Journal of food protection最新文献

The potential of Raman hyperspectral imaging with a 785 nm excitation line laser was examined for the detection of aflatoxin contamination in corn kernels. Nine-hundred kernels were artificially inoculated in the laboratory, with 300 kernels each inoculated with AF13 (aflatoxigenic) fungus, AF36 (nonaflatoxigenic) fungus, and sterile distilled water (control). One-hundred kernels from each treatment were subsequently incubated for 3, 5, and 8 days. The mean spectra of single kernels were extracted from the endosperm side and the embryo area of the germ side, and local Raman peaks were identified based upon the calculated reference spectra of aflatoxin-negative and -positive categories separately. The principal component analysis-linear discriminant analysis models were established using different types of variable inputs including original full spectra, preprocessed full spectra, and identified local peaks over kernel endosperm-side, germ-side, and both sides. The results of the established discriminant models showed that the germ-side spectra performed better than the endosperm-side spectra. Based upon the 20 ppb-threshold, the best mean prediction accuracy of 82.6% was achieved for the aflatoxin-negative category using the original spectra in the combined form of both kernel sides, and the best mean prediction accuracy of 86.7% was obtained for the -positive category using the preprocessed germ-side spectra. Based upon the 100 ppb-threshold, the best mean prediction accuracies of 85.0% and 89.6% were achieved for the aflatoxin-negative and -positive categories separately, using the same type of variable inputs for the 20 ppb-threshold. In terms of overall prediction accuracy, the models established upon the original spectra in the combined form of both kernel sides achieved the best predictive performance, regardless of the threshold. The mean overall prediction accuracies of 81.8% and 84.5% were achieved with the 20 ppb- and 100 ppb-thresholds, respectively.

Listeria monocytogenes and Cronobacter sakazakii are two important foodborne bacterial pathogens. Bacterial endophytes, which reside in plant cells, can produce antimicrobial compounds to protect the host organism or inhibit pathogens. This study investigated the bacterial community of tropical fruits for their potential to inactivate L. monocytogenes or C. sakazakii in cantaloupe and liquid infant formula, respectively. Tropical fruits including papayas, dragon fruits, and sugar apples, were sourced from several countries. Candidate bacterial endophytes were recovered from these tropical fruits using blood agar and Reasoner’s 2A (R2A) agar and tested for potential inhibition against L. monocytogenes and C. sakazakii. A total of 196 bacterial endophytes were recovered from papayas, dragon fruits, and sugar apples. Among these bacterial endophytes, 33 (16.8%) and 13 (6.6%) of them demonstrated an inhibition zone against L. monocytogenes and C. sakazakii, respectively. The inhibitory strains were identified using 16S rRNA sequencing as Bacillus spp., Enterobacter spp., Klebsiella spp., Microbacterium spp., Pantoea spp., and Pseudomonas spp. A cocktail of Pantoea spp. and Enterobacter spp. was used in challenge studies with cantaloupe and significantly reduced the number of L. monocytogenes by approximately 2.5 log₁₀ CFU/g. In addition, P. stewartii demonstrated antagonistic activity against C. sakazakii in liquid infant formula, i.e., it significantly decreased the number of C. sakazakii by at least 1 log₁₀ CFU/mL. Thus, the use of bacterial endophytes recovered from fruits and vegetables could be a promising area of research. Their use as potential biocontrol agents to control bacterial pathogens in ready-to-eat foods warrants further investigation.

