FOSC 111

What are the 5 main human senses?

Touch, smell, feel, sight and hearing

What is Gustation?

Taste

What is olfaction

odour

What is chemesthesis?

Trigeminal irritation

What are the 5 basic tastes?

Sour, sweet, salty, umami and bitter

what is the purpose of pasturisation?

To kill all pathogenic organisms and inactivate enzymes that could lead to spoilage

What are the 4 methods of milk processing and preservation?

Homogenization, pasteurization, coagulating and dehydration

What enzyme is used to test if milk has been correctly pasturised?

Alkaline phosphatase (ALP)

How do acids clot milk?

They lower the pH and isoelectric point of caseins, making the caseins less soluble and coagulate into a curd

How do enzymes clot milk?

The enzyme cuts off the negative charge on the casein, stopping repulsion and the micelles begin to join together, forming a curd.

What are the two types of proteins in milk

Casein and whey

What % are casein and whey found as the proteins in milk

18% whey and 80% casein

What are the toxins that E.coli produce called?

Shiga toxin 1 and Shiga toxin 2

What symptoms do the toxins from E.coli give you?

They cause damage to the intestines, leading to blood in stool.

What % of patients who get STEC food poisoning develop haemolytic uremic syndrome?

upto 15

What shape does campylobacter have?

A twisted spiral shape

What are the most common species of campylobacter in NZ?

C. jejuni and C. coli

What is the most common bacterial cause of food poisoning in NZ?

Campylobacter strains C. jejuni and C. coli

What is the source of campylobacter?

Run off from land with cattle, sheep or chickens. Often from undercooked chicken.

How can campylobacter be prevented?

Good personal hygiene, ensure chicken is cooked to 72C, avoid swimming in areas with agricultural run off and prevent cross contamination (use separate boards for preparing food)

What happens when salmonella enters the body?

It releases a toxin in the small intestine

Symptoms of salmonella

Fever, vomiting, diarrhoea and headache

Bacteria that can cause typhoid fever

Salmonella

Salmonella is found in

Raw meat, unpasteurized eggs and milk and sometimes spices

What is scombroid?

A type of histamine fish poisoning, an allergic reaction

Why are pregnant women advised to not eat deli meats, soft cheeses and rock melon?

They can contract listeriosis from the deli meat, which can cross through the placenta wall and harm the baby inside.

What is L. monocytogenes usually associated with?

plants, soil, water and animal digestive tracts

What pathogen can grow at refrigerator temperatures

Listeria monocytogenes

Methods to control listeria at home

Rinse fruits and veges, don’t leave fruits sitting out, YOPI do not eat risky foods such as deli meats, smoked seafoods and raw milk products

Where is staphylococcus aureus found?

Skin infections, impetigo, other skin conditions

Which food bourne pathogens can cause meningitis?

Staphylococcus aureus and cronobacter

Why do the symptoms of Staphylococcus aureus have such a short onset period (2-6 hrs)

Due to the preformed toxin

Which bacteria has an advantage in salty foods?

Staphylococcus aureus

What is the danger zone for food?

5 - 60C

Who is most at risk of cronobacter?

Formula fed babies

Norovirus symptoms

Projectile vomit and explosive diarrhoea

Why is norovirus so easy to spread

Very low infectious dose, the vomit is hard to clean and therefore easily spread

Where is norovirus most commonly found

Shellfish and salad foods

What is the most common cause of food poisoning in NZ

Norovirus

What are the two major roles of water in food?

Reaction medium and reagent

Free water

Water which is able to react, bulk water

Bound water

Water of crystallization, water that is chemically bound

What is lipid oxidation

When fats and oils are exposed to oxygen and form products such as aldehydes and ketones

Carbohydrates

Organic compounds found in plants, animals and microorganisms. Ratio is C:H:O 1:2:1

Basic unit for carbohydrates

saccharide

suffix for sugars

-ose

What is lactose used for?

Browning agent and filler

Where is lactose found?

Milk from mammals

Use of maltose

Beer (adds colour), flavouring agent

What is fibre?

A group of polysaccharides that are not readily digested.

What does polyphenol oxidase do?

Cause discolouration

What does the lactic acid bacteria use for growth during fermentation?

Lactose

What type of process is sensation?

Top - down

What are the % for the salt content, total acidity and pH of sauerkraut?

Salt = 2-3%, total acidity = 1.5-2.5% and pH is 3.1-3.7

What two bacterial species are used in commercial production of yoghurt?

Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus

What chemical compound is added to salami to prevent the production of a deadly toxin?

Sodium nitrate