In recent years, there have been numerous recalls of frozen vegetable products due to Listeria monocytogenes contamination, which causes listeriosis. In pregnant women, listeriosis can cause miscarriage, stillbirth, and other serious complications. Manufacturing guidelines are created with the intention that frozen vegetables will be cooked prior to consumption. However, consumers may prepare and eat frozen vegetables without prior cooking. Therefore, it is necessary to assess behaviors that could be risky for L. monocytogenes exposure. A 10-question online survey was distributed to women between the ages of 18-54 to investigate frozen vegetable consumption behaviors. The prevalence of uncooked frozen vegetable consumption, reading preparation instructions, and listeriosis knowledge was assessed. Data were analyzed using logistic and ordered logit regression. Of 1,001 complete responses, 531 (53%) indicated that they consumed frozen vegetables in the past week, and of those 35.6% (n = 189) indicated that they consumed frozen vegetables without prior heating. Women who had not heard of listeriosis and had not read preparation instructions had significantly higher odds of uncooked frozen vegetable consumption (Odds Ratio (OR): 2.30, 95% Confidence Interval (CI): 1.48, 3.55; OR: 1.85, 95% CI: 1.13, 3.01, respectively). These results will guide future research on safe food handling practices for frozen vegetable products. The findings support the need for updating public health guidelines to include frozen vegetables as foods that are risky for listeriosis in pregnancy. Additionally, these findings have implications for future research to inform food policy governing labeling regulation on frozen vegetable products to reflect current consumer behavior.

Accurate detection, identification, and subsequent confirmation of pathogens causing foodborne illness are essential for the prevention and investigation of foodborne outbreaks. This is particularly true when the causative agent is an enteric virus that has a very low infectious dose and is likely to be present at or near the limit of detection. In this study, whole-genome sequencing (WGS) was combined with either of two non-targeted pre-amplification methods (SPIA and SISPA) to investigate their utility as a confirmatory method for RT-qPCR positive results of foods contaminated with enteric viruses. Frozen berries (raspberries, strawberries, and blackberries) were chosen as the food matrix of interest due to their association with numerous outbreaks of foodborne illness. The hepatitis A virus (HAV) and human norovirus (HuNoV) were used as the contaminating agents. The non-targeted WGS strategy employed in this study could detect and confirm HuNoV and HAV at genomic copy numbers in the single digit range, and in a few cases, identified viruses present in samples that had been found negative by RT-qPCR analyses. However, some RT-qPCR-positive samples could not be confirmed using the WGS method, and in cases with very high Ct values, only a few viral reads and short sequences were recovered from the samples. WGS techniques show great potential for confirmation and identification of virally contaminated food items. The approaches described here should be further optimized for routine application to confirm the viral contamination in berries.

A microbiological study was conducted on 41 insect product samples (29 raw frozen [21 domestic and 8 imported], 10 powdered, and 2 processed), which were commercially available in Japan. The total aerobic count for raw frozen insects was 5.61 log cfu/g (range: 2.52-8.40), whereas the powdered insect count was 2.89 log cfu/g (range: 1.00-4.57). The bacterial count was significantly higher in raw frozen insects (p < 0.05). The coliform count for the raw frozen insects ranged from <1 to 6.90 log cfu/g, and that for the powdered insects ranged from <1 to 1.00 log cfu/g. The number of samples with values above the detection limit was significantly higher in raw frozen insects (p < 0.05). The detection frequencies of aerobic spores (<1-4.63 log cfu/g), anaerobic spores (<0-4.40 log cfu/g), and Bacillus cereus (<1.7-3.83 log cfu/g) showed no sample type-related significant difference. Listeria spp. was isolated from four samples of raw frozen insects, one of which was Listeria monocytogenes. We did not detect any of the following: Salmonella spp., Shiga toxin-producing E. coli (STEC), Campylobacter jejuni/coli, or pathogenic Yersinia. We isolated insect products retailed in Japan harboring food poisoning bacteria, including L. monocytogenes and B. cereus. In particular, raw frozen products displayed high levels of hygienic indicator bacteria.

