intro

Question 1

Why are foods fermented?

Answer 1

• texture, aroma, taste
• nutrient value
• preservation, storage

Question 2

Microorganisms involved and eg of its products

Answer 2

Lactic acid bacteria (LAB): cheeses, yoghurt, salami, sauerkraut

Yeasts: bread, cider, beer, wine

Yeasts + LAB: African beers, sourdough bread, soy sauce, kefir (from Eastern Europe), kimchi (from Korea), miso (from Japan)

Question 3

Fermentaion

Answer 3

= Metabolic process

= Condition determine outcome:
~ Substrate lv (raw product, additions)
~ Fermentation process (temp, pH)
~ Starter culture/ inoculation

= Resultant acidity and low pH inhospitable to many spoilage microorganisms

Question 4

Traditional fermented food industry (9)

Answer 4

Small scales
inconsistant quality 
Manual
Insentive to time
Safety is a minor concern
Open 
Septic
No sterile medium
Significant exposure to contaminants

Question 5

Modern fermented food industry

Answer 5

Time sensitive
Aseptic 
Machinery / automated
consistant quality 
Safety is a major concern
Minimum exposure to contaminant
Contained
Large scale 
Pasteurised or heat treated medium

Question 6

Bacteria size

Answer 6

1-10 um

Question 7

Difference between Gram +ve & -ve bacteria

Answer 7

+ve has a thick peptidoglycan wall

-ve has a thin peptidoglycan wall, an outter membrane with periplasmic space in between

Question 8

Bacteria cell shape

Answer 8

cocci
bacilli
spirilla (Spiral)
spirochaetes (Cockscrew)
vibrios (comma)

Question 9

Bacteria cell grouping

Answer 9

Chain of rod and cocci
clusters of cocci
Pair of cocci
Tetra of cocci

Question 10

Archaea

Answer 10

has no peptidoglycan wall

found in extreme environment

Question 11

Fungi

Answer 11

Cell bound by cell wall composed mainly with chitin, some prtein and glycoprotein

Question 12

Chitin

Answer 12

N- acetyl glucosamin residue - a Nitrogen containing polysaccharide

Question 13

Yeast

Answer 13

• Saccharomyces cerevisiae
• egg shaped unicellular eukaryotic cell
• larger than bacteria
• reproduced by budding (asexually) (or sexually)
• No flagella

Question 14

Moulds

Answer 14

• Fungi
• Hyphae - Long branched filaments- interwine to form mycelium
• Growth at tips

Question 15

Microbes macronutrients (95%)

Answer 15

Carbon / Hydrogen / Nitrogen / Oxygen / Phosphorous

Sulphur

Question 16

macronutrients can use to compose

Answer 16

carbohydrate, lipid, protein, nucleic acids

Question 17

Other microbes macronutrients

Answer 17

Magnesium- enzyme cofactors, complex ATP, stablize membrane & ribosomes

Iron - electron transport, enzyme cofactors

Potassium - enzyme activity

Calcium - endospore heat resistance

Question 18

microbes micronutrients

Answer 18

Copper / Cobalt / manganese / zinc /Nickel / Molybdenum

Mostly used in enzyme

Question 19

Metabolism

Answer 19

Chemical reaction in cell to yield energy and material for growth

Each reaction need enzyme to speed up reaction and lower the energy needed

Specific for a given substrate

When a bond is broken, energy is released and used to run other reactions

Question 20

Enzyme purpose

Answer 20

lower energy required for metabolic reactions and increase the rate

Question 21

energy stored in cell as

Answer 21

ATP (adenosine triphosphate)

Question 22

Catabolism

Answer 22

Breaking down complex molecules into small molecule
Release energy( ATP) and heat and produce energy- poor end products (CO2, H2O), NH3)

oxidation, exergonic

Question 23

Anabolism

Answer 23

Synthesis cell marcomolecules (Protein, Lipids etc) using precursor molecules (amino acids, fatty acid etc)

Energy required, reductive, endergonic

Question 24

Oxidising agent

Answer 24

oxidise substrate and reduce itself

Question 25

Reducing agent

Answer 25

reduce substrate and oxidise itself

Question 26

Eg of Electron carrier (oxidized form & reduced form)

Answer 26

(Ox) (Re)
NAD+ 2e- + 2H+ NADH + H+
FAD + 2e- + 2H+ FADH2

NADP+ + 2e- + 2H+ NADPH + H+