An indirect ELISA system for the detection of heat-stable Pseudomonas endopeptidases (AprX) in milk

Heat-stable endopeptidases in raw milk, especially the alkaline metallopeptidase AprX secreted by Pseudomonas spp., are a well-known challenge for the dairy industry. They can withstand UHT treatment and may cause quality defects over the shelf life of milk products. Therefore, we established an indirect ELISA for the detection of Pseudomonas AprX in milk. We developed a 2-step sample treatment for milk contaminated with AprX to avoid the interference of milk proteins with the detection system. First, casein micelles were destabilized by the detraction of Ca²⁺ using trisodium citrate; then, AprX was concentrated 10-fold using hydrophobic interaction chromatography. The recovery of AprX in spiked milk samples after the 2-step treatment was 43 ± 0.1%. Specific antibodies for purified AprX from Pseudomonas lactis were produced to establish the ELISA. Western blot experiments showed that the binding affinity of these antibodies depended on the sequence homology of the AprX from P. lactis and several other Pseudomonas spp. The indirect ELISA, which was completed in 6 to 7 h, had a limit of detection of 21.0 ng mL^?1 and a limit of quantification of 25.7 ng mL^?1. Milk proteins or milk endogenous peptidases were not detected by the antibodies. The ELISA had high precision, with a CV between 0.2 and 0.8% measured on the same day (intraday) and 5.6 and 6.8% measured on 5 separate days (interday). Milk samples were spiked with different AprX activity levels [7.5–150 nkat Na-caseinate/o-phthalaldehyde (OPA) mL^?1] and evaluated by ELISA. The recovery of the ELISA was 92.3 ± 1.6 to 105 ± 4.7%. The lowest AprX activity quantifiable in the spiked milk samples was 500 pkat Na-caseinate/OPA mL^?1. The proof of concept to detect heat-stable Pseudomonas AprX in milk by ELISA was established.     

High-humidity hot air impingement blanching (HHAIB): An emerging technology for tomato peeling

Peeling is an essential operation for tomato processing. A new peeling method, high-humidity hot air impingement blanching (HHAIB) heating technology, was developed as an alternative to the conventional lye and hot-water peeling to eliminate the use of chemicals and the discharge of wastewater. The current work explored the feasibility of HHAIB for tomato peeling. The effects of heating temperature (100–120 °C), relative humidity (20%–40%) and heating time (0–180 s) on the peeling performance were investigated. The optimum treatment was found to be 110 °C heating temperature in combination with 40% of relative humidity and 75 s treatment time, which resulted in lower peeling loss, firmness loss and color deterioration compared with other HHAIB conditions that achieved 100% peelability. The comparative study of optimized HHAIB peeling with conventional lye and hot-water peeling showed that HHAIB peeled tomato obtained lower peeling loss and firmness loss, and higher preservation of phytochemicals, antioxidant capacity and color. In addition, compared with fresh tomatoes, HHAIB processing increased the antioxidant activity, lycopene, and total phenolic content in peeled tomatoes by 16.01%, 10.46%, 12.80%, respectively. The laser scanning confocal microscopy image of fresh tomato skin surface and the scanning electron microscope images of peels and flesh showed that HHAIB caused cracking of the epidermis and melting of the cuticular membrane while reduced the serious damage of flesh.Industrial practicePeeling is a necessary step in tomato processing, which impacts subsequent processing efficiency and product quality. At present, the most common used peeling methods in the industry are hot water or/and alkali peeling, but it induces the loss of water-soluble nutrients, chemical residues and waste liquid treatment. Therefore, the industry urgently needs an alternative peeling technology. The current work shows that HHAIB is a very promising peeling technology as it not only has an excellent peeling performance, but also enhances the preservation of phytochemicals, antioxidant capacity and quality attributes compared to conventional lye and hot-water peeling.     

An immunoluminometric assay (ILMA) for the detection of staphylococcal enterotoxins

An immunoluminometric assay (ILMA) was developed for the detection of staphylococcal enterotoxins (SE) A, B, C and D in food (milk and rice). Polystyrene tubes coated with specific anti-SE-sheep IgG were simultaneously incubated with the toxin containing sample and the different isoluminol conjugated anti-SE-sheep IgG. After a wash step and addition of a microperoxidase oxidation system (pH 8.6 and pH 13.0) the induced luminescence was measured. Extracts of milk and rice previously spiked with SE or contaminated with enterotoxic strains of Staphylococcus aureus were assayed by the ILMA and in comparison by a sandwich enzyme-linked immunosorbent assay (ELISA). At a similar sensitivity the ILMA proved to be the faster method with a satisfactory recovery of added toxin.     

