food microbiology

Obligate areobes

Usually associated with surface growth ,need oxygen to grow

Microareophilic

Bacteria prefer limited oxygen conditions,middle of test tube

Facultative anearobes

Grow well in oxygen but can survive in anerobic conditions, entire tube

Obligate anaerobes

Grow where oxygen is absent , bottom of test tube

Indifferent

Bacteria don’t need oxygen for growth but can survive, evenly dispersed

Calculation for water activity

PH acidity

Most foods fall below 7 on the ph scale , most pathogens can grow at ph values between 4.6 and 9.0 , high acid foods are considered less of equal to 4.6 and discourage the growth of many microorganisms

Environmental factors impacting microbial growth

Nutrient availability, temperature,oxygen,ph acidity,time,water activity

Bacterial pathogens

Spore forming bacterial pathogens , non spore forming bacterial pathogens

Spore forming bacterial pathogens

Clostridium botulinum (Botox is a purified kind of this pathogen)

Non spore forming bacterial pathogens

Salmonella, E-coli

Spores

Develop in response to unfavourable growth conditions, vegetative bacteria will die while pores remain paeudodormant

Implications of spores

Have a greater resistance to heat , drying and irradiation processing than bacteria and many are thermodoric and acid resistant meaning that higher heat or longer processing times are required

Fungi

Molds and yeast

Molds

Grow in a tangled mass of mycelium, replicated by spores called conidia visible at the top of the hyphae , spores are dispersed in the air and root like structures called rhizoids anchor mold to a food . Many molds are spoilage organisms and can cause allergic reactions and respiratory problems

Yeast

Can be a spoilage organism , perform food fermentation and can be started cultures in bread , wine and beer

Microbes

Microspsopic organisms (viruses,bacteria,yeast,molds and parasites)

Viruses

Viral pathogens , food is a transportation medium between hosts, don’t multiply in foods ex. Hepatitis A and norovirus

Foodborne infections

Resulting from the ingestion of living pathogens that invade and multiply in the hosts organs after the consumption of contaminated food , resulting in sickness ex. Salmonella and listeria monocytes

Foodborne intoxication

Caused by the toxin preformed by the pathogenic microorganism in the food but the microorganisms are destroyed ex. Clostridium botulinum , staphylococcus

Toxico infections

Resulting in the ingestion of large numbers of live pathogens which then produce or release toxins in the gastrointestinal tract . Ex. E-coli

Listeria monocytogens

Responsible for nearly all human listeriosis cases , raw milk , ready to eat meals , leafy greens , flu like symptoms can cause meningitis,miscarriage and stillbirth in pregnant women

Salmonella

Causes salmonellosis ( Foodborne gastroenteritis), spread by consuming contaminated foods mainly animal products such as raw and undercooked meat eggs or unpasteurized dairy can form biofilms

E-coli

Intestines of cattle,poultry and other animals ,raw foods can easily get cross contaminated and the bacteria is not yet killed

Danger zone

4-60C

PRPS

Prerequisites program

SOP

standard operating procedure

Pickles

Lactic acid

Yogurt

Lactic acid

Blue cheese

Molds

Beer,wine, bread

Yeast