Post on 16-Jan-2016
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 ??