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.     

Bactericidal effect of saffron (Crocus sativus L.) on Salmonella enterica during storage

The presence of pathogenic bacteria in spices represents a public health risk as a possible cause of food contamination. Salmonella has been found in several spices and it has been involved in food-borne outbreaks, but this bacterium has not been reported as a contaminant of saffron (Crocus sativus L.). We examined a possible antibacterial effect of saffron using samples from Iran, Greece and Spain which were artificially contaminated with clinical isolates belonging to five different serovars of Salmonella. We detected a loss of viability during the room-temperature storage of the saffron samples, with bacteria being undetectable at day 16 except in the case of the DT104 strain of the Typhimurium serovar, in all of the samples, and of the Hadar serovar in the Iranian sample, both of which gave negative culture at day 32. The laboratory strain LT2 of the Typhimurium serovar was undetectable at day 4. To gain an insight into the basis for this bactericidal effect, we measured the inhibitory and bactericidal concentrations of safranal and crocin, the main compounds responsible for the flavouring and colouring capabilities of saffron. They were in the order of 8–16 mg/mL and 64–128 mg/mL for safranal and crocin, respectively. These data suggest that these compounds, and probably their chemical relatives, are involved in the antibacterial activity of saffron, and that this effect can significantly reduce the risk of food contamination with Salmonella by this spice.     

Effect of gamma radiation on reduction of mycotoxins in black pepper

Gamma ray was applied to reduce mycotoxins, i.e. ochratoxin A (OTA) and aflatoxins B₁, B₂, G₁ and G₂ (AFB₁, AFB₂, AFG₁ and AFG₂) in black pepper. Response surface methodology (RSM) was applied to evaluate the effect of dose of gamma ray ranging from 0 to 60 kGy and mycotoxin concentration ranging from 10 to 100 ng g⁻¹ on the mycotoxin reduction. The maximum reduction was found at 60 kGy which was 52%, 43%, 24%, 40% and 36% for OTA, AFB₁, AFB₂, AFG₁ and AFG₂, respectively. Results showed the gamma rays even at 60 kGy were not effective in completely destroying of ochratoxin and aflatoxins.     

Inactivation of foodborne pathogens in powdered red pepper (Capsicum annuum L.) using combined UV-C irradiation and mild heat treatment

This study was performed to investigate the effectiveness of combined ultraviolet (UV-C) irradiation and mild heating as an alternative to conventional inactivation of foodborne pathogens, including Escherichia coli O157:H7 and Salmonella Typhimurium on powdered red pepper. A cocktail of three strains of E. coli O157:H7 ATCC 35150, ATCC 43889, ATCC 43890) and S. Typhimurium (ATCC 19585, ATCC 43971, DT 104) was inoculated onto powdered red pepper and then treated with UV-C irradiation and mild heat. A constant UV intensity (3.40 mW/cm²) of the emitting lamps was applied to samples for 5, and 10 min at 25, 35, 45, 55, and 65 °C, respectively. Also, quality change of powdered red pepper was measured in order to identify the efficiency of combined treatment. The reduction levels of E. coli O157:H7 and S. Typhimurium on powdered red pepper when treated with UV-C irradiation alone at 20.4 kJ/m² for 10 min was 0.22 and 0.29 log CFU/g, respectively. While, combined treatment with mild heating at 65 °C reduced the surviving numbers of each pathogens by 2.88 and 3.06 log CFU/g, respectively. Although the inactivation efficiency was influenced less by the UV-C radiation dose, the synergistic effect was observed with increasing temperature and UV-C radiation dose. CIE color value and extractable color value were not significantly (P > 0.05) different between non-treated and combination treated samples. The moisture and capsaicinoids contents showed significant (P < 0.05) differences when treated at 65 °C because of sample drying during heat treatment. Therefore, these results suggest that UV-C irradiation combined with mild heating can be utilized by the food industry in order to effectively inactivate E. coli O157:H7 and S. Typhimurium without incurring quality deterioration of powdered red pepper.     

