What it is and why it is used
The Food and Agriculture Organization (FAO) explains that sulphur dioxide is added to foods for its antimicrobial, antioxidant and reducing properties, and to prevent browning reactions. It lists dried fruits and vegetables among its main uses. It can be used as a gas or as sulphite, bisulphite and metabisulphite salts.
The Hong Kong Centre for Food Safety describes the same job in dried fruit such as apricots. It slows yeasts, bacteria and moulds, and it prevents the darkening that light-coloured fruit shows when exposed to air.
Colour alone cannot tell you whether it was used. The label is the place to look.
What FSSAI requires on the label
The Food Safety and Standards (Labelling and Display) Regulations, 2020, in the FSSAI compendium (version of September 2025), set the rules for packaged food. Three points matter here.
- The list of ingredients must appear under a title such as 'Ingredients', in descending order by weight at the time of manufacture.
- Food additives must be declared with their functional class together with the specific name or the International Numbering System (INS) number.
- Sulphite at 10 mg/kg or more must be declared as 'Contains sulphite'.
So a compliant label might show a line like 'Preservative (INS 220)' in the ingredients, and a separate 'Contains sulphite' statement. The FSSAI additive standards list sulphur dioxide as INS 220.
The INS number range
The Irish food safety regulator and the Hong Kong authority both describe the sulphur dioxide and sulphite family as numbers 220 to 228 (Hong Kong also adds 539). If you see a number in that range under a preservative heading, it belongs to this family.
Reading a label step by step
- Find the ingredients list. For dried grapes, it should say 'raisins' or 'dried grapes' and nothing else if nothing was added.
- Look for the words 'preservative' or 'sulphite', and for any INS number from 220 to 228.
- Look near the ingredients for 'Contains sulphite'.
- Check the FSSAI logo and licence or registration number, and the date marking.
Because the declaration rule starts at 10 mg/kg, a missing statement means the level is below that threshold. It does not by itself prove the level is zero. If it matters to you, ask the brand how the product is made.
Why regulators treat it as an allergen
The Food Safety Authority of Ireland notes that sulphur dioxide and sulphites are classed as allergens under EU rules because they can trigger reactions in sensitive people, particularly those with asthma. The Hong Kong authority advises sensitive people to check labels before buying.
If you are unsure whether it is suitable for you, please ask your doctor. We do not give medical advice.
What to ask a seller
A good small producer should be able to tell you whether any sulphur-based treatment was used, in plain words, and show where it is on the label. It is a fair question, and a straight answer is a good sign.
Frequently asked questions
What does INS 220 mean?
INS is the International Numbering System for food additives. The FSSAI additive standards list sulphur dioxide as INS 220.
When must 'Contains sulphite' be printed?
The FSSAI labelling compendium says sulphite at concentrations of 10 mg/kg or more must be declared as 'Contains sulphite'.
Does colour tell me if fruit has sulphur dioxide?
Not reliably. FAO says sulphur dioxide helps prevent browning, but the label is the dependable guide.
Sources
- FSSAI: Food Safety and Standards (Labelling and Display) Regulations compendium, Version VIII (Sept 2025)
- FSSAI: Compendium, Substances Added to Food (Chapter 3)
- FAO: Fruit and vegetable processing, general preservation procedures
- Hong Kong Centre for Food Safety: A Closer Look at Sulphur Dioxide in Foods
- Food Safety Authority of Ireland: Sulphur Dioxide and Sulphites