HPLC analysis of the pigments produced by the microflora isolated from the ‘Protected Designation of Origin’ French red-smear soft cheeses Munster, Epoisses, Reblochon and Livarot

Deciphering Rind Color Heterogeneity of Smear-Ripened Munster Cheese and Its Association with Microbiota

Color is one of the first criteria to assess the quality of cheese. However, very limited data are available on the color heterogeneity of the rind and its relationship with microbial community structure. In this study, the color of a wide range of smear-ripened Munster cheeses from various origins was monitored during storage by photographic imaging and data analysis in the CIELAB color space using luminance, chroma, and hue angle as descriptors. Different levels of inter- and intra-cheese heterogeneity were observed. The most heterogeneous Munster cheeses were the darkest with orange-red colors. The most homogeneous were the brightest with yellow-orange. K-means clustering revealed three clusters distinguished by their color heterogeneity. Color analysis coupled with metabarcoding showed that rinds with heterogeneous color exhibited higher microbial diversity associated with important changes in their microbial community structure during storage. In addition, intra-cheese community structure fluctuations were associated with heterogeneity in rind color. The species Glutamicibacter arilaitensis and Psychrobacter nivimaris/piscatorii were found to be positively associated with the presence of undesirable brown patches. This study highlights the close relationship between the heterogeneity of the cheese rind and its microbiota.

Comparison of the carotenoid profiles of commonly consumed smear-ripened cheeses

The objective of this study was to identify the carotenoids imparting the orange colour to the rind, and pale yellow color to the core, of selected smear-ripened cheeses. The cheeses investigated were Charloe, Ashbrook, Taleggio, and Limburger, and were sourced from artisanal markets. Samples of the rind and core were extracted using non-polar solvents, followed by saponification to hydrolyze triglycerides to remove fatty acids, and to release carotenoid esters. Extracts were tested using ultra-high pressure liquid chromatograph-diode array detector-high resolution mass spectrometry (UHPLC-DAD-MS and -MS/MS), and identities of α- and β-carotene, lycopene, and β-cryptoxanthin confirmed with authentic standards. β-Carotene was the predominant species in both the rind and core, absorbing ~70% of the signal at 450 nm in all cheese extracts tested, as well as minor quantities of β-cryptoxanthin and α-carotene. Carotenoids unique to the rind included lycopene as well as the rare bacterial carotenoids previously identified in bacterial isolates of cheeses (i.e. decaprenoxanthin, sarcinaxanthin, and echinenone). This is the first detailed characterisation of carotenoids extracted directly from smear-ripened cheeses, and reveals that smear-ripened cheese can contribute both provitamin A carotenoids as well as C50 carotenoids to the human diet.

Biotechnological approaches for the production of designer cheese with improved functionality

Cheese is a product of ancient biotechnological practices, which has been revolutionized as a functional food product in many parts of the world. Bioactive compounds, such as peptides, polysaccharides, and fatty acids, have been identified in traditional cheese products, which demonstrate functional properties such as antihypertensive, antioxidant, immunomodulation, antidiabetic, and anticancer activities. Besides, cheese-making probiotic lactic acid bacteria (LAB) exert a positive impact on gut health, aiding in digestion, and improved nutrient absorption. Advancement in biotechnological research revealed the potential of metabolite production with prebiotics and bioactive functions in several strains of LAB, yeast, and filamentous fungi. The application of specific biocatalyst producing microbial strains enhances nutraceutical value, resulting in designer cheese products with multifarious health beneficial effects. This review summarizes the biotechnological approaches applied in designing cheese products with improved functional properties.

Production of carotenoids by Arthrobacter arilaitensis strains isolated from smear-ripened cheeses

Arthrobacter arilaitensis is one of the major microorganisms responsible for the coloration of cheese surface, particularly in smear-ripened cheeses. This study investigated the occurrence of pigment synthesis among A. arilaitensis strains in several aspects covering (1) UV-Vis absorption spectra and HPLC chromatograms of pigment extracts, (2) diversity of pigment production among strains, (3) influence of light on the production of pigment, and (4) kinetic of pigment synthesis. Based on absorption spectra and HPLC analysis, the 14 A. arilaitensis strains studied could be divided into two groups depending on their ability to produce carotenoids, carotenoid-producing, and nonpigmented strains. The methanolic extracts prepared from eight carotenoid-producing strains contained at least four carotenoids represented mainly as polar molecules. The diversity of pigment concentrations among these strains was low, with carotenoids ranging from 0.40 to 0.76 mg L(-1) culture and specific productivities from 0.14 to 0.25 mg pigment per g dry biomass, under light condition. When cultivating these A. arilaitensis strains under darkness condition, carotenoid biosynthesis was lower within a 0.17-0.25 mg L(-1) range. The pigment production time curve of a representative colored A. arilaitensis strain displayed a sigmoid shape which paralleled cell growth, probably indicating a growth-associated pigmentation.

The type of cheese curds determined the colouring capacity of Brevibacterium and Arthrobacter species

This study compares the colouring capacity of Brevibacterium aurantiacum (BA), Brevibacterium BL and Arthrobacter species AS in relation to deacidified media made from lactic curd (Epoisses), mixed curds (Munster) and rennet curds (Livarot or Reblochon). BA colouring capacity proved to be constant, leading to a dark orange colour, irrespective of the deacidified media. However, it gave too dark a colour for Reblochon. The strains BL and AS were not adapted to the colouring of Epoisses deacidified medium. On the Livarot or Munster deacidified medium, these two strains provided a light yellow orange colour range that was not suitable for these cheeses. However, these two strains (BL and AS) produced a suitable colour for Reblochon deacidified medium.