16 - biological control of foodborn bacteria Flashcards
What is biopreservation
The use of microorganisms, their metabolic products or both to preserve foods (exclude fermentation).
What is controlled aciditication
the production of acids by LAB and then these acids are used as a preservative in food.
What is microgard ?
it is a small bundle composed of a fermentable carbohydrte and a bacterial culture added to regfrigerated foods to for preservation
What are the benefits of microGARD?
- protect shelf life
- maintain the organileptic qualities of food
- meet consumer’s demand for natural products
what will be the factors that influence the effectiveness of microGARD?
1-products pH
2- buffering capacity
3- target spoilage microorganisms
4- concentration of fermentable CHO
T or F : the microGARD is effective against clostridium bottulinum
true
What is the wisconsin process ?
the reducement in nitrites in bacon by adding sucrose and LAB to prevent the growth of clostridium bottulinum
what are bacteriocins?
antimicrobial peptides that can be lethal to bacteria.
T or F : bacteriocins are produced virtually by all bacteria
true
What are the four classes of bacteriocins?
Class I-IV
Nisin and subtilin are found in the class ___ of bacteriocins
Class I
Nisin is effective against gram ___
positive
What is the class I of bacteriocins?
contains unsual amino acids like lanthionine that are produced by modification after the translation.
What are lantibiotics ?
bacteriocins that contain lanthionine rings. Lanthionine rings are amino acids that have reacted with cysteine to form thioether lanthionine.
What is the class II of bacteriocins?
bacteriocins in this class are small heat stable proteins with a consensus lader sequence
What are the three sub-classes of class II bacteriocins
IIa : bacteriocins active against listeria monocytogenes
IIb : require 2 peptides for activity
IIc : require cystein for activity
What are the class III bacteriocins
really big proteins and heat liable
What are classs IV ?
proteins with lipid and cho moieties
How are bacteriocin discovered?
overlap of the colony producing the bacteriocin on a agar inoculated with the colony that the bacteriocin is against
How can you be sure the inhibition zone is due to a bacteriocin
putting proteolyitic enzyme at the center of the inhibition zone and if there is growth then the colony was producing a bacteriocin
Bacteriocin inhibition zone edges are _____
sharp
Bacteriophage inhibition zone edges are _____
clear but there is no colony at the center
Inhibition zone produced by organic acids have edges that are _____
fuzzy
how does the bacteriocin produced by LAB work?
they work by disrupting the cytoplasmic membrane