An indirect ELISA and a PCR technique for the detection of Grouper ( Epinephelus marginatus ) mislabeling

An indirect enzyme-linked immunosorbent assay (ELISA) and a multiplex polymerase chain reaction (PCR) procedure was applied for the detection of Grouper (Epinephelus marginatus) mislabelling in the fish market. An indirect ELISA (microtiter-plate format) using two monoclonal antibodies (3D12 and 1A4) was assayed and multiplex PCR performed using species-specific primers of the 5S rDNA gene for the rapid authentication of grouper. A total of 70 commercial fish fillet samples, collected from local markets and supermarkets, labelled as grouper were analysed: 12 of the 70 samples were confirmed to be Grouper. The PCR technique permitted the detection of Nile Perch (Lates niloticus) in the commercial fillet samples, which was not possible using ELISA. The results suggest that both ELISA and PCR are specific and reliable tools for the detection of Grouper mislabelling/adulteration and the accurate implementation of traceability for successful regulatory food controls.     

An indirect ELISA and a PCR technique for the detection of Grouper (Epinephelus marginatus) mislabeling

An indirect enzyme-linked immunosorbent assay (ELISA) and a multiplex polymerase chain reaction (PCR) procedure was applied for the detection of Grouper (Epinephelus marginatus) mislabelling in the fish market. An indirect ELISA (microtiter-plate format) using two monoclonal antibodies (3D12 and 1A4) was assayed and multiplex PCR performed using species-specific primers of the 5S rDNA gene for the rapid authentication of grouper. A total of 70 commercial fish fillet samples, collected from local markets and supermarkets, labelled as grouper were analysed: 12 of the 70 samples were confirmed to be Grouper. The PCR technique permitted the detection of Nile Perch (Lates niloticus) in the commercial fillet samples, which was not possible using ELISA. The results suggest that both ELISA and PCR are specific and reliable tools for the detection of Grouper mislabelling/adulteration and the accurate implementation of traceability for successful regulatory food controls.     

Conventional and emerging detection techniques for pathogenic bacteria in food science: A review

BackgroundContinuous transformation and development of new detection tools for bacteria has converted the laborious scientific work into smart apparatus in recent years. The journey had begun with the culture-based plate enumeration, and now it has evolved into several culture-independent techniques. Polymerase chain reaction (PCR) is on the top of the list that is now a routinely used biological approach to detect bacterial cells. Instrumental techniques are also helpful in this regard, as they are more sensitive for detection of various microbes.Scope and approachIn this review, we described new trends and their practical application in the fields of detection microbiology and food technology. This study provides a brief overview of conventional and modern detection techniques which includes nucleic-acid sequence based techniques to non-destructive imaging techniques.Key findings and conclusionsBesides the availability of antibiotics and clinical treatments, bacterial infections significantly increase the mortality rate. It is necessary to detect apparent infectious agents beforehand. Therefore, the detection methods for microorganisms should be more rapid, smart and reliable in response to the need. Conventional detection techniques are slow and time-consuming but more accurate and reliable than the modern detection techniques. By combing the mentioned techniques, scientists can achieve better results.     

Potential sources of food hazards in emerging commercial aquaculture industry in sub-Saharan Africa: a case study for Uganda

A study was conducted to assess sources of food hazards in Uganda's emerging commercial aquaculture industry based on Hazard Analysis Critical Control Point (HACCP), focusing on inputs, their sources and farm-practices on ten representative commercial farms. Critical control points (CCPs) were identified to reveal potential hazards that would jeopardise any export trade. Site selection, water quality, fertiliser, fish seed, fish rearing facilities, feeds, and post-harvest practices were the main CCPs identified. Animal manure was used to generate plankton as pond fertiliser in nine of the ten surveyed farms and veterinary drugs were not found in any of the ten farms, which is starkly different from aquaculture in indutrialised countries. Potential sources of hazards from water were mainly: municipal waste flow which was more likely on five of the ten farms, domestic waste (four farms), agricultural run-off (three farms), and low water pH (three farms). Fish fry and fingerlings from other farms, feeds formulated on-farm from unapproved sources, chemical products, uncontrolled fish predators, and domestic animal and human activities were the other potential sources of hazards. A complete application of HACCP is recommended for producing safe products that meet the strict market standards of developed countries.     

Applications of emerging imaging techniques for meat quality and safety detection and evaluation: A review

With improvement in people's living standards, many people nowadays pay more attention to quality and safety of meat. However, traditional methods for meat quality and safety detection and evaluation, such as manual inspection, mechanical methods, and chemical methods, are tedious, time-consuming, and destructive, which cannot meet the requirements of modern meat industry. Therefore, seeking out rapid, non-destructive, and accurate inspection techniques is important for the meat industry. In recent years, a number of novel and noninvasive imaging techniques, such as optical imaging, ultrasound imaging, tomographic imaging, thermal imaging, and odor imaging, have emerged and shown great potential in quality and safety assessment. In this paper, a detailed overview of advanced applications of these emerging imaging techniques for quality and safety assessment of different types of meat (pork, beef, lamb, chicken, and fish) is presented. In addition, advantages and disadvantages of each imaging technique are also summarized. Finally, future trends for these emerging imaging techniques are discussed, including integration of multiple imaging techniques, cost reduction, and developing powerful image-processing algorithms.     

