Physicochemical and microbiological changes of bovine blood due to high hydrostatic pressure treatment

Bovine blood samples were treated with high hydrostatic pressure (HHP) to examine the changes that may occur in the blood related to its colour, microbiological characteristics, protein denaturation, and dynamic viscosity. Pressure treatments were carried out from 100 to 600 MPa in 100 MPa scale up, with 5 min holding time. The blood samples were treated with anticoagulant (EDTA) to eliminate the possible measurement distorting effects. We found that 2 log reduction in the microbial load could be achieved with a pressure treatment above 400 MPa. According to the protein denaturation measurements (DSC), blood proteins were resistant to pressure treatment, even at 300–400 MPa a substantial part of proteins remained in native state. The colour of the samples got darker with the rising pressure, however, visible colour change was observed only above 400 MPa. It can be established, that the HHP treatment was suitable to increase the microbiological stability of blood, without significantly changing its techno-functional properties.

Mechanically deboned turkey meat with improved digestibility and biological value

Enzymatic hydrolysates of mechanically deboned meat (MDM) for a long time have been used as flavouring and functional food ingredients in the food industry and also as the bases of formula foods for special dietary uses.

The aim of the present study was to produce MDM hypo-antigenic products with improved digestibility and high biological value to be used as a milk protein alternative. turkey MDM was treated with digestive enzymes (trypsin and/or α-chymotrypsin, or pancreatin), followed by freeze drying. The optimised reaction conditions of hydrolysis were at 6% (w/v) of meat protein in 0.1% NaHCO3 buffer, pH 7.5; pancreatin enzyme with 50 TAME units/g meat protein substrate, 37 °C and 60 min). Hydrolysates (MDMH) were assessed for degree of hydrolyses (DH, %) by using trinitrobenzenesulphonic acid method and MW distribution by SDS-PAGE. Modification of immune reactive binding sites in MDMHs was monitored by immunoblot with cow’s milk, chicken egg or meat allergic human patients’ sera. Biological value indices (True Digestibility (TD), Net Protein Utilisation (NPU), Biological Value (BV)) were determined using rat feeding trials. Among the MDMH products, the pancreatic hydrolysate proved to be the most favourable in terms of biological value and digestibility as well as hypoallergenic property.

Effect of methionine enrichment on the biological activities of food proteins

A special enzymatic technique, the enzymatic peptide modification (EPM) reactions have been worked out in our laboratory, by which proteins can be modified with respect to their biological activities. Enzymatic modification methods provide several advantages in producing proteins of desired nutritional properties. Proteolytic modification, particularly when combined with methionine enrichment, significantly altered the biological activities and leads to increased nutritional value.

[The effect of keeping condition and genotype on the electrophoretic properties of pork proteins]

Besides differentiation of animal species the electrophoretic methods are efficient also in determinations of the factors effecting the protein patterns. The goal of this study is to compare the effect of the genotype and the keeping conditions on the electrophoretic behaviour of the pork meat proteins. Isoelectric focusing was found to be more efficient than SDS-PAGE concerning studies of the effect of these factors. An optimal separation has been achieved with an ampholyte-mixture at pH ranges 2-11, 5-7 and 7-9. Peroxidase activity of the separated myoglobines of the meat samples was stained for detecting the differences in protein zones according to the keeping conditions. The myoglobin zones stained with o-dianisidin were evaluated by densitometry. The protein zones of the organic meat samples showed higher intensity than those of the control-samples.