Principal:
Analysis of different food constituent is performed by method of “proximate analysis’ proximate analysis stand for a method which determines the value of the macronutrient in food samples. In general those values r being declared as nutritional facts shown usually on the label of the final food products but they are also being determined during the production process. The beginning of the nutritional analysis originates back in 1861 and since then it has been continuously developed modified and improved. The proximate analysis of food include:
Moisture
Ash
Crude lipid
Crude Protein
Crude fibre
Nitrogen free extract
These food component may be of interested in the food industry for product development quality control (OC) or regulatory purposes.
Sample preparation :
Rename inedible portion from the object to obtain a represent you sample that is to be analysed.
1. Only inedible portion from fruit’ vegetable’ meet poultry 🍗 ‘fish and nuts are taken for analysis.
2.Crush’mince or macerate them.
3. All liquids force such as milk’ juice’ oils etc’ are mixed well.
4.Cereal,grains and legumes are ground to fine powder.
5. Homogeneous foods such as butter are taken as such.
Determination of moisture:
Principal:
To acquaint student with a simple method used for determining mixture in food.
Procedure:
1. Wait on empty flat bottomed dish.
2. Place the sample in the weight dish.
3. Weight the dish with sample.
4. Place the dish in the oven at 100•c or vacuum own at 70•c .
5. Remove the dish after 4 hours, cool in a desiccator and weight.
6. Place the dish again in the oven for another 2hours and weight again.
7. Repeat till constant reading is obtained.
Moisture (%)=
Wt. Of fresh sample -
Wt .of sample after ×100 drying
Wt. of sample
Determination of protein:
Purpose:
To familiarize the students with method of analyzing protein in food.
Material requirement:
Digestion flask
Heating mental
Kjeldahl apparatus
Titration unit
Reagents:
90% concentrated sulphuric acid.
Digestion mixture (copper sulphate).
Potassium sulphate, (ferrous sulphate 5:94:1).
40% sodium hydroxide (40g sodium bye dioxide in to 100 ml distilled water).
Methyl red indicator (10 mg methyl red, 300 ml ethanol, dilute with distilled water 💦 to 500ml)
N/10 sulphuric acid.
Procedure:
1.Where the sample (fruit or vegetables 5 g, cereal 2g, boneless meat 2g, liquid 10 ml and donate as y).
2. Transfer the weight sample to digestion flask.
3.Add 2–3 g digestion mixture and 25 ml concentrated sulphuric acid and digest.
4. Remove the flask cool and transfer the material to 250 ml volumetric flask. Rinse with small portion of water and then make up the volume with the distilled water.
5. Take 50 ml of prepared sample add 10 ml of alkali solution(40% NAOH)
6. Distill in to 25 ml of 4% boric acid using methyl red as indicator.
7. Titrate the end solution with N/10 sulphuric acid solution.
Calculation:
Calculate nitrogen and protein:
Percentage as yellow
Determination of ash;
Determine the presence of inorganic residue remaining after the organic matter has been incinerated.
Procedure:
1.Remove seed stone and other inedible from the sample (fruit 🍓 ,vegetable 🥒,meat 🍖 fish 🐟).
2. Place a homogeneous sample.
3. Place the sample in weighed crucible and weigh.
4. Place the crucible on heat at 100°c until water in expelled from the sample.
5. Then char sample gently over allow flame.
6. Place the crucible in muffle furnace set at 525°c and leave until while ash is obtained.
7. Mast Ash with water , dry on steam and then on hot plate.
9.Re- ash in muffle furnace 525°C to constant weight.
Calculation:
Ash(%)
Wt. of sample after
Ashing. ×100
Wt. of sample
Determination of crude fat:
Purpose:
To acquaint the student with the method of estimation of fat oil in a simple food 🥝.
Material required :
Food sample
Filter paper
Soxhlet apparatus
Weighing balance
Chemical required:
Diethyl ether or hexam
Procedure:
1.Sample in an oven set at 100°C for 3 -4 hor.
2. Way 2g of dehydrated sample.
3. Place the sample in soxhlet apparatus and extract with 75 ml on 100 ml of solvent.
4. Remove the sample from soxhlet and let it cool in the desiccator.
Precaution: solvent used is highly flammable avoid open flame near station 🚉 apparatus.
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Determination of fibre:
Purpose:
To familiarize students 😊 with method of crude fibre determination.
Material required:
Condenser reflex condenser
Abettor
Beaker
Bunsen burner
chemical required:
0.225N H2 SO4
0.313N Na OH
Petroleum ether
Procedure:
1. Take about 3g well mixed the sample
2. Dehydrate sample in oven.
3. Extractor to GF this dry material petroleum idhar to remove crowd fat.
