Microbial Analysis of Food Flashcards
what is the standard plate count technique used for
determine the number of mesophilic aerobes
-the quantity of these bacteria will affect the shelf life and quality of a product and may indicate if a food has been prepared under unsanitary conditions or if the food was transported or stored incorrectly
foodborne infections
-occur when live pathogenic bacterua are consumed by eating raw or undercooked food products
foodborne intoxications
-bacterial toxins that were relelased by bacteria growing in raw food are present in raw, undercoocked or cooked food products
how can pathogens be introduced
-animals
-fecal matter
-unsanitary food handling
are toxins heat stable
-yes
S aureus infection
-common cause of food-borne intoxication
-part of normal flora
-unsanitary handling is typically the cause
-heat stable enterotoxins causing GI symptoms when consumed
common indirect indicator to predict whether intestinal pathogens are present
-determine whether food had been contaminated with fecal matter
-testing presence of seage indicsator or fecal organisms
enrichment cultures
-provide conditions conducive for growth of specific oranisms and inhospital conditions for others, allowing for selection of specific bacteria and growth of a small amoutn of the organism into detectable levels
0azide dextrose, and TSB + 7.5% NaCl
azide dextrose
-selective medium
0axide blocks electron transport along cytochrome chain and inhibits most respiring organisms
-aerotolerant anaerobes (enterococcus and streptococci)
TSB + 7.5% NaCl
-selective
-inhibits most bacteria through dehydration of cytoplasm and plasmolysis of the cell
-staphlycoccus are salt tolerant and can maintain water activity and can grow in up to 10% NaCl
-turbitidity indicated organism with high salt tolerance
staphylococcus species
-salt tolerant up to 10%
-normal skin flora
-shec during persperation
–staph increase K+ cytoplasmic concentrations to resist hydration
