Ultrasensitive green spectrofluorimetric approach for quantification of Hg(II) in environmental samples (water and fish samples) using cysteine@MnO2 dots

Mercury (Hg²⁺) is a natural element present in foods such as fish, water and soil. Exposure to mercury leads to severe toxic effects on the nervous, digestive, and immune systems. Here, a novel, green, and environmentally friendly fluorescent probe decorated with cysteine/MnO₂ quantum dots (Cys@MnO₂ QDs) was synthesized. This synthesis was carried out using a simple ultrasound technique with the aid of cysteine for fabricating Cys@MnO₂ QDs to estimate Hg levels in fish and water samples. In this morphological study, Cys@MnO₂ QDs were fully characterized using high-resolution transmission electron microscopy, zeta potential analysis, fluorescence, ultraviolet–visible and infrared spectroscopy. The fluorescence of the synthesized Cys@MnO₂ QDs was significantly quenched by gradually increasing the Hg(II) concentration. The quenching mechanism based on the Hg–S bonds strengthened the utility of the Cys@MnO₂ QDs as a novel luminescent nanoprobe. The estimation of Hg was linear in the concentration range 0.7–100.0 ng mL⁻¹ with a limit of quantitation equal to 0.30 ng mL⁻¹. The Cys@MnO₂ QDs are fluorescent probes with various benefits such as speed, ease of use, cost- effective, and being environmentally friendly; they are easily applied in food manufacturing and for public health improvement.     

Polymerase chain reaction for detection of Clostridium botulinum types A, B and E in food, soil and infant faeces

The application of the polymerase chain reaction (PCR) for detection of Clostridium botulinum types A, B and E in foods, environmental and clinical samples was evaluated and compared to the mouse bioassay. Samples inoculated with 10, 100 and 1000 spores of Cl. botulinum types A and B included pasteurized milk, UHT milk, infant formula, infant faeces, meat juice, canned tuna, mushrooms, blood sausage and soil. Clostridium botulinum type E spores were inoculated into fish eggs, canned tuna, picked herring, raw fish and soil at similar levels. Spores were added to 2.5 g of each sample with the exception of soil which was inoculated in 10 g samples. The presence of Cl. botulinum in sample enrichments was determined by both PCR and the bioassay. An overall correlation of 95.6% was observed between PCR results and the mouse bioassay. Of the total of 114 samples tested there was disparity between the mouse bioassay and the PCR in three samples of soil inoculated with 100 type A or E spores and 10 type B spores per 10 g, respectively, and two samples of infant faeces inoculated with 10 type A or B spores per 2.5 g. All of these samples gave negative animal results and positive PCR results.     

Application of a virulent bacteriophage cocktail leads to reduction of Salmonella enterica serovar Enteritidis counts in processed meat products

Salmonella enterica serotype Enteritidis (SE) is a major cause of food-borne disease outbreaks worldwide. We evaluated the effectiveness of five lytic bacteriophages applied as a cocktail to reduce the counts of SE in two types of processed meat products: cooked (turkey ham (TB) and chicken sausage (CS)) and cured sausage (Italian salami (IS) and barbecue sausage (BS)). Groups of 25 samples each were contaminated with SE, treated with a phage cocktail using a multiplicity of infection of 10⁵ and then incubated for ten days at 18°C and 4°C. A significant reduction in bacteria was obtained on days 3, 6 and 10 in all matrices incubated at 18°C (from 0.48 to 2.12?log Colony Forming Units (CFU)?g^?1) and at 4°C (from 0.23 to 2.06?log CFU?g^?1), with the exception of BS at day 3 at 4°C, and IS at both incubation temperatures throughout the trial. The viral titre remained stable in all matrices analysed except in BS. These results show the effectiveness of this bacteriophage cocktail against S. enterica serovar Enteritidis in some processed meat products such as CS, BS and TB.     

Environmental assessment of Peruvian anchoveta food products: is less refined better?

Purpose

Life cycle assessments (LCAs) of various anchovy (anchoveta) direct human consumption products processed in Peru were carried out, to evaluate their relative environmental performance as alternative products to enhance nutrition of communities with low access to fish products in the country.

