Homologies in amino acidic composition could justify the cross-reactivity observed between proteins from different animal species. On the other hand, the phylogenetic difference could be responsible for the failed recognition of camel's proteins by circulating IgEs and monoclonal antibodies.

Bovine β-lactoglobulin was hydrolyzed with trypsin or chymotrypsin before, during and after treatment at 600 MPa and pH 6·8 for 10 min at 30, 37 and 44 °C. The extent of β-lactoglobulin hydrolysis under pressure was noticeably higher than at atmospheric pressure, particularly when chymotrypsin was used. Addition of proteases at ambient pressure to previously pressure-treated β-lactoglobulin gave only a modest increase in proteolysis with respect to the untreated protein. Products of enzyme hydrolysis under pressure were separated by reverse-phase HPLC, and were found to be different from those obtained at atmospheric pressure when chymotrypsin was used. The residual immunochemical reactivity of the products of combined pressure-enzyme treatment was assessed on the unresolved hydrolysates by ELISA tests using polyclonal and monoclonal antibodies, and on individual hydrolytic fractions by Western Blotting using sera of paediatric patients allergic to whey proteins in cow milk. The immunoreactivity of the whole hydrolysates was related to their content of residual intact β-lactoglobulin, and no immunochemical reactivity was found for all the products of chymotrypsin hydrolysis under pressure. The results indicate that chymotrypsin effectively hydrolysed hydrophobic regions of β-lactoglobulin that were transiently exposed during the pressure treatments and that were not accessible in the native protein or in the protein that had been previously pressure treated.

Patulin is a mycotoxin produced by certain species of Penicillium and Aspergillus, often detectable in mouldy fruits and their derivatives. On the basis of a PMTDI of 0.4 microgram/kg bw, limit values of 50 micrograms/kg or 50 micrograms/l of patulin have been set in fruit derivatives. To estimate the quantity of patulin that can be taken in with the diet, we analysed by HPLC samples of apples and apple derivatives which are most likely to be contaminated with patulin. In apple juices and in homogenized baby-foods, the mycotoxin concentration was always below the established limits, while in some samples of juice with pulp the mycotoxin content exceeded the safe levels. In rotten apples, not only was the amount of patulin extraordinarily high in the rotten area, but the mycotoxin had also spread to the part unaffected by mould. The data presented in this study indicate that the intake of patulin with apple derivatives is usually below the tolerable level of 0.4 microgram/kg bw/day, but since the patulin content in apples can vary considerably, the quality of fruits used in the production of apple derivatives should be strictly controlled in order not to exceed the safe limits.

Ochratoxin A is a typical cereal contaminant with strong nephrotoxic activity. To estimate the quantity of ochratoxin A that can be taken in by a child in the weaning period, several samples of cereal-based baby foods were analysed. Although most samples analysed contained ochratoxin A in undetectable amounts or below the Italian legal limit of 0.5 microg kg(-1), some irregular products were found. In particular, the analyses of the 119 batches (338 samples) of baby foods considered indicated that: 20 batches (16.8%) contained detectable quantities of ochratoxin A and four of these (3.4% of the total) contained ochratoxin A above the Italian permitted value. All samples coming from agricultural practices based on integrated pest management contained undetectable amounts of ochratoxin A, while approximately 5% of batches coming from conventional and organic agricultural practices were above the legal limit. On the basis of the established provisional tolerable weekly intake (PTWI), there is no significant toxicological risk for a child who occasionally consumes a formula with ochratoxin concentration slightly above the permitted level. However, stricter controls have to be applied to reject the batches containing irregular concentrations of ochratoxin A.

No abstract

During the last few years, advances in the care of low-birth-weight and preterm neonates has stimulated research on the best dietetic program to improve survival and to reduce handicap incidence. At present, fortification of human milk with artificial formulas is the most usual dietetic solution. As yet, however, little is known about the composition of milk from mothers giving birth prematurely. The aim of this study was the quantification of different proteins in human milk during the lactation period. By use of an electrophoretic method, lactoferrin (LF), alpha-lactalbumin, beta-casein, and lysozyme concentrations were measured in milk from mothers delivering normally (TM) or prematurely (PM). LF concentration in milk from TM presented higher values in the very first days and a fast decrease to d 10. After d 10, the concentration reached a plateau. In milk from PM, the LF concentration in the first days was lower than for TM. Similar profiles of alpha-lactalbumin, beta-casein, and lysozyme concentrations were found in milk from TM and PM. A general higher variability in PM samples was observed both between different mothers and for the same woman during the lactation period. Lactation profiles for four human milk proteins are described here. No significant difference was observed (apart from LF in the very first days) between preterm and term milk samples, confirming the unsuitability of unfortified breast milk for preterm neonates.

Background: Bovine serum albumin (BSA) is one of the most widely studied proteins; its structure is well known and its antigenic characteristics have been described in several papers. The aim of this research was the identification of the BSA antigenic determinants. Methods: This study was performed using limited proteolysis and an immunoblotting technique, in which a commercial murine antibody and sera from children sensitized to BSA were used. Results: Findings suggest amino acids (aa) 524–598 as an epitopic area for human species. The most critical sequence seems to be aa 524–542, even if it must be included in a longer fragment to be recognized by antibodies. Murine IgG antibodies also recognize fragments contained in the first half (NH₂-terminal portion) of BSA. Conclusions: The results presented in this study indicate that the epitopic sites of an antigenic protein can be different when different species are considered, so that data obtained with antibodies from animal species cannot be directly extrapolated to the behavior of human IgEs.

Since casein proteolysis has a critical role in defining the typical characteristics of Grana Padano cheese, we evaluated the hydrolysis of alphas-casein during the ripening process. Thanks to the high specificity of the anti-alphas((alphas1 + alphas2)-casein monoclonal antibody and amino acid sequence determination, it was possible to identify three main alphas-casein-derived polypeptides in cheese: alphaa, alphab, and alphac. Their production by the three enzymes most involved in cheese proteolysis (pepsin, chymosin, and plasmin) was evaluated by performing in vitro digestions. Data showed that alphaa was released in cheese mainly by the chymosin attack, while alphab and alphac were due to the action of plasmin. A significant correlation between the abundance of some polypeptides and ripening process was shown.