Marie-Therese Fröhlich-Wyder

Agroscope · Food Microbial Systems

Charakteristisch für Käse des Typs Emmentaler ist die Propionsäuregärung. Das primäre Substrat der Propionsäuregärung durch Propionibacterium freudenreichii ist die Milchsäure, die im frischen Käse immer im Übermass vorhanden ist. Die Propionsäuregärung beeinflusst den Käse auf eine einzigartige Weise; sie ist verantwortlich für die typischen, gros...

Propionibacterium freudenreichii is crucial in Swiss-type cheese manufacture. Classic propionic acid fermentation yields the nutty flavor and the typical eyes. Co-metabolism of aspartate pronounces the flavor of the cheese; however, it also increases the size of the eyes, which can induce splitting and reduce the cheese quality. Aspartase (EC 4.3.1...

Histamine formation by four histaminogenic Lactobacillus parabuchneri strains in experimental cheeses was investigated. Firstly, Raclette cheeses were manufactured from pasteurised milk inoculated with different levels of selected L. parabuchneri strains ranging from 10¹ to 10⁴ cfu mL⁻¹. Secondly, cheeses were produced using four different curd coo...

The extent of the transfer of raw milk biodiversity into the finished cheese is currently underestimated. Farm management practices, hygiene of milking and storage all influence the vat milk microbiota. Although applied technology and starter cultures primarily impact upon the product quality of fresh cheese, raw milk microorganisms fully express t...

Propionic acid fermentation by Propionibacterium freudenreichii is the fermentation of lactic acid, which influences the sensory characteristics of cheese in various ways. In addition to the usually pronounced eye formation, cheeses with propionic acid fermentation are especially characterized by a distinctive sweet taste. This article takes a comp...

Genomic evidence has led to the division of genus Propionibacterium into Propionibacterium and Acidipropionibacterium. They are pleomorphic rods, anaerobic to aerotolerant, mesophilic, Gram-positive and of high G+C. They produce propionic acid as a major end product from many substrates. P. freudenreichii is used as ripening culture in Swiss-type c...

Rohmilch und Rohmilchprodukte können unsere Gesundheit in positiver und negativer Hinsicht beein-flussen. Es ist wichtig, die negativen Auswirkungen nicht zu überschätzen und die positiven Effekte nicht zu unterschätzen. Das Wissen über die sichere Roh-milchproduktion hat sich in den letzten Jahren stark verbessert, und die für den Rohmilch-Verkauf...

Das empfindliche Gleichgewicht zwischen pro- und anti-inflammatorischen Mechanismen, das für die Immunhomöostase des Darms wesentlich ist, wird durch die Zusammensetzung der mikrobiellen Gemeinschaft beeinflusst. Bakterielle Metaboliten stellen die Kommunikation zwischen den Darm-Mikrobiota und dem Immunsystem sicher und beeinflussen das Gleichgewi...

Numerous traditionally aged cheeses are surface ripened and develop a biofilm, known as the cheese rind, on their surfaces. The rind of such cheeses comprises a complex community of bacterial and fungal species that are jointly responsible for the typical characteristics of the various cheese varieties. Surface ripening starts directly after brinin...

The influence of three brining times (0, 1, and 3 d) on two propionibacteria (PAB) cultures (Prop A and Prop B) on eye formation was investigated in experimental Swiss-type cheeses by comparing PAB counts, biochemical parameters, eye numbers, diameters and volumes. Prop A was strongly inhibited with increasing NaCl content. As a result, eye volume...

https://authors.elsevier.com/a/1XJrp3P~ryB0Er The arginine deiminase (ADI) pathway catalyses the degradation of L-arginine via the intermediate L-citrulline into L-ornithine, ammonia, and CO2. This constitutes an important metabolic feature of some lactic acid bacteria (LAB) in their response to acid stress. We investigated the capacity of four th...

Propionic acid fermentation in cheese leads to characteristic eyes and a nutty and slightly sweet flavor. Generic Emmental cheeses and other Swiss-type cheeses are produced in large quantities worldwide by the use of a culture of selected propionic acid bacteria (PAB). Among the four dairy PAB species, preferably selected strains of Propionibacteri...

