Utility of rapid tests to assess the prevalence of indicator organisms (Aerobic plate count, Enterobacteriaceae, coliforms, Escherichia coli, and Listeria spp.) in apple packinghouses

Before and After: Evaluation of Microbial and Organic Loads in Produce Handling and Packing Operations with Diverse Cleaning and Sanitizing Procedures

Inadequate cleaning and/or sanitation (C/S) of food contact surfaces (FCSs) has been frequently reported during Produce Safety Rule inspections; however, limited data are available evaluating the effectiveness of C/S processes in produce operations. Different C/S practices were evaluated in four fresh produce operations for their efficacy in reducing microbial and organic loads on various FCSs. Microbial (aerobic plate counts; APC) and organic (ATP) loads were quantified during production, after cleaning, and after sanitizing, if applicable. Operations included: a berry packinghouse (BerryPK; wet cleaning), a blueberry harvest contractor (BerryHC; cleaning + sanitizing, C+S), and two mixed vegetable packinghouses (MixedV1; C+S, and MixedV2; rinsing + sanitizing, R+S). Following wet cleaning, significant reductions in APCs (p < 0.05) were seen on high-density polyethylene (HDPE) storage trays (n = 50) in BerryPK (3.1 ± 0.9 to 2.5 ± 0.7 log CFU/100 cm2). In BerryHC, a greater reduction in APCs was seen on HDPE harvest buckets (n = 25) following C+S (3.8 ± 0.5 to 1.1 ± 0.4 log CFU/100 cm2), compared to wet cleaning only in BerryPK. Stainless steel and conveyor belt FCSs (n = 16) in MixedV1 were sampled, and a significant reduction in APCs (p < 0.05) was observed when comparing in-use (4.8 ± 1.3 log CFU/100 cm2) to post-C+S (3.9 ± 0.7 log CFU/100 cm2). When similar FCSs (n = 17) were sampled in MixedV2, R+S also led to significant reduction in APCs (3.3 ± 0.6 to 1.9 ± 0.6 log CFU/100 cm2) (p < 0.05). ATP testing in fresh produce settings yielded inconsistent results, with no correlation between organic and bacterial loads detected during production (R2 = 0.00) across four operations, and weak correlations observed after cleaning (R2 = 0.18) and after sanitation (R2 = 0.33). The results from this study provide the foundational basis for future research on practical and effective C/S methods tailored to the produce industry.

Comparison of coliform paper test and ATP bioluminescence assay for monitoring the disinfection of kitchen utensils in canteens of hebei, China

Background

Two common techniques used in canteen hygiene supervision, are the coliform paper assay, which is the standard method, and the adenosine triphosphate (ATP) bioluminescence method. The coliform paper assay requires the incubation of the sample, which is time-consuming and does not provide a real-time assessment. Meanwhile, the ATP bioluminescence assay can provide real-time kitchenware cleanliness data.

Objective

This study aimed to compare these two methods for evaluating the sanitary condition of kitchenware and explore whether the ATP bioluminescence assay can be used as a standard method in sanitary inspection.

Methods

In this study, the cluster random sampling method was used to sample kitchenware from six canteens in the Hebei province, China. Samples were, assessed through the coliform paper test and ATP bioluminescence assay.

Results

Kitchenware negative rates for the coliform paper method and the ATP test were 64.39% and 49.07%, respectively. The Escherichia coli positive detection rate grew steadily as the relative light units (RLU) value for the ATP technique increased. The kappa coefficient for the two methods was 0.549, indicating that the two methods yield relatively consistent results.

Conclusion

Although currently not considered a standard method, simply using ATP detection is advantageous for quick on-site detection in catering unit hygiene supervision.

Minimally processed fruits as vehicles for foodborne pathogens

The consumption of minimally processed fruit (MPF) has increased over the last decade due to a novel trend in the food market along with the raising consumers demand for fresh, organic, convenient foods and the search for healthier lifestyles. Although represented by one of the most expanded sectors in recent years, the microbiological safety of MPF and its role as an emergent foodborne vehicle has caused great concern to the food industry and public health authorities. Such food products may expose consumers to a risk of foodborne infection as they are not subjected to prior microbial lethal methods to ensure the removal or destruction of pathogens before consumption. A considerable number of foodborne disease cases linked to MPF have been reported and pathogenic strains of Salmonella enterica, Escherichia coli, Listeria monocytogenes, as well as Norovirus accounted for the majority of cases. Microbial spoilage is also an issue of concern as it may result in huge economic losses among the various stakeholders involved in the manufacturing and commercialization of MPF. Contamination can take place at any step of production/manufacturing and identifying the nature and sources of microbial growth in the farm-to-fork chain is crucial to ensure appropriate handling practices for producers, retailers, and consumers. This review aims to summarize information about the microbiological hazards associated with the consumption of MPF and also highlight the importance of establishing effective control measures and developing coordinated strategies in order to enhance their safety.

