In:
Journal of Dairy Research, Cambridge University Press (CUP), Vol. 67, No. 2 ( 2000-05), p. 261-271
Abstract:
Intracellular peptidases of Lactobacillus helveticus may play a major role
in the proteolysis of Swiss cheeses, provided that they are released through bacterial lysis. Experimental Swiss cheeses were manufactured on a small scale from
thermized and microfiltered milk using as starters (in addition to Streptococcus
thermophilus and Propionibacterium freudenreichii ) one of two Lb. helveticus strains,
ITGLH1 and ITGLH77, which undergo lysis to different extents in vitro . All the
cheeses were biochemically identical after pressing. The viability of Lb. helveticus ITGLH1 and ITGLH77 decreased to a similar extent (96–98%) while in the cold
room, but the concomitant release of intracellular lactate dehydrogenase in cheeses made with strain ITGLH1 was 5–7-fold that in cheeses made with ITGLH77. Protein
profiles and immunoblot detection of the dipeptidase PepD confirmed a greater degree of lysis of the ITGLH1 strain. Free active peptidases were detected in aqueous
extracts of cheese for both strains, and proteolysis occurred principally in the warm room. Reversed-phase HPLC revealed a more extensive peptide hydrolysis for ITGLH1, which was confirmed by the greater release of free NH 2 groups (+33%)
and free amino acids (+75%) compared with ITGLH77. As the intracellular peptidase activities of ITGLH1 and ITGLH77 have previously been shown to be
similar, our results indicated that the extent of lysis of Lb. helveticus could have a
direct impact on the degree of proteolysis in Swiss cheeses.
Type of Medium:
Online Resource
ISSN:
0022-0299
,
1469-7629
DOI:
10.1017/S0022029900004118
Language:
English
Publisher:
Cambridge University Press (CUP)
Publication Date:
2000
detail.hit.zdb_id:
2000010-8
SSG:
22
Permalink