In March 2019, the Finnish Institute for Health and Welfare and Finnish Food Authority started an outbreak investigation after a notification of food business operators\' recall of frozen bilberries due to a norovirus finding. A retrospective search was conducted in the food and waterborne outbreak notification system to identify the notifications linked to norovirus and consumption of bilberries in January-March 2019. Five outbreaks were found in which norovirus GII or GII.17 had been detected in patient samples. A pooled retrospective cohort study was performed for those four in which a questionnaire study had been done. A case was defined as a person with diarrhoea or vomiting within 2 days after consuming a meal studied at one of the outbreak locations. Of 79 participants, 45 (57%) cases were identified. Persons that had consumed foods containing unheated bilberries were three times more likely to get ill than those who had not consumed them (RR 3.1, CI 95% 1.2-8.1, p = 0.02). Norovirus GII.17 was found in 16/17 patient samples sent for further typing. Identical norovirus GII.17 was detected in frozen Finnish bilberries and patient samples. At the berry packaging premises, signs of norovirus GII contamination were found in packaging lines. A new procedure for extracting viral nucleic acid from food and environmental samples was used during the outbreak investigation. Consumption of industrially packed frozen berries as heated would be one of the means to prevent norovirus infections.

Magnetic field individually applied on the maximum ice crystal formation zone (MMF) and the whole freezing process (WMF) was compared to improve the quality of multiple freezing-thawing treated dough. All treatments showed that the breadmaking performances of magnetic field-assisted freezing were better than the conventional freezing. Especially, the WMF-treated breads exhibited higher resilience and lower firmness than MMF-treated breads. WMF treatment made dough remained a continuous and compact gluten-starch matrix while the starches and glutens got separated in MMF-treated dough. It could keep the gluten macropolymer from freezing-induced depolymerization with the decreased free sulfhydryl by 7.09% and more ordered secondary structure. WMF had positive effects on the homogeneous water distribution and high water-binding ability in frozen dough where the freezable water decreased from 32.47% to 30.77%. This comparative study of different freezing stages provided new insights into the better application of magnetic field on frozen dough-based food.

The French Lentil & Leek Crumbles frozen food product was recently recalled due to reports of gastrointestinal issues. So far, 393 adverse illness complaints and 133 hospitalizations have been reported from consumption of this food, and the tara (Tara spinosa) protein flour ingredient is hypothesized to be responsible. A multipronged approach resulted in identification of (S)-(-)-baikiain in tara as a compound of interest due to its abundance, possible metabolic fate, and close resemblance to irreversible inhibitors of L-pipecolate oxidase. Oral administration of baikiain in ND4 mice showed a statistically significant increase in blood ALT levels and a reduction in liver GSH.

The effectiveness of static magnetic fields with different intensities (5, 10, 15 mT) combined with liquid carbon dioxide spray freezing (LCSF) technique in improving the quality of frozen honeydew melon was investigated. The results showed that LCSF with magnetic fields above 10 mT significantly improved ice nucleation and quality of frozen melons compared to conventional -20 °C freezing, -80 °C freezing and LCSF method without magnetic field assistance (P < 0.05). 15 mT strength static magnetic field assistance suggested the best results, with a 15.0% reduction in total freezing time, 17.7% increase in average freezing rate, 26.6% reduction in drip loss, and better maintenance of sample quality compared to LCSF. These findings demonstrate that LCSF with static magnetic field assistance is promising in improving the quality of frozen foods.

