Evaluation of an enterocin AS-48 enriched bioactive powder obtained by spray drying.

Enterocin AS-48 is a cationic cyclic bacteriocin produced by Enterococcus faecalis with broad bactericidal activity. Currently we are assaying the efficacy of AS-48 as biopreservative in foods. In this work we have applied the spray drying process to different AS-48 liquid samples to obtain active dried preparations.

Correlation of base consumption with the degree of hydrolysis in enzymic protein hydrolysis.

It is fairly easy to control the enzymic hydrolysis of proteins in alkaline conditions by measuring the base consumption required to keep the pH constant in the reactor. Unfortunately, however, base consumption is not related in any simple way to the degree of hydrolysis reached at any given moment and to establish this relationship it is essential to find out the mean pK of the alpha-amino groups released during the hydrolytic process. We have shown here that the correct mean pK value varies according to the pH of the working conditions and that the relationship between these values may depend upon the kind of protein and protease used.

Partition coefficients of alpha-amylase in aqueous two-phase systems PEG + MgSO4.7H2O + H2O at 298 K.

Partition coefficients of alpha-amylase have been determined in a polyethylene glycol (average molecular mass 8000)/MgSO4.7H2O aqueous two-phase system at 298 K and the influence of polymer, salt and initial enzyme concentration on partition was investigated. Correlations are proposed which relates the partition coefficient to the initial enzyme concentration and the concentration difference between phases of polymer and salt.

Enzymatic hydrolysis of whey proteins: I. Kinetic models.

We have studied the enzymatic hydrolysis of whey proteins at pH 8 and50 degrees C with two proteases of bacterial origin, MKC Protease 660 L, and one of animal origin, PEM 2500 S. Our results show that a greater degree of hydrolysis is achieved under the same experimental conditions with the bacterial proteases than with the animal one. In our interpretation of the results we propose a mechanism in which the hydrolytic reaction is a zero-order one for the substrate, and the enzyme denaturalizes simultaneously via a second-order kinetic process due to free enzyme attacking enzyme bound to the substrate.