Enological Microbiology
A.Y. 2025/2026
Learning objectives
The Wine Microbiology course aims to provide students with a solid scientific foundation on the role and metabolism of microorganisms involved in winemaking processes. Specifically, the course explores in depth the identity, physiology, and technological relevance of yeasts and lactic acid bacteria in alcoholic and malolactic fermentations, as well as the behavior of other microorganisms—such as molds and spoilage yeasts—that may contribute to wine alterations. The course is designed to develop specific competencies in the microbiological management of the vinification process, enhancing the student's ability to monitor fermentations, use starter cultures responsibly, and address potential fermentation issues. Practical laboratory sessions are aimed at reinforcing theoretical knowledge through microbiological analysis of musts and wines, technological characterization of microorganisms, and assessment of the microbiological quality of the final product. The course builds directly upon the knowledge acquired in General Microbiology and Enological and Fermentation Chemistry, and it is functionally integrated with the course Enology 2 (Mod. 1: Enological Processes and Technologies). Together, these courses contribute to the development of a professional profile capable of managing production processes and ensuring microbiological quality control in the wine sector with scientific awareness.
Expected learning outcomes
By the end of the course, the student will acquire a solid understanding of the fundamental metabolic processes of yeast and lactic acid bacteria during alcoholic and malolactic fermentation, with particular emphasis on carbon, nitrogen, and sulfur metabolism. The student will also become familiar with the main methods for isolating and cultivating microorganisms relevant to enology—tools that are essential for monitoring the winemaking process and for identifying and preventing microbial spoilage of wine. She/he will be able to competently manage the microbiological variables related to alcoholic fermentation, including the appropriate selection and inoculation of starter cultures for controlled fermentations. The student will develop a comprehensive understanding of the dual role of microorganisms in the winemaking process, both in their beneficial contribution to the transformation of must into wine, and in their potential to cause defects or contamination. She/he will also be able to apply practical knowledge to ensure hygienic conditions in the winery, including carrying out key microbiological analyses needed to assess the quality and safety of the final product. The course is designed to foster critical thinking and independent judgment through laboratory work, case study analysis, seminars, and interpretation of experimental laboratory data, enhancing the student's ability to assess real-world scenarios in a production context. In parallel, classroom discussions will help refine communication skills, enabling the student to convey acquired knowledge clearly, accurately, and appropriately, including in professional and interdisciplinary settings. Finally, the use of up-to-date scientific sources and topic-focused exploration will provide the foundation for developing lifelong autonomous learning skills, ensuring the student is able to continuously update their competencies throughout their professional career.
Lesson period: First semester
Assessment methods: Esame
Assessment result: voto verbalizzato in trentesimi
Single course
This course cannot be attended as a single course. Please check our list of single courses to find the ones available for enrolment.
Course syllabus and organization
Single session
Responsible
Lesson period
First semester
Course syllabus
Frontal lessons:
1. Taxonomy and ecology of the wine yeasts. Classification criteria and wine yeast ecology: the different yeast species in must and wine;
2. Yeast cell structure and the morphological characteristics of wine yeasts;
3. Carbon metabolism in yeast and its regulation: Pasteur, Crabtree and Custer effects (Brettanomyces: a case of study);
4. Nitrogen metabolism in yeast;
5. Sulfur metabolism in yeast;
6. Microbiological analysis at different stages of vinification;
7. Microbiological control of must and Spontaneous fermentations;
8. Growth kinetics of yeasts and factors affecting yeast growth during fermentation;
9. Controlled fermentations and the selection of commercial wine yeast: selection and management of the starter yeast selection for technological characteristics and quality traits. The fermentative power and vigour, Alcohol tolerance, SO2 resistance, Killer character and yeast proliferation;
10. Yeast starter cultures and their usage: isolation, control and maintenance of a pure culture of yeast (the laboratory phase, the phase of the cellar, the direct inoculation). The types of commercial starters. The operation for starter management;
11. Genetic improvement of wine yeasts: Yeast genome organization, The life style of Saccharomyces cerevisiae, Yeast genetics: heterotallic and homotallic yeast strain. The genetic interconversion phenomena;
12. Lactic acid bacteria (LAB) in musts and wines and their interaction with yeasts during alcoholic fermentation. Metabolism of sugars, organic acids and aminoacids. Effect of ethanol and temperature on the LAB growth. Spontaneous and controlled malolactic fermentation. Malolactic starter cultures;
13. Microbiological aspects of stuck fermentation;
14. Sparkling wines and Yeast autolysis;
15. Microbiological stabilization techniques for wine;
16. Hygiene and Good Hygienic Practices in cellar;
17. The HACCP method and the application of the hygiene system;
18. The manual of good practice for the wine industry;
19. Sources of contamination in the cellar. Sanitation of equipment and facilities. Detergents and disinfectants. Water management process.
