A structural modeling on food safety knowledge,attitude, and behaviour among Bum Bum Island community of Semporna,Sabah

The objective of this study was to evaluate the relationship among food safety knowledge, attitude and behavior in Bum Bum Island community, Semporna, Sabah. Proportional stratified sampling method was used in this survey. A total of 250 respondents were selected randomly from ten villages in Bum Bum Island. Face-to-face interview was conducted to complete the questionnaire. In general, respondents exhibited average food safety knowledge level especially in their awareness of personal hygiene and kitchenware hygiene. Food safety attitude of the community was found strongly affected their food safety behavior in positive way, which was proven by the highest standard β among variables tested (β₁ = 0.885, p < 0.05). However, food safety knowledge was negatively affected the food safety behavior of the respondents (β₁ = −0.128, p < 0.05). Our result confirmed that Structural Equation Modeling (SEM) was successfully used to model the relationship among food safety knowledge, attitude and behavior.     

Aflatoxin B1 production by Aspergillus parasiticus and strains of Aspergillus section Nigri in currants of Greek origin

Aflatoxin B₁ (AFB₁) mostly produced by Aspergillus flavus and Aspergillus parasiticus, is an extremely toxic and carcinogenic metabolite. Currants are used in the Mediterranean diet as a food with antioxidant properties. Four strains of Aspergillus section Nigri have been isolated from currants originated from Crete and Corinth. In this study AFB₁ production by A. parasiticus and the four strains of Aspergillus section Nigri in Cretan and Corinthian currants (Vitis vinifera L.) is investigated. AFB₁ determination was performed by HPLC–FID. Results revealed that the four strains Aspergillus section Nigri, as well as the aflatoxigenic strain A. parasiticus produced AFB₁ (0.0052–1.31 μg AFB₁ 15 g⁻¹, corresponding to 0.0003–0.087 μg AFB₁ g⁻¹) in both type of currants (Cretan and Corinthian) on the 12th day of observation. Moreover, AFB₁ production, by A. parasiticus in the synthetic Yeast Extract Sucrose (YES) medium was also studied. The ability of AFB₁ production has been affected by the special characteristics of each isolate and the currants substrate.     

Bioaccessibility and changes on cylindrospermopsin concentration in edible mussels with storage and processing time

The alkaloid cylindrospermopsin has been recognized of increased concern due to the global expansion of its main producer, Cylindrospermopsis raciborskii. Previous studies have shown that bivalves can accumulate high levels of cylindrospermopsin. Based on the potential for human health risks, a provisional tolerable daily intake of 0.03 μg/kg-body weight has been recommended. However, the human exposure assessment has been based on the cylindrospermopsin concentration in raw food items. Thus, this study aimed to assess the changes on cylindrospermopsin concentration in edible mussels with storage and processing time as well as cylindrospermopsin bioaccessibility. Mussels, (Mytilus galloprovincialis) fed cylindrospermopsin-producing C. raciborskii, were subjected to the treatments and then analyzed by LC-MS/MS. Mussels stored frozen allowed a significantly higher recovery of cylindrospermopsin (52.5% in 48 h and 57.7% in one week). The cooking treatments did not produce significant differences in cylindrospermopsin concentration in the mussel matrices (flesh), however, cylindrospermopsin was found in the cooking water, suggesting that heat processing can be used to reduce the availability of cylindrospermopsin. The in vitro digestion considerably decreased the cylindrospermopsin availability in uncooked and steamed mussels, highlighting the importance in integrating the bioaccessibility of cylindrospermopsinin in the human health risk assessment.     

