ABSTRACT
The freezing of the food is one of the most important technological developments for the storage of food in terms of quality and safety. The aim of this work was to study the role of an ice structuring protein (ISP) on freezing-thawing cycles of different solutions and commercial Italian pasta sauces. Ice structuring proteins were related to the modification of the structure of ice. The results showed that the freezing time of an aqueous solution containing the protein was reduced to about 20% with respect to a pure water solution. The same effect was demonstrated in sugar-containing solutions and in lipid-containing sauces. The study proved a specific role of ISP during thawing, inducing a time decrease similar to that of freezing and even more important in the case of tomato-based sauces. This work demonstrated the role of ISP in the freezing-thawing process, showing a significant reduction of processing in the freezing and thawing phase by adding the protein to pure water and different sugar-, salt- and lipid-containing solutions and commercial sauces, with considerable benefits for the food industry in terms of costs and food quality.
ABSTRACT
An immunoassay-based lateral flow device for the quantitative determination of four major aflatoxins in maize has been developed. The one-step assay has performance comparably with that of other screening methods, as confirmed by the intra- and the inter-day precision of the data (RSD 10-22%), and can be completed in 10 min. Quantification was obtained by acquiring images of the strip and correlating intensities of the coloured lines with analyte concentration by means of a stored calibration curve carried out by diluting aflatoxins in the extract from a blank maize sample. Limit of detection (1 µg kg⻹) and dynamic range (2-40 µg kg⻹) allows the direct assessment of aflatoxin contamination in maize at all levels of regulatory relevance. All reagents are immobilized on the lateral flow device. In addition, very simple sample preparation, using an aqueous buffered solution, has been demonstrated to allow the quantitative extraction of aflatoxins. Twenty-five maize samples were extracted with the aqueous medium and analyzed by the developed assay. A good correlation was observed (y = 0.97x + 0.07, r²= 0.980) when data was compared with that obtained through an official method. The developed method is reliable, rapid and allows for application outside the laboratory as a point-of-use test for screening purposes.
Subject(s)
Aflatoxins/analysis , Crops, Agricultural/chemistry , Edible Grain/chemistry , Food Contamination , Zea mays/chemistry , Analytic Sample Preparation Methods , Animal Feed/analysis , Calibration , Food Inspection/methods , Immunoassay/instrumentation , Immunoassay/methods , Limit of Detection , Reagent Strips , Reproducibility of Results , Seeds/chemistry , Starch/chemistry , Technology TransferABSTRACT
A quantitative lateral flow immunoassay for measuring fumonisins in maize was developed. Strip preparation and assay parameters were optimized to obtain a dipstick usable outside the laboratory with different samples, and which shows performance comparable with that of other screening methods, as confirmed by the intra- and the inter-day precision of data (RSD 5-16%). Quantification was obtained by an external calibration curve, which can be stored and used for measurements made with strips of the same batch in different days and at varying temperatures (22-37°C). Limit of detection (120 µgL(-1)) and dynamic range (200-5000 µgL(-1)) allow the direct assessment of fumonisin contamination at all levels of regulatory relevance. Twenty-seven maize samples were analyzed after a simple sample preparation which avoids the use of organic solvent. Linear correlation was observed (y=1.071x-0.2, r(2)=0.990) when data was compared with that obtained through a reference LC-MS/MS method, across a wide range of fumonisin contamination.
Subject(s)
Fumonisins/analysis , Fumonisins/immunology , Immunoassay/methods , Zea mays/chemistry , Antibodies/immunology , Calibration , Chromatography, Liquid , Limit of Detection , Tandem Mass SpectrometryABSTRACT
The official methods for the quantification of aflatoxin M1 in dairy products (cheese and yogurt) include extraction into dichloromethane or chloroform, evaporation of the solvent, partitioning of the reconstituted residue with hexane, and subsequent analysis. To secure a rapid and inexpensive screen for aflatoxin M1 contamination, a sensitive competitive ELISA, using a rabbit polyclonal antibody, was developed for measuring aflatoxin M1 in milk and used in a comparative study for measuring the extraction efficiency of aflatoxin M1 in aqueous or organic solvent buffers using yogurt samples. An aqueous sodium citrate solution was found to be suitable for extracting aflatoxin M1, thus eliminating the need for organic solvents. The citrate extraction proved to be efficient (recovery ranged from 70 to 124%) in fortified samples of very different kinds of dairy products, including yogurt and six types of cheese. Fourteen yogurt and cheese samples were extracted with citrate solution and analyzed by ELISA. A good correlation was observed (y=0.95x-0.59, r2=0.98) when the data were compared with those obtained through the official method, across a wide range of aflatoxin M1 contaminations (10-200 ng/kg).