An indirect ELISA and a PCR technique for the detection of Grouper (Epinephelus marginatus) mislabeling.

An indirect enzyme-linked immunosorbent assay (ELISA) and a multiplex polymerase chain reaction (PCR) procedure was applied for the detection of Grouper (Epinephelus marginatus) mislabelling in the fish market. An indirect ELISA (microtiter-plate format) using two monoclonal antibodies (3D12 and 1A4) was assayed and multiplex PCR performed using species-specific primers of the 5S rDNA gene for the rapid authentication of grouper. A total of 70 commercial fish fillet samples, collected from local markets and supermarkets, labelled as grouper were analysed: 12 of the 70 samples were confirmed to be Grouper. The PCR technique permitted the detection of Nile Perch (Lates niloticus) in the commercial fillet samples, which was not possible using ELISA. The results suggest that both ELISA and PCR are specific and reliable tools for the detection of Grouper mislabelling/adulteration and the accurate implementation of traceability for successful regulatory food controls.     

An adaptive neural-fuzzy inference system (ANFIS) for detection of bruises on Chinese bayberry (Myrica rubra) based on fractal dimension and RGB intensity color

This paper introduces an adaptive neural-fuzzy inference system (ANFIS) model to detect bruises on Chinese bayberries as a function of fractal dimension (FD) and RGB intensity values. The ANFIS with different types of input membership functions (MFs) was developed. Our results showed that ‘gauss2mf’ MF performs much better than other mentioned MFs for defect inspection. The classification accuracy of the ANFIS with ‘gauss2mf’ MF was 100% and 78.57% for healthy and bruised fruits, respectively, and the total correct classification rate was 90.00%. Therefore, this study indicated the possibility of developing a potentially useful classification tool using the ANFIS technique based on FD and RGB values for detecting bruises of not only Chinese bayberries, but also of other fruits during processing, storage and distribution.     

Specific antigen-based and emerging detection technologies of mycotoxins

Mycotoxins are secondary fungal metabolites produced by certain types of filamentous fungi or molds, such as Aspergillus, Fusarium, Penicillium, and Alternaria spp. Mycotoxins are natural contaminants of agricultural commodities, and their prevalence may increase due to global warming. According to the Food and Agriculture Organization of the United Nations, approximately 25% of the world's food crops are annually contaminated with mycotoxins. Mycotoxin-contaminated food and feed pose a high risk to both human and animal health. For instance, they possess carcinogenic, immunosuppressive, hepatotoxic, nephrotoxic, and neurotoxic effects. Hence, various approaches have been used to assess and control mycotoxin contamination. Significant challenges still exist because of the complex heterogeneous nature of food and feed composition. The potential of antigen-based approaches, such as enzyme-linked immunosorbent assay, flow injection immunoassay, chemiluminescence immunoassay, lateral flow immunoassay, and flow-through immunoassay, would contribute to our understanding about mycotoxins' rapid identification, their isolation, and the basic principles of the detection technologies. Additionally, we address other emerging technologies of potential application in the detection of mycotoxins. The data included in this review focus on basic principles and results of the detection technologies and would be useful as benchmark information for future research. © 2019 Society of Chemical Industry     

An overview of near-infrared spectroscopy (NIRS) for the detection of insect pests in stored grains

Applications of near-infrared spectroscopy for measuring various aspects of grain quality have expanded rapidly in recent years. One application that could be of particular use to growers and industry is the detection of insect pests across a range of stored grains. This prospect was first reported over 20 years ago, but the accuracy of this technique does not currently meet FDA standards for the quantification of insect fragments in bulk wheat and flour samples. When considering bulk samples, near-infrared spectroscopy may be suitable for identifying the presence of infestation in samples, followed by flotation testing to provide an accurate quantitative value. Much higher accuracy has been found for the detection of pest species at the single-kernel level. With faster spectrophotometers and kernel sorting systems, single-kernel analysis is likely to be utilised more in the future and could even render bulk analysis of samples redundant. This technology could allow for the detection and identification of pest species in every single kernel of a representative grain sample. The development and application of more sensitive spectrophotometers, such as FT-NIR (Fourier transform near infrared) and more powerful chemometric data analysis techniques are also likely to provide significant improvements, through allowing the minute chemical differences present in bulk infested grains to be accurately detected and quantified.     

