water in food ljw2009 bua/hauc nof/f&fm as a food component use in food processing as a nutrient...

WATER IN FOODLJW2009 BUA/HAUC

NOF/F&FM

AS A FOOD COMPONENT USE IN FOOD PROCESSING AS A NUTRIENT FOR LIFE

PROPERTIES OF WATER

naturally occurring in 3 states unchanged when utilised within body high melting/boiling points excellent conductor unique configuration no smell/taste/colour

ROLE IN NUTRITION

CONTINUOUS LOSS FROM BODY ;

Urine – 1300 mls/day

Faeces – 60 mls/day

Lungs (via respiration) – 300 mls/day

Skin (via perspiration) – 920 mls/day

ROLE IN NUTRITION cont

SUPPLY IS FROM A VARIETY OF SOURCES ;

Food – 1120mls/day

Drink – 1180 mls/day

Oxidation (metabolism of food) – 280mls

What do you understand by the recommendations to consume 2l /day?

‘is thirst a reliable indicator of needs?’

Under normal circumstances intakes = losses SELF REGULATING DEHYDRATION – losses exceeding 10% of

body water What causes dehydration ? deprivation disease thermal extreme – heat OR cold

Water in the human body

PROPERTIES OF WATER WITHIN THE BODY

Universal solvent – electrovalent covalent Biochemical reactions Transport & absorptionHomeostasisEvaporation /heat loss Excretion Protection Lubrication

WATER IN FOOD

The presence of water in food can be considered in 2 ways ;

(i) Moisture percentage – by composition

(ii) Water Activity – its availability for chemical/physical reactions within the food and microbial activity

WATER ACTIVITY

Expressed as a value on a scale from 1.00 down to 0.00

Pure water has a Aw of 1.00 Vegetable oil has an Aw of 0.00 The higher the value – the more water is

available ; for reactions

for microbial growth

WATER ACTIVITY ( Aw) cont

Aw % water

• Fresh meat 0.99 70%

• Bread 0.94 40%

• Rice 0.44 11%

• Sugar 0.2 0.2%

• Vegetable Oil 0.00 0.00

WATER IN FOOD PROCESSING-

FREEZINGDRYING

SALTING/SMOKINGMAP

All remove or reduce the availability of water

Water : food interactions

Aids mixing Aids heat transfer Acts as a lubricant

Water also – dissolves

effects boiling & freezing points

forms gels

can be ‘bound’ into foods

‘TAP’ or ‘BOTTLED’??

Is any water pure ? Dissolved gases + salts ( minerals) Impurities Is tap water clean ? • EU regulated• Filtered • Chlorinated ( 0.5ppm)• Fluorinated ( 1ppm)

BOTTLED MINERAL WATERS

Sterilised with Ozone ( 1-2ppm)

Dissolved salts determine hardness

Sparkling (natural or artificial carbonation) or still

Added flavours or fortification ( eg calcium)

Bottled Water - definitions

• Spring Water can be collected only at the spring and must be bottled at source. May be treated to meet hygiene standards

• Mineral Water contains more than 250 ppm of total

dissolved solids which are present at the point of emergence from the source. No minerals can be added to this water nor can it be drawn from a municipal source. In Europe, any recognized spring water with minerals can be called mineral water. May not be treated –only filtered

• Sparkling Water contains the same amount of carbon dioxide that it had when it was drawn from the source.

Vital fluids - drinks in our diet + culture

Early settlement/ development determined by availability of water

- is this becoming an issue again ??

How certain are we of the provision /sustainability of water for drinking ,food production , and sanitation ??

Nature of Food should also consider the wider aspects of liquids in our diet

and culture

Think about - • Food preservation – fermentation of fruit

and cereals produced wine + beers• Nutrition – carbonated + alcoholic

beverages can make substantial contributions ( with +ve and –ve effects)

• Food culture – the role of drinks is often a key marker/ element

History of the world in five glasses !!

• Brewing beers made water safe to drink • Wine is a key element in culture + religion • Distilled spirits (rum , whisky + brandy) played a

large part in global trade + exploration • Coffee + tea were associated with commercial ,

intellectual and political developments• Coca cola can be seen as the emblem of a

global market place ,the USA as a super power and consumer capitalism

Do we encourage the drinking of waters ?

What would be the important issues ??