Comprehensive Guide to Harvesting and Producing Sulfur-Dried Apricots

Sulfurized Dried Apricot

Sulfurized-dried apricots are obtained by drying ripe harvested apricots in direct sunlight after chemical treatment, such as sulfurization.

How to Harvest Apricots for Sulfurized Sun Drying

The apricot harvest usually takes place over a period of approximately three weeks, usually starting in mid-July. Hand harvesting is the best method as it minimizes damage to the fruit and tree, resulting in high-quality fruits. The hand-picking process involves starting with the top of the tree and then moving to the middle and lower branches, ensuring that the fruit is at the same stage of ripeness. Traditional harvesting methods, such as shaking the branches and using a stick to knock the fruit to the ground, or modern methods such as using eccentric shakers attached to the tractors, cause damage to the branches and contaminate the crop with soil and stone fragments. Additionally, both ripe and unripe fruit can fall during this process, causing significant quality losses. The aim is to minimize these quality losses during the harvest process to maintain the overall quality of the apricots for later processing stages.

How to Produce Sulfur-Dried Apricots

The apricots intended for sulfur-drying must be fully ripe before harvesting to achieve the desired golden-orange color and balance between sweetness and sourness (depending on the harvesting time, this ratio may differ). Of course, it takes more than ripe apricots and enough sunlight to achieve this color, flavor, and texture. It also requires years of experience and knowledge. Apricots should not be exposed to rain during the drying process since it can cause a slightly sour taste. The timing of harvest and duration of the drying process plays a pivotal role in the end quality of the product.

Fortunately, the farmers of Malatya in Turkey, the apricot capital of the world, have this knowledge and experience. For this reason, almost every part of Malatya province is suitable for growing and drying apricots. This is why the region has a reputation for its superior quality sun-dried apricots, produced with care and having an exceptional taste, color, and smell (the three most prominent qualities sought in dried apricots; If one of the quality traits is missing, the other traits wouldn’t be enough for attracting consumers.

Steps for Sulfurization Process

Sulfurization is carried out to reduce the drying time of the apricots, preserve the product's natural golden yellow color, extend its shelf life, and prevent fermentation and insect infestation. In the traditional sulfuring process, the harvested fruit is placed in crates and placed in the sulfurization room. In one corner of the room, a stove is lit with powdered sulfur (2 kg of powdered sulfur for 1 tonne of fresh apricots), and the room door is closed tightly. The fruits are left in the room for 6-8 hours to absorb the sulfur gas.

In the traditional sulphurization process, apricot producers unconsciously use high doses of sulfur to prevent spoilage and guarantee their product's quality, resulting in high levels of residual sulfur. However, countries that import dried apricots have set limits on the amount of residual sulfur that can be found in dried apricots. For the amount of residual sulfur in dried apricots, Germany and England have set a limit of 2000 ppm (ppm =mg/kg), France and Denmark 1000 ppm, Italy 600 ppm, Austria 300 ppm, USA, Canada, New Zealand, and Australia do not apply a definite limit but allow the importation of dried apricots containing up to 3000 ppm of sulfur. In Turkey, the maximum sulfur level in dried apricots has been set at 2000 ppm. A different technique has been developed as an alternative to traditional methods of sulphurization. This method involves the application of sulfur dioxide gas and immersion in sodium metabisulfite solution. This technique uses an 8% solution of sodium metabisulfite. Fresh apricots are immersed in this solution for 30 minutes. The sulfur content of the apricots is about 1500 ppm, which is necessary to preserve the natural color of the apricots.. In practical applications, the immersion technique for sulphurization has proven to be more effective, practical, and cost-effective compared to traditional methods.

After sulfurization, the fruit is removed from the sulfurization room and laid out in a sunny place to dry. 36-40 °C is the optimum temperature. Sulfurizing apricots and drying them under direct sunlight effectively prevent insect infestations during the drying process. Apricots should be dried on nets with tiny holes that allow soil contact and good air ventilation around 2 days after sulfurization. Soil