Impact of NaCl reduction in Danish semi-hard Samsoe cheeses on proliferation and autolysis of DL-starter cultures

Research output: Contribution to journalJournal article

Reduction of sodium chloride (NaCl) in cheese manufacturing is a challenge for the dairy industry. NaCl has a profound role on microbial development influencing cheese sensory and technological properties. The purpose of this work was to investigate how proliferation, distribution and autolysis of two commercial DL-starter cultures (C1 and C2) used in the production of Danish semi-hard Samsoe cheeses were affected by reduced NaCl levels. Cheeses containing <0.3% (unsalted), 2.3% (reduced-salt) and 3.4% (normal-salted) (w/v) NaCl in moisture were produced and analyzed during 12weeks of ripening. Lactic acid bacteria (LAB), distribution of bacteria as single cells or microcolonies, their viability in the cheeses and cell autolysis were monitored during ripening, as well as the impact of NaCl content and autolysis on the formation of free amino acids (FAA). Reduction of NaCl resulted in higher LAB counts at the early stages of ripening, with differences between the two DL-starter cultures. The unsalted cheeses produced with C1 had retained a significantly higher number of the initial LAB counts (cfu/g) after 1 and 2weeks of ripening (i.e. 58% and 71%), compared to the normal-salted cheeses (i.e. 22% and 21%), whereas no significant difference was found between the reduced-salt (i.e. 31% and 35%) and normal-salted cheeses. At the later stages of ripening (i.e. 7 and 11weeks) NaCl had no significant influence. For cheeses produced with C2, a significant influence of NaCl was only found in cheeses ripened for 7weeks, where the unsalted and reduced-salt cheeses had retained a significantly higher number of the initial LAB counts (cfu/g) (i.e. 39% and 38%), compared to the normal-salted cheeses (i.e. 21%). In the Samsoe cheeses, bacteria were organized as single cells, in groups of 2-3 cells or in groups of ≥4 cells. During ripening the decrease in the number of viable bacteria was mainly due to a reduction in the number of viable bacteria organized in groups of ≥4 cells. A negative correlation between NaCl content and PepX activity was observed. At the end of ripening the total FAA content was lower in the unsalted cheeses, compared to the reduced- and normal-salted cheeses. In conclusion, NaCl had a significant influence on proliferation of both DL-starter cultures. However, the influence of NaCl on culture development was more pronounced in cheeses produced with DL-starter culture C1. As both texture and taste are parameters known to be affected by the development of the starter culture, the design of starter cultures for reduced NaCl cheeses is recommended.

Original languageEnglish
JournalInternational Journal of Food Microbiology
Volume213
Pages (from-to)59-70
Number of pages12
ISSN0168-1605
DOIs
Publication statusPublished - 2015
Event24th International ICFMH Conference: From single cells to functions of consortia in food microbiology - Nantes, France
Duration: 1 Sep 20144 Sep 2014
Conference number: 24

Conference

Conference24th International ICFMH Conference
Number24
CountryFrance
CityNantes
Period01/09/201404/09/2014

Bibliographical note

Special Issue: FoodMicro 2014, 24th International ICFMH Conference, From single cells to functions of consortia in food microbiology, 1 - 4 September, 2014, Nantes, France.

ID: 147581394