This chapter discusses various extra-hard cheeses, such as Parmigiano Reggiano Protected Designation of Origin (PDO), and Sbrinz PDO. Raw cow's milk is used to produce Parmigiano Reggiano PDO. The colour of the cheese is between light straw to straw. The aroma and flavour of the paste is fragrant, delicate, tasty but not spicy. Reggianito cheese is...

Danbo is mainly produced industrially at several dairy plants, and it is the most popular cheese in Denmark. Danbo is pale yellow and has a closed texture with small round eyes and a soft consistency that permits slicing with a thin wire. Epoisses PDO is a soft cheese, acid coagulated and harbouring a smear rind. It is manufactured exclusively in t...

This chapter presents various hard cheeses, such as Allgau Mountain cheese, Berner Alpkase Protected Designation of Origin (PDO) and Berner Hobelkase PDO, and Cheddar and explores its types, method of manufacture and relevant research. Allgau mountain cheese is a traditional and popular cheese from the Allgau region in Germany and is manufactured f...

This chapter reviews various semi-hard cheeses, such as Appenzeller, Arzua-Ulloa Protected Designation of Origin (PDO), Castelmagno PDO, Comte PDO and Flaouna Cheeses, and explores its type, description and sensory characteristics, method of manufacture, and relevant research. Appenzeller is a semi-hard cheese which is very popular for its unmistak...

Allgau Emmental cheese is a well-known and popular cheese in Germany which is consumed throughout the year. Emmentaler must have good storage qualities, allowing it to reach its optimal maturity without any loss in quality. Emmentaler PDO is characterised by its regular round eyes and its sweet and nutty flavour. After Mozzarella and Gruyere PDO, E...

Texture properties are very important quality parameters of Appenzeller® cheese. The Appenzeller® Cheese Makers Association defines optimal texture quality as being characterised by a softness that lasts at least three months. During winter production, texture-related problems are sporadically encountered. In the present study, ten Appenzeller® che...

In the present case study, we investigated the causes of consistently elevated histamine content in raw milk cheeses from a Swiss cheese dairy. Screenings of milk samples from 67 farmers revealed that 19.1% of the raw milk samples were contaminated with histamine-forming bacteria. Lactobacillus parabuchneri was detected in 97% of contaminated milk...

Thirty-one isolates of Lactobacillus parabuchneri were obtained from cheese containing histamine; of these, 26 were found to possess the hdcA gene encoding histidine decarboxylase. By analysing the genome data of 13 isolates, specific targets for the development of PCR-based detection and typing systems for L. parabuchneri were identified. The real...

Cheese eyes in traditional Swiss-type cheese are an ‘eye-catcher’ and therefore a key factor for quality. In contrast to the widespread X-ray radiography, in the computed tomography (CT) system, the density difference between gas and the cheese body is imaged three-dimensionally. To quantify the eye volume and distribution in the cheese matrix, thr...

Übersicht - Käsesorten mit sortentypischer Lochung bzw. mit unerwünschter Lochung - CO2 Bildung in Milchsäurebakterien - Der Arginin Deiminase(ADI)-Stoffwechsel - ADI-Stoffwechsel von Milchsäurebakterien in Starterkulturen und dessen Bedeutung für die Käsequalität - ADI-Stoffwechsel von Milchsäurebakterien der Rohmilchfloraund dessen Bedeutung...

For various types of hard-cheese the absence of eyes is preferred. The arginine deiminase (ADI) pathway, occurring in various lactic acid bacteria, produces ornithine, ammonia and CO2 and, therefore, can contribute to eye formation. We studied two thermophilic cultures with high (AOP-G1 and RMK 291) and two cultures with low ornithine-producing cap...

Abstract Round-shaped and uniformly distributed eyes are important quality features for several Swiss semi-hard cheese varieties such as Tilsit. Recently, the growth of histamineproducing strains of Lactobacillus parabuchneri has been associated with cheese defects, such as crack formation and burning taste. In this paper, the influence of pH on th...

http://www.sciencedirect.com/science/article/pii/S0958694615000631 The production of Swiss-type cheeses with a typical number, size, and distribution of eyes is a difficult task, especially when bactofuged or microfiltrated milk is utilised. In this study, the potential of microparticles (plant origin) to influence eye formation in cheese, was asse...

