03833 - Microbiology of Animal Food Products

Learning outcomes

The aim of the course is to furnish the fundamental information concerning microorganism (pathogenic, spoilage and responsible for desired fermentations) in foods of animal origin. Particular attention is given to the transformation and preservation of fermented foods, such as dairy products and fermented cured meats, focusing the attention on the use of starter cultures. At the end of the course the student is able to evaluate microbiological risks, to select and use starter cultures, to independently manage fermentative processes in dairy and cured meat industries and to carry out evaluations regarding the most important spoilage/pathogenic microrganisms.

Course contents

General characteristics of the microrganism with technological effect:

• Growth kinetics (multiplication, survival). Tools for the modelization of growth curve

Principal foodborne microrganisms:

• Lactic acid bacteria, Bifidobacteria, Enterobacteria, pseudomonads and related groups, Vibrio, Listeria, staphylococci, Bacilli and Clostridia, other microorganism related to food. Fungi: moulds and yeasts. Metabolic pathways and therir effect on foods

Microbial ecology: main factors influencing microbial growth in foodsi.

• Extrinsic and intrinsic factors:

• pH and redox potential,

• water activity (aw),

• temperature,

• preservatives,

• gas composition,

• food composition (nutrients, natural antimicrobial compounds)

• Process factors. Reduction of microbial contamination in food: thermal and non-thermal treatment.

• Cell death kinetics

• Sterilization, pasteurization and set up of decontamination processes

• Fermentation as a food preservation method

• Microrganisms responsible for food fermentations

• Starter cultures

• Probiotics

• Bioprotective cultures

Milk and dairy products

• Raw microbial population of milk and effects of the processes

• Cheesemaking: role of microrganisms in cheese-making and ripening in different cheese typology.

• Use of starter cultures (natural and selected).

• Role of non starter microrganisms.

• Fermented milks: microrganisms involved in different type of fermented milks and processes applied.

Meat and meat product

• Microbial population of meat and shelf life of not processed meat

• Cured meat: use of salt for meat preservation.

• Microbiology of not fermented cured meat.

• Fermented sausages: classification in relation to their characteristics.

• Microbiology of fermented sausages during fermentation, drying and ripening.

• Spontaneous fermentations.

• Guided fermentatiions: starter cultures.

• Role of moulds and yeasts in cured meat production

Readings/Bibliography

Mucchetti G., Neviani E., Microbiologia e tecnologia lattiero-casearia. Tecniche nuove, Milano, 2006

Grazia L., Coloretti F., Zambonelli C., Tecnologie dei salumi, Edagricole, Bologna, 2011

Jay J. J., Loessner J. L., Golden D. A. Microbiologia degli alimenti. Springer, Milano, 2009

Teaching methods

Lessons concerning the course arguments

Laboratory practice

Visits to factories (dairy and cured meats)

Seminars

Assessment methods

The verification of the learning level consists in a final oral test based on three questions. The first argument is chosen by the student. The second argument concerns a specific topic of the course. The third question is aimed to verify the overall mindset and skills acquired by the student and the capacity to elaborate transversal connection between the topics considered. The final grade is defined by the arithmetic average of the evaluation of the three arguments.

Teaching tools

Slides of the lessons

Office hours

See the website of Fausto Gardini