Development of an aptasensor for the fast detection of Versicolorin A

Aflatoxins (AFs) are secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus. The molds may contribute to pre-harvest aflatoxin contamination of susceptible crops. For the customer and food producer, a predictive model for aflatoxin detection is very desirable. Versicolorin A (VerA), which is the first precursor in the pathway of aflatoxin B₁ (AFB₁) biosynthesis, shares similar toxic group with the furofuran structure in aflatoxin B₁. VerA exhibits a much lower teratogenic toxicity than AFB₁ and may be used as a predictive indicator for aflatoxin B₁ contamination of storage crops. Therefore, the development of a fast detection method for VerA is important. One of the randomly computer-generated aptamers of VerA was confirmed by isothermal titration calorimetry with K_d = 9.26 × 10⁻⁶ mol l⁻¹. In addition, a simple and sensitive label-free aptasensor was developed for the electrochemical detection of VerA. According to the results from differential pulse voltammetry (DPV), a linear relationship existed between the log conc. of VerA (ranged from 0.01 to 100 ng ml⁻¹) and the current (△I_p) with a limit of detection (LOD) of 10 pg ml⁻¹. The resulting aptasensor exhibited good reproducibility for detecting VerA and stability after storage for 15 days at 4 °C with acceptable anti-interference against ZEN, OTA, DON, and FB₁. When used in corn samples, the recoveries of VerA were determined to be in the range of 81.3%–104.4 %. Although with some intercross, result suggests that the obtained aptamer for VerA is potentially used as a sorbent for the preparation of solid-phase-extraction procedure to clean up food samples in conjunction with high-performance liquid chromatography analysis.     

Prevalence and antimicrobial resistance of Salmonella isolated from an integrated broiler chicken supply chain in Qingdao,China

The present study analyzed the prevalence and antimicrobial resistance of Salmonella along an integrated broiler chicken supply chain. A total of 172 Salmonella isolates were recovered from 1148 samples collected from four sample sources (breeder farms, broiler farms, abattoir, and retail markets), representing nine production stages. These Salmonella isolates were examined for antimicrobial susceptibility to 12 different antimicrobial agents using a disk diffusion assay. Among them, 168 were identified as six different serotypes of Salmonella enterica. The predominant serotype was S. Enteritidis (n = 116), followed by S. Infantis (n = 18), S. Gueuletapee (n = 16), S. Derby (n = 12), S. Meleagridis (n = 4), and S. London (n = 2). The remaining four isolates were serogroup-untypeable. A majority of the 172 isolates (96.51%) was resistant to one or more antibiotics and 61.05% of the Salmonella isolates showed a multidrug resistance phenotype. Statistical analysis indicated the one risk product stage for Salmonella contamination occurred in the sample source at the abattoir, specifically the stage of Carcasses after chilling. The majority of S. Enteritidis isolates shared the same pulsed-field gel electrophoresis (PFGE) cluster, suggesting that the S. Enteritidis strain might spread along the broiler chicken supply chain. The prevalence and antimicrobial resistance of Salmonella in different production stages suggest the importance of controlling Salmonella in the broiler chicken supply chain for public health, underlying the need for improved measures of reducing carcass contamination in abattoirs and the appropriate use of antimicrobials in broiler flocks.     

Species determination of pine nuts in commercial samples causing pine nut syndrome

Consumption of pine nuts from the species of Pinus armandii has been reported to cause dysgeusia, commonly known as pine mouth, or pine nut syndrome (PNS). However, the number of reports on pine nut consumptions of the different species and PNS is limited. This leaves open the possibility that other pine species than P. armandii could be involved in PNS as well. This study investigated 18 samples involved in PNS and received at the Danish Veterinary and Food Administration in 2011 through 2012. Samples were subjected to gas chromatographic analysis of fatty acids. The content of 11 individual fatty acids was used together with the diagnostic index and the sum of Δ5-fatty acids as diagnostic parameters. Diagnostic parameters from samples were then compared to reference material and literature data to determine the species. In a limited number of samples, the diagnostic parameters matched neither our reference materials nor literature data. However, the morphology, the fatty acid analysis, and externally obtained DNA sequencing data suggest a P. armandii subspecies or a variety. With these possible P. armandii subspecies, P. armandii was identified in all analyzed samples. The application of principal component analysis (PCA) to the data set showed a satisfactory separation of the majority of the 13 pine species included in the study.     