The influence of pH on the metabolic activity of Lactobacillus buchneri and Lactobacillus parabuchneri was studied in experimental Tilsit cheese. Cheeses with “low” pH were obtained by modifying cheese making (no curd washing, ripening within a plastic film). Lactate, free amino acids, free short-chain fatty acids, and 1,2-propanediol were determin...

a b s t r a c t The influence of various strains of Lactobacillus buchneri and Lactobacillus parabuchneri on cheese ripening was studied. The strains that originated from silage cultures and cheese were able to form 1,2-propanediol and ornithine, and differed in the production of histamine and g-aminobutyric acid. The strains were added as adjuncts...

Eye formation is an important quality parameter in the dairy industry for (semi-)hard cheeses in Switzerland. To monitor the formation of eyes in cheese, radiography and, more recently, computed tomography (CT) technology, are employed. In the present study, two quality indicators (eye number and total eye volume) are calculated from radiographs by...

Eye formation is an important feature for various cheese varieties. This study firstly aimed to evaluate the potential of X-ray computed tomography (CT) and image analysis software as a non-invasive method to quantify cheese eye volume. The quantification of the eye volume by CT was validated with 12 eyeless hard cheeses made with the inclusion of...

Eye formation is an important feature for various cheese varieties. This study firstly aimed to evaluate the potential of X-ray computed tomography (CT) and image analysis software as a non-invasive method to quantify cheese eye volume. The quantification of the eye volume by CT was validated with 12 eyeless hard cheeses made with the inclusion of...

Salz ist bereits seit alters her für seine Eigenschaften als Würz- und Konservierungsstoff bei der Zubereitung von Nahrungsmitteln bekannt. Es wirkt geschmacksverstärkend, wodurch sich seine weitverbreitete Verwendung in der Küche erklärt. Auch bei der Herstellung von Käse ist Salz, im Hinblick auf Geschmack und Qualität, ein unentbehrlicher Bestan...

Raw milk cheeses are made from milk that has not been heated beyond 40 °C or undergone any treatment that has an equivalent effect before cheesemaking. Independent of the cheese variety, raw milk cheeses develop a more diversified and intense flavor than pasteurized milk cheeses. The superior flavor characteristics are linked to earlier and more ex...

IntroductionSwiss-type cheeses were originally manufactured in the Emmen valley (Swiss German: Emmental) in Switzerland; their precursors were mountain cheeses.The cheese type Emmental is probably the best-known Swiss-type cheese and is frequently referred to simply as Swiss cheese; it comprises cheeses with the desired propionic acid fermentation....

Propionibacteria are naturally present in raw milk at low levels, but little is known regarding the influence of these wild-type strains on cheese quality. To evaluate the prevalence of wild strains of propionibacteria in Emmental cheese, three cheeses were manufactured from the same raw milk using three commercial Propionibacterium freudenreichii...

Emmentaler cheese originates 500 years ago in the Swiss region of the river Emme. Nowadays it is locally produced out of raw milk in Switzerland whereas other Swiss-type cheeses often are produced in centralised factories out of heat treated milk. Swiss Emmentaler with a protected designation of origin (PDO) is mostly produced with propionic acid b...

The aim of this study was to demonstrate the influence of calcium (Ca) reduction on model Raclette cheese meltability using different technological and chemical methods. Analysis was carried out on the detailed chemical, textural and rheological properties of six different model Raclette cheeses: control Raclette cheese manufacture (CON); pre-ripen...

ALP conducted studies with experimental raclette cheese made from pasteurised milk to obtain a better understanding of the influence of calcium on the melting properties of raclette cheese. The trial presented here achieved its aim of using various factors to lower the calcium content of the cheese and to increase the proportion of dissolved calciu...

Among other topics dealt with in a previous ALP paper was the effect of citric acid on the melting properties of raclette. The citric acid extracted a lot of calcium from the casein matrix and improved melting. A further study was carried out in order to examine the importance of the type, extent and time of pH reduction during production. The pH-r...

