Determination of aflatoxin M1 in milk samples by an OWLS-based immunosensor

An immunoreaction-based method was investigated for the detection of aflatoxin M1 (AFM1), which is the hydroxylated metabolite of aflatoxin B1 (AFB1). This mycotoxin may be found in milk and milk products obtained from livestock that have ingested contaminated feed. Quantitative analysis of AFM1 was carried out using indirect (competitive) immunoassay method, which can be used for low weight molecules. The real-time measurement was done with Optical Waveguide Lightmode Spectroscopy (OWLS) technique. After the optimization of the chemical and biochemical parameters (determination of the optimal concentration of the immobilized AFM1-protein conjugate, determination of the AFM1 antibody content of the samples, etc.) real samples were also examined. Three kinds of milk sample preparation methods (filtration, centrifugation, size exclusion centrifugation) and two dilution rates (100 and 200 fold) were compared. The presented competitive immunoassay method showed the best results when 100 fold diluted filtered or centrifuged milk samples were examined. The dynamic measuring ranges for AFM1 were 0.001–0.1 ng ml−1 and 0.0005–0.01 ng ml−1, respectively

Amperometrijski biosenzor za određivanje L-askorbinske kiseline u napicima pomoću imobilizirane askorbat oksidaze

A novel biosensor for l-ascorbic acid determination in different beverages was elaborated. The ascorbate oxidase enzyme (AAO) from Cucurbita sp., EC 1.10.3.3, was immobilized on a screen-printed carbon electrode with poly(ethylene glycol) (400) diglycidyl ether (PEGDGE) as a crosslinking agent. The standards and samples were measured first with a blank electrode. An inert protein, bovine serum albumin (BSA), was immobilized on the surface of this electrode with PEGDGE. The BSA mass was equivalent to the mass of 10 U of AAO enzyme immobilized on the electrodes (0.021 mg). The linear measuring range for l-ascorbic acid was between 5 and 150 μmol/L. As l-ascorbic acid is a vital vitamin and a common antioxidant used in food industry, fruit juices and vitamin C effervescent tablets were examined. The results were compared to HPLC measurements.Razvijen je novi biosenzor za određivanje L-askorbinske kiseline (vitamina C) u sokovima pomoću askorbat oksidaze izolirane iz bundeve (Cucurbita sp.; EC 1.10.3.3), imobilizirane na grafitnoj elektrodi dodatkom polietilen glikol diglicidil etera (PEGDGE). Standardi i uzorci najprije su ispitani pomoću referentne elektrode. Zatim je inertni protein, i to goveđi serum albumin (BSA), imobiliziran na površinu elektrode pomoću PEGDGE. Masa BSA bila je jednaka masi 10 jedinica askorbat oksidaze imobilizirane na elektrodi (0,021 mg). Linearni raspon mjerenja bio je između 5 i 150 μmol/L askorbinske kiseline. Askorbinska kiselina je esencijalni vitamin i često se primjenjuje kao antioksidans u prehrambenoj industriji, pa je ispitan njezin udjel u voćnim sokovima i šumećim tabletama, a rezultati su uspoređeni s onima dobivenim tekućinskom kromatografijom

Quality Management in Spice Paprika Production: From Cultivation to End Product

There is ample historical and scientifically proven information regarding the health benefits of spice paprika, including favourable physiological effects, anti-oxidant and anti-inflammatory properties. Nonetheless, even though it is consumed in small portions, spice paprika has occasionally been reported for chemical/microbiological contamination, as well as fraud or food adulteration. Quality management can guarantee effective reduction of such contamination cases. Different production stages within cultivation and production are subject to different contamination types. Cultivation is a common source of pesticide residues, and unfavourable harvest conditions may give rise to mycotoxins by pathogenic fungi. Storage and post-ripening prior to processing is attributed with microbial contamination and possible increase in mycotoxin content may significantly affect quality features. Technology steps, for example, washing, separation, drying may worsen microbial contamination or quality, but normally do not lead to increase in mycotoxins; nonetheless, decontamination technology is a prerequisite for microbial safety of the product. Upon effective decontamination, finishing steps in the processing technology, for example, grinding, packaging and end product handling do not affect the microbial status, but other, occasionally deliberate contamination due to mixing and adulteration may occur at this stage