Methods

LCA was carried out for fresh, frozen, canned, salted and cured anchoveta products, both at plant gate and featuring local and national distribution over non-refrigerated, chilled and fully refrigerated distribution chain. The functional unit used was 1 kg of fish in the final product.

Results and discussion

Results demonstrate that, in environmental terms, more-refined products (cured and canned anchoveta products) represent a much higher burden than less- refined products (fresh, frozen and salted). Although this is a likely result, the magnitude of this difference (4 to 27 times when expressed as an environmental single score) is higher than expected and had not been quantified before for salted and cured products, as far as we know. This difference is mainly due to differences in energy consumption between types of products. Furthermore, cured and salted products feature larger biotic resource use, when calculated based on the whole fish equivalent, due to higher processing losses/discards. The relevance of taking into account the different transportation and storage needs is highlighted. For those products requiring refrigerated transportation and storage, over a national distribution chain, those activities increase the overall environmental impacts of the products by 55 % (fresh chilled) to 67 % (frozen). However, such an increase does not worsen the environmental performance of fresh and frozen products in comparison to the energy-intensive canned and cured products.

Conclusions

It is concluded that a more sustainability-oriented analysis, including the social and economic pillars of sustainability, is required towards decision-making involving promotion of either product for addressing nutritional deficiencies in Peru.     

A dual‐readout nanosensor based on biomass‐based C‐dots and chitosan@AuNPs with hyaluronic acid for determination of hyaluronidase

A dual‐signal strategy is proposed based on fluorescent biomass‐based carbon dots (BC‐dots) and chitosan stabilized AuNPs (CS@AuNPs) to determine hyaluronidase (HAase). BC‐dots can induce aggregation of CS@AuNPs nanoparticles with a colour change from red to blue. Positively charged CS@AuNPs interacted with the negatively charged hyaluronic acid (HA) through electrostatic adsorption, and CS@AuNPs maintained stability due to the semirigid coil conformation of HA. However, in the presence of HAase, due to enzymatic hydrolysis of HA by HAase, the CS@AuNPs agglomerated. Based on the change of fluorescence and colour, quantitative analysis of HAase was achieved. Linear ranges for the fluorometric and colorimetric determinations were 2.0–70 U mL^?1 and 8–60 U mL^?1, respectively, with a detection limit of 0.27 U mL^?1. This dual‐signal sensing system possesses high potential for determination of HAase in biological matrices.     

Suitability of the enzyme treatment and ammonium sulfate precipitation method for detection of staphylococcal enterotoxin from different foods

Summary An enzyme treatment and ammonium sulfate precipitation procedure was adapted to the detection of staphylococcal enterotoxin from high-protein foods. The enterotoxin is extracted from food with distilled water, after which soluble proteins are acid-precipitated (pH 4.5) and the supernatant washed with chloroform (pH 7.5). The extract is then treated with trypsin andPseudomonas peptidase for 2 h at +37°C. Residual unhydrolyzed material is precipitated with 60% ammonium sulfate for 15 min at +4°C. The precipitate is redissolved in phosphate buffer and concentrated by dialysis against polyethyleneglycol. The concentrate is washed with chloroform and lyophilized. The dry material is dissolved in 0.2 ml distilled water and enterotoxin detected by the micro-slide method with 24 h incubation at +37°C. Using this method, it has been possible within three days to detect 0.2–1.0 g staphylococcal enterotoxin A added to minced meat, dry sausage, smoked fish, cheese and milk.     

Application of real-time PCR for quantitative detection of Clostridium botulinum type A toxin gene in food

The TaqMan real-time PCR method for the quantitative detection of C. botulinum type A was developed based on sequence-specific hybridization probes. The validity of this assay was verified by using 10 genera of 20 strains, including reference strains of C. botulinum types A, B, C, D, E and F. The detection limit of this assay was evaluated on C. botulinum type A, using a 10-fold dilution series of DNA and spores . The DNA and spores were detected up to level of 0.1 ng/ml and 10(2)spores/ml, respectively. Spore spiked food sample preparation prior to the real-time PCR was performed by two methods, heat treatment and GuSCN. The detection limits after heat treatment showed 10(2) spores/ml for spiked sausage slurry, and 10(3) spores/ml for spiked canned corn slurry, while detection limits after GuSCN precipitation showed 10(2) spores/ml in both sausage and canned corn. Therefore the real-time PCR assay after GuSCN precipitation is useful for the quantification of C. botulinum type A because it showed identical CT values in both pure spore solutions and food slurries. We suggest that quantitative analysis of C. botulinum type A by TaqMan real-time PCR can be a rapid and accurate assessment method for botulinal risk in food samples.     