Isolation of recombinant antibody fragments (scFv) by phage display technology for detection of almond allergens in food products

Tree nut allergies are considered an important health issue in developed countries. To comply with the regulations on food labeling, reliable allergen detection methods are required. In this work we isolated almond-specific recombinant antibody fragments (scFv) from a commercial phage display library bypassing the use of live animals, hence being consistent with the latest policies on animal welfare. To this end an iterative selection procedure employing the Tomlinson I phage display library and a crude almond protein extract was carried out. Two different almond-specific scFv (named PD1F6 and PD2C9) were isolated after two rounds of biopanning, and an indirect phage ELISA was implemented to detect the presence of almond protein in foodstuffs. The isolated scFvs demonstrated to be highly specific and allowed detection of 40 ng mL⁻¹ and 100 ng mL⁻¹ of raw and roasted almond protein, respectively. The practical detection limit of the assay in almond spiked food products was 0.1 mg g⁻¹ (110–120 ppm). The developed indirect phage ELISA was validated by analysis of 92 commercial food products, showing good correlation with the results obtained by a previously developed real-time PCR method for the detection of almond in foodstuffs. The selected phage clones can be affinity maturated to improve their sensitivity and genetically engineered to be employed in different assay formats.     

The efficacy of disinfectant misting in the lairage of a pig abattoir to reduce Salmonella and Enterobacteriaceae on pigs prior to slaughter

Water misting/showers are used in abattoir lairages to improve meat quality, and to cool and calm pigs after transport and during hot weather. One novel approach, which has not been investigated to date, is to add a disinfectant to the misting water as a means of topically reducing Salmonella on pigs prior to slaughter, thereby potentially controlling this organism in the abattoir. The objective of this study was therefore to evaluate misting with water or with Virkon^® S (an approved disinfectant for use in the presence of animals), for their ability to topically reduce Salmonella on high seroprevalence pig herds before stunning and to reduce Enterobacteriaceae.Three experimental groups were investigated: control group (i.e., no misting); water group (misting with cold, 15–17 °C, water, herein referred to as water); and a disinfectant group (misting with 0.5% Virkon^® S). As pigs entered the abattoir, each animal was swabbed along its back before being allocated to its experimental group. Each group was randomly assigned to one of 3 lairage pens that were separated by non-trial pens. After 30 min of misting with water or disinfectant, pigs were moved to the stunning area, where each pig was again swabbed, as above. Swabs were analyzed for the presence of Salmonella and enumeration of Enterobacteriaceae.Before misting, Salmonella prevalence on the pigs was 79.0%, 72.1% and 83.6% for the control, water and disinfectant groups, respectively. After misting, Salmonella prevalence increased to 94.3% in the water group; whereas for the disinfectant group, the prevalence increased marginally to 85.9%. No change in Salmonella prevalence was detected for the control group. In line with the Salmonella results, no significant differences were observed in Enterobacteriaceae counts in the control group at either time point (4.37 and 5.01 log₁₀ CFU/cm², respectively) or in the disinfectant group before and after misting (4.02 and 4.26 log₁₀ CFU/cm², respectively). However, a 2.3 log₁₀ CFU/cm² increase in Enterobacteriaceae was recorded for the water group after misting as compared to before misting (p < 0.05).Since misting with water alone increased topical Salmonella contamination on pigs before slaughter, a risk assessment based on known Salmonella data, meat quality and welfare is recommended to determine whether its use is justifiable. On the other hand, the findings from this study suggest that misting with Virkon^® S at 0.5% could have a role in topical antisepsis of pigs contaminated with Salmonella prior to slaughter and as such this warrants further investigation.     

Polyphenolic extract from Rosa rugosa tea inhibits bacterial quorum sensing and biofilm formation

Quorum sensing (QS) is an intercellular signaling and gene regulatory mechanism, which is implicated in bacterial pathogenicity and food spoilage. Therefore, blocking bacterial QS system may prevent QS-controlled phenotypes responsible for food spoilage. In the present study, we aimed to investigate the anti-biofilm and quorum sensing inhibitory potentials of Rosa rugosa tea polyphenol (RTP) extract, which is rich in polyphenols (87.52%) and flavonoids (61.03%). The RTP specifically inhibited QS-controlled violacein production in Chromobacterium violaceum 026 with 87.56% reduction without significantly affecting its growth. Moreover, RTP exhibited inhibition in swarming motility (84.90% and 78.03%) and biofilm formation (67.02% and 72.90%) of Escherichia coli K-12 and Pseudomonas aeruginosa PAO1 in a concentration-dependent manner, respectively. These findings strongly suggest that RTP potentially could be developed as a new QS inhibitor and/or anti-biofilm agent to enhance the shelf life and increase food safety.     