Listeria monocytogenes is a foodborne pathogen that lives in nature as a saprophyte. Two of the three most common serotypes that cause foodborne listeriosis are 1/2a and 4b. Within serotype 4b, there is a variant called 4bv-1. In the last decade, several produce-related outbreaks (linked to leafy salad, caramel apples, and stone fruit) were linked to 4bv-1 strains, specifically those of Sequence Type 382. This study assessed the fitness of ST 382 strains on lettuce leaf sections to determine if they are more fit on produce than strains of other serotypes. Strains of serotypes 1/2a, 4b, and ST 382 were inoculated as mixtures onto lettuce and incubated at 4 °C for 7 days or 25 °C for 24 h. Thirty L. monocytogenes colonies resulting from the growth on each lettuce piece were characterized for serotype by multiplex PCR, and the percentages of each serotype recovered were compared. In the individual mixtures with three strains, none of the ST 382 strains showed better fitness for growth on lettuce at either 4 °C or 25 °C. Overall, ST 382 strains showed better recovery from lettuce sections grown at 4 °C than at 25 °C. Statistical analysis of the recovery of twelve strains tested in competition experiments indicated that ST 382 strains were less fit for lettuce growth when competing against the other serotypes. The data indicate that ST 382 strains do not have a competitive fitness advantage on cut lettuce sections.

Over 40% of all U.S. Salmonella illnesses are attributed to consumption of contaminated meat and poultry products each year. Determining which serotypes cause the most outbreak illnesses associated with specific meat and poultry types can inform prevention measures. We developed an approach to categorize serotypes using outbreak illness burden (high, moderate, low) and trajectory (increased, stable, decreased). We used data from 192 foodborne Salmonella outbreaks resulting in 7,077 illnesses, 1,330 hospitalizations, and 9 deaths associated with chicken, turkey, beef, or pork during 2012–2021. We linked each meat and poultry type to 1–3 serotypes that we categorized as high outbreak illness burden and increased trajectory during 2021. Calculation and public display of outbreak illness burden and trajectory annually could facilitate the prioritization of serotypes for prevention by federal and state health and regulatory agencies and by the meat and poultry industry.

In-shell pecans are typically harvested after falling from trees to the ground, presenting a potential route of contamination of foodborne pathogens from soil contact. In-shell pecans are often subjected to various processing or washing steps prior to being shelled. This study determined Shiga toxin-producing Escherichia coli (STEC) reductions after treatment with antimicrobial washes on direct and soil-inoculated in-shell pecans and evaluated the cross-contamination potential of the spent pecan washes after treatment. Pecans were directly and soil-inoculated with an STEC cocktail (O157:H7, O157:NM, O121, O26). Direct inoculation was achieved by spraying the STEC cocktail on the pecans. For soil-inoculation pecans, autoclaved soil was sprayed with the STEC cocktail, homogenized for 2 min, and used to coat in-shell pecans. Inoculated pecans were washed in treatments of 2% lactic acid (LA), 1,000 ppm free chlorine (sodium hypochlorite; NaClO), hot water (HW; 85 ± 2 °C), or ambient water (C [control]; 18 ± 2 °C) for 2, 5, and 10 min and diluted to enumerate STEC populations. After treatments, 100 mL of the spent wash was vacuum filtered through a 0.45-µm membrane and plated on selective agar. HW significantly reduced STEC populations from pecans with and without soil regardless of treatment time (p < 0.05), NaClO reduced STEC populations more than the ambient control wash on directly inoculated pecans, but there were no significant differences between STEC reductions from ambient water (C), LA, and NaClO treatments on soil-inoculated pecans (p > 0.05). Larger STEC populations were enumerated from ambient water wash compared to the antimicrobial washes (p < 0.05). The HW, LA, and NaClO treatments were effective at maintaining the quality of the wash water, with STEC levels being generally at or below the detection limit (<1 CFU/100 mL), while HW was the most effective at reducing STEC from in-shell pecans with and without a soil coating (>5-log CFU/mL reductions).

