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The necessity to use metabisulfites to increase the shelf life of dried fruit and nuts

How to increase the shelf life of dried fruit and nuts using metabisulfites? As we know, metabisulfites such as sodium metabisulfite and potassium metabisulfite, and other sulfite compounds have the essential element of sulfur. Sulfur is an antioxidant and prevents the discoloration and spoilage of dried fruits and nuts by absorbing and preventing oxygen activity. Its daily intake is about 0.7 mg/kg of human weight. Sulfites are not harmful to the body, but their use in people with allergies can cause allergies and asthma. Therefore, the processed products such as sausages, seafood, soybean, dried fruits, and nuts should be consumed with caution because of the presence of sulfites and metabisulfites.

All products including dried fruit and nut of Food Lord Company are completely natural and the company’s policy is to research and develop natural preservatives to replace sulfites and sulfur materials and to supply healthy and high-quality products. Therefore, everyone can use these products.

Is there any alternative for metabisulfites?

All the current preservatives to increase the shelf life of dried fruit and nut

Sugar solutions

Sugar solutions are prepared in different percentages of sugar and water mixture. These solutions are used as a pretreatment to increase the quality and color retention before drying operations of fruit. In addition, other compounds can be used in these solutions. The sliced fruits are exposed to these sugar solutions usually with a ratio of 1/4 to 1/10 of fruit weight to solution for 2 h at 40-50 °C. Then, the fruits are taken out and dried.

Ascorbic acid solution (vitamin C)

Aforementioned, other preservatives can be also used in the sugar solution. One of these preservatives is vitamin C or ascorbic acid. It is an antioxidant so prevents phenolic reactions and the browning process of fruits. The added ascorbic acid is 1% of the solved sugar in water to prepare a more proper sugar solution for the dried fruit. - dried fruit

Citric acid solution

Another solution used to increase the shelf life of dried fruit is a citric acid solution. This solution prevents the browning of fruits and is used as a pretreatment. Putting sliced fruits in the solution will have a faster and better effect than whole fruits. Dissolve 2-3 g of citric acid in 1 l cold water and put the fruits in it for 5 min before drying. If the fruits are not sliced, this time should be increased up to 3 times.


The results of scientists’ research show that sulfite, bisulfite, and meta-sulfites can be used to prepare sulfite solution. The most popular types of metabisulfites are sodium metabisulfite and potassium metabisulfite. Sulfur compounds can be used in both gaseous and solution states. In the gaseous state, the dried fruit is placed in a container of a certain volume and smoked by spreading sulfur gas. The used sulfur in this method should not be more than 40-80 g sulfur/m3 of the space. In this method, vitamins A and C in fruits are also preserved in addition to preserving the color of the product. Based on the definition of WHO,  metabisulfites consumption is permitted in the range of 0-0.7 mg/kg body weight.

The method of using sulfur solutions is easier and more popular. According to the national standard of Iran, there is a standard limit for each dried fruit and nut. And the maximum concentration of sulfur dioxide is determined for each one. In this method, the concentration of the remained sulfur in the dried fruit should not exceed the permitted limit. Because the sulfurous materials can make sensitivity for asthmatic people. The maximum permitted level of metabisulfites can be calculated based on the ratio of sulfur in SO2 to other metabisulfites for dried fruit and nuts. Gently wash the fruits after 5-15 min floating in the sulfurous solution and put on the sieves of dryers. Aforementioned, all of these methods are pre-treatment and should be conducted before drying.

Advantages and disadvantages of using sulfur compounds


Allergy and sensitivity to sulfur

Metabisulfites do not make a health risk themselves, but the presence of sulfur can cause sore throat and anaphylaxis for people with allergies. Sodium metabisulfites aggravate asthma, headache, respiratory distress, irregular heartbeat, nausea, vomiting, and diarrhea. To solve this problem, dried fruits can be used that do not use sulfate metabolic preservatives.

The Food Lord brand is proud to produce and supply all kinds of natural dried fruits and nuts.


Metabisulfites are used in food-grade in a wide range of foods including chips, soybean, beverage powders, dried fruits, nuts, etc., and do not make a health risk by themselves. These materials are chemical antioxidants and have the properties of sterilizing, decolorizing, and extending the life of products, especially dried fruits. In addition, it is used in the water treatment process as an antibacterial agent.


The necessity of using metabisulfites in dried fruit


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