Proximate analysis Flashcards
what is food analysis and why is it important?
- the development, application and study of analytical methods for characterizing foods and their constituents
- important for allergies, health consequences, optimal performance, optimal health, safe and nutritious foods and consumer trust
how is food analysis applied in government regulations and quality control?
Government regulations: maintain the quality of foods, ensure the food industry makes safe food with high quality, fair competition between companies producing the same product, eliminate economic fraud
Quality control: ensure that food composition doesn’t change (decrease), characterize raw material
Nutrient Density
Nutrient-dense foods: lots of value, little calories
empty calorie foods: little value, lots of calories
- need nutrient-dense foods in a nutritious diet
true or false caloric content predicts nutrient content in food
false
What is proximate analysis?
analytical determination of moisture content, ether extract (fat content), Ash content (mineral content), nitrogen (protein content) and crude fibre
why is determining the water content in feed important?
- water is weight (part of the price of feed)
- more water weight = higher shipping cost
- storage conditions: how long food can sit on the shelf and how safe it is on the shelf
- too much moisture and food will spoil quickly
- too little moisture and the food will be less palatable
- moisture dilutes energy and nutrients in food
- moisture is important for optimum intake and performance of animals
how do you isolate the moisture content in a feed sample
- start with the feed sample (wet weight) and air dry it to get dry matter
- what you removed is the moisture (water content)
potential sources of error / limitations for determining moisture content
- drying can remove other volatile compounds like SCFAs and some minerals
- can cause a slight underestimation of drying weight
how can you mathematically determine % moisture
% moisture = (wet weight - dry weight) / (wet weight) x 100
how can you determine the % dry matter from a feed sample
dry matter = 100% - % moisture
What are the differences between human and agricultural applications of moisture content
- the agricultural industry is more interested in the composition of dry matter (animal feed)
- human food labelling is based on wet weight
how do you isolate ether extract (fat content) from a feed sample?
-treat the dry matter with an organic solvent (ether extraction) to yield the fat content
- the solution is transferred to a new tube and then dried. the solution is the fat and anything not fat would have precipitated out
how can you calculate % crude fat?
% crude fat = (weight of ether extract / wet weight of sample) x 100%
Potential source of error / limitations determining crude fat
- other things are soluble in organic solvents such as chlorophyll, resins, waxes in plants
- could over-estimate crude fat determination
why is it important to measure ASH (mineral) content?
- nutritional labelling
- quality and taste of food
- microbiological stability
- nutritional requirements
- manufacturer processing