Fresh produce is traditionally labeled with plastic price lookup (PLU) stickers that are attached to the produce surface using edible glue. However, both the stickers and glue are environmental contaminants, and the stickers can still easily detach from the produce surface during handling and disrupt traceability. An alternative method of labeling, the CO₂ laser-labeling technology (LLT), has been gaining attention in recent years. However, engraving Quick Response (QR) code using LLT is unique, and the performance of this technology varies from produce item to produce item, and information on its effects on postharvest quality, microbial safety, and economic feasibility has not been reported. The objectives of this study were to investigate the effect of laser-labeling technology on (1) postharvest quality, (2) microbial safety, and (3) economic analysis of this technology. Three horticultural crops, ‘Red Delicious’ apple (Malus pumila), green bell pepper (Capsicum annuum), and cucumber (Cucumis sativus) were procured from a local grocery store. Each produce was engraved with a Quick Response (QR) code or 6-digit alphanumerical (text) code using the commercially available Trotec Speedy 300 CO₂ laser engraver, followed by the application of edible wax. Fresh weight loss for laser-printed produce was higher compared to controls, but no difference in visual quality ratings was observed. The laser-labeled produce was assessed for microbial contamination by artificially inoculating rifampicin-resistant Escherichia coli (E. coli) log₁₀ 6 CFU/mL to the labeled fruit. The results showed that the population of rifampicin-resistant E. coli was statistically higher in all three products labeled with text code compared to the nontreated controls. The QR-coded treatments were similar to the controls. The wax application did not affect the microbial attachment on the laser-labeled produce. The CO₂ laser labeling technology has the potential for industrial application.

Histamine is one of the biogenic amines produced naturally in the human body, but also in foods, especially those rich in protein. Exogenous and endogenous histamine is subject to degradation in vivo, but in the case of sensitive groups, including children, these degradation processes may be less intense, resulting in adverse health effects from histamine excess. The aim of the study was to determine the histamine content in jarred baby foods containing fish, taking into account the selected product characteristics and storage conditions. The study included 140 meals with added fish, intended for infants and young children, from 5 leading manufacturers available in Poland. The infant meals were analyzed on the day of opening, after 24 h and 48 h of storage in the refrigerator and at room temperature. Histamine concentration was determined by ELISA. The THQ was calculated from the EDI values for histamine. Histamine was present in all analyzed baby foods. On the day of opening, the products had a lower content of this monoamine (Me = 2.59 mg/kg), which increased systematically during storage. Samples taken at 2 °C after 48 h showed an average histamine content of 4.4 mg/kg, while products stored at 22 °C at the same time showed a 1.8-fold higher concentration of this monoamine (Me = 7.9 mg/kg). Dishes containing tuna and sea fish had higher histamine levels on average than those containing pollock. The storage conditions of the children’s food had a significant effect on histamine concentration. The level of histamine in baby foods was related to the amount and type of fish in certain products. The results indicate the need for increased awareness of the risks associated with histamine, especially in a group of people with increased sensitivity to this amine, which may include infants and young children.

Salmonella in raw cocoa beans (n = 870) from main sourcing areas over nine months was analyzed. It was detected in 71 (ca. 8.2%) samples, with a contamination level of 0.3–46 MPN/g except for one sample (4.1 × 10⁴ CFU/g). Using prevalence and concentration data as input, the impact of thermal treatment in cocoa processing on the risk estimate of acquiring salmonellosis by a random Belgian chocolate consumer was calculated by a quantitative microbiological risk assessment (QMRA) approach. A modular process risk model from raw cocoa beans to cocoa liquor up to a hypothetical final product (70–90% dark chocolate tablet) was set up to understand changes in Salmonella concentrations following the production process. Different thermal treatments during bean or nib steam, nib roasting, or liquor sterilization (achieving a 0–6 log reduction of Salmonella) were simulated. Based on the generic FAO/WHO Salmonella dose–response model and the chocolate consumption data in Belgium, salmonellosis risk per serving and cases per year at population level were estimated. When a 5 log reduction of Salmonella was achieved, the estimated mean risk per serving was 3.35 × 10⁻⁸ (95% CI: 3.27 × 10⁻¹⁰–1.59 × 10⁻⁷), and estimated salmonellosis cases per year (11.7 million population) was 88 (95% CI: <1–418). The estimated mean risk per serving was 3.35 × 10⁻⁹ (95% CI: 3.27 × 10⁻¹¹–1.59 × 10⁻⁸), and the estimated salmonellosis cases per year was 9 (95% CI: <1–42), for a 6 log reduction. The current QMRA model solely considered Salmonella reduction in a single-step thermal treatment in the cocoa process. Inactivation obtained during other process steps (e.g. grinding) might occur but was not considered. As the purpose was to use QMRA as a tool to evaluate the log reduction in the cocoa processing, no postcontamination from the processing environment and ingredients was included. A minimum of 5 log reduction of Salmonella in the single-step thermal treatment of cocoa process was considered to be adequate.

