Ochratoxin A in cereal-based baby foods: occurrence and safety evaluation.

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.

Antigenic determinants of bovine serum albumin.

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 (NH(2)-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.

Proteolysis of beta-casein as a marker of Grana Padano cheese ripening.

Proteolysis has a critical role in defining the typical organoleptic characteristics of Grana Padano, a well-known Italian cheese. During the ripening process, hydrolysis of beta-casein produces different fragments, the most abundant and widely studied of which are gamma-caseins, three polypeptides containing the HOOC-terminal portion of beta-casein. By sodium dodecyl sulfate-PAGE and a specific anti-beta-casein monoclonal antibody, two beta-casein-derived bands were identified in Grana Padano cheese: betaa and betab. Thanks to the identification of the amino acid sequences, it was shown that: a) betaa contains gamma1-casein [beta-casein (29-209)] and the correlated peptide [beta-casein (30-209)]; b) betab contains gamma2-casein [beta-casein (106-209)] and gamma3-casein [beta-casein (108-209)]. The production of betaa and betab by the three enzymes most involved in cheese proteolysis (pepsin, chymosin, and plasmin) was evaluated by performing in vitro digestions. A significant correlation between abundance of some polypeptides and ripening process was shown.

Patulin in apple-based foods: occurrence and safety evaluation.

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.

Proteolysis of alphas-casein as a marker of Grana Padano cheese ripening.

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.

Evaluation of the presence of bovine proteins in human milk as a possible cause of allergic symptoms in breast-fed children.

BACKGROUND: It is generally believed that the elimination of certain foods from the diet of mothers during the lactation period produces a significant improvement in breast-fed children who develop allergic symptoms. Several studies have shown the presence of food proteins in human milk; on the other hand, no study has been able to correlate unequivocally the presence of these allergens in human milk with newborn sensitization. OBJECTIVE: The aim of this study was to evaluate the presence of bovine proteins in breast milk. METHODS: Milk samples were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). To detect bovine proteins in human milk, immunoblotting was performed by using monoclonal antibodies (MA) specific for beta-lactoglobulin and bovine caseins. RESULTS: The results of this study do not confirm the presence of bovine proteins in breast milk suggested by other authors and shows unequivocally that the conflicting results reported in the literature about the presence of betalactoglobulin in human milk are due to cross-reactivity between bovine milk proteins and human proteins. CONCLUSIONS: Components other than bovine betalactoglobulin or caseins could be involved in the induction of allergic symptoms in exclusively breast-fed children.

Cross-reactivity between milk proteins from different animal species.

BACKGROUND: Cow's milk allergy is quite frequent in the first years of human life. When breast-feeding is not possible, a cow's milk substitute must be provided for allergic subjects. Different alternatives to cow's milk have been suggested as protein sources (soy, hydrolysed proteins, goat's milk, etc.), but all these dietetic solutions are not without risks for polyallergic or more sensitive subjects. OBJECTIVE: To obtain new information on the suitability of other mammalian milks for allergic children, we evaluated the cross-reactivity between milk proteins from different animal species. METHODS: Milk samples were analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). To detect antibody-antigen complexes, immunoblotting was performed by using sera from children allergic to cow's and ewe's milk (RAST class >/= 4) and monoclonal antibodies (MoAb) specific for bovine proteins (caseins and beta-lactoglobulin). RESULTS: IgEs from children allergic to cow's milk are capable of recognizing most part of milk proteins from mammals bred in European countries (ewe, goat, buffalo), while no serum used in this study contains IgEs reacting with camel's milk proteins. Camel's milk was also not recognized from circulating IgEs from a child specifically allergic to ewe's milk. Specific antibovine monoclonal antibodies cross-reacted with proteins from other mammalian species, apart from those of camel. CONCLUSIONS: 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.

Protein profiles in breast milk from mothers delivering term and preterm babies.

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.

Carob is not allergenic in peanut-allergic subjects.

BACKGROUND: The antigenic potential of proteins from the carob bean, a member of the legume family used as a food additive, have not so far been investigated and legumes share antigenic proteins with peanut, a potent trigger of anaphylaxis. OBJECTIVE: To assess the carob protein determinants of sensitization in peanut-allergic children. METHODS: In a prospective, double-blind, placebo-controlled study 12 patients (median age 9.5 years) with a history of hyperreactivity to peanut (anaphylaxis) were assessed. Skin prick tests with a commercial peanut allergen, raw carob pulp, raw and cooked carob cotyledon formula were used to confirm the history. RAST for peanuts and cooked carob were used to evaluate sensitization to these proteins. Carob-specific IgE were identified by immunoblotting analyses. Allergic reactivity was evaluated during double-blind placebo-controlled food challenges (DBPCFC; 5.5 g carob extract and cooked carob cotyledon formula). RESULTS: Peanut allergen-induced skin prick test positivity in all children (confirmed during double-blinded challenge in 6/12 patients), carob pulp in 3/12 patients, raw carob bean in 6/12, and cooked carob cotyledon formula in none. RAST were positive for peanut in all cases but negative for carob beans in 9/12 cases. Immunoblot analyses found peanut-specific IgE in all cases and raw carob bean-specific IgE in eight cases. Carob allergens were identified in the 17.5, 48, and 66 kDa MW bands. The least allergenic density was found for cooked carob proteins. There was no clinical reactivity with either raw or cooked carob during DBPCFC. CONCLUSIONS: These data suggest that carob-specific sensitization, apparent both in vitro and in SPTs, can be concordant with peanut allergy and that cooked carob can be ingested by children who are allergic to peanuts. That heat-processing deactivates carob protein allergenicity has dietary implications for polyallergic children.