Study of Heat Resistance of Extra Virgin Olive Oil – Based Oleogels by Differential Scanning Calorimetry

In the present study, the oxidative stability of extra virgin olive oil-based oleogels developed with beeswax, glycerol monostearate and ethylcellulose as gelators was determined using DSC in non-isothermal mode. Samples were heated at different heating rates (5, 7.5, 10, 12.5, 15 °C/min) and, by using the Ozawa-Flynn-Wall method, oxidation kinetics parameters such as activation energy, pre-exponential factor and oxidation rate constant were evaluated. The results highlighted that glycerol monostearate-based oleogels have the highest oxidative stability, followed by ethylcellulose-based oleogel. However, bulk extra virgin olive oil showed higher stability than beeswax-based oleogel, probably due to the presence in the wax of minor components with prooxidant activity

Development and optimization of Electrochemical Affinity Biosensors for the control of food safety

2016 - 2017The guarantee of food safety requires a fast and accurate control for all chemicals and bacteria, which are harmful for human health. In the food industry, the safety of a product is evaluated through periodic chemical and microbiological analysis; these procedures use techniques as chromatography, spectrophotometry, and electrophoresis that are expensive, time consuming, require highly trained personnel and require steps of sample pretreatment, increasing the time of analysis. Therefore, the demand for developing simple, rapid, accurate, low-cost and portable analytical instruments is growing and detection of chemical and microbiological contaminants (mycotoxins, pathogenic microorganisms, pesticides and allergens) that endanger the food safety. Biosensors, analytical devices composed of a biological recognition element (such as enzyme, antibody, receptor) coupled to a chemical or physical transducer (electrochemical, mass, optical), offer a possible alternative to common approaches, by allowing rapid on site analysis, and providing real-time information during the food production process. Biosensor literature in the field of food safety is focused mainly on affinity biosensors, which are considered as a further subset of biosensors that use an antibody, sequence of DNA or protein interfaced to a signal transducer to measure a binding event; most of them are based on the very high-affinity interaction between antigen and specific antibodies, but novel specific ligands (e.g. aptamers) are emerging. However, the affinity biosensors described in literature belong to the “labelled affinity biosensors” which require the use of labels (commonly enzymes), linked to the target biomolecule, able to detect the immune-complex thanks to the production of substances easily detected by electrochemical or optical transducer systems. The drawback of immunosensors labelled is due to extra costs and time for labelling step and the impossibility of real time detection... [edited by Author]XVI n.s. (XXX ciclo

Sensitive Detection of Escherichia coli O157:H7 in Food Products by Impedimetric Immunosensors

In this work, the development of an impedimetric label-free immunosensor for the detection of Escherichia coli O157:H7 is reported. Different immobilization techniques of monoclonal anti-E. coli were tested, in order to reach the very low limit of detections. The comparison between the immobilization procedures underlined the advantages of the oriented procedure and the use of a dendrimer, which allowed for immobilizing a higher number of antibody units, reaching a very high sensitivity. However, the use of activated ferrocene as electron-transferring mediator, which improved the electrical properties of the system, resulted in a very low limit of detection equal to 3 cfu/mL. This immunosensor was used to analyze milk and meat samples obtaining a good agreement with the results of the ELISA methods

Sensitive detection of escherichia coli O157:H7 in food products by impedimetric immunosensors

In this work, the development of an impedimetric label-free immunosensor for the detection of Escherichia coli O157:H7 is reported. Different immobilization techniques of monoclonal anti-E. coli were tested, in order to reach the very low limit of detections. The comparison between the immobilization procedures underlined the advantages of the oriented procedure and the use of a dendrimer, which allowed for immobilizing a higher number of antibody units, reaching a very high sensitivity. However, the use of activated ferrocene as electron-transferring mediator, which improved the electrical properties of the system, resulted in a very low limit of detection equal to 3 cfu/mL. This immunosensor was used to analyze milk and meat samples obtaining a good agreement with the results of the ELISA methods

Rapid Detection of Deoxynivalenol in Dry Pasta Using a Label‐Free Immunosensor

This work focused on the development and optimization of an impedimetric label-free immunosensor for detecting deoxynivalenol (DON). A monoclonal antibody for DON detection was immobilized on a modified gold electrode with a cysteamine layer and polyamidoamine (PAMAM) dendrimers. Cyclic voltammetry and electrochemical impedance spectroscopy techniques were used to monitor the layer-by-layer development of the immunosensor design, while electrochemical impedance spectroscopy and differential pulse voltammetry were employed to investigate the antigen/antibody interaction. The PAMAM dendrimers, allowing to immobilize a large number of monoclonal antibodies, permitted reaching, through the DPV technique, a high sensitivity and a low limit of detection equal to 1 ppb. The evaluation of the possible reuse of the immunosensors highlighted a decrease in the analytical performances of the regenerated immunosensors. After evaluating the matrix effect, the developed immunosensor was used to quantify DON in pasta samples spiked with a known mycotoxin concentration. Taking into consideration the DON extraction procedure used for the pasta samples and the matrix effect related to the sample, the proposed immunosensor showed a limit of detection of 50 ppb, which is lower than the maximum residual limit imposed by European Regulation for DON in dry pasta (750 ppb)

A new label-free impedimetric aptasensor for gluten detection

Celiac disease is a serious autoimmune disorder caused by the ingestion of gluten. Gliadin is the gluten fraction responsible for the triggering of disease. The only cure for the celiac patients, known until now, is a diet with gluten-free foods, classified by the European regulation doesn't exceed 20 ppm in gluten. With the aim to guarantee the food safety for celiac patients in this study the developing and optimization of a fast and reliable label free impedimetric aptasensor for gliadin detection is reported. The aptamer (Gli1) at 0.5 μmol and poly (amidoamine) dendrimer of fourth generation (PAMAM G4) at 2 mg/ml were chosen during the developing steps of the sensing platform because the best ones for the detection of low gluten concentrations with the highest sensitivity. The aptasensor showed linearity in the range of 5–50 μg/l and 50–1000 μg/l in gliadin, a limit of detection of 5 μg/l corresponding to 5 ppm of gluten, a reproducibility lower than 5% and a storage stability at 4 °C of two months. Finally the aptasensor was used to measure gluten, in gluten and gluten-free food products, showing a good agreement with the results obtained with official R5 ELISA method

Olive Oil-Based Oleogel as Fat Replacer in a Sponge Cake: A Comparative Study and Optimization

Oleogels (defined as structured solid-like materials with a high amount of oil entrapped within a three-dimensional network of gelator molecules) represent a healthy alternative to fats that are rich in saturated and trans fatty acids. Given its fatty acids composition (oleic, linoleic, and linolenic acids), olive oil is an excellent candidate for the use of oleogels in the food industry. In this study, a D-optimal mixture design was employed to optimize the replacement of butter with olive oil-based oleogel in a type of sponge cake formulation: the plum cake. In addition, emulsifiers and whey proteins were used as recipe ingredients to extend the product's shelf life by delaying staling phenomena and mold growth. In the experimental design, oleogel, emulsifier, and whey protein variables were set as the ingredients that change in specific ranges, while hardness, porosity, water activity, and moistness were used to characterize the obtained formulations. The experimental data of each response were fitted through polynomial regression models with the aim of identifying the best plum cake formulation. The results revealed that the best mixture was the formulation containing 76.98% olive oil-based oleogel, 7.28% emulsifier E471, and 15.73% whey protein. We stored the optimized plum cake for 3 months at room temperature and then checked for any hardness and moistness changes or mold spoilage