Production of penicillin by fungi growing on food products: identification of a complete penicillin gene cluster in Penicillium griseofulvum and a truncated cluster in Penicillium verrucosum

Mycobiota growing on food is often beneficial for the ripening and development of the specific flavor characteristics of the product, but it can also be harmful due to the production of undesirable compounds such as mycotoxins or antibiotics. Some of the fungi most frequently isolated from fermented and cured meat products such as Penicillium chrysogenum and Penicillium nalgiovense are known penicillin producers; the latter has been shown to be able to produce penicillin when growing on the surface of meat products and secrete it to the medium. The presence of penicillin in food must be avoided, since it can lead to allergic reactions and the arising of penicillin resistance in human-pathogenic bacteria. In this article we describe a study of the penicillin production ability among fungi of the genus Penicillium that are used as starters for cheese and meat products or that are frequently isolated from food products. Penicillium griseofulvum was found to be a new penicillin producer and to have a penicillin gene cluster similar to that of Penicillium chrysogenum. No other species among the studied fungi were found to produce penicillin or to possess the penicillin biosynthetic genes, except P. verrucosum, which contains the pcbAB gene (as shown by hybridization and PCR cloning of fragments of the gene) but lacks pcbC and penDE. Antibacterial activities due to the production of secondary metabolites other than penicillin were observed in some fungi.     

Production of Penicillin by Fungi Growing on Food Products: Identification of a Complete Penicillin Gene Cluster in Penicillium griseofulvum and a Truncated Cluster in Penicillium verrucosum

Mycobiota growing on food is often beneficial for the ripening and development of the specific flavor characteristics of the product, but it can also be harmful due to the production of undesirable compounds such as mycotoxins or antibiotics. Some of the fungi most frequently isolated from fermented and cured meat products such as Penicillium chrysogenum and Penicillium nalgiovense are known penicillin producers; the latter has been shown to be able to produce penicillin when growing on the surface of meat products and secrete it to the medium. The presence of penicillin in food must be avoided, since it can lead to allergic reactions and the arising of penicillin resistance in human-pathogenic bacteria. In this article we describe a study of the penicillin production ability among fungi of the genus Penicillium that are used as starters for cheese and meat products or that are frequently isolated from food products. Penicillium griseofulvum was found to be a new penicillin producer and to have a penicillin gene cluster similar to that of Penicillium chrysogenum. No other species among the studied fungi were found to produce penicillin or to possess the penicillin biosynthetic genes, except P. verrucosum, which contains the pcbAB gene (as shown by hybridization and PCR cloning of fragments of the gene) but lacks pcbC and penDE. Antibacterial activities due to the production of secondary metabolites other than penicillin were observed in some fungi.     

Effect of prior refrigeration on botulinal outgrowth in perishable canned cured meat when temperature abused.

Perishable canned cured meat inoculated with Clostridium botulinum spores was placed at 4.4 or 10 degrees C after manufacture. Spore germination occurred at 10 degrees C. The germinated cell count remained stable over a period of 16 to 18 weeks. During that time period the inhibitory system and residual nitrite descreased. These factors combine to make perishable canned cured meats more prone to spoilage and potential hazard if they are temperature abused after a period of refrigerated storage.     

Effect of prior refrigeration on botulinal outgrowth in perishable canned cured meat when temperature abused.

Perishable canned cured meat inoculated with Clostridium botulinum spores was placed at 4.4 or 10 degrees C after manufacture. Spore germination occurred at 10 degrees C. The germinated cell count remained stable over a period of 16 to 18 weeks. During that time period the inhibitory system and residual nitrite descreased. These factors combine to make perishable canned cured meats more prone to spoilage and potential hazard if they are temperature abused after a period of refrigerated storage.     

Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications

Fluorescent nanocrystals, specifically quantum dots, have been a useful tool for many biomedical applications. For successful use in biological systems, quantum dots should be highly fluorescent and small/monodisperse in size. While commonly used cadmium-based quantum dots possess these qualities, they are potentially toxic due to the possible release of Cd²⁺ ions through nanoparticle degradation. Indium-based quantum dots, specifically InP/ZnS, have recently been explored as a viable alternative to cadmium-based quantum dots due to their relatively similar fluorescence characteristics and size. The synthesis presented here uses standard hot-injection techniques for effective nanoparticle growth; however, nanoparticle properties such as size, emission wavelength, and emission intensity can drastically change due to small changes in the reaction conditions. Therefore, reaction conditions such temperature, reaction duration, and precursor concentration should be maintained precisely to yield reproducible products. Because quantum dots are not inherently soluble in aqueous solutions, they must also undergo surface modification to impart solubility in water. In this protocol, an amphiphilic polymer is used to interact with both hydrophobic ligands on the quantum dot surface and bulk solvent water molecules. Here, a detailed protocol is provided for the synthesis of highly fluorescent InP/ZnS quantum dots that are suitable for use in biomedical applications.     

Solid‐phase synthesis of graphene quantum dots from the food additive citric acid under microwave irradiation and their use in live‐cell imaging

The work demonstrated that solid citric acid, one of the most common food additives, can be converted to graphene quantum dots (GQDs) under microwave heating. The as‐prepared GQDs were further characterized by various analytical techniques like transmission electron microscopy, atomic force microscopy, X‐ray diffraction, X–ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, fluorescence and UV‐visible spectroscopy. Cytotoxicity of the GQDs was evaluated using HeLa cells. The result showed that the GQDs almost did not exhibit cytotoxicity at concentrations as high as 1000 µg mL^–1. In addition, it was found that the GQDs showed good solubility, excellent photostability, and excitation‐dependent multicolor photoluminescence. Subsequently, the multicolor GQDs were successfully used as a fluorescence light‐up probe for live‐cell imaging. Copyright © 2015 John Wiley & Sons, Ltd.     

Effect of domestic processing on bioactive compounds

Nowadays, most of the consumed foods are rarely ready for direct consumption. Food can be purchased at the local supermarket as fresh raw product such as meat, fruit, fish etc. or as manufactured product after an industrial processing (canned meat, dried fish, packed fruit etc.). But later on, both food types are usually submitted to culinary treatments which will transform the selected food into a cooked dish ready to eat. Domestic methods of food processing have been developed over the centuries to make the final product more attractive in flavour, appearance, taste and consistency. But, until the last centuries, none of the gourmets realize that at the same time, the cooking process was making their foods more digestible, microbiologically safer and more or less nutritive depending on the selected cooking technology. Besides consumer preferences, the selected cooking method is an important factor affecting not only the food chemical composition, but also the intake of bioactive compounds under normal dietary conditions. Therefore, in this work, the different culinary treatments and domestic cooking methods will be compared to define the optimal process to reduce the degradation of biologically active metabolites present in foods commonly consumed as an elaborated dish. Compounds such as carotenoids, glucosinolates, flavonoids and other phenolic compounds, ω-3 fatty acids, tocopherols, phytosterols, etc. have been pointed as bioactive compounds beneficial for human health. Apparently, they are able to prevent cardiovascular diseases (CVD), tumour formation, hiper-cholesterolemia in blood and other deleterious disorders. An adequate domestic practice might help to increase in taking of those functional molecules enhancing their functionality and reducing the risk of chronic diseases.     

Lactic-acid fermentation as a low-cost means of food preservation in tropical countries

Abstract The range of traditional lactic-acid-fermented foods in tropical countries is briefly reviewed. Recent studies on the lactic acid fermentation of fish and cassava products are described. Lactic-acid-fermented fish products may offer considerable scope for the development of new food products and for the use of under-utilised fish species. Lactic-acid-fermented fish products are common in parts of Asia; methods to improve the product and shelf-life quality, to reduce microbial risks and to accelerate the process are described. This work is based on fish/salt/carbohydrate model systems. The nutritional aspects of cassava fermentation are discussed with respect to factors involved in determining residual cyanide levels; the possible anti-nutritional rôle of condensed tannins is mentioned. The increasing consumption of meat products in tropical countries emphasises the need for a preservation method that does not depend on refrigeration. The possible production of sausage ingredients preserved by lactic acid fermentation, and the associated research needs are described.     

