Courses

Food Microbiology

General

Course Contents

Unit 1: The most important food microorganisms

  • Fungi and Yeasts: Morphological, cultural and physiological characteristics of fungi and yeasts. Sexual and asexual reproduction. Classification and identification. Importance of fungi and yeasts in Microbiology and Food Hygiene.
  • Bacteria: Morphological, cultural and physiological characteristics of bacteria.

Description of the most important bacteria in food:

  1. Gram-negative bacteria, rods or coccobacilli: Pseudomonas, Acetobacter, Gluconobacter, Brucella, Escherichia, Salmonella, Shigella, Yersinia, Vibrio, Aeromonas etc.
  2. Gram-positive bacteria, spherical or cocci: Micrococcus, Staphylococcus, Lactococcus, Streptococcus, Enterococcus, Pediococcus, Leuconostoc.
  3. Gram-positive bacteria, sporulating rods: Bacillus, Clostridium, Desulfotomaculum.
  4. Gram-positive bacteria, sporulating rods or irregular in shape: Lactobacillus, Listeria, Propionibacterium, Bifidobacterium.
  5. Probiotic microorganisms – Prebiotics.

Unit 2: Sources of food contamination

  • Microbiota of the soil.
  • Water microbiota.
  • Microbiota of the air.
  • Plant microbiota.
  • Human and animal microbiota.
  • The animals’ environment, utensils and equipment.

Unit 3: Preservation of food

  • Food preservation principles. The death of microorganisms.
  • Heat: Mechanism of thermal death of microbes. Survival curve – value D. Curve of thermal death times – Z value. Factors affecting the heat resistance of microbes. Heat preservation methods (pasteurization – sterilization).
  • The cold: Interaction of the cold with other factors. Mechanisms of action of cold and freezing on microbes. Factors affecting the action of cold. Food preservation methods at low temperatures.
  • The preservation of food and the model of obstacles.

Unit 4: Food spoilage

  • General principles governing alterations. Factors affecting food spoilage. Changes in the color, structure, smell and taste of food.
  • Microbiology and alterations of milk and its products.
  • Microbiology and spoilage of meat and poultry.
  • Microbiology and spoilage of fish.
  • Microbiology and spoilage of grains and their products.
  • Microbiology and spoilage of fruits and vegetables.
  • Microbiology and spoilage of fruit and vegetable beverages.
  • Microbiology and spoilage of fermented foods.
  • Microbiology and spoilage of canned foods.

Unit 5: Food and disease

  • Food poisoning: Causes of food poisoning. Dominant bacteria. Food vehicles. Places of occurrence of food poisoning. Types of food poisoning.
  • Food poisoning: Staphylococcal food poisoning. Botulism. Mycotoxicosis.
  • Food infections: Salmonellosis. Listeriosis. Gastroenteritis from Escherichia coli. Campylobacteriosis. Vibrio parahaemolyticus gastroenteritis.
  • Infections: Gastroenteritis from Clostridium perfringens. Bacillus cereus gastroenteritis.

Titles of Laboratory Exercises

  • Groups of microbes important to food.
  • Moulds and Yeasts: Study of morphological and physiological characteristics. Growth substrates. Isolation. Identification.
  • Enterobacteriaceae family: Morphological, culturing characteristics of bacteria, physiological and biochemical characteristics. Isolation – selective substrates. Identification. Coliforms. E. coli. Salmonella spp.
  • Micrococcaceae family: Micrococcus spp., Staphylococcus spp. Isolation and identification. Differentiation of S. aureus from other staphylococci. Isolation of S. aureus from the nasal cavity. Selective substrates.
  • Bacillus: Taxonomic position. Morphological, culturing characteristics of bacteria. Identification. Endospore formation and staining.
  • Enumeration techniques of the microbial load of food and water.
  • Standard plate colony enumeration method.
  • Most probable number method (MPN-method).
  • Membrane filtration method – Microbiological analyzes of food.
  • Microbiological analysis of milk (sampling, microbiological tests-techniques, evaluation of results, microbiological standard ).
  • Microbiological analysis of cheeses (sampling, microbiological tests-techniques, evaluation of results, microbiological standard).
  • Microbiological analysis of meat (sampling, microbiological tests-techniques, evaluation of results, microbiological standard).
  • Microbiological analysis of drinking water (sampling, technical microbiological tests, evaluation of results, microbiological standard).

Educational Goals

The course aims to achieve the following learning outcomes for students:

  • Acquiring basic knowledge about microorganisms that are important in food.
  • Familiarity with the methodology applied to microbiological food testing and the choice of food sampling plan and food analysis techniques.
  • The evaluation of the results of the analyses which must be done with accuracy and based on the applicable microbiological standards.
  • The consolidation of all the above knowledge in order to assess the microbiological quality of food on the one hand and to ensure the health of the consumer on the other.

General Skills

  • Interpretation and evaluation of results obtained from experimental analyses.
  • Search for further relevant information with the use of information technologies for the purpose of thorough knowledge and understanding of the subject.
  • Promotion of analytical, productive and inductive thinking.
  • Work in an interdisciplinary environment.
  • Autonomous work.
  • Teamwork.
  • Decision making.

Teaching Methods

Face to face:

  • Lectures (theory and exercises) in the classroom.
  • Individual and group laboratory exercises in the microbiological laboratory.

Use of ICT means

  • Lectures on PowerPoint slides using PC and projector.
  • Notes and solved exercises in electronic format.
  • Use of videos and online applications in teaching.
  • Post course material and communicate with students on the Moodle online platform.

Teaching Organization

ActivitySemester workload
Lectures20
Laboratory exercises40
Processing results of laboratory exercises30
Independent study60
Total150

Students Evaluation

Evaluation methods:

  • Mandatory attendance at (at least) 80% of the laboratory exercises.
  • Written final exams in the theoretical part of the course and solving exercises.
  • Written final exams in the laboratory part of the course with short development questions and critical questions.

The evaluation criteria are presented and analyzed to the students at the beginning of the semester.

Recommended Bibliography

  1. Παπαντωνίου Δ., Μικροβιολογία Τροφίμων, ΑΤΕΙ-Θεσσαλονίκης, 2013.
  2. Montville, T. J. and Matthews, K. R., Μικροβιολογία Τροφίμων, επιμέλεια: Β. Σπηλιώτης και Ι. Γιαβάσης, Εκδόσεις ΙΩΝ, Αθήνα, 2010.
  3. BROCK ΒΙΟΛΟΓΙΑ ΤΩΝ ΜΙΚΡΟΟΡΓΑΝΙΣΜΩΝ, Έκδοση: 1η/2018, Συγγραφείς: Michael T. Madigan, John M. Martinko, Kelly S. Bender, Daniel H. Buckley, David A. Stahl, Διαθέτης (Εκδότης): ΙΔΡΥΜΑ ΤΕΧΝΟΛΟΓΙΑΣ & ΕΡΕΥΝΑΣ-ΠΑΝΕΠΙΣΤΗΜΙΑΚΕΣ ΕΚΔΟΣΕΙΣ ΚΡΗΤΗΣ, ISBN: 978-960-524-523-8.
  4. Adams M.R. & Moss M.O. Food Microbiology, 3rd edition, 2008, Cambridge, UK RSC Publishing.
  5. Μικροβιολογία Τροφίμων, Μπαλατσούρας Γ., 1η Έκδοση, 2006, Εκδόσεις Βασιλειάδης Στυλιανός.
  6. Wistreich, A. G., Microbiology Laboratory. Fundamentals and Applications. 2nd ed., Pearson Education, 2003.