chemical tests in spice industry

CHEMICAL ANALYSIS

There are different chemical tests done for different products. The main Chemical test done are Ash, acid insoluble ash, non-volatile ethyl extract moisture, water insoluble ash, alkalinity of soluble ash aqueous extract, crude fiber, (Fineness, Extraneous matter insect damage, Bulk density pinheads, Light berries Tendrils, mother cloves, khoker cloves, headless cloves) caffeine, metanil yellow, Lead chromate (damaged grains, wievelled grains, other edible grains).

1. MOISTURE:

Take 3gm of sample in moisture analyzer moisture content is automatically read in the instrument. Manually moisture can be determined by Toluene method.

2. TOTAL ASH:

Ash is the mineral content of the sample weight 2 gm of sample in crucible and kept in oven. It become ash and calculates the percentage.

PURPOSE:

To determine the ash content of the given sample

SCOPE:

Powders of chilly, coriander, turmeric, black pepper.

APPARATUS:

Flat bottomed crucible with a capacity of 10-25ml electrical muffle furnace, with indicating pyrometer and automatic thermo regulator desiccators containing and efficient desiccant such as an anhydrous copper sulfate or silica gel.

Reagents : Distilled water

PROCEDURE:

Ignite the flat bottomed dish or crucible to dull redness cool to room temperature desiccators and weigh use sample under preparation of sample. Weigh accurately 2-3gms well mixed samples in tarred flat bottomed dish or crucible. Weigh the dish or crucible in the entrance of the open muffle furnace until the sample is well carbonized. The sample must not catch fire.

Place the carbonized sample in the furnace at 600+20°C for 2 hours. Check for the presence of carbon for this cool the dish crucible to room temperature of wet the wash with several drops of distilled water. If carbon particles are seen, dry the dish and ashing. Repeat wetting and heating until no particles of carbon are visible and ignite in the muffle furnace for this after the disappearance of carbon remains wash ash with hot water and ignite in the muffle at 1000+20°C until the ash is white, cool in a desiccators and weight.

CALCULATIONS:

Total ash percent by = Weight of ash in Gms × 100

Weight of sample in Gms

3. ACID INSOLUBLE ASH:

PURPOSE:

To determine the acid insoluble ash

SCOPE:

All mixed curry powders, chilly powders, turmeric powder and black pepper Powder.

REAGENTS:

HCL solutions 1: 2: 5 (dilution) 100ml of Concentrated HCL with 250 ml of distilled water.

APPARATUS:

Funnel, water glass, silica crucible, muffle furnace , filter paper.

PROCEDURE:

Use total ash obtained on total ash determination. To this added 5-10 ml of the HCL solution and filter and cover the dish to a watch glass to prevent scattering. Filter through ash less filter Paper. Wash the filter paper with hot water until washing, are free from HCL acid, as Tested by silver nitrate solution, and Return to the dish. Evaporate carefully on the Water bath and ignite in the muffle furnace at 550 ±25 20° for 1 hour. Cool the dish in desiccators and weigh. Repeat the Operations of igniting for 1 hour, cooling and wetting till the difference in the mass between two successive weighing is less than 0.001 g. Note the lowest mass.

CALCULATION:

Acid insoluble ash percent by mass = (M₄ –M₀) × 100 ×100 – H

M₁-M₀

Where,

M₄ - Mass in gm of the dish

M₀ - Mass in gm of the empty dish

M₁ - Mass in gm of the dish and test portion

H - Moisture content of the sample as received

4. ALKALINITY OF SOLUBLE ASH:

PROCEDURE:

The filtrate obtained in water soluble ash is titrated against 0.In Hcl solution using methyl orange as indicator.

