SOP: Determination of Salt Content in Spices

GIFSQ — Global Institute for Food Safety & Quality

Introduction

PFA Act 1954 and PFA Rule 1955 define salt as NaCl and nothing else, which is determined volumetrically by titrating the salt containing extract with silver nitrate, employing potassium chromate as indicator. Spice commodities generally contain 0.61% salt in terms of NaCl. Estimation of salt percentage gives an idea about the extent to which salt is employed as adulterant in spice and condiments.

1. Principle

Salt is extracted from sample with hot water. Pigment free water extract is acidified with dilute nitric acid and titrated against std. AgNO₃ solution by using K₂CrO₄ as indicator. Volume of the standard AgNO₃ solution is proportional to the salt percentage.

2. Application

This method is applicable to spices and other food products.

3. Apparatus

Beaker, burette, pipette, conical flask, filter paper, stand.

4. Reagents

0.1 N AgNO₃ solution; 2% HNO₃ solution; K₂CrO₄.

5. Procedure

Take 5 g of sample in 250 mL beaker

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Add 100 mL hot water and stir with glass rod

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Keep about 15 minutes

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Filter through No. 1

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Take 10 mL of filtrate and acidify with 1–2 drops HNO₃

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Titrate with std. AgNO₃ solution

6. Calculation

% Salt = [V(AgNO₃) × S(AgNO₃) × 58.44] ÷ Wt. of sample taken

Where,
– V(AgNO₃) = volume of standard AgNO₃ used in the titration (mL)
– S(AgNO₃) = strength (normality) of the standard AgNO₃
– 58.44 = equivalent weight of NaCl

7. Limit of detection

It is the volumetric analysis, which estimates the salt percentage in spice about or more than 0.5%.

8. Precautions

• Color of water extract may interfere the end point of titration. So end point should be noted carefully.
• Starch containing samples should be leached with low temp. water.
• Titration should be carried out to acidify sample with 2% HNO₃.

References

Rangana S. (1986), Handbook of analysis and quality control for fruit and vegetable products, 2nd edn, Page 204.