The effects of oxygenation aeration treatment on dissipation behaviors of tricaine mesylate in carp (Cyprinus carpio) muscle and water

Tricaine mesylate (MS-222) is one of the most used anesthetics in fish. It can be absorbed by the human body via food consumption, with related detriments to human health. In this study, a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was developed for the determination of MS-222 in carp muscle and water samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). For cleanup procedure, multiplug filtration cleanup (m-PFC) method with n-Hexane delipidation was adopted. The extraction solvent, cleanup methods and sorbents were optimized. All method validation parameters were in the acceptable range. The dissipation behavior study was followed by the method development. Firstly, the anesthesia dose and time were optimized in application study. Secondly, carps were revived for different period of time with (experimental group) and without (control group) the oxygenation aeration treatment to compare the dissipation rate of MS-222. After being anesthetized for 6 h at 50 mg/L and 12 h of elimination, the concentrations of MS-222 in crap muscle and water of experimental group was lower than those of control group. After 36 h of elimination under oxygenation aeration, over 90% of MS-222 was dissipated in carp muscle. The results showed that the half-life of MS-222 in carp muscle was 6.2 h. The findings suggested that the commonly-used oxygenation aeration treatment in aquaculture production had potential effects in accelerating the dissipation of MS-222 in carp and water. In this study, three days of withdrawal period was recommended in carps after MS-222 administration under oxygenation aeration.     

Contamination of Opisthorchis viverrini and Haplorchis taichui metacercariae in fermented fish products in northeastern Thailand markets

Consumption of raw or inadequately cooked cyprinid fish as well as related products (often contaminated with Opisthorchis viverrini and/or Haplorchis taichui) is one of the major causes of fish-borne trematode (FBT) infection, which is still endemic in the Greater Mekong Subregion including northeastern Thailand. This study surveyed FBT metacercariae (FBTM) in fermented fish dishes (pla-ra and pla-som) obtained from 73 local markets in 20 provinces of northeastern Thailand during April to November 2011. Fish were identified and examined for FBTM under a microscope. In addition, the coexistence of H. taichui in O. viverrini-positive samples was confirmed by multiplex PCR. FBTM were detected in fermented fish dishes from markets located in five provinces: Si Sa Ket, Sakon Nakhon, Mukdahan, Khon Kaen and Udon Thani. FBTM contamination was found in 9.58% (7/73) of markets, mainly in pla-ra. FBTM were found in four species of fish: Henicorhynchus siamensis, Puntius bimaculatus, Puntius orphoides and Hampala dispar. Multiplex PCR revealed 186 and 330 bp PCR products in most of FBTM-positive samples, indicating the coexistence of H. taichui and O. viverrini in fermented fish dishes. These results suggest that fermented fish dishes are frequently contaminated with FBTM and may serve as important sources of FBT infection in people who typically eat raw or undercooked fish dishes. This study might provide evidence leading to improved public health awareness for surveillance and control of FBT contamination in fermented fish dishes.     

Potential use of carvacrol and citral to inactivate biofilm cells and eliminate biofouling

Biofouling (i.e., accumulation of microorganisms on wetted surfaces) represents a major problem in the food industries, since bacterial biofilms are common sources of persistent infections due to their resilience to cleaning and disinfection treatments. Therefore, alternative treatments based on the use of essential oils or their individual compounds against this bacterial adaptation phenomenon are currently being studied. This work presents a quantitative comparison of the disinfectant potential of 500–2000 μL/L of carvacrol or citral against mature biofilms of Staphylococcus aureus SC-01, Listeria monocytogenes EGD-e or Escherichia coli MG1655. Treatments with 1000 ppm of carvacrol or citral at 45 °C for 60 min were capable of reducing more than 5 logarithmic cycles of the sessile cells forming part of mature biofilms of all the three species. Furthermore, the synergism observed between carvacrol and heat allowed for the physical removal of biofilms by treatments simulating in situ wash conditions (80 °C/60 s). These results demonstrate the great potential of the essential oils’ constituents citral and carvacrol in the eradication of biofilms formed by foodborne pathogenic microorganisms.     