Esnaf Lokantalarında Kullanılan Kesme/Doğrama Tahtalarının Gıda Güvenliği Açısından Değerlendirilmesi: İstanbul Örneği

Amaç: Çalışma, gastronomi kültürünün vazgeçilmez bir unsuru olan esnaf lokantalarında gerçekleşmesi olası kritik halk sağlığı ve gıda güvenliği risklerinin başında gelen kesme/doğrama tahtalarından kaynaklı mikrobiyal risklerin belirlenmesi amaçlanmıştır.Yöntem: Çalışma kapsamında İstanbul’un ilçeleri Büyükçekmece, Çatalca ve Silivri’de faaliyet gösteren esnaf lokantalarının mutfaklarında kullanılan kesme/doğrama tahtaların yüzeylerinden steril swap ile mikrobiyolojik numuneler alınmıştır. Numuneler uygun sıcaklık ve sürede inkübasyona bırakılarak, toplam mezofilik aerobik bakteri, Staphylococcus aureus, Escherichia coli ve küf-maya sayımı yapılmıştır.Bulgular: Kesme/doğrama tahtalarının yüzeylerinden alınan mikrobiyolojik numunelerde Staphylococcus aureus, Escherichia coli, toplam mezofil aerob bakteri sayısı ve küf - maya sayısının ortalamaları sırasıyla 0,74; 0,61; 1,53 ve 1,21 logkob/10 cm2 tespit edilmiştir. Numunelerde değişik sayılarda Staphylococcus aureus tespit edilmesi personel kaynaklı bir kontaminasyona ve yine değişik sayılarda Escherichia coli tespit edilmesi ise fekal kaynaklı bir kontaminasyona işaret etmektedir.Sonuç: Esnaf lokantalarının gıda güvenliği uygulamalarından biri olan iyi üretim uygulamalarına yeterince uyulmadığı tespit edilmiştir. Esnaf lokantalarında gıda güvenliğinin tamamen sağlanabilmesi için Hazard Analysis and Critical Control Point - Tehlike Analizleri ve Kritik Kontrol Noktaları (HACCP) gibi gıda güvenliği kontrol sistemlerinin de etkin şekilde uygulanması gerektiğini ifade etmek mümkündür.

Relationship between ATP Bioluminescence Measurements and Microbial Assessments in Studies Conducted in Food Establishments: A Systematic Literature Review and Meta-Analysis

ABSTRACT

Adherence to proper environmental cleaning practices is critical in food establishments. To validate cleanliness, cleaning practices should be routinely monitored, preferably by a rapid, reliable, and cost-effective method. The aim of this study was to determine whether a correlation exists between ATP bioluminescence measurements and selected microbial assessments in studies conducted in food establishments. A systematic literature review and meta-analysis was conducted using the principles of preferred reporting items for systematic reviews and meta-analyses. Twelve online databases and search engines were selected for the review. Peer-reviewed articles published in English between January 2000 and July 2020 were included in the search. From a total of 19 eligible studies, 3 that included Pearson correlation coefficients (r) between ATP bioluminescence measurements and microbial assessments were used for the meta-analysis calculations. Only the fixed-effect model produced a strong correlation because one value dominated the estimates: r = 0.9339 (0.9278, 0.9399). In contrast, both the random effects model, 0.2978 (0.24, 0.3471), and the mixed effects model, r = 0.3162 (-0.0387, 0.6711), indicated a weak relationship between ATP bioluminescence and microbial assessments, with no evidence of a strong correlation. The meta-analysis results indicated no sufficient evidence of a strong correlation between ATP bioluminescence measurements and microbial assessments when applied within food establishments. This lack of evidence for a strong correlation between the results of these two monitoring tools suggests that food establishments cannot depend on only one method. Yet, with immediate feedback and quantification of organic soiling, ATP bioluminescence could be an effective monitoring tool to use in food establishments.

HIGHLIGHTS

Persistence of Listeria innocua on Fresh Apples during Long-Term Controlled Atmosphere Cold Storage with Postharvest Fungal Decay

ABSTRACT

Recent apple-related recall and outbreak events have exposed a need for better food safety controls along the supply chain. Following harvest, apples can be stored under a controlled atmosphere for up to 1 year after harvest before packing and distribution, making the crop susceptible to many opportunities for contamination that increase the quantity of postharvest losses. Botrytis cinerea and Penicillium expansum cause significant rot-associated losses to the apple industry. These fungi can colonize and destroy apple tissue as storage duration increases, which may also impact the growth of saprophytic foodborne pathogens like Listeria monocytogenes. Thus, the objective of this study was to observe population changes of Listeria innocua as a surrogate for L. monocytogenes on apples inoculated with B. cinerea or P. expansum under long-term controlled atmosphere cold storage conditions to identify the effect of postharvest mold growth on growth patterns of a microorganism relevant to food safety. 'Gala' and 'WA 38' apples (n = 1,080) were harvested, treated with pyrimethanil, and inoculated with L. innocua only or with L. innocua and one of the mold species on wounded and unwounded portions of the apple equator. Apples were treated with 1-methylcyclopropene and stored at a controlled atmosphere (2 kPa O2, 1 kPa CO2, 1°C) for 1 week and 1, 3, 6, 9, and 11 months before enumeration. After 3 months, L. innocua consistently fell below the limit of detection (2.35 Log CFU/g), and samples were enriched following a modified Bacteriological Analytical Manual method with PCR confirmation. Listeria persistence was dependent on the storage duration and type of fungal contamination (P ≤ 0.05). Surface wounding may impact these trends, depending on the apple variety. Prevalence of L. innocua was greater in Gala apples. Future studies should more closely examine the interactions on the fruit surface that occur during the seemingly critical time frame of 3 to 6 months in storage.

