Energetics 2 Flashcards
How is fat content analysed?
Rapid Soxhlet Extraction
How is protein content analysed?
Thermo scientific flash/protein analyser
How is salt content analysed?
Digital salt meter
How is sugar content analysed?
Digital meter
How are energy values measured?
Bomb calorimetry
Bomb calorimetry procedure (3)
Measures heat of combustion of a particular reaction
Determines the heat of combustion
Or calorific value of materials which are burned as fuels
Bomb calorimetry measures _____ energy
Gross
Why isn’t all gross energy available to the body?(2)
Not all food eaten is absorbed from digestive tract
Not all energy in protein is released
Define metabolisable energy (2)
Proportion of energy available to the body
After urine and faeces loss from gross energy
Problems with ME (6)
Assume that all macronutrients are equal
Some forms of starch are indigestible
Assumes he 6.25g of protein contains 1g of nitrogen
Different FAs have different digestibility
Animal and plant protein have different ME
Assumes fibre does not contribute to ME
Direct calorimetry (2)
Measures heat generated by the body over a given period of time
Performed in live in chambers
Disadvantages of direct calorimetry (3)
Has to be made over long periods of time
Not applicable for sports or occupational activities
Corrections required for all heat entering and leaving chamber
Indirect calorimetry (3)
Method of estimating energy expenditure by measuring respiratory gases
Measures the consumption of oxygen and production of carbon dioxide
When foods are oxidised in the body oxygen is used and carbon dioxide is produced
Respiratory quotient (2)
The ratio of carbon dioxide produced to the oxygen used on oxidation of a given amount of the nutrient at the cellular level
Respiratory exchange ratio (2)
The ratio of carbon dioxide produced to the oxygen used on oxidation of a given amount of the nutrient measured from expired air
