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Int J Food Microbiol

Title:		Can the development and autolysis of lactic acid bacteria influence the cheese volatile fraction? The case of Grana Padano
Author(s):		Lazzi C; Povolo M; Locci F; Bernini V; Neviani E; Gatti M;
Address:		"Dipartimento di Scienze degli Alimenti, Universita degli Studi di Parma, Parco Area delle Scienze, 49/A, 43124, Parma, Italy. Electronic address: camilla.lazzi@unipr.it. Consiglio per la Ricerca e la sperimentazione in Agricoltura, Centro di Ricerca per le Produzioni Foraggere e Lattiero-Casearie, via A. Lombardo, 11, 26900 Lodi, Italy. Dipartimento di Scienze degli Alimenti, Universita degli Studi di Parma, Parco Area delle Scienze, 49/A, 43124, Parma, Italy. Dipartimento di Scienze degli Alimenti, Universita degli Studi di Parma, Parco Area delle Scienze, 49/A, 43124, Parma, Italy; Multidisciplinary Interdepartmental Dairy Center - MILC, University of Parma, Parma, Italy. Electronic address: monica.gatti@unipr.it"
Journal Title:		Int J Food Microbiol
Year:		2016
Volume:		20160608
Issue:
Page Number:		20 - 28
DOI:		10.1016/j.ijfoodmicro.2016.06.009
ISSN/ISBN:		1879-3460 (Electronic) 0168-1605 (Linking)
Abstract:		"In this study, the relationship between the dynamics of the growth and lysis of lactic acid bacteria in Grana Padano cheese and the formation of the volatile flavor compounds during cheese ripening was investigated. The microbial dynamics of Grana Padano cheeses that were produced in two different dairies were followed during ripening. The total and cultivable lactic microflora, community composition as determined by length heterogeneity-PCR (LH-PCR), and extent of bacterial lysis using an intracellular enzymatic activity assay were compared among cheeses after 2, 6 and 13months of ripening in two dairies. The evolution of whole and lysed microbiota was different between the two dairies. In dairy 2, the number of total cells was higher than that in dairy 1 in all samples, and the number of cells that lysed during ripening was lower. In addition, at the beginning of ripening (2months), the community structure of the cheese from dairy 2 was more complex and was composed of starter lactic acid bacteria (Lactobacillus helveticus and Lactobacillus delbrueckii) and NSLAB, possibly arising from raw milk, including Lactobacillus rhamnosus/Lactobacillus casei and Pediococcus acidilactici. On the other hand, the cheese from dairy 1 that ripened for 2months was mainly composed of the SLAB L. helveticus and L. delbrueckii. An evaluation of the free-DNA fraction through LH-PCR identified those species that had a high degree of lysis. Data on the dynamics of bacterial growth and lysis were evaluated with respect to the volatile profile and the organic acid content of the two cheeses after 13months of ripening, producing very different results. Cheese from dairy 1 showed a higher content of free fatty acids, particularly those deriving from milk fat lipolysis, benzaldehyde and organic acids, such as pGlu and citric. In contrast, cheese from dairy 2 had a greater amount of ketones, alcohols, hydrocarbons, acetic acid and propionic acid. Based on these results, we can conclude that in the first cheese, the intracellular enzymes that were released from lysis were mainly involved in aroma formation, whereas in the second cheese, the greater complexity of volatile compounds may be associated with its more complex microbial composition caused from SLAB lysis and NSLAB (mainly L. rhamnosus/L. casei) growth during ripening"
Keywords:		Bacteriolysis Cheese/analysis/*microbiology Fatty Acids/metabolism Fermentation Flavoring Agents/analysis/*metabolism Humans Lactic Acid/analysis/metabolism Lactobacillaceae/genetics/*growth & development/*metabolism Polymerase Chain Reaction Taste Aroma;
Notes:		"MedlineLazzi, Camilla Povolo, Milena Locci, Francesco Bernini, Valentina Neviani, Erasmo Gatti, Monica eng Netherlands 2016/06/15 Int J Food Microbiol. 2016 Sep 16; 233:20-28. doi: 10.1016/j.ijfoodmicro.2016.06.009. Epub 2016 Jun 8"