Lactobacillus helveticus as a tool to change proteolysis and functionality in Swiss-type cheeses

Abstract

Lactobacillus helveticus exhibits a great biodiversity in terms of protease gene content, with 1 to 4 cell envelope proteinases. Among them, proteinases PrtH and PrtH2 were shown to have different cleavage specificity on pure α(s1)-casein. The aim of this work was to investigate the proteolytic activity of 2L. helveticus strains in cheese matrix: ITGLH77 (PrtH2 only) and ITGLH1 (at least 2 proteinases, PrtH and PrtH2). Cell viability, proteolysis, autolysis, and stretchability of experimental Emmental cheeses were measured during ripening. The peptides identified by mass spectrometry showed very different profiles in the 2 cheeses. Regardless of the casein origin, the number of different peptides containing more than 20 amino acids was greater in cheeses manufactured with strain ITGLH77. This accumulation of large peptides, including those from α(s1)- and α(s2)-caseins, was in agreement with the lower overall extent of proteolysis obtained in ITGLH77 cheeses, which can be attributed to the presence of one cell envelope proteinase of the lactobacilli strains or lesser release of intracellular peptidases into the cheese aqueous phase. In parallel, stretchability was measured throughout ripening time. Emmental strands observed by confocal laser scanning microscopy showed microstructure similar to that of mozzarella strands. Stretchability was correlated with a specific type of peptide (hydrophobic), as shown by principal component analysis, and with a lower degree of proteolysis.

Peptidomic study of Spanish blue cheese (Valdeón) and changes after simulated gastrointestinal digestion

“…The last sequence has been often found after simulated digestion of different dairy products, including in vivo studies . However, the two first peptides have been found only in cheese and not in simulated digests of other dairy products, which could indicate that they are generated by the fermentation process . Regarding the α s1 ‐casein resistant peptides, the sequences f83–89 (KEDVPSE), f84–90 (EDVPSER), and f83–90 (KEDVPSER) survived digestion.…”

Strain-to-strain differences within lactic and propionic acid bacteria species strongly impact the properties of cheese–A review

“…The 15 strains studied in vitro rapidly hydrolysed pure β-casein, but differed in the hydrolysis kinetics of α s1 -casein, depending on their number of CEPs (Sadat-Mekmene et al 2011a). Moreover, in cheese, the degree of proteolysis differed by a factor of 1.5 in Emmental cheeses manufactured using either L. helveticus ITGLH77 with only PrtH2 and a low level of lysis, or L. helveticus ITGLH1 having at least PrtH and PrtH2 encoding genes and a high lytic activity (Sadat-Mekmene et al 2013). The kinetics of α s1 -casein hydrolysis in these cheeses was in agreement with the results observed in vitro.…”

“…Such a difference was correlated with a peculiar type of peptides, i.e. hydrophobic ones and with a size over 20 amino acid residues (Sadat-Mekmene et al 2013). …”

“…It was not correlated to the total amount of peptides but to a balance between hydrophobic and hydrophilic peptides (Richoux et al 2009). The relation with the number and/or activities of L. helveticus CEP and the ability of strains to lyse and to release their intracellular peptidases was a determinant in the stretchability, and differences in strand length between strains of more than 100 mm were observed (Sadat-Mekmene et al 2013). Such a difference was correlated with a peculiar type of peptides, i.e.…”

Fluorescence-based tools for single-cell approaches in food microbiology

“…Using a gel cassette system filled with coagulated ultra-filtered milk retentate, Jeanson et al (2011) demonstrated the crucial influence of the inoculation level on the spatial distribution and mean diameter of Lactococcus lactis colonies. Other studies reported a close association between embedded technologically useful bacteria and proteins/fat interfaces in milk products (Brisson et al, 2010;Lopez et al, 2006;Sadat-Mekmene et al, 2013). Fig.…”