In Untersuchungen von ALP hatte sich herausgestellt, dass der Kalziumgehalt eine Rolle für die Schmelzeigenschaften von Raclette spielt. Ein tieferer Gehalt bewirkte bessere Schmelzeigenschaften, bei zu viel gebundenem Kalzium wurden die Käse gummig.

Gute Schmelzeigenschaften sind auch bei kurz gereiftem Raclettekäse wichtig. Vor allem gebundenes Kalzium lässt die Käse aber gummig werden. Lässt sich das technologisch verhindern?

Raclette cheese: less calcium for better melting properties ALP conducted studies with experimental raclette cheese made from pasteurised milk to obtain a better understanding of the influence of calcium on the melting properties of raclette cheese. The trial presented here achieved its aim of using various factors to lower the calcium content of t...

In der Schweiz und anderen westeuropäischen Ländern beträgt die tägliche Kochsalzzufuhr das Doppelte der empfohlenen Menge. Deshalb hat sich ALP zum Ziel gesetzt, Wege zu finden, um den Salzgehalt im Käse zu reduzieren.

Aus gesundheitlichen Gründen wäre es wünschenswert, den Kochsalzgehalt im Käse zu senken. An ALP wird daran geforscht, wie viel Salz zur Verhinderung einer Nachgärung überhaupt notwendig ist.

Quite a large number of cheese varieties are characterized by the development of a specific surface microbiota. Practical experience had shown that cheeses with a visible, natural growth of white mould seldom become sticky. Anticollanti, a white mould, often occurred on the surface of nonsticky cheeses, but rarely on cheeses with the defect of stic...

Laboruntersuchungen am ALP hatten gezeigt, dass Propionsäurebakterien auch bei tiefen Temperaturen (14°C) relativ gut wachsen können. Dies konnte nicht nur für die beiden Kulturen Prop 01 und Prop 96 nachgewiesen werden, sondern für viele andere Stämme auch. Es scheint sogar sehr wahrscheinlich, dass sämtliche Propionsäurebakterien diese Fähigkeit...

Laboratory investigations at Agroscope Liebefeld-Posieux, Swiss Federal Research Station for Animal Production and Dairy Products (ALP), had shown that propionibacteria are also able to grow relatively well at low temperatures (14º C). This could be proven not only for the two cultures Prop 01 and Prop 96, but also for many other strains too. It ev...

This chapter describes the propionic acid fermentation that leads to characteristic eyes and nutty flavor, and can either occur spontaneously or can be achieved by a culture of selected propionibacteria. Facultatively, heterofermentative nonstarter lactobacilli are used in the Swiss artisanal cheese industry to slow down the propionic acid fermenta...

The addition of pyruvate to Gruyere-type cheese milk significantly increased cheese aroma. This effect was accompanied by a decrease in the concentration of some amino acids, especially leucine, lysine, methionine, phenylalanine and valine. There was a corresponding increase in aroma components derived from the catabolism of amino acids, such as is...

8.1 Introduction In 1680 yeasts were discovered by the Dutch scientist Antonie van Leeuwenhoek. During the second half of the nineteenth century, the French biochemist Louis Pasteur showed that yeasts were responsible for the conversion of sugar to ethanol and carbon dioxide [111]. It was only with the development of a technique to isolate pure cul...

Numerous traditional Swiss cheese varieties are smear-ripened e.g. Gruyère, Raclette, Appenzeller and Tilsiter. In recent years, there has been an increase in the occurrence of stickiness of the smear. During ripening, the smear becomes bright and viscous like honey. The consequences are an alteration of the typical flavour and a labour-intensive h...

Ketosäuren sind Stoffe, die in Mikroorganismen natürlich vorkommen. Beim Abbau von Aminosäuren spielen sie als Aminogruppen-Akzeptoren eine unentbehrliche Rolle. Im Käse können so die aus der Proteolyse freigesetzten Aminosäuren weiter abgebaut werden. Es entstehen dabei die verschiedensten Aromakomponenten. – An der FAM konnte in Käsereiversuchen...

Thermophilic lactic acid bacteria, propionibacteria (PAB) and facultatively heterofermentative lactobacilli (FHL) form the main flora of Swiss-type cheeses. The aim of this work was to investigate their interactions and impact on product quality, and in particular on the defect of late fermentation. For this purpose Emmental model cheeses were prod...