Antibacterial mechanism of bifidocin A,a novel broad-spectrum bacteriocin produced by Bifidobacterium animalis BB04

Bifidocin A, a novel broad-spectrum bacteriocin produced by Bifidobacterium animalis BB04, was isolated from the feces of a healthy centenarian. To understand the mechanism of the antibacterial action of bifidocin A against gram-negative bacteria, its effects at a minimum inhibitory concentration on cell morphology, intracellular organization, membrane permeability, membrane integrity, and membrane proton motive force (PMF) of Escherichia coli 1.90 were investigated. Scanning and transmission electron microscopy analyses showed that bifidocin A induced alterations in the morphology and intracellular organization of E. coli cells. The intracellular organization was more susceptible to changes induced by bifidocin A than the morphology. Bifidocin A treatment caused the leakage of K⁺ and inorganic phosphate, the release of ATP and UV-absorbing materials, and a collapse of the transmembrane electrical potential and pH gradient in E. coli cells. Confocal laser scanning microscopy images showed that E. coli cells treated with bifidocin A took up propidium iodide. These results suggested that the mechanism of action bifidocin A against E. coli involved dissipation of the PMF of the cytoplasmic membrane, an increase in membrane permeability, pore formation in the cell membrane, a change in membrane integrity, and complete cell disintegration.     

Moiety and linker site heterologies for highly sensitive immunoanalysis of cyprodinil in fermented alcoholic drinks

Cyprodinil is a new-generation anilinopyrimidine fungicide widely used in crop protection and frequently found in fruits. In this study, novel derivatives of cyprodinil with linker site heterologies were synthesized and employed in order to produce antibodies with enhanced affinity. Moreover, moiety-heterologous haptens were designed and prepared for assay sensitivity improvement. Two competitive enzyme-linked immunosorbent assays for the analysis of this active substance were developed using direct and indirect formats, achieving IC₅₀ values around 0.15 μg/L. Analytical figures of merit and usability of the optimized assays were evaluated with wine and cider as model food processed matrices. The obtained recoveries were from 90% to 120%, and the limit of quantification was in the 1–5 μg/L range. Finally, a monitoring study (n = 150) was performed to estimate the occurrence and the concentration of cyprodinil in commercial wine and cider products from different origins. We found that 28% of the analysed wine samples contained cyprodinil residues at levels higher than 5 μg/L.     

Mycological quality and mycotoxin contamination of Sri Lankan peppers (Piper nigrum L.) and subsequent exposure assessment

The aim of the study was to characterize the toxigenic moulds and to screen different mycotoxins in peppers (Piper nigrum L.) of Sri Lankan origin. Aspergillus flavus, Aspergillus parasiticus, Aspergillus niger and Penicillium spp. were found to be the most dominant fungi. Characterization of the moulds was carried out in A. flavus and parasiticus agar (AFPA) and malt extract agar (MEA) in 77 black pepper (BP) and 11 white pepper (WP) samples. In total, 73% of the BP and 64% of the WP samples were contaminated with A. flavus and/or A. parasiticus (AfAp). A BP sample with water activity (a_w) 0.70 recorded the highest count of AfAp (4.3*10⁴ CFU/g). Moreover, 75% of the BP samples exceeded the safe a_w limit (0.65) set by the European Spice Association (ESA). The frequency of occurrence of A. niger in BP was 62% with counts up to 1.3*10³ CFU/g. Penicillium spp. were found in 61% and 55% of the BP and WP samples, respectively. In BP 94% of the samples had a Penicillium contamination below 10³ CFU/g. Other Aspergillus spp, found in peppers included, Aspergillus terrus, Aspergillus tamarii, Aspergillus candidus, Aspergillus penicilloides, Aspergillus sydowii and Aspergillus fumigatus. Mould counts in BP (10²–10⁴ CFU/g) were significantly higher than that of WP (<10² CFU/g). Apart from the occurrence of “classical mycotoxins” of spices, aflatoxins (<LOQ-18 μg/kg) and ochratoxin A (<LOQ-79 μg/kg), other toxins including fumonisin B1 (<LOQ-135 μg/kg), sterigmatocystin (<LOQ-49 μg/kg) and citrinin (<LOQ-112 μg/kg) were detected in peppers. In total, 63% of the BP samples were contaminated with at least one mycotoxin. Mycotoxin contamination in WP was significantly less compared to BP. The exposure to aflatoxins and ochratoxin A by consuming pepper remains harmless considering the existing pepper dietary intake data of the Sri Lankan population.     

