MEDI 2371 FOOD Microbiology Introduction Prof Dr Abdelraouf

MEDI 2371 FOOD Microbiology Introduction Prof. Dr. Abdelraouf A. Elmanama Islamic University of Gaza , Palestine

Course evaluation * Midterm Exam =25 * Final Exam = 60 * Attendance = 5 * Quizzes =10 Course description Food products safety and security are issues of growing importance especially with growing number of foodborne illnesses related to raw and ready-to-eat food products. This course deals with basic concepts in food microbiology, factors affecting various types of foods, sources and growth of microbes in food, foodborne microorganisms and their relationship to the food supply and public safety. Factors, that influence microbial proliferation in foods, affect food spoilage, food preservation and disease are provided. Food borne illnesses outbreak investigation is also discussed. Quality systems used in food industries (HACCP) constitute an integral part of the course.

Intended Learning Outcomes Upon the completion of this course, students will be expected to: 1) Develop knowledge of the microbiology of food systems, including the intrinsic and extrinsic factors, which govern microbial proliferation in foods, 2) Understand theory of the effects of microorganisms in foods, including food preservation, fermentation, spoilage and disease, 3) Obtain a working knowledge of the techniques used to identify, enumerate and determine the metabolic activities of food-borne bacteria, 4) Develop/improve critical thinking, problem solving, and communication skills.

Outline of course content 1. Introduction 2. Historical role of microbiology in food preservation and safety 3. Microbial classification and taxonomy 4. Sources of organisms of significance to foods 5. Survey of organisms of significance to foods 6. Sampling methodology 7. Microbial ecology of foods 8. Microbial food spoilage 9. Methods of Food Preservation 10. Food borne Illnesses 11. Sanitation and quality control programs 12. Trends in Food Microbiology Rapid and molecular methods Emerging pathogens and surveillance

Definition Food Microbiology: is the study of microorganisms that inhabit, make or contaminate food. Many microorganisms are used to make food e. g • Bacteria which converts liquid milk into yogurt or cheese, • Yeast for making bread, through fermentation. Other microorganisms or the toxins they produce cause spoilage of food.

• Foodborne diseases e. g gastroenteritis and salmonellosis results from eating contaminated food with various types of microorganisms. • Safety of food must be ensured to protect human health. • Food preservation is being used to avoid health hazards. • Preservation methods include • Drying, • Cooking, • Smoking, • Salting, • Sugaring, • Low temperature storage • Radiation.

Following the discovery of microorganisms, scientists associated the role of these organisms with: 1. Food spoilage, 2. Fermentation/Food production 3. Foodborne diseases.

MEDI 2371 FOOD Microbiology Historical Development of Food Microbiology Prof. Dr. Abdelraouf A. Elmanama Islamic University of Gaza , Palestine

Historical Development of Food Microbiology FOOD Fermentation • Louis Pasteur (1860) showed that fermentation of lactic acid and alcohol from sugar was the result of growth of specific bacteria and yeast. • He concluded that souring of milk was caused by the growth of organisms in it. • Theodor Schwan (1837) named the organism involved in sugar fermentation as Saccharomyces (sugar fungus). • Emil Chirstian hansen (1883) used pure culture of yeasts to ferment sugars.

FOOD Spoilage • Harry Russell (1895) showed that gaseous swelling with bad odors in canned peas was due to growth of heat-resistant bacteria (spores). • Tyndall(1876) observed that bacteria in decomposing substances were always traceable to air, substances or containers. • Bacillus coagulans was first isolated from coagulated milk by Hammer (1915). • In 1902 the term psychrophile was first used by Schmidt. Nielsen for organisms that grow at 0 o. C.

Food Poisoning In 1857 milk was incriminated as a transmitter of typhoid fever by W. Taylor In 1888 Gaertner first isolated Salmonella enteritidis from meat that had caused 57 cases of food poisoning. In 1894 T. Denys was the first to associate Staphylococci in food poisoning. In 1896 Van Ermengen first discovered Clostridium botulinum.