Probiotic meat products and human nutrition

Raw cured and ripened meat products have been traditionally manufactured using the fermentation of native or added carbohydrates by lactic acid bacteria found in meat or in its environment. The commercial application of probiotic microorganisms in dry fermented meat products is not yet common. Probiotic bacterial strains that can be used in the manufacturing of dry fermented meat products should be capable of surviving in conditions found in fermented products; furthermore, they should dominate other microorganisms found in the finished product. The initial number of microorganisms in sausage filling or on the surface of ham or loin cannot be reduced as in milk pasteurization, for example. Therefore, the choice of appropriate microorganisms is important. Probiotic meat products are a relatively new and not very well recognized field of meat industry, but the most important issue is to find a compromise between technological aspects, safety, quality and health-beneficial effects of food. Therefore, the object of this review is on the one hand to analyze technological possibilities and quality parameters of probiotic meat products, and on the other hand to discuss risks and benefits of probiotic meat used in human nutrition.     

Iron and the antibotulinal efficacy of nitrite.

Combination of nitrite, isoascorbate, and ethylenediaminetetraacetic acid were compared for their antibotulinal efficacy in perishable canned cured meat. A dose response relationship of available iron to the antibotulinal efficacy of nitrite was demonstrated.     

Design and application of a pre-composting test step to determine the effect of high fat food wastes on an industrial scale in-vessel composting system

The high fat content in food wastes was suspected to inhibit an industrial in-vessel composting process from reaching the European Union Animal By-Product Regulation (composting temperature >70 °C for 1 h). The aim of this study was to design a test step to guide the mixing ratio of food waste to green waste to meet the regulation. A 15-compartment composting unit was designed to contain the compost mixes. Sausage and cheese wastes were mixed with green waste at 1:1; 1:2; 1:3 and 1:4 ratios by wet weight volume. Only the sausage waste mix ratio of 1:4 gave an average temperature of 70 °C for at least 1 h after 2 days of composting (fat content - 17%; C: N ratio - 8.6). All the cheese waste mixes did not reach 70 °C after 15 days of composting. This study demonstrated that using a simple pre-composting test step could reduce the chances of process failure during industrial composting. Although both sausage and cheese wastes are high in fat, they performed very differently in the composting process. Two linear equations were fitted to model the impact of these wastes on the maximum composting temperature.     

Iron and the antibotulinal efficacy of nitrite.

Combination of nitrite, isoascorbate, and ethylenediaminetetraacetic acid were compared for their antibotulinal efficacy in perishable canned cured meat. A dose response relationship of available iron to the antibotulinal efficacy of nitrite was demonstrated.     

Detection and characterization of the most common foodborne pathogens by using multiplex PCR procedure

Food Microbial contamination is one of the most serious problems. A large percentage of food-borne illnesses are caused by food-borne pathogens, and diarrheal agents comprise more than half of the overall prevalence of food-borne illnesses in the globe, and more commonly in developing countries. This study aimed to identify the most-common foodborne organisms from foods in Khartoum state by PCR.A total of 207 food samples (raw milk, fresh cheese, yogurt, fish, sausage, mortadella, and eggs) were collected. DNA was extracted from food samples by guanidine chloride protocol, and then species-specific primers were used to identify Escherichia coli O157: H7, Listeria monocytogenes, Salmonella spp., Vibrio cholerae, V. parahaemolyticus, and Staphylococcus aureus. Out of 207 samples, five (2.41%) were positive for L. monocytogenes, one (0.48%) was positive for S. aureus, and one (0.48%) was positive for both Vibrio cholerae and Vibrio parahaemolyticus. From 91 fresh cheese samples, 2 (2.19%) were positive for L. monocytogenes, and one (1.1%) sample was positive for two different foodborne pathogens (V. cholerae and V. parahaemolyticus). Out of 43 Cow's milk samples, three (7%) samples were positive for L. monocytogenes, and out of 4 sausage samples, one (25 %) was positive for S. aureus. Our study revealed the presence of L. monocytogenes and V. cholera in raw milk and fresh cheese samples. Their presence is considered a potential problem and needs intensive hygiene efforts and standard safety measures before, during, and after food processing operations.