Laboratory class:
1. Determination of yeasts in a fermenting grape must (enumeration of non-Saccaromyces species and S. cerevisiae). Microscopic observations: morphological traits of wine yeasts;
2. Checking the hygiene of personnel and of surfaces by the use of Petri-Contact;
3. Microbial air monitoring;
4. Fermentative power and vigour of a commercial wine yeast;
5. Analysis of a commercial wine yeast: determination of the total yeast count using a cultural method and the microscopic observation with counting chamber;
6. Analysis of the technological traits of a wine yeast: H2S production;
7. Microbiological stability of bottled wine with plate count technique and filtration: determination of malolactic bacteria, determination of B. bruxellensis and acetic bacteria;
8. Microbiological control of drinking water;
9. Assessing the contamination of a bottle cork cap;
10. Assessing the flocculation character of a wine yeast.
1. Taxonomy and ecology of the wine yeasts. Classification criteria and wine yeast ecology: the different yeast species in must and wine;
2. Yeast cell structure and the morphological characteristics of wine yeasts;
3. Carbon metabolism in yeast and its regulation: Pasteur, Crabtree and Custer effects (Brettanomyces: a case of study);
4. Nitrogen metabolism in yeast;
5. Sulfur metabolism in yeast;
6. Microbiological analysis at different stages of vinification;
7. Microbiological control of must and Spontaneous fermentations;
8. Growth kinetics of yeasts and factors affecting yeast growth during fermentation;
9. Controlled fermentations and the selection of commercial wine yeast: selection and management of the starter yeast selection for technological characteristics and quality traits. The fermentative power and vigour, Alcohol tolerance, SO2 resistance, Killer character and yeast proliferation;
10. Yeast starter cultures and their usage: isolation, control and maintenance of a pure culture of yeast (the laboratory phase, the phase of the cellar, the direct inoculation). The types of commercial starters. The operation for starter management;
11. Genetic improvement of wine yeasts: Yeast genome organization, The life style of Saccharomyces cerevisiae, Yeast genetics: heterotallic and homotallic yeast strain. The genetic interconversion phenomena;
12. Lactic acid bacteria (LAB) in musts and wines and their interaction with yeasts during alcoholic fermentation. Metabolism of sugars, organic acids and aminoacids. Effect of ethanol and temperature on the LAB growth. Spontaneous and controlled malolactic fermentation. Malolactic starter cultures;
13. Microbiological aspects of stuck fermentation;
14. Sparkling wines and Yeast autolysis;
15. Microbiological stabilization techniques for wine;
16. Hygiene and Good Hygienic Practices in cellar;
17. The HACCP method and the application of the hygiene system;
18. The manual of good practice for the wine industry;
19. Sources of contamination in the cellar. Sanitation of equipment and facilities. Detergents and disinfectants. Water management process.
Laboratory class:
1. Determination of yeasts in a fermenting grape must (enumeration of non-Saccaromyces species and S. cerevisiae). Microscopic observations: morphological traits of wine yeasts;
2. Checking the hygiene of personnel and of surfaces by the use of Petri-Contact;
3. Microbial air monitoring;
4. Fermentative power and vigour of a commercial wine yeast;
5. Analysis of a commercial wine yeast: determination of the total yeast count using a cultural method and the microscopic observation with counting chamber;
6. Analysis of the technological traits of a wine yeast: H2S production;
7. Microbiological stability of bottled wine with plate count technique and filtration: determination of malolactic bacteria, determination of B. bruxellensis and acetic bacteria;
8. Microbiological control of drinking water;
9. Assessing the contamination of a bottle cork cap;
10. Assessing the flocculation character of a wine yeast.
Prerequisites for admission
The course of Microbiology is propedeutic. The notions acquired during the course of Biochemistry are considered useful.
Teaching methods
Teaching is provided through frontal lessons and a laboratory class. Laboratory attendance is not mandatory; however, the concepts associated with this activity may be the subject of questions in the written test.
Teaching Resources
Teaching material available on Ariel. Furthermore, use the "Manual of good hygiene practice for the wine sector".
Teaching text:
MICROBIOLOGIA DELLA VITE E DEL VINO (2022)
P. Romano, M. Ciani, L. Cocolin
Edizione CEA - Casa Editrice Ambrosiana
Teaching text:
MICROBIOLOGIA DELLA VITE E DEL VINO (2022)
P. Romano, M. Ciani, L. Cocolin
Edizione CEA - Casa Editrice Ambrosiana
Assessment methods and Criteria
Type of exam: Written. Exams will usually be held in person.
The written test is organized in open-ended questions (10 questions, 6 minutes of time available for each answer, questions projected in succession); effective duration of 60 minutes. The exam is unique and includes questions regarding both the topics covered by the frontal lessons and the laboratory class. Registration to the exam session by UNIMIA system is mandatory.
Evaluation parameters: demonstration of acquisition of the concepts; ability to organize knowledge; correct use of the specialized vocabulary.
Evaluation: mark out of thirty.
Checking of the result of the written exam: the student will receive an e-mail with an attached copy of the exam report in the University email box. The result can be rejected.
Students with specific learning disabilities or other disabilities are requested to contact the teacher via email at least 15 days before the exam session to agree on any personal compensatory measure. In the email addressed to the teacher, the respective University services must be reported in CC: [email protected] (for students with LD) and [email protected] (for students with other disabilities).
The written test is organized in open-ended questions (10 questions, 6 minutes of time available for each answer, questions projected in succession); effective duration of 60 minutes. The exam is unique and includes questions regarding both the topics covered by the frontal lessons and the laboratory class. Registration to the exam session by UNIMIA system is mandatory.
Evaluation parameters: demonstration of acquisition of the concepts; ability to organize knowledge; correct use of the specialized vocabulary.
Evaluation: mark out of thirty.
Checking of the result of the written exam: the student will receive an e-mail with an attached copy of the exam report in the University email box. The result can be rejected.
Students with specific learning disabilities or other disabilities are requested to contact the teacher via email at least 15 days before the exam session to agree on any personal compensatory measure. In the email addressed to the teacher, the respective University services must be reported in CC: [email protected] (for students with LD) and [email protected] (for students with other disabilities).
AGR/16 - AGRICULTURAL MICROBIOLOGY - University credits: 6
Laboratories: 16 hours
Lessons: 40 hours
Lessons: 40 hours
Professor:
Vigentini Ileana
Professor(s)