Validation of real-time PCR for detection of six major pathogens in seafood products

Seafood can pose a public health concern to consumers. It is often consumed raw and may be contaminated with several foodborne pathogens. In order to guarantee the safety of seafood, real-time polymerase chain reaction (PCR) protocols may be used as these enable results to be provided within 24 h.The first goal of our work was to develop real-time PCR protocols enabling the detection of six foodborne pathogens that may be present in seafood products (Campylobacter jejuni, Campylobacter coli, enterohemorrhagic Escherichia coli, Salmonella spp., Vibrio parahaemolyticus, and Vibrio vulnificus). The corresponding gene targets were: 50S/VS1, rfbE, ttr, tlh, and vvp. A multiplex PCR was also developed to detect the virulence genes of V. parahaemolyticus: tdh and trh. A total of 420 bacterial strains belonging to four different genera/strains were used in this study. Sensitivity and specificity were always 100%, except in the case of Salmonella spp., where three strains were not detected by our PCR protocols.The second objective of our work was to assess the detection limit of our real-time PCR protocols on artificially contaminated seafood products (raw shrimps, cooked shrimps, and raw mussels), purchased in public stores. Six different levels of contamination were assayed in four replicates for each matrix. The real-time PCR protocols enabled a better level of detection than the ISO methods, except for Salmonella in raw shrimps and for V. vulnificus in shrimps (raw and cooked). The estimated level of detection was between 1 and 47 cfu/25 g sample for the ISO norms and between 1 and 315 cfu/25 g sample for the real-time PCR protocols tailored in our work.The real-time PCRs developed in our work allowed for good selectivity, sensitivity, and specificity. The sensitivity on seafood products was estimated at a level of 100%, except for Salmonella (97%). In the spiking assays, the levels of detection were lower with the real-time PCR protocol than those obtained with the ISO method. This was not the case for V. vulnificus in raw and cooked shrimps and for Salmonella in raw shrimps.These real-time PCR protocols appear to be good alternative methods for surveillance of seafood products to ensure the absence of foodborne pathogens.One additional conclusion is that laboratories have to use enrichment media that are compatible with those recommended by ISO standards. This may facilitate the isolation of the pathogen if the real-time PCR protocol gives a suspect positive signal during the first step of the seafood analysis.     

Antimicrobial activity of kaempferol and resveratrol in binary combinations with parabens or propyl gallate against Enterococcus faecalis

Antimicrobial activity of two natural phenolic compounds (resveratrol and kaempferol) and three synthetic (propyl gallate, propyl- and heptyl paraben) against two strains of Enterococcus faecalis were analyzed by checkerboard and time-kill methods. Heptyl paraben was the most effective followed by resveratrol, kaempferol, propyl gallate and propyl paraben, according to their minimal inhibitory concentrations (MICs) ranging from 13.4 μg mL⁻¹ (heptyl paraben) to 881.82 μg mL⁻¹ (propyl paraben). Kaempferol plus resveratrol and binary combinations of each one with propyl gallate or parabens showed no interaction effects by the checkerboard method. Kaempferol and resveratrol in combination produce a growth inhibition in cation adjusted Mueller-Hinton broth and in skimmed milk, characterized by an increase in the lag phase and a decrease in the maximum specific growth rate. Heptyl paraben alone or in combination with kaempferol showed bacteriostatic effects. Kaempferol combined with resveratrol, propyl gallate, propyl- or heptyl paraben produces antagonistic effect in antioxidant activity, obtaining the highest effect with the two parabens (approximately a 25% reduction). The antagonistic effects analyzed by regeneration mechanisms are discussed in relation to the increase of the antimicrobial activity shown by the binary combinations tested against the two strains of E. faecalis.     

