Hans-Peter Bachmann

Hans-Peter Bachmann
Agroscope · Research Unit Microbial Food Systems

PhD

About

43
Publications
29,748
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720
Citations
Citations since 2017
14 Research Items
263 Citations
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Introduction
The highly biodiverse Liebefeld Strain Collection is used to develop new starter- and special cultures. Thanks to interdisciplinary project cooperation, knowledge about these complex fermented systems is amassed and products are influenced in a targeted fashion through the proper choice and use of microorganisms.

Publications

Publications (43)
Article
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...
Article
Full-text available
As components of many cheese starter cultures, strains of Lactobacillus delbrueckii subsp. lactis (LDL) must be tested for their antimicrobial susceptibility to avoid the potential horizontal transfer of antibiotic resistance (ABR) determinants in the human body or in the environment. To this end, a phenotypic test, as well as a screening for antib...
Article
Full-text available
Undefined starter cultures are poorly characterized bacterial communities from environmental origin used in cheese making. They are phenotypically stable and have evolved through domestication by repeated propagation in closed and highly controlled environments over centuries. This makes them interesting for understanding eco-evolutionary dynamics...
Preprint
Full-text available
Undefined starter cultures are poorly characterized bacterial communities from environmental origin used in cheese making. They are phenotypically stable and propagated under constant conditions in milk. This makes them interesting for understanding eco-evolutionary dynamics governing microbial communities. While cheese starter cultures are known t...
Chapter
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...
Chapter
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...
Chapter
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
Safety clearances for the Liebefeld cultures The microbial strains that Agroscope uses for practical trials and which, if successful, subsequently become part of a defined mixed culture, must demonstrate a high level of safety. With this end in view, 186 strains of lactic acid bacteria from the Agroscope Culture Collection were tested for transfera...
Article
Full-text available
Safety clearances for the Liebefeld cultures The microbial strains that Agroscope uses for practical trials and which, if successful, subsequently become part of a defined mixed culture, must demonstrate a high level of safety. With this end in view, 186 strains of lactic acid bacteria from the Agroscope Culture Collection were tested for transfera...
Poster
Full-text available
In Switzerland most of the traditional cheese varieties are made from raw milk. Their manufacture adheres to strict rules, so as to guarantee quality and purity of the end product. This raises production costs and means consumers pay more. It also opens the door to cut-rate forgeries claiming to be made to the stringent standards and causing consid...
Poster
Full-text available
In 2017 in Europe there were 343 reported cases of outbreaks caused by enterotoxins of Staphylococcus aureus. To reduce this risk as far as possible, the European legislation stipulates that cheese must be examined for coagulase-positive staphylococci (CPS) when the amount of cells is supposed to be highest. If at this point CPS counts exceed 105 C...
Article
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...
Chapter
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...
Chapter
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....
Article
Full-text available
World champion cheese cultures Swiss cheeses regularly win prizes at international contests. Experts widely agree that the microbial cultures from Liebefeld have contributed greatly to this success story. Thanks to the use of cultures with bacteria originally stemming from biodiversity in the nearby area, the connection between traditional Swiss ch...
Article
Full-text available
The three Agroscope research stations, Changins-Wadenswil ACW, Liebefeld-Posieux ALP and Reckenholz-Tanikon ART, will jointly carry Out three multidisciplinary research programs during the period 2008 - 2011. "ProfiCrops" aims at developing, preparing, evaluating and exchanging information in order to ensure a future for Swiss vegetable production...
Article
To study the influence of native milk flora on the flavour and texture of raw milk cheese it is necessary to produce milk without its native flora. Three procedures to eliminate native flora from milk can be discernedfrom the literature: aseptically drawn milk, heat treatment of whole milk and physical treatment of skim milk with subsequent additio...
Cover Page
Full-text available
Die Früherkennung wichtiger Entwicklungen ist eines von sechs strategischen Zielen der landwirtschaftlichen Forschungsanstalten. In den letzten Jahren zeigte sich, dass Nutrigenomics in absehbarer Zukunft die Ernährung massgeblich mitbestimmen könnte.
Article
Full-text available
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...
Chapter
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
Full-text available
Cheese analogues are usually defined as products made by blending individual constituents, including non-dairy fats or proteins, to produce a cheese-like product to meet specific requirements. They are being used increasingly due to their cost-effectiveness, attributable to the simplicity of their manufacture and the replacement of selected milk in...
Article
The influence of ripening temperature (11, 14, 17, 20°C) and ripening time (60, 90 days) on sensory properties and melting quality of Raclette cheeses made from raw milk, pasteurised milk and microfiltered milk has been investigated using the 'special cubic model' experimental design. With increased ripening temperature substantial acceleration of...
Article
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...
Article
The ripening of Emmental cheese samples from 30 dairies was followed over 12 months. Biochemical, chemical, microbiological, rheological and sensory properties were measured. Only a few parameters measured at 1 and 20 d could predict flavour and texture development after 3, 6 and 12 months. The sum of free amino acids measured after 1 d with the Cd...
Article
An interlaboratory comparison on cheese making trials was conducted to examine the differences between model cheeses manufactured in pilot plants at six European laboratories. The experimental design (within each laboratory) for the model cheese was an unreplicated 23full factorial design in one block of eight cheese vats. The three factors were th...
Article
The present work describes the ripening of eight quarters of raw milk Swiss Emmental cheese loaves which were packaged at 3 months in a plastic sheet. The loaves were manufactured with and without addition ofL. caseisubsp.caseito the usual starter cultures. Samples were taken at 3, 6, 9 and 12 months of ripening. The following parameters were measu...
Article
Full-text available
This study examined the ability of potentially pathogenic bacteria to grow and to survive during the manufacture and ripening of Swiss hard and semihard cheese varieties made from raw milk. The results show that hard cheeses are hygienically safe; 1 wk after fabrication, the inoculated pathogens (Aeromonas hydrophila. Campylobacter jejuni, Escheric...

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Projects (13)