Two U.S. outbreaks of salmonellosis in 2020 and 2021 were epidemiologically linked to red onions. The 2020 outbreak investigation implicated the production of agricultural water as a likely contamination source. Field trials were designed to investigate the prevalence and survival of Escherichia coli (surrogate for Salmonella) on dry bulb onions after the application of contaminated irrigation water at the end of the growing period. Irrigation water was inoculated at 3 log most probable number (MPN)/100 mL (2022 and 2023) or 5 log MPN/100 mL (2023, drip only) with a cocktail of rifampin-resistant E. coli and applied with the final irrigation (0.4 acre-inch/0.4 ha-cm) to onions. Onion bulbs (40 or 80) were sampled immediately after irrigation and throughout field curing (4 weeks) and E. coli was enumerated using an MPN method. For drip irrigation, at 3 log MPN/100 mL E. coli was detected on 13% of onions at 24 h but not detected at 0 h; at 5 log MPN/100 mL for drip irrigation applied to saturated soil, E. coli was detected in 63% of onions at 0 h. Prevalence significantly (P < 0.05), decreased after 7 d of curing with cell densities of 1–1,400 MPN/onion. At the end of field curing in 2023, 1/80 of onions had detectable E. coli (2.04 MPN/onion). E. coli was detected in a significantly smaller percentage of onions (2022: 13%; 2023: 68%) after a contaminated drip irrigation event compared to overhead irrigation (98–100%; P < 0.05). After overhead irrigation, E. coli was detected in onions (1–1,000 MPN/onion) on day 0. Prevalence decreased significantly (P < 0.05) after 7 d of field curing in both years (2022: 15%; 2023: 7%). E. coli was not detected on Calibra onions (80/year) at the end of field curing in either year but was detected at <12 MPN/onion in 2.5–3.75% of onions (n = 80) for other cultivars. These data confirm limited contamination risk associated with drip irrigation water quality and begin to quantify contamination risks associated with overhead irrigation of dry bulb onions.

Controlling Listeria in produce packinghouses can be challenging due to the large number of potential contamination routes. For example, repeated isolation of the same Listeria subtype in a packinghouse could indicate persistence in the packinghouse or reintroduction of the same Listeria from an upstream source. To improve understanding of Listeria transmission patterns in packinghouses, we performed a longitudinal study in four apple packinghouses, including testing of 1,339 environmental sponges and whole genome sequencing (WGS)-based characterization of 280 isolates. Root cause analysis and subsequent intervention implementation were also performed and assessed for effectiveness. Listeria prevalence among environmental sponges collected from the four packinghouses was 20% (range of 5–31% for individual packinghouses). Sites that showed high Listeria prevalence included drains, forklift tires and forks, forklift stops, and waxing area equipment frames. A total of 240/280 WGS-characterized isolates were represented in 41 clusters, each containing two or more isolates that differed by ≤50 high-quality single nucleotide polymorphisms (hqSNPs); 21 clusters were isolated from one packinghouse over ≥2 samplings (suggesting persistence or possibly reintroduction), while 11 clusters included isolates from >2 packinghouses, suggesting common upstream sources. Some interventions successfully (i) reduced Listeria detection on forklift tires and forks (across packinghouses) and (ii) mitigated packinghouse-specific Listeria issues (e.g., in catch pans). However, interventions that lacked enhanced equipment disassembly when persistence was suspected typically appeared to be unsuccessful. Overall, while our data suggest a combination of intensive environmental sampling with subtyping and root cause analysis can help identify effective interventions, implementation of effective interventions continues to be a challenge in packinghouses.