Microbial Contamination and Control

Question 1

Bacteria, Prokaryotic

Answer 1

Do not have a nucleus, rarely have membrane-bound organelles. Only a few can survive in the presence of alcohol, these are non-pathogenic.

Question 2

Fungi, eukaryotic

Answer 2

They have nuclei and membrane-bound organelles. Yeast: single celled. Fungi: long chains of elongated cell. Mold can be present in raw materials and present aflatoxins, which can cause cancer.

Question 3

Protozoa, eukaryotic

Answer 3

Have a nucleus and membrane-bound organelles. Can be found in water systems, tend to be larger than bacteria or yeast. Eg. Cryptosporidium: common water-borne parasites that cause intestinal or respiratory problems. Can survive in beer, so must be removed from water.

Question 4

2 steps to detect microbial contamination

Answer 4

Determine the type of contamination and the amount of contamination

Question 5

Culturing

Answer 5

The controlled growth of microbes

Question 6

Nutrient media

Answer 6

Allows growth of several different organisms, eg universal beer agar or broth.

Question 7

Selective media

Answer 7

Key nutrients for microorganisms of interest, biocide to prevent growth of other microorganisms.

Question 8

ATP Bioluminescence test

Answer 8

Adenosine tri-phosphate found in all living cells reacts with luminescent chemicals in a luminometer, which detects the light to measure the presence of microbes.

Question 9

Polymerase Chain Reaction

Answer 9

Detects DNA from target microbes (living or dead) to determine their presence

Question 10

UV Light

Answer 10

Kills up to 90% bacteria, fungi, and viruses by destroying their DNA. No residual effects; re-infection can occur.

Question 11

Ozone (O3)

Answer 11

Injected into cold/ambient line as a sanitizer or main CIP, high kill rate for bacteria, fungi, and spores. Non-corrosive but aggressive on rubber. Can’t be stored (breaks down to O2).

Question 12

Chlorine Dioxide

Answer 12

Oxidizing agent with high kill rate of bacteria, fungi, and viruses. Combats biofilms. Less corrosive and doesn’t taint product like other chlorine cleaners. Residual effect; re-infection is unlikely.

Question 13

No-rinse sanitizers: Peroxyacetic acid (PAA)

Answer 13

Hydrogen peroxide + acetic acid. Good residual effectiveness, non-corrosive, breaks down into non toxic components, effective over a wide range of temps.