Determination of aflatoxins in walnut sujuk and Turkish delight by HPLC-FLD method

This study aims to assess the risk of aflatoxins (AFs) in traditional confectionery products (walnut sujuk and Turkish delight) of Turkey. A high performance liquid chromatography coupled with fluorescence detection (HPLC-FLD) method was used for the determination of AFs. Evaluation of the method showed good selectivity, linearity, recovery and precision. The limit of quantification (LOQ) ranged from 0.106 to 0.374 μg kg⁻¹. The expanded measurement uncertainty was less than 40% for all target analytes. The validated method was successfully applied to the determination of AFs in 112 traditional confectionery products containing nuts (hazelnuts and walnuts). AFs were detected in 43.8% of walnuts and 60.9% of hazelnuts used as ingredients in walnut sujuk and Turkish delight and at levels ranging from 0.58 to 15.2 μg kg⁻¹ and 0.43–63.4 μg kg⁻¹, respectively. This means that AFs levels in walnut sujuk and Turkish delight were up to levels of 6.1 and 9.5 μg kg⁻¹, respectively. Six walnut samples and twenty-one hazelnut samples were above the EU maximum limits (MLs) of 2 and 5 μg kg⁻¹ for aflatoxin B₁ (AFB₁), respectively.     

Growth or penetration of Salmonella into citrus fruit is not facilitated by natural-light labels

In natural-light labeling of fruits and vegetables, the desired information is etched onto the produce surface using a low-energy carbon dioxide laser beam (10,600 nm). Etched characters are formed by surface depressions in the epidermis that may facilitate entrance of decay and pathogenic organisms. The objective of this study was to determine the effects of natural-light labeling and different postharvest treatments on Salmonella populations' ability to survive/grow and penetrate into citrus fruit. A five-strain cocktail of Salmonella was spot inoculated onto Valencia orange in different application sequences with wax and natural-light etching. Samples were stored at 10, 26 °C, or combinations of both, for up to 42 days. Etched peels and corresponding juices were extracted from whole oranges following storage and enumerated for Salmonella. No set of conditions involving natural-light labeling promoted the growth of Salmonella on the fruit surface or resulted in the detection of Salmonella from the juice of sound fruit. Survival of Salmonella populations on the peel surface did not differ between any of the treatment and control samples. In all cases, Salmonella declined between 1.5 and 3.0 log CFU/orange after 30 days, with faster decline noted at 10 °C. Based on the data obtained from all treatments and under conditions extremely unfavorable and unrealistic in terms of fruit storage, natural-light labeling citrus fruit peels and subsequent waxing in any order did not allow for the growth or influence the natural decline of Salmonella populations on citrus fruit surfaces, or movement into juices, as compared to controls.     

Antibacterial activity and mechanism of bifidocin A against Listeria monocytogenes

Bifidocin A, produced by Bifidobacterium animalis BB04, is a novel bacteriocin with antimicrobial activity against a wide range of gram-positive and gram-negative foodborne bacteria. The objective of this study was to investigate the antibacterial activity and mechanism of action of bifidocin A against Listeria monocytogenes, one of the most susceptible bacteria to this bacteriocin. The minimum inhibitory concentration (MIC) of bifidocin A for L. monocytogenes 35152 was 0.029 mg/mL. Time-kill assays showed that bifidocin A effectively inhibited the growth of L. monocytogenes in a time-and concentration-dependent manner. The mechanism of action of bifidocin A was studied by analyzing its effects at a MIC on the cell morphology, intracellular organization, membrane permeability, membrane integrity, and membrane proton motive force (PMF) of L. monocytogenes. Scanning and transmission electron microscopy analyses showed that bifidocin A induced alterations in the morphology and intracellular organization of L. monocytogenes cells. Confocal laser scanning microscopy images showed that L. monocytogenes cells treated with bifidocin A took up propidium iodide. Bifidocin A treatment also induced the leakage of K⁺ and inorganic phosphate, the hydrolysis and release of ATP, and a collapse of the transmembrane electrical potential and pH gradient in L. monocytogenes cells. These results suggested that bifidocin A exerted its anti-Listeria monocytogenes effect through the dissipation of the cytoplasmic membrane PMF, increased membrane permeability, cell membrane pore formation, destruction of membrane integrity, and ultimately complete disintegration of the cells.