HIGHLIGHTS

Low-cost portable bioluminescence detector based on silicon photomultiplier for on-site colony detection

A low-cost, portable bioluminescence detector based on a silicon photomultiplier (SiPM) was developed for on-site colony detection, the main components of which are a low-noise photoelectric signal detection and processing circuit, power management module, and high-performance embedded microcontroller subsystem with peripheral circuits. Balanced chopper modulation and lock-in amplification techniques were adopted to improve the signal-to-noise ratio, and a zero-adjustment technique was used to eliminate the dark current of the SiPM to expand the dynamic range. Using this bioluminescence detector, adenosine triphosphate could be determined in the range of 3.6 × 10^-6 to 3.6 × 10^-11 mol/L, and bacterial colonies could be determined in the range of 1.0 × 10³ to 1.0 × 10⁹ CFU/mL, with a limit of quantitation of 1.0 × 10³ CFU/mL. Satisfactory recoveries and precision were obtained. Actual samples were accurately tested and the data were verified by comparison with those from the national standard method. The manufacturing cost of the bioluminescence detector was only $30, which is only approximately 1% of the price of current commercial instruments. This study provides a tool for rapid on-site detection of bacterial colonies, as well as a new concept for the development of low-cost portable detection equipment.

Comparison of the disinfecting effect of sodium hypochlorite aqueous solution and surfactant on hospital kitchen hygiene using adenosine triphosphate swab testing

The Japanese Ministry of Health requires large-scale cooking facilities to use sodium hypochlorite aqueous solution (HYP) on food preparation tools, equipment, and facilities to prevent secondary contamination. This study aimed to compare the disinfecting effect of HYP and surfactant using adenosine triphosphate (ATP) swab testing on large-scale equipment and facilities that could not be disassembled and disinfected in hospital kitchen. From May 2018 to July 2018, ATP swab tests were performed on the following six locations in the Shizuoka Cancer Centre Dietary Department Kitchen: cooking counter, mobile cooking counter, refrigerator handle, conveyor belt, tap handle, and sink. Six relative light unit (RLU) measurements were taken from each location. The log₁₀ values of the RLU measurements were evaluated by dividing the samples into two groups: the control group (surfactant followed by HYP swabbing) and the HYP group (HYP swabbing only). The results showed that the RLUs (log₁₀ values) in both the groups improved after disinfection (p<0.05), except for the RLUs (log₁₀ values) of the mobile cooking counter, tap handle, and sink in the control group after the HYP swab. The changes in the RLU (log₁₀ value) did not differ between the two groups for all locations of the kitchen. Hence, HYP swabbing of large-scale equipment and facilities provides the same level of disinfection as surfactants and can be as beneficial.

Prevalence of Listeria Species on Food Contact Surfaces in Washington State Apple Packinghouses

The 2014 caramel apple listeriosis outbreak was traced back to cross-contamination between food contact surfaces (FCS) of equipment used for packing and fresh apples. For Washington state, the leading apple producer in the United States with 79% of its total production directed to the fresh market, managing the risk of apple contamination with Listeria monocytogenes within the packing environment is crucial. The objectives of this study were to determine the prevalence of Listeria spp. on FCS in Washington state apple packinghouses over two packing seasons and to identify those FCS types with the greatest likelihood to harbor Listeria spp. Five commercial apple packinghouses were visited quarterly over two consecutive year-long packing seasons. A range of 27 to 50 FCS were swabbed at each facility to detect Listeria spp. at two sample times, (i) postsanitation and (ii) in-process (3 h of packinghouse operation), following a modified protocol of the FDA's Bacteriological Analytical Manual method. Among 2,988 samples tested, 4.6% (n = 136) were positive for Listeria spp. Wax coating was the unit operation from which Listeria spp. were most frequently isolated. The FCS that showed the greatest prevalence of Listeria spp. were polishing brushes, stainless steel dividers and brushes under fans/blowers, and dryer rollers. The prevalence of Listeria spp. on FCS increased throughout apple storage time. The results of this study will aid apple packers in controlling for contamination and harborage of L. monocytogenes and improving cleaning and practices for sanitation of the FCS on which Listeria spp. are the most prevalent.IMPORTANCE Since 2014, fresh apples have been linked to outbreaks and recalls associated with postharvest cross-contamination with the foodborne pathogen L. monocytogenes These situations drive both public health burden and economic loss and underscore the need for continued scrutiny of packinghouse management to eliminate potential Listeria niches. This research assesses the prevalence of Listeria spp. on FCS in apple packinghouses and identifies those FCS most likely to harbor Listeria spp. Such findings are essential for the apple-packing industry striving to further understand and exhaustively mitigate the risk of contamination with L. monocytogenes to prevent future listeriosis outbreaks and recalls.