Crustaceans (shrimp,crab, and lobster): A comprehensive review of their potential health hazards and detection methods to assure their biosafety

Crustaceans are popular seafood items worldwide owing to their rich nutritional value, unique tastes, and their incorporation in a variety of cuisines. There has been a great concern about the safety of crustaceans for human consumption being more prone to hazardous contaminants due to their exposure to diverse habitats and unhealthy farming and handling practices. These hazards can arise from chemical contaminants such as heavy metals, environmental pollutants, and biotoxins or biological sources, that is, pathogenic microbes and parasites. The different types of chemical contamination of crustaceans as well as biological hazards are reviewed as major part of this review. Although there are many reviews on contaminants in fisheries, nothing is traces to crustaceans. The current review compiles the food safety hazards of crustaceans arising from both chemical and biological origins and their impact on human health in farmed versus wild origins. The different methods of contaminants detection, viz. microbiological, molecular, and analytical methods, as well as control measures viz. cooking and processing methods that can be implemented to safeguard consumer safety are also reviewed. Future perspectives have been raised toward HACCP protocol implementation during handling, processing, and storage of crustaceans and posing real-time freshness monitoring tools such as intelligent packaging.     

食品中化学危害物检测的样品前处理方法选择及开发策略

食品中化学危害物种类多,含量一般在痕量和超痕量水平;食品基质复杂,要在低含量水平获得可靠的检测结果,选择合适样品前处理技术至关重要。本文针对不同类别化合物的检测需要,根据不同食品基质的特性及分析目的,依靠近10年来食品化学危害物的样品前处理方法开发经验,探讨样品前处理技术的选择,综述前沿技术进展。提出基于“食品基质”和“分析目标物”的具有实际应用性的前处理方法选择策略,并结合应用实例,提出针对性前处理方法开发的建议,旨在为基层技术人员选择可靠的前处理方法提供借鉴。     

食品中荧光假单胞菌的危害及其快速检测方法研究进展

荧光假单胞菌(Pseudomonas Fluorescens)隶属于假单胞菌属,是食品中常见的一种嗜冷致病微生物。它能够产生极其耐热的蛋白酶和脂肪酶,这些酶在高温处理后仍有残留,并在食品储藏过程中继续分解其中的脂肪和蛋白质,导致产品的风味和质地发生变化。因此,研发出一种既快速又实用的荧光假单胞菌检测方法成为食品行业关注的焦点。本文对食品中荧光假单胞菌的危害特点及国内外的一些快速检测方法,如聚合酶链式反应(PCR)、荧光定量PCR、荧光原位杂交、流式细胞术等方法进行了综述,比较各方法的优缺点并展望了荧光假单胞菌快速检测方法的发展趋势。      

应用DPO技术检测食源性致病菌的多重PCR的研究

DPO是经特殊设计的特异性引物,本研究根据单增李斯特菌的prfA gene、O157的rfb Egene和副溶血弧菌的tlgene和志贺氏菌的ipaH gene设计四对DPO引物,采用多重PCR的方法,建立了检测单增李斯特菌、大肠杆菌O157:H7、副溶血弧菌和志贺氏菌的快速检测体系。实验结果表明:该体系特异性强,操作简单,为食源性致病菌的检测提供了新型的有效手段。     

食源性蜡样芽孢杆菌的危害及其检测方法研究进展

蜡样芽孢杆菌是一种常见的食源性致病菌,可通过污染乳制品、米饭、散装熟肉制品和豆制品等食品引起婴幼儿及成人食物中毒。采用准确、高效的蜡样芽孢杆菌检测方法,是预防食源性蜡样芽孢杆菌病及食品安全质量控制的关键。蜡样芽孢杆菌检测方法主要包括细菌培养分离鉴定法、免疫学检测方法和核酸检测方法等。本文总结了各类检测方法的核心技术特征和应用实例,为食源性蜡样芽孢杆菌的快速检测方法的研发和使用提供思路。     

An accurate real-time PCR test for the detection and quantification of cauliflower mosaïc virus (CaMV): applicable in GMO screening

Maher Chaouachi and Marie Noelle Fortabat are contributed equally to this work.     

An emerging trend in functional foods for the prevention of cardiovascular disease and diabetes: Marine algal polyphenols

Marine macroalgae are gaining recognition among the scientific community as a significant source of functional food ingredients. Due to the harsh environments in which macroalgae survive, they produce unique bioactive compounds that are not found in terrestrial plants. Polyphenols are the predominant bioactive compound in brown algae and are accountable for the majority of its biological activity. Phlorotannins are a type of polyphenol that are unique to marine sources and have exhibited protective effects against hyperglycemia, hyperlipidemia, inflammation and oxidative stress, known risk factors for cardiovascular disease and diabetic complications, in cell culture, animal studies and some human studies. This review updates the information on marine polyphenols, with a particular focus on phlorotannins and their potential health benefits in relation to the prevention and treatment of risk factors for type 2 diabetes and cardiovascular diseases.