MO and food Flashcards
(90 cards)
bacteria
Beneficial, Spoilage, Pathogenic
Reproduce by fission
mold
Multicellular, Filamentous
Reproduce by spores
yeast
One cell Microorganism
Reproduce by budding
Yeasts usually grow well in a slightly basic medium and in presence of some source of energy, such as sugar and water. T/F
F, should be acidic
Yeasts and molds can easily grow in dried food with less than 10% moisture content. T/F
F, Yeasts need at least 20% moisture in food to remain viable
Molds generally represent a far greater potential for food spoilage than do yeasts. T/F
T
extrinsic factors affect bacterial growth
Depends on Storage environment
Temp. Humidity, Environmental gases (O2, CO2, etc.)
intrinsic factors affect bacterial growth
Properties inherent to foods,
Biological structure (skin, shell)
pH, water activity, anti-microbial compounds, nutrients
what is the difference between water activity and water content
Water Activity is a measurement of the availability of free water for biological reactions.
Water Content is a measurement of bound and free water.
What is the effect of Freezing, Solutes, Drying on water activity?
they decrease water activity.
Most fresh-type foods have a water activity (aw) of about
0.96-0.99
bacteria that cause food-borne illness will grow on foods that have a water activity above
0.85
based on the tempature requirments bacterias can be classified as
Psychrophilic
Thermophilic
Mesophilic
what is psychrophilic
cold-loving
an example of a psychrophilic bacteria
Pseudomonas fluorescens: spoilage bacteria荧光假单胞菌
temp for a mesophilic bacteria
~30 C
what is the tempature requiement for a thermophilic bacteria
> 40 C
what are the differences between spore formers and vegetative cells
spore formers:Special protective coating, Dormant
vegetative cells: Active Reproducing Cells
an example of chemical spoilage
oxidation of lipids
an example of physicla spoilage
Bruising/dehydration
the bacteria that causes microbial spoilage
Pseudomonas fluorescens荧光假单胞菌
a bacteria that can cause a food-borne illness
E.coli
2 virus that cause food-borne illness
Hepatitis A,
Bacterio-phages细菌噬菌体
Parasite that causes food-borne illness
Trichinella spiralis
旋毛虫:一种寄生在肌肉组织中的线虫,通过食用受感染的肉类而感染人体,导致旋毛虫病