animal Production.

The focus of this review was to assess what evidence exists on whether, and to what extent, the use of biocides (disinfectants and sanitizers) and certain metals (used in feed and other uses) in animal production (both land and aquatic) leads to the development and spread of AMR within the food chain. A comprehensive literature search identified 3434 publications, which after screening were reduced to 154 relevant publications from which some data were extracted to address the focus of the review. The review has shown that there is some evidence that biocides and metals used in food animal production may have an impact on the development of AMR. There is clear evidence that metals used in food animal production will persist, accumulate, and may impact on the development of AMR in primary animal and food production environments for many years. There is less evidence on the persistence and impact of biocides. There is also particularly little, if any, data on the impact of biocides/metal use in aquaculture on AMR. Although it is recognized that AMR from food animal production is a risk to human health there is not sufficient evidence to undertake an assessment of the impact of biocide or metal use on this risk and further focused in-field studies are needed provide the evidence required.

Assessing the Impact of Heat Treatment of Food on Antimicrobial Resistance Genes and Their Potential Uptake by Other Bacteria-A Critical Review.

The dissemination of antibiotic resistance genes (ARGs) is a global health concern. This study identifies and critically reviews the published evidence on whether cooking (heating) food to eliminate bacterial contamination induces sufficient damage to the functionality of ARGs. Overall, the review found that there is evidence in the literature that Antimicrobial Resistant (AMR) bacteria are no more heat resistant than non-AMR bacteria. Consequently, recommended heat treatments sufficient to kill non-AMR bacteria in food (70 °C for at least 2 min, or equivalent) should be equally effective in killing AMR bacteria. The literature shows there are several mechanisms through which functional genes from AMR bacteria could theoretically persist in heat-treated food and be transferred to other bacteria. The literature search found sparce published evidence on whether ARGs may actually persist in food after effective heat treatments, and whether functional genes can be transferred to other bacteria. However, three publications have demonstrated that functional ARGs in plasmids may be capable of persisting in foods after effective heat treatments. Given the global impact of AMR, there is clearly a need for further practical research on this topic to provide sufficient evidence to fully assess whether there is a risk to human health from the persistence of functional ARGs in heat-treated and cooked foods.

An evaluation of improvements in carcass hygiene through the use of anal plugging of pig carcasses prior to scalding and dehairing.

This study evaluated the effect of plugging the anuses of pork carcasses prior to scalding and dehairing on Enterobacteriaceae contamination on pork carcass surfaces. Results showed that Enterobacteriaceae counts around the anuses of unplugged carcasses increased by 1.15 log CFU/cm(2) after the scalding and dehairing process, while counts in the same sample area from plugged carcasses showed no significant change in Enterobacteriaceae numbers. The percentage of plugged carcasses with Enterobacteriaceae counts (measured around the anuses of carcasses) below the level of detection (<1 log) was 23.5%, whereas only 2.9% of unplugged carcasses were below this level. In the context of a multiple-hurdle approach where incremental reductions in microbiological counts may be seen as positive, anal plugging may have particular benefit.

Decontamination of poultry carcasses using steam or hot water in combination with rapid cooling, chilling or freezing of carcass surfaces.

The effects of the application of steam at atmospheric pressure for times up to 20 s on the numbers of inoculated Campylobacter jejuni and Escherichia coli on whole chicken carcasses were investigated in a pilot steam cabinet. Steam treatments reduced the numbers of C. jejuni AR6 by ca. 1.8, 2.6 and 3.3 log(10) cfu cm(-2) in 10, 12 and 20 s, respectively. Corresponding reductions in numbers of E. coli K12 were 1.7, 2.3 and 2.8 log(10) cfu cm(-2). However, such treatments caused the skin to shrink and change colour. The optimum treatment for maximum reductions of C. jejuni and E. coli, least skin shrinkage and change of colour was concluded to be <12 s. Further work was carried out to determine whether a modified air chilling system in combination with steam or hot water decontamination treatments could be used to reduce numbers of pathogens, particularly campylobacters, on the surface of poultry carcasses. Whole chicken carcasses inoculated with C. jejuni and E. coli were either not treated, treated with steam at atmospheric pressure for up to 10 s or treated with hot water at 80 degrees C for up to 20 s, then either chilled by crust freezing, chilled at 0 degrees C, or chilled at 15 degrees C, in a pilot chilling chamber. The optimum combination was treatment with water at 80 degrees C for 20 s followed by crust freezing, which reduced the numbers of C. jejuni and E. coli by ca. 2.9 and 3.2 log(10) cfu cm(-2), respectively, without extensive degradation of carcass appearance.

The effect of air temperature, velocity and visual lean (VL) composition on the tempering times of frozen boneless beef blocks.

Beef blocks of two compositions, 100% and 50% visual lean (VL), in standard commercial packaging with nominal dimensions of 510×390×150mm were tempered from -18°C to -3°C using air at temperatures from 3°C to -3°C and velocities of 0.5 and 5ms(-1). These conditions were then modelled using a finite difference mathematical model and the accuracy of the model assessed by comparison with the experimental results. An extended range of conditions (including an intermediate air velocity of 2ms(-1) and an intermediate composition of 75% VL) was then modelled to produce data that can be used to design tempering processes. The results show that single stage air tempering of even single blocks within their cartons needs to be a long process. In air at 3°C and 5ms(-1), blocks of 50% VL rose to deep temperatures of -10°C and -3°C after 4.0 and 22.5h, respectively, while with 100% VL 4.6 and 27.3h were required. Under these conditions, the surface layers of the meat would have spent many hours in a thawed condition that would be detrimental to both drip and optimal processing. Using lower temperatures avoids thawing and at the same time produces an optimum temperature difference for subsequent processing. However, tempering times are substantially extended. For example, times to the above temperatures using air at -1°C and 5ms(-1) were 4.8 and 37.5h for 50% VL and 5.1 and 44.5h for 100% VL.