Autor(es):
Pintado, Ana I. 
; Macedo, Angela C. ; Teixeira, Grimaneza ; Pais, Salomé ; Clemente, Alda ; Malcata, F. Xavier
Data: 2001
Identificador Persistente: http://hdl.handle.net/10400.14/6900
Origem: Veritati - Repositório Institucional da Universidade Católica Portuguesa
Descrição
The rates and extents of hydrolysis of RS- and â-caseins from bovine, caprine, and
ovine sodium caseinates produced by an enzymatic extract of the fruit of Opuntia ficusindica,
(L.) Miller were evaluated and compared with those produced by a commercial
animal rennet. A mechanistic model based on a pseudo-first-order enzymatic reaction,
in the presence of first-order deactivation of the enzyme, was postulated and
successfully fitted to the experimental data. The animal rennet exhibited higher
enzymatic efficiency than the fruit extract, irrespective of the source (i.e., bovine,
caprine, or ovine) and the type (i.e., RS- or â-casein) of substrate. The enzymatic
efficiency (kcat/Km) for RS-casein ranged from 72 to 220 and from 43 to 65 L g-1 h-1,
and for â-casein from 242 to 742 and from 55 to 164 L g-1 h-1, for the animal rennet
and the enzymatic extract of O. ficus-indica, respectively. Finally, it was observed
that â-casein from caprine and ovine caseinates was degraded by O. ficus-indica faster
than its RS counterpart, but the reverse was observed for bovine caseinate.
