Why do they add sulfur dioxide to apricots? An In-Depth Look at Fruit Preservation

December 2, 2025 •

3 min read

According to the Centre for Food Safety, sulfur dioxide has been used in food production for centuries due to its versatile properties as a preservative. This is why they add sulfur dioxide to apricots, specifically to maintain their bright orange color and extend their shelf life.

Quick Summary

Sulfur dioxide is added to apricots before drying to prevent enzymatic browning and inhibit microbial growth. This preserves their golden color, extends shelf life, and affects flavor. The practice is regulated, but some sensitive individuals may have reactions.

Key Points

Color Retention: Sulfur dioxide acts as an antioxidant, inhibiting the enzyme polyphenol oxidase to prevent apricots from browning during the drying process, maintaining their bright orange color.
Extended Shelf Life: As an antimicrobial agent, SO2 halts the growth of yeasts, molds, and bacteria, thereby preventing spoilage and significantly prolonging the product's shelf life.
Health Concerns: While safe for most people, sulfites can trigger adverse reactions, especially in individuals with asthma, causing respiratory symptoms, hives, or other allergy-like issues.
Sulfured vs. Unsulfured: The main difference is appearance and taste; sulfured apricots are bright and slightly tart, while unsulfured are darker, sweeter, and more caramel-like but have a shorter shelf life.
Available Alternatives: Methods like pre-soaking in lemon juice, controlled atmosphere drying, and natural plant extracts offer alternatives for those seeking to avoid sulfites, albeit with varying degrees of effectiveness.
Strict Regulation: The use and maximum levels of sulfur dioxide in dried fruits are regulated in many countries, with mandatory labeling for concentrations above a specific limit.

The Primary Reasons for Sulfurizing Apricots

Sulfur dioxide (SO2) is a colorless gas used as a food additive with two key roles in drying apricots: it acts as an antioxidant and an antimicrobial agent. Without this treatment, dried apricots would appear and taste different from the bright, soft products commonly found. The application involves exposing the fruit to sulfur fumes or a sodium metabisulfite solution.

How SO2 Prevents Browning

Natural oxidation, driven by the enzyme polyphenol oxidase (PPO), causes fruits like apricots to brown when exposed to air. Sulfur dioxide acts as an antioxidant by inhibiting this enzyme and interacting with browning compounds. This is crucial for maintaining the desired vibrant golden-orange color of sulfured apricots. Unsulfured apricots, in contrast, develop a darker, brownish hue as they dry.

Stopping Spoilage and Extending Shelf Life

The antimicrobial action of sulfur dioxide is vital for the safety and shelf life of dried apricots. It effectively prevents the growth of yeasts, molds, and bacteria that cause spoilage. By disrupting microbial activity, SO2 significantly extends how long the fruit remains safe and suitable for consumption and commercial distribution. This protection is particularly important during the initial sun-drying phase when contamination risk is higher.

List of Benefits from Sulfurization

Preserves Color: Prevents browning, keeping the apricots their desired golden-orange color.
Extends Shelf Life: Inhibits microbial growth, reducing spoilage.
Retains Nutrients: Helps preserve certain vitamins, such as carotene.
Improves Texture: Aids in maintaining a softer texture by limiting moisture absorption.
Protects Against Contamination: Reduces the risk of contamination by substances like ochratoxin A (OTA).

Sulfured vs. Unsulfured Apricots: A Comparison

Dried apricots are available in both sulfured and unsulfured varieties. The choice often depends on whether appearance or a more natural product is preferred. The table below outlines key differences.


Feature	Sulfured Dried Apricots	Unsulfured Dried Apricots
Appearance	Bright, vibrant golden-orange color.	Darker, brown to almost black color.
Taste	Often more tart or fruity.	Richer, sweeter, and more caramel-like.
Texture	Softer and more pliable.	Can be softer but often more chewy or tougher.
Shelf Life	Significantly longer due to preservative action.	Shorter due to lack of antimicrobial protection.
Additives	Contains sulfur dioxide (labeled as E220 in Europe).	Contains no added sulfur compounds.

Potential Health Considerations

While generally safe for most, sulfur dioxide can cause adverse reactions in some individuals.

Asthma and Sulfite Sensitivity

The main health concern is for asthmatics, as a portion are sensitive to sulfites and may experience respiratory symptoms like wheezing, chest tightness, and coughing. Other symptoms, such as hives or a runny nose, are also possible. Anaphylaxis, though rare, can occur in severe cases.

Labeling and Regulations

Due to these potential sensitivities, regulations globally require clear labeling for products containing sulfites above certain levels, enabling consumers to make informed choices. For instance, in the EU, concentrations exceeding 10 mg/kg must be declared. The use and maximum levels of sulfites are strictly controlled.

Exploring Alternatives to Sulfur Dioxide

Individuals and producers wishing to avoid sulfur dioxide have alternative options, though they may offer less color protection or shelf life extension.

Lemon Juice or Citric Acid: Soaking fruits in a lemon juice or citric acid solution before drying can help reduce browning.
Natural Plant Extracts: Research is ongoing into using natural extracts from food by-products as potential alternatives.
Temperature and Airflow Control: Specific drying methods can help reduce SO2 content and limit spoilage.
Modified Atmosphere Packaging: This technology can control oxygen levels to limit oxidation and spoilage.

Conclusion: Balancing Preservation and Preference

Adding sulfur dioxide to apricots is a traditional practice providing preservation, color, and extended shelf life benefits. Sulfured dried apricots are safe and appealing for most people. However, unsulfured options are important for those with sulfite sensitivities, offering a different taste and appearance and a shorter shelf life. The availability of both types allows consumers to choose based on health needs and taste.

The decision often involves balancing the bright color and freshness from sulfurization against the more natural look and flavor of unsulfured fruit. Reading labels and understanding the process helps in making informed dietary choices. For details on sulfite sensitivities, consult health authorities.

Frequently Asked Questions

Yes, for the majority of people, sulfur dioxide in dried fruits is considered safe for consumption. However, individuals with asthma or a known sulfite sensitivity can have adverse reactions, and should read labels carefully.

Dried apricots that are brown or dark in color have not been treated with sulfur dioxide. Without the SO2 to inhibit the enzyme polyphenol oxidase, the natural oxidation process causes the fruit to turn a dark brown color as it dries.

Yes, sulfur dioxide can affect the flavor. Sulfured apricots tend to have a tarter, fruitier taste, while unsulfured apricots are known for a richer, sweeter, and more caramel-like flavor profile.

The most common method for removing some of the sulfur dioxide is to soak the dried fruit in warm water. Research also suggests that soaking in solutions like citric acid or hydrogen peroxide can be effective, though this is more complex.

Sulfur dioxide is more commonly an intolerance, especially for asthmatics who may experience respiratory symptoms. True allergic reactions, like anaphylaxis, are possible but very rare.

Unsulfured apricots are free of the added preservative, which is the primary health benefit for those with sensitivities. While sulfites can reduce some B vitamins, sulfured apricots retain carotene better. The 'healthier' choice depends on individual dietary needs and sensitivities.

Sulfur dioxide is less essential for other fruits like dates or raisins, which have naturally longer shelf lives due to high sugar and low water content. For fruits where color is not a primary consumer concern, or where the natural preservation is sufficient, sulfur dioxide is not always necessary.