Quaternary ammonium compounds (QACs) are a class of cationic surfactants that can be used as the main active ingredient of disinfectants. The increased use of QACs is concerning as exposure from inhalation or ingestion to these compounds that has been associated with adverse effects on the reproductive and respiratory systems. Humans are exposed to QACs primarily by food consumption and inhalation of air. QAC residues pose significant threats to public health. Given the importance of assessing potential residue levels for QACs in food, therefore, a method was developed for the simultaneous detection of six common QACs and one emerging QAC (Ephemora) in frozen food by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) coupled with the modified QuEChERS method. The main factors governing the response, recovery, and sensitivity of the method, including extraction solvents, types and dosages of adsorbents, apparatus conditions, and mobile phases, were optimized in the course of sample pretreatment and instrument analysis. QAC residues in frozen food were extracted using 20 mL methanol-water (90∶10, containing 0.5% formic acid) for 20 min by the vortex shock method. The mixture was ultrasonicated for 10 min and centrifuged at 10000 r/min for 10 min. A 1-mL aliquot of the supernatant was transferred to a new tube and purified using 100 mg of PSA adsorbents. After mixing and centrifugation at 10000 r/min for 5 min, the purified solution was analyzed. Target analytes were separated on an ACQUITY UPLC BEH C8 chromatographic column (50 mm×2.1 mm, 1.7 μm) at a column temperature of 40 ℃ and a flow rate of 0.3 mL/min. The injection volume was 1 μL. Gradient elution was performed using methanol and 5 mmol/L ammonium acetate solution as the mobile phases. Multiple reaction monitoring (MRM) was conducted in the positive electrospray ionization (ESI+) mode. The matrix-matched external standard method was used to quantify seven QACs. The optimized chromatography-based method completely separated the seven analytes. Good linear relationships were obtained for the seven QACs in the range of 0.1-100.0 ng/mL. The correlation coefficient (r2) ranged from 0.9971 to 0.9983. The limits of detection and limits of quantification ranged from 0.5 to 1.0 μg/kg and 1.5 to 3.0 μg/kg, respectively. Accuracy and precision were determined by spiking salmon and chicken samples with 3.0, 10.0, and 100.0 μg/kg of analytes, in compliance with the current legislation, with six replicates per determination. The average recoveries of the seven QACs ranged from 65.4% to 101%. The relative standard deviations (RSDs) were between 0.64% and 16.8%. Matrix effects of the analytes were between -27.5% and 33.4% in salmon and chicken samples after purifying using PSA. The developed method was applied to the determination of seven QACs in rural samples. QACs were detected in only one sample; the level did not exceed European Food Safety Authority specified residue limit standards. The detection method has high sensitivity, good selectivity and stability, and the results are accurate and reliable. It is suitable for the simultaneous rapid determination of seven QAC residues in frozen food. The results provide valuable information for future risk assessment studies targeting this class of compounds.

The effects of freeze-thaw (F-T) cycles on the shape retention of antifreeze peptides-based surimi ink (ASI) 3D structures were analyzed. The results showed that the ASI 3D structure has good shape retention ability, and the width, height, weight, and water holding capacity were 22.42 mm, 21.07 mm, 9.99 g, and 68.30 % even after F-T 4 times, respectively. The average area and equivalent diameter of ice crystals in ASI 3D structures only expand from 0.001 mm2 and 0.040 mm to 0.015 mm2 and 0.139 mm, respectively. The α-helix and β-sheet of myofibrillar protein in ASI 3D structure were slightly decreased by 44.16 ± 0.98 % to 33.33 ± 0.92 % and increased by 18.28 ± 4.45 % to 24.43 ± 1.60 %, respectively. The chemical bond and protein interaction have changed to some extent. AFPs can prevent denaturation and juice loss of surimi 3D structures after F-T. The results provide theoretical guidance for maintaining the shape retention of frozen 3D food structures.

The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from cold-chain foods to frontline workers poses a serious public health threat during the current global pandemic. There is an urgent need to design concise approaches for effective virus inactivation under different physicochemical conditions to reduce the risk of contagion through viral contaminated surfaces of cold-chain foods. By employing a time course of electron beam exposure to a high titer of SARS-CoV-2 at cold-chain temperatures, a radiation dose of 2 ​kGy was demonstrated to reduce the viral titer from 104.5 to 0 median tissue culture infectious dose (TCID50)/mL. Next, using human coronavirus OC43 (HCoV-OC43) as a suitable SARS-CoV-2 surrogate, 3 ​kGy of high-energy electron radiation was defined as the inactivation dose for a titer reduction of more than 4 log units on tested packaging materials. Furthermore, quantitative reverse transcription PCR (RT-qPCR) was used to test three viral genes, namely, E, N, and ORF1ab. There was a strong correlation between TCID50 and RT-qPCR for SARS-CoV-2 detection. However, RT-qPCR could not differentiate between the infectivity of the radiation-inactivated and nonirradiated control viruses. As the defined radiation dose for effective viral inactivation fell far below the upper safe dose limit for food processing, our results provide a basis for designing radiation-based approaches for the decontamination of SARS-CoV-2 in frozen food products. We further demonstrate that cell-based virus assays are essential to evaluate the SARS-CoV-2 inactivation efficiency for the decontaminating strategies.