Search

A novel screening method was developed for simple and rapid detection of aflatoxin M1 contamination in raw ewe's milk samples without the need for sample pretreatment. The method was based on the use of a commercial head space sensor array system constituted by 12 metal oxide semiconductor sensors, 10 metal oxide semiconductor field-effect transistor sensors, and a pattern recognition software. Twenty-four raw milk samples collected from two different groups of ewes fed with a formulated feed that contained increasing amounts of aflatoxin B1 and six noncontaminated ewe's milk samples were analyzed. The results obtained by using the head space sensor array, processed by statistical methods, made it possible to group the samples according to the presence or the absence of aflatoxin M1. Sample classification was in complete agreement with the aflatoxin M1 content measured by an enzyme-linked immunosorbent assay procedure. This is the first report, to our knowledge, of detection of aflatoxin M1 in ewe's milk by a multisensor array.

Enzymatic hydrolysis of allergenic food proteins (betalactoglobulin, ovalbumin) was carried out during treatment at different combinations of time, pressure and temperature, with the aim of hydrolyzing the protein conformers transiently formed in the course of physical treatment in conditions where no irreversible modification of the target protein occurs. The amount of residual intact betalactoglobulin after 10min at 600 MPa in the presence of trypsin or chymotrypsin was found to decrease markedly with increasing temperature (30-44°C). The temperature sensitivity of the enzymatic hydrolysis of ovalbumin during similar treatments was much less pronounced than that of betalactoglobulin. The effects of temperature on the accessibility of betalactoglobulin conformers to proteases were studied at higher temperatures (55-65°C), and indicated that complete hydrolysis of betalactoglobulin cannot be achieved in a short time in the absence of a pressure treatment. None of the hydrolysis products of either protein was immunoreactive in Western-blot immunoassays.

Modifications induced by the combined application of pressure (up to 800 MPa) and temperature (up to 80° C) were studied on wet and dry semolina, and on fresh pasta as such and after cooking. Rheological and immunochemical properties of the treated products were investigated, along with parameters indicating the extent of protein denaturation. No modification occurs in semolina treated at less than 45% water, below 60°C/800MPa for 10min. Egg noodles prepared from pressure/heat treated semolina had increased protein digestibility and low recognition by anti-gliadin antibodies either before or after cooking. The same effects were observed in heat/pressure treated pasta, but were lost upon subsequent cooking, although we found decreased immunochemical reactivity after heat/pressure treatment of cooked pasta. No sensory difference was found between cooked and pressure-treated semolina products.