In 1906 Bacillus cereus food poisoning was recognized. In 1937 paralytic shellfish poisoning was recognized. In 1939 gastroenteritis caused by Yersinia enterocolitica was first recognized by Schleifstein and Coleman In 1951 Vibrio parahaemolyticus was shown to be an agent of food poisoning. In 1960 the production of aflatoxin by Aspergillus flavus was first reported. In 1986 Bovine spongiform encephalopathy was first diagnosed in cattle in U. K.

Food Preservation In 1810 preservation of food by canning was developed by Appert in France. Fish and Fruits were first canned in 1840. In 1842 H- Benjamin in U. K. introduced freezing foods by immersion in an ice and salt brine. In 1878 the first successful cargo of frozen meat went from Australia to England. In 1890 pasteurization of milk began in USA. In 1907, Metchnikoff isolated one of yogurt bacteria (Lactobacillus bulgaricus). In 1943, Procter in USA employed ionizing radiation to preserve hamburger meat.

MEDI 2371 FOOD Microbiology Groups of Microorganisms In Food Prof. Dr. Abdelraouf A. Elmanama Islamic University of Gaza , Palestine

Groups of Microorganisms In Food Viruses Enteric Viruses • Hepatitis A and Hepatitis E Viruses • Rotavirus • Astrovirus • Enteric Adenovirus • Human Caliciviruses (Noroviruses and Sapporo Viruses)

Parasites • • Ascaris Trichinella Taenia Giardia Entamoeba Cyclospora Toxoplasma

Molds Produce Mycotoxins Species of • Aspergillus, • Fusarium, • Penicillium, • Claviceps Mycotoxins include: • Aflatoxin, • Ochratoxin, • Ergot Alkaloids

Bacteria • • • Yersinia Vibrio Staphylococci Campylobacter Listeria Salmonells Shigella Escherichia coli Clostridia Bacillus cereus

Important Bacterial Groups in Food Bacteria have • A rapid growth rate. • Ability to grow under a wide range of conditions such as: • Temperature • Aerobiosis • p. H • Water activity • Utilization of food nutrients • They better survive adverse conditions such as survival of spores at high temperatures.

1 - Lactic Acid Bacteria These bacteria produce large quantities of lactic acid from carbohydrates, species from genera • Lactococcus • Leuconostoc • Pediococcus • Lactobacillus • Streptococcus thermophilus.

2 - Acetic Acid Bacteria They are bacteria that produce acetic acid , such as Acetobacter aceti 3 - Propionic Acid Bacteria They produce propionic acid and are used in dairy fermentation e. g Propionibacterium freudenreichii

4 - Butyric Acid Bacteria They are the bacteria that produce butyric acid in relatively large amounts, Clostridium butyricum is included in this group. 5 - Proteolytic Bacteria Clostridium butyricum They are bacteria that can hydrolyze proteins because they produce extracellular proteinases, they include species in the genera Micrococcus, Alteromonas, Staphylococcus Flavobacterium Bacillus Alcaligenes Clostridium some Enterobacteriaceae Pseudomonas Brevibacterium.

6 - Lipolytic Bacteria They hydrolyze triglycerides as they produce lipases. Species in genera Micrococcus, Alteromonas Staphylococcus Flavobacterium Pseudomonas 7 - Saccharolytic Bacteria They hydrolyze complex carbohydrates, Species in the genera Bacillus Pseudomonas Clostridium Enterobacter.

8 - Thermophilic Bacteria They are the bacteria that are able to grow at 50 o. C and above. Species from genera Bacillus Streptococcus Clostridium Lactobacillus Pediococcus, 9 - Psychrotrophic Bacteria They are the bacteria that are able to grow at refrigerated temperature. Some species from Pseudomonas Yersinia Alteromonas Aeromonas Listeria,

10 - Thermoduric Bacteria They are the bacteria that are able to survive Pasteurization temperature treatment. Some species from Micrococcus, enterococcus, Lactobacillus, Bacillus(spores), and Clostridium (spores) are included in this group. 11 - Halotolerant Bacteria that are able to survive high salt concentration. Some species from Bacillus, Stahylococcus, Vibrio are included in this group.