Antimicrobial effect of blueberry (Vaccinium corymbosum L.) extracts against the growth of Listeria monocytogenes and Salmonella Enteritidis

This study examined the antimicrobial effect of blueberry (Vaccinium corymbosum L.) extracts obtained from four cultivars (Elliott, Darrow, Bluecrop, and Duke) on the growth of Listeria monocytogenes and Salmonella Enteritidis. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts against L. monocytogenes and S. Enteritidis in tryptic soy broth were determined. Concentrations of total phenolic compounds and four individual phenolic (chlorogenic acid, ellagic acid, quercetin, and quercetin-3-galactoside) in the extracts were determined using Folin-Ciocalteau method and HPLC analysis, respectively. All four extracts at 112.5–900 mg/mL exhibited a dose-dependent growth-inhibitory effect against L. monocytogenes and S. Enteritidis. L. monocytogenes was significantly more sensitive to the antimicrobial effect of the extracts than S. Enteritidis. Phenolic compounds in the extracts such as chlorogenic acid, quercetin, ellagic acid, and quercetin-3-galactoside were the active antimicrobial compounds in the blueberry extracts. The results of this study suggest that blueberry extract or extract-derived components may be used to control pathogenic microorganisms. More studies on the use of blueberry as a natural antimicrobial in food products are warranted.     

Viscometry as a detection method for electron beam irradiation of black pepper

Samples of black pepper (Piper nigrum) packed in polyethylene pouches were irradiated at doses of 4.8 kGy and 9.6 kGy. Untreated and irradiated samples of black pepper were suspended in water, alkalized and after heat gelatinization the apparent viscosity was determined by a rotational viscometer. The black pepper samples showed a considerable loss of viscosity as a function of radiation dose in the dose range required for microbial decontamination of spices. Differences in apparent viscosity of heat gelatinised suspensions remained detectable over the entire four week period between the irradiated and unirradiated samples. Reproducible results obtained with this technique showed that the method is promising for detecting electron beam irradiated black pepper.     

The inhibitory effect of black pepper on formation of heterocyclic aromatic amines in high-fat meatball

The effect of black pepper on the formation of heterocyclic aromatic amines (HCAs) in high-fat meatball fried at three different frying temperatures (175 °C, 200 °C, and 225 °C) was investigated. The fried samples were analyzed for five HCAs, including 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), and 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP). In control group meatballs without black pepper, the total HCAs amount increased in parallel with the frying temperature increased. The highest total HCA amount was found 37.81 ng/g in control group meatballs fried at 225 °C, 31.80 ng/g of which belonged to PhIP accounting.  The reduction of black pepper on PhIP compound was 100%. On the perspective of total HCA amount, black pepper has an inhibitory effect (ranging from about 12 to 100%). MeIQx was not detected in any of chops samples.     

Decontamination of whole black pepper using different cold atmospheric pressure plasma applications

Whole black pepper is a dry product, which is often naturally contaminated with bacterial endospores and sometimes also with human pathogens like Salmonella. Dry pepper itself is a shelf-stable product, but if it is incorporated into high moisture minimally processed food, the microorganisms can reduce the shelf-life of the final product and/or can cause foodborne diseases. In this study the antimicrobial effect of two different atmospheric pressure plasma applications for the decontamination of whole black pepper was investigated. Naturally contaminated peppercorns and with Bacillus subtilis spores, Bacillus atrophaeus spores and Salmonella enterica inoculated ones were treated using a plasma jet or a microwave-driven remote plasma. Surface color and the content of essential oils and piperine was measured. S. enterica, B. subtilis spores and B. atrophaeus spores were reduced by 4.1, 2.4 and 2.8 log, respectively, after 30 min remote plasma treatment. Direct plasma jet treatment did not result in equivalent inactivation levels. However, both plasma applications did not considerable affect the quality parameters.     

Antifungal activity of lemon (Citrus lemon L.), mandarin (Citrus reticulata L.), grapefruit (Citrus paradisi L.) and orange (Citrus sinensis L.) essential oils

The objective of this work was to study the effect of the essential oils of lemon (Citrus lemon L.), mandarin (Citrus reticulata L.), grapefruit (Citrus paradisi L.) and orange (Citrus sinensis L.) on the growth of moulds commonly associated with food spoilage: Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum and Penicillium verrucosum, using the agar dilution method. All the oils showed antifungal activity against all the moulds. Orange essential oil was the most effective against A. niger, mandarin essential oil was most effective at reducing the growth of Aspergillus flavus while grapefruit was the best inhibitor of the moulds P. chrysogenum and P. verrucosum. Citrus essential oils could be considered suitable alternatives to chemical additives for use in the food industry.     

