Proximate Analysis Flashcards
Quantitative method used to determine the distribution of products when the samples are heated under specified conditions
Proximate analysis
Basic principles of proximate analysis
- Moisture content
- Ash content
- Volatile matter
- Fixed carbon
- Crude fiber
How to get the moisture content in proximate analysis
• Heating the sample to evaporate the water and then measuring the weight loss to calculate the moisture content
• TYPICALLY DONE BY COMPARING THE WEIGHT BEFORE AND AFTER DRYING
How to get the ash content in PA
Heating the sample to high temperature until all organic material is oxidized and only ash remains
Volatile matter?
Heating the sample at a controlled temperature to drive off these volatile components, which are then collected and measured
How to get Fixed carbon?
Heating the sample to high temperatures in an inert atmosphere to remove the volatile matter
Crude fiber
Treating the sample with boiling acid and alkali solutions to remove soluble components living behind the insoluble fiber fraction
Components and analytical steps of Proximate analysis
- Moisture content
- Ash content
- Crude protein
- Crude lipid
- Crude fiber
- Nitrogen free extract
Moisture content:
Initially, weigh the dish, add the sample, and dry it in a vacuum oven at 100°C for about ___ hrs. Keep drying and weighing until the weight change between each drying session, done hourly, is less than __
5 hours
5 mg
Ash content:
The procedure involves weighing a sample in a crucible, drying it at 100°C for 24 hours, then ashing it at 550°C for __ hrs or until obtaining a white ash. If a white ash isn’t achieved, __ and __ until constant weight, then weigh the crucible after cooling
8 hrs
Moisten
Re-ash
Crude protein:
Weigh the material, add ____, ___, ___ __ __, and conc ___ to a digestion flask. Digest until the solution turns almost colorless, then cool, add water, and distill the ammonia collected into standard acid for titration with NaOH.
Na2SO4, CuSO4, selenized boiling granules, and conc H2SO4
Crude lipid:
Secure thimbles in the extractor, add ___ __ to beakers, clamp tightly, heat, and extract for at least 4 hours on high or 16 hours on low setting before allowing ether to drain.
diethyl ether
Crude fiber:
Heat the sample in an oven at 105°C until constant weight to determine the moisture, then weigh 1 g of ground sample (approximately 1 mm) and treat with ___ boiling for 30 minutes before filtering and drying to obtain the crude fiber plus ash content.
Sulfuric acid
Nitrogen free extract estimates nonfibrous ___ through a calculation based on the differences in other components
carbohydrates
Nitrogen Free Extract formula
% NFE = 100% - (% EE + % CP + % Ash + % CF).