Chlorophyll fluorescence instrumentation for a rapid, in situ measurement of algal density

In the project reported, we are developing an instrument for measuring algal density based on the detection of chlorophyll fluorescence. Following the adjustment of several parameters defined during preliminary analyses, measurements were made on different concentrations of model green and blue algal cultures. Fluorescent signal intensities measured by the prototypes of the fluorometer module were compared to values determined by other, widely used methods for estimation of algal density (i.e. Bürker chamber cell counting, optical density measurement and chlorophyll-a measurement with ethanol extraction method). Fluorometer results correlated well with the other methods, resulting high correlation coefficients (R2>0.9%). Limits of detection and limits of quantification showed a decreasing trend during the development phases resulting in a highly sensitive instrument

Book reviews

Foods, nutrients and food ingredients with authorised EU health claims. M.J. SADLER (Ed.). Woodhead Publishing is an imprint of Elsevier, Cambridge, UK, Waltham, US, Kidlington, UK, Series in Food Science, Technology and Nutrition: Number 263, 2014 ISBN 978-0-85709-842-9 (print), ISBN 978-0-85709-848-1 (e-book), 397 page

Book reviews

N.N. MISRA, O.K. SCHLÜTER and P.J. KULLEN (Eds): Cold plasma in food and agriculture. Fundamentals and applications. Elsevier Science Publishing Co Inc., 2016, 125 London Wall, London EC2Y 5AS, United Kingdom ISBN: 978-0-12-801365-6, 380 pages | K. KNOERZER, P. JULIANO and G. SMITHERS (Eds): Innovative food processing technologies. Extraction, separation, component modifi cation and process intensifi cation. Woodhead Publishing, The Offi cers’ Mess Business Centre, Royston Road, Duxford, CB22 4QH, UK, 50 Hampshire Street, 5th Floor, Cambridge, MA 02139, USA The Boulevard, Langford Lane, Kidlington, OX5 1GB, UK ISBN: 978-0-08-100294-0, 481 pages | R. CARLE and R.M. SCHWEIGGERT (Eds): Handbook on natural pigments in food and beverages. Industrial applications for improving food color. Woodhead Publishing Series in Food Science, Technology and Nutrition ,Vol. 295. Woodhead Publisher is an imprint of Elsevier, The Offi cers’ Mess Business Centre, Royston Road, Duxford, CB22 4QH. UK ISBN: 978-0-08-100371-8, 509 pages | J. SINGH and L. KAUR (Eds): Advances in potato chemistry and technology. Academic Press is an Imprint of Elsevier, London, San Diego, Cambridge, Oxford, 2nd edition, ISBN: 978-0-12-800002-1 (print), 725 page

Interfacial enzyme partitioning as a tool for constructing biosensors

To explore new possibilities of enzyme immobilization, we investigated bioactive layers prepared by a new procedure based on three-phase partitioning (TPP) of proteins. By this method a third phase or midlayer as a protein layer can be developed at the interface of a protein system containing two phases (organic solvent/aqueous salt solution). Proteins of meat origin partitioned together with bioselective material (e.g. an enzyme) after centrifugation resulted in excellent bioactive layers.In the newly developed sensor, glucose oxidase was immobilized in a layer, which was fixed on the surface of a platinum ring electrode. The biosensor was built in a flow injection analyzer (FIA) system, where the hydrogen peroxide generated during the enzymatic reactions was determined by an amperometric cell. The parameters for biochemical and electrochemical reactions (ion concentration and pH of buffer, flow rate) were optimized. The linear range of analysis by the newly developed sensor was from 0.5 to 10 mmol l–1 glucose. The biosensor could be used for more than 300 analysis