Inactivation of Salmonella spp. in ground chicken using high pressure processing

High Pressure Processing (HPP) is a safe and effective process for improving the microbial safety and shelf-life of foods. Salmonella is a common contaminant in poultry meat and is frequently responsible for foodborne illness associated with contaminated poultry meat. In this study the inactivation of a five-isolate cocktail of Salmonella spp. in ground chicken (95% lean) using HPP at refrigeration temperature (4–6 °C) was studied. More than 5-log CFU/g inactivation was achieved at 450 MPa for10 min. In contrast, HPP treatment at 250 MPa or 350 MPa (single-cycle, 15 min) inactivated 0.5 log or 1.7 log CFU/g, respectively. The multiple-cycle HPP mode at 250 or 350 MPa (3-cycle with 5 min/cycle) showed higher cell reduction at 1.3 or 3.3 log CFU/g, respectively. HPP at 550 MPa for 10 min may reduce the cell counts, initially at 8.5 log CFU/g, to below the detection limit (1.0 log CFU/g) in current study. The images (electron microscopy) of the HPP shocked cells were examined for structural damage, which demonstrated that Salmonella cells may still look intact (with damages on rough/irregular surface at 450 MPa stress) under Scanning Electron Microscopy (SEM), but have significant damage internally (voids and uneven mass distribution patterns) under Transmission Electron Microscopy (TEM).     

Effect of polyphosphates on the quality of frozen light salted cod (Gadus morhua L.) fillets

Frozen light salted fillets have been subject to discussion concerning their definition as foodstuff. EU has recently placed these products in the frozen category. The aim was to investigate how a commercial polyphosphate blend affected the quality of light salted fillets. Fresh and previously frozen fillets of cod were injected with a brine containing 0, 4.5, 9 or 18 g/L of Carnal 2110. Quality, chemical characteristics and phosphate residues were analyzed in fillets. Compared to previously frozen, light salted fillets from fresh raw materials had a whither and less yellow color while significantly lower yields and oxidation levels were registered. No differences were found in drip loss during thawing. Addition of polyphosphate contributed to increased whiteness of both frozen and thawed fillets from both raw material groups, while no effects on yields or drip loss were detected. Polyphosphate reduced oxidation only in the frozen raw material group. Total phosphate contents were higher in fillets from fresh than frozen raw materials and residues were mainly detected as monophosphate. The choice of raw material will affect the end quality and yields and results suggest that polyphosphate can improve light salted fillet quality and therefor may be defined as a food additive.     

Cl~-浓度对316L不锈钢点蚀行为的影响

运用电化学动电位扫描、电化学交流阻抗技术、金相显微以及电子扫描显微技术,对常温常压下,不同浓度的Cl-对316 L不锈钢的CO2腐蚀作用进行了一系列实验。经过实验结果发现,316 L不锈钢呈现出整体腐蚀速率不高而局部腐蚀严重的态势,当氯离子的浓度升高时,316 L的腐蚀表现出整体腐蚀速率有很小的上升,而点蚀电位随着氯离子浓度的上升而降低,导致严重的点蚀。说明氯离子浓度的升高使点蚀电位严重下降,在该环境下316 L不锈钢的腐蚀主要为点蚀特征。     

Antimicrobial and antioxidant activities of Chinese sumac (Rhus typhina L.) fruit extract

Sumac plant (Rhus typhina) is mainly used for forestation and gardening, whereas its fruit can be used to prepare a kind of beverage called “sumac-ade” and to treat gastrointestinal disorders. This study aimed at assaying the antimicrobial and antioxidant activities of R. typhina growing in China. The antimicrobial activity of R. typhina fruit extract was tested against twelve strains including Gram-positive and Gram-negative bacteria as well as yeasts. The extract showed a strong antimicrobial activity with a concentration-dependence and a broad antimicrobial spectrum for all tested bacteria species. Bacillus cereus and Helicobacter pylori were found to be the most sensitive Gram-positive and Gram-negative bacteria respectively, with a minimum inhibitory concentration (MIC) of 0.10%. However, yeasts exhibited much lower sensitivity, with MICs of 0.60–0.75%. Furthermore, the antioxidant activity of the extract was investigated, including scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals (0.016 mg/ml as IC₅₀ value) and reducing power (IC₅₀ value of 0.041 mg/ml). To our knowledge, this is the first report on the biological activities of R. typhina fruit extract and our findings suggest the possibility of using the fruit of R. typhina as a novel source of natural antimicrobial and antioxidant agents for the food and pharmaceutical industries.     