CALCULATION:

For Tea = 4.7 x V x N

(M₁ –M)

V= Volume of STD HCL used

N= Normality of HCL

M₁= Mass in gm of crucible + material

M= Mass of crucible empty

5. AQUEOUS EXTRACT:

This test is carried out to detect the solubility of coffee

To determine this:

1. 2g sample is taken in a condensing flask

2. 100ml distilled water is added

3. Condense for 1 hr with air condenser at 30⁰C

4. Make up to 250 ml

5. Filter through am ordinary filter paper

6. Weigh through an ordinary filter paper

7. Weigh a small beaker

8. Take 50 ml of filtrate in this beaker

9. Dry the beaker in 100⁰C & cool & weight

CALCULATION:

% of aqueous extract = Weight difference x 250

50

Sample wt

6. VOLATILE OIL:

Take 50g sample in 1000ml R.B flask. Add 500ml of water. Connect it with a Clevenger trap apparatus and condenser. Fill the trap with water. Heat the condense of the flask over a heating mantle. Collect the volatile oil in the trap continue the boiling till oil collecting the trap ceases. Take the reading of the volatile oil and calculate the percent of volatile oil.

CALCULATION

Volume of Oil in ml

Volatile oil =

Wt of sample

7. CRUDE FIBRE:

REAGENTS:

· Petroleum ether

· Dilute H2SO4 - 1.25%

· NaOH - 1.25%

· Ethanol - 95%

PROCEDURE:

1) Weigh 2.5 g of the ground material into a thimble.

2) Extract for about 1 hour with petroleum ether using soxhlet apparatus.

3) Transfer the material to a 1 litre flask.

4) Take 200ml of the dilute Hcl in a beaker and boil.

5) Transfer the whole of the boiling acid to the flask and immediately connect with a water-cooled reflux condenser.

6) Continue boiling for 30 minutes.

7) Remove the flask and filter through fine linen.

8) Bring some quantity of NaOH solution to boil under a reflux condenser.

9) Wash the residue on the filter into the flask with 200ml of boiling NaOH solution.

10) Immediately connect the flask with the reflux condenser and boil for extract 30 minutes.

11) Remove the flask and immediately filter through the linen.

12) Thoroughly wash the residue with boiling water and transfer to a Gooch crucible prepared with a thin but compact layer of ignited asbestos.

13) Wash the residue first with hot water and then wash with ethanol and with three successive washings of 15 ml of petroleum ether.

14) Dry the Gooch crucible at 105±1°c in an air oven for 3 hours, cool and weigh.

15) Repeat the drying process for 30 minutes.

16) Incinerate the contents of the Gooch crucible in the muffle furnace at 550±20°c until all the carbonaceous matter is burnt.

17) Cool the Gooch crucible containing the ash in a desiccators and weigh.

CALCULATION:

Crude fiber (on dry basis) percent by mass = 100(M₁-M₂)×100

M×100-H

Where,

M₁ = mass in g of Gooch crucible and contents before ashing

M₂ = mass in g of Gooch crucible containing asbestos and ash.

M = mass in g of the material taken for the test

H = moisture content of the sample as received in percent.

8. NON VOLATILE ETHER EXTRACT:

PROCEDURE:

Take 2g well mixed sample in a paper and put it in thimble. Thimble is kept in round bottom flask. Add 150ml petroleum ether and kept in soxhlet apparatus. Reflux for 18hrs at 40⁰ – 60⁰c.

CALCULATION:

NVEE = 100 ( M₁-M₂)

M

Where, M1 - Mass in gm of flask with non volatile ether extract

M2 - Mass in gm of flask with non volatile ether extract

after decantation

M - Mass in g of the material taken in the test

9. COLD WATER EXTRACT:

Cold water extract is used to find the solubility.

PROCEDURE:

Take 2g sample. Make up to 100ml. Shake it at every half an hour kept overnight. Take 50ml of this without shaking in a pre weighed beaker. Reflux for 1 hour and weight is taken.

ADULTERATION TESTS

a) METANIL YELLOW:

Concentrated HCL is added in to sample. Violet color appears. Add distilled water into it. The Violet color changes to yellow. This indicates the absence of metanil yellow.

B) LEAD CHROMATE:

Ash 2gm sample. 1: 7ml H₂50₄ is added to 5ml ethanol and 0.1 g biphenyl carboside mixture. This mixture is added to the ash. Presence of purple colour indicates the presence of lead chromate.