Preliminary trials at Liebefeld and at Fromex in Moudon led to the production of two promising new cultures: OMK 702 and OMK 703. The surface culture 703 in addition contains Geotrichum canidum, which contributes to the drying of the smear. Both cultures have been tested in 20 cheese factories (9 producing Gruyere and 11 producing half-hard cheeses...

Several MO are able to produce exopolysacharides. Such slime-producing lactic acid bacteria strains are used for the fabrication of Scandinavian sour milk products. In chees fabrication, particularly in fat-reduced mozzarella cheese, their use leads to a higher moisture content and therefore to an increased meltability.

Thermophilic lactic acid bacteria, propionibacteria (PAB) and facultatively heterofermentative lactobacilli (FHL) form the main flora of Swiss-type cheeses. The aim of this work was to investigate their interactions and impact on product quality, and in particular on the defect of late fermentation. For this purpose Emmental model cheeses were prod...

The objective of the work is to get a better understanding of the yeast flora composition and its development during cheese ripening. Please note: date of realisation is 2001.

Dichloran 18% glycerol (DG18) agar was originally developed to enumerate xerophilic foodborne moulds. However, some laboratories are using DG18 agar as a general medium to enumerate foodborne moulds and yeasts. A collaborative study, with the participation of seven laboratories, was undertaken to compare DG18 agar with dichloran rose bengal chloram...

Propionibacteria are used in the Swiss cheese industry to achieve the characteristic eyes and nutty flavour of Emmental or Swiss-type cheese. The aim of the present work was to further understand the influence of 2 different propionibacterial cultures, Prop 96 and P-culture, on the characteristics of Emmental cheeses. The P-culture has a strong abi...

The new species Saccharomyces turicensis sp. nov. isolated from different kefyr grains is described. Although its morphological properties differ, its physiological characteristics come close to those of Saccharomyces bayanus Saccardo and Saccharomyces pastorianus Reess ex E. C. Hansen. However, electrophoretic karyotyping and restriction fragment...

The purpose of this study was to investigate selected yeasts (Galactomyces geotrichum, Pichia jadinii, Yarrowia lipolytica, Debaryomyces hansenii) for lactic acid utilization, lipolysis, proteolysis and flavour development in foil ripened Raclette cheeses. Foil ripening was chosen in order to exclude the influence of the surface flora. An unreplica...

Yeasts are found within the surface microflora of many cheese types, but not much is known about their direct contribution to cheese ripening. The aim of this study was to investigate, on a laboratory scale, the direct influence of yeasts on cheese ripening by means of aseptic cheese curd slurries. Isolates of all species found in three smear ripen...

Yeasts are found within the surface microflora of many cheese types, but not much is known about their direct contribution to cheese ripening. The aim of this study was to investigate, on a laboratory scale, the direct influence of yeasts on cheese ripening by means of aseptic cheese curd slurries. Isolates of all species found in three smear ripen...

In a large number of cheese varieties, yeasts belong to the specific surface microflora composed of moulds, yeasts, micrococci and coryneform bacteria. They are known for their high tolerance towards low pH, moisture and temperature, and contribute mainly to the de-acidification process. The aim of the project was to investigate the occurrence of y...

The traditional starter for manufacture of kefyr is kefyr grain which consists of a gelatinous matrix in which lactic acid bacteria, yeasts and mostly also acetic acid bacteria are embedded. The typical microflora of kefyr is, however not exactly defined. The aim of this project was to isolate and characterise yeasts from kefyr grains and kefyr in...

The 2 ITS-regions (Internal Transcribed Spacers) flanking the highly conserved 5.8S-rDNA-gene are known to vary between, but to be similar within fungal species. The yeast flora of 5 different kefyr grains was investigated and traditionally identified. The restriction analysis of the ITS-regions with different enzymes resulted in specific patterns...

The two ITS regions (Internal Transcribed Spacers) flanking the highly conserved 5.8S rDNA gene are known to vary between, but to be similar within, fungal species. The yeast flora of five different kefir grains has been investigated and traditionally identified. The RFLP analysis of the ITS regions resulted in species-specific patterns, and the ye...

Diss. no. 12842 techn. sc. SFIT Zurich. Literaturverz.