Reduction of Escherichia coli O157, Listeria monocytogenes and Salmonella enterica sv. Typhimurium populations on fresh-cut bell pepper using gaseous ozone

Bacterial contamination is the main cause of food poisoning which can lead to diarrhoea, abdominal cramp, vomiting as well as death. Bacterial contamination can potentially be controlled by application of gaseous ozone due to its antibacterial activity. Therefore, the objective of this study was to investigate the efficacy of gaseous ozone for reducing food-borne pathogens such as Escherichia coli O157, Listeria monocytogenes and Salmonella enterica sv. Typhimurium on fresh-cut bell pepper. Efficacy of gaseous ozone to reduce bacterial populations was investigated in vitro and in vivo. Results showed that optimum effect of ozone on reducing bacterial populations was achieved with short term exposures of less than 6 h. Ozone reduced the bacterial population by disrupting bacterial cell structure, which lead to cellular death. Results also showed that bacterial cells have different resistance to ozone where ozone was more effective against L. monocytogenes, followed by E. coli O157 and Salmonella Typhimurium. Optimal reduction of the bacterial population on fresh-cut bell pepper was achieved with exposure to 9 ppm ozone for 6 h. This treatment reduced 2.89, 2.56 and 3.06 log of E. coli O157, Salmonella Typhimurium and L. monocytogenes populations, respectively. In conclusion, exposure to 9 ppm ozone for 6 h helps in reducing food-borne pathogen on fresh-cut bell pepper and has high potential to be an alternative sanitization treatment to reduce pathogen population on fruit.     

Exploiting DNA mini-barcodes as molecular markers to authenticate saffron (Crocus sativus L.)

Saffron (Crocus sativus) is the most expensive spice in the world. As a consequence, saffron has frequently been associated with an unrivalled degree of adulteration. The aim of this work was searching for DNA-barcode candidates as molecular markers to differentiate C. sativus from allied species and assessing the authenticity of saffron. New primers were specifically designed targeting three DNA barcode loci, namely ITS1, ITS2 and matK. A real-time PCR assay combined with high resolution melting (HRM) analysis was carried out in order to discriminate different Crocus spp., being further confirmed by sequencing. Data from HRM analysis showed that ITS1 and matK loci were Crocus genus specific, while ITS2 locus was species-specific for C. sativus and Crocus cartwrightianus. This study revealed that genomic tools, and specifically DNA mini-barcodes combined with HRM analysis, can provide simple, fast and highly reliable methods for saffron authentication.     

Effect of corona discharge plasma jet treatment on decontamination and sprouting of rapeseed (Brassica napus L.) seeds

Sprout-related outbreaks of foodborne illnesses are increasingly becoming a food safety concern. Different pathogenic microorganisms that originate from sprout seeds are known to play a crucial role in the pathogenesis of such outbreaks. Therefore, in order to decontaminate and also to enhance the germination of seeds, the applications of non-thermal plasma based techniques are increasingly being investigated in the field of agricultural science as an alternative to conventional pre-germination treatments. This work was aimed to evaluate the effectiveness of corona discharge plasma jet (CDPJ) for microbial decontamination of rapeseed seeds, and also studied the plasma treatment effect on the seed germination and physicochemical properties of sprouts (grown from the plasma-treated seeds). Aerobic bacteria, molds and yeast, Bacillus cereus, Escherichia coli, Salmonella spp. were detected as contaminants in the seeds. All the detected microorganisms were reduced in the range of 1.2–2.2 log CFU/g upon the CDPJ treatment for 3 min. The inactivation patterns are better explained using pseudo-first-order kinetics. The plasma treatment of seeds up to 2 min showed positive effects on their germination rate and seedling growth. Physicochemical and sensory characteristics of rape sprouts were unaffected due to the CDPJ treatment of their respective seeds. Therefore, the CDPJ treatment of rapeseed seeds has not only reduced the seed microbial load, but also contributed to the enhancement of their germination rate and seedling growth, without adversely affecting the physicochemical and sensory characteristics of their corresponding sprouts.     