12 - Aciduric Bacteria • They are the bacteria that can survive low p. H. • Some species from Lactobacillus, Lactococcus, Enterococcus, and Streptococcus are included in this group. 13 - Osmophilic Bacteria • Bacteria that can grow at a relatively higher osmotic environment than that needed for other bacteria. • Some species from genera Staphylococci, Leuconostic, and Lactobacillus are included in this group. • They are much less osmotic than yeasts and molds.

14 - Gas producing Bacteria They are bacteria that produce gas(CO 2, H 2 S) during metabolism of nutrients. Species from genera Leuconostic, Lactobacillus, Propionibacterium, Escherichia, Enterobacter, Clostridium and Desulfotomaculum are included in this group. 15 - Slime- producing Bacteria They are the bacteria that produce slime because they synthesize polysaccharides. Examples include Xanthomonas, Leuconostic, Alcaligenes, Enterobacter and lactobacillus.

15 - Spore-Forming Bacteria They are the bacteria that have the ability to produce spores. Species from Bacillus, Clostridium, and Desulfotomaculum are included in this group. They are further divided into: • Aerobic sporeformers • Anaerobic sporeformers • Flat sour sporeformers • Thermophilic sporeformers • Sulfide-producing sporeformers

17 - Aerobic Bacteria They are the bacteria that require oxygen for growth and multiplication. Examples include Pseudomonas, Bacillus, and Flavobacterium 18 - Anaerobic Bacteria They are the bacteria that cannot grow in the presence of oxygen. Species from Clostridium are included in this group.

19 - Facultative anaerobic Bacteria They are bacteria that are able to grow in both the presence and absence of oxygen. Lactobacillus, Pediococcus, Leuconostoc. Enteric pathogens, and some species of Bacillus, Serratia and Coliforms are included in this group. 20 - Coliform Bacteria Species from Escherichia, Enterobacter, Cirtbacter and Klebsiella are included in this group. They are used as index of sanitation.

20 - Fecal Coliform Bacteria Mainly Escherichia coli is included in this group. They are also used as an index of sanitation. 21 - Enteric Pathogenic Bacteria Pathogenic Salmonella, Shigella, Campylobacter, Yersinia, Escherichia, Vibrio, Listeria, and others that can cause gastrointestinal infection are included in this group

Descriptive Terms Indicator organism (s) An indicator organism or group of organisms is one whose numbers in a product reflect the success or failure of (good manufacturing practices). GMP Coliform group of microorganisms and Escherichia coli are commonly used as indicator organisms.

Index organism An index organism is one whose presence implies the possible occurrence of a similar but pathogenic organism. E. coli is used as an index organism and its presence indicates possible presence of pathogenic enterobacteriacea e. g Salmonella sp.

Food borne diseases 1 - Those which cause the disease by infection (food infection) 2 - Those which produce toxin in food (food poisoning or intoxication) Those which cause infection when consumed together with food. Common organisms in this category include Salmonella typhimurium, enteropathogenic E. coli, Vibrio parahaemolyticus Yersinia enterocolitica

Toxin-Producing Organisms These are microorganisms which cause intoxication, they must grow in food in large numbers and produce enough toxin and when consumed together with food cause intoxication. Common microorganisms in this category include • Clostridium botulinum, • Staphylococcus aureus • Toxigenic fungi e. g. Aspergillus flavus.

• • Infectious Microorganisms These are the organisms whose presence in small numbers in food or water and when consumed can cause infection. In this case the food acts as a vector but not necessarily as a growth medium. Infectious organisms can be transmitted by various ways including man to man and are said to be contagious. Organisms in this group include; • • Vibrio cholerae O 1, Salmonella typhi, Shigella sonnei, Hepatitis A …etc.

Spoilage Organisms • Spoilage organisms are the organisms whose growth in the food causes undesirable characteristics in that food. • Any organism which is not intentionally added into food is considered a contaminant. • Growth of the contaminant in that food will spoil the food making it unfit for human consumption. • Some useful microorganisms e. g. Lactic acid bacteria are considered as spoilage organisms when in alcohol but not in milk.

Thank you Please review presentation and summarize important points End of Lecture