Essential oil composition and biological/pharmacological properties of Salmea scandens (L.) DC

Salmea scandens (L.) DC is an indigenous edible plant whose stem bark is traditionally used as food by people of Oaxaca, México. Proximate analysis of the edible stem bark revealed abundant amounts of fiber (43.67%) and protein (9.27%). GC and GC-MS analyses demonstrated that the essential oil from leaves contained high levels of germacrene D (47.1%) and elemol (15.3%), whereas that of the stem bark contained the alkylamides N-Isobutyl-(2E,4E,8Z,10E/Z)-dodecatetraenamide isomers (39.7%). Levels of these compounds in the essential oil from both organs were in similar concentrations in all seasons except winter. The HPLC purified N-Isobutyl-(2E,4E,8Z,10E/Z)-dodecatetraenamide isomers produced a non-competitive inhibition on porcine pancreatic lipase. The enzymatic assays with these compounds revealed a modification on V_max (0.0431–0.0533 mM min⁻¹) whereas the K_m value (0.880–0.881 mM) was not significantly changed. Essential oil from the stem bark showed a high anti-microbial activity against some phytopathogenic microorganisms. The MIC's in μg mL⁻¹ for Pseudomonas syringae pathovars were tabaci 56.1, tomato 91.2 and phaseolitica 196.4, for Clavibacter michiganensis 35.8 and Erwinia carotovora 48.1. The fungi Fusarium oxysporum and Phytophthora infestans had MIC's in μg mL⁻¹ of 3.3 and 2.4 respectively. Same essential oil was highly effective against larvae from Aedes aegypti (LC₅₀ = 0.3 μg mL⁻¹) and Anopheles albimanis (LC₅₀ = 2.5 μg mL⁻¹).     

Elimination of Yersinia enterocolitica on carrots (Daucus carota L.) by using household sanitisers

In this study, the effects of lemon juice, the mixture of lemon juice–vinegar (1:1) and lemon dressing against Yersinia enterocolitica on carrot were investigated. Carrots inoculated with Y. enterocolitica cells (approximately 10⁶ cfu/ml) were treated with 100%, 75% and 50% lemon juice, a mixture of lemon juice–vinegar, and lemon dressing for 0, 15, 30 and 60 min. Enumeration of Y. enterocolitica populations on CIN agar beside TSA agar by using two methods as then performed. One hundred percent lemon juice was the most effective agent used, completely inhibiting viable cells of Y. enterocolitica on carrot after 15 min exposure. Although no growth was observed on carrots treated with 100% lemon juice for 15 min, there was no statistical difference between the antibacterial effects of 100% lemon juice, 75% lemon juice, the mixture of lemon juice–vinegar and lemon dressing whilst the effect of 50% lemon juice was statistically different from those solutions (P < 0.05) and its definite inhibitive activity was seen after 60 min treatment.     

Natural mycotoxin contamination of maize (Zea mays L.) in the South region of Brazil

The natural co-occurrence of fungal metabolites in maize samples from the South region of Brazil was studied using an LC-MS/MS based multi-mycotoxin method. All maize samples (n = 148) were contaminated with fumonisin B₁ (FB₁) and fumonisin B₂ (FB₂). Aflatoxin B₁ (AFB₁) and aflatoxin G₁ (AFG₁) were detected in 38 and 11 samples, respectively, while zearalenone (ZEN) and deoxynivalenol (DON), which were first regulated in 2014, were found in 110 and 71 samples, respectively. Apart from regulated mycotoxins, a broad range of non-regulated metabolites, from Aspergillus, Fusarium, Alternaria, Penicillium and other microbes, were also detected in maize sample. Fusarin C, a possible carcinogenic compound to humans, produced by Fusarium species and not addressed by Brazilian legislation, was detected in 54.2% of maize samples. All analysed maize samples were found to be contaminated by at least ten different metabolites, with the largest number of metabolites found in the same sample being 51.     

Prevalence of L. monocytogenes and Salmonella spp. in Tulum cheese

Tulum cheese, which is produced from raw milk, is one of the most popular semi-hard cheeses in Turkey. The growth of some food pathogens such as Listeria monocytogenes and Salmonella spp. in cheese and other dairy products may cause serious health problems for consumers. The aim of this study was to assess the presence of L. monocytogenes and Salmonella spp. in Tulum cheese sold in Istanbul. During the period March 2004–March 2005, a total of 250 Tulum cheese samples were obtained from various markets located in Istanbul and the presence of L. monocytogenes and Salmonella spp. was analyzed according to “The US Food and Drug Administration” (FDA) methods. The results were positive for L. monocytogenes and Salmonella spp. in 12 (4.8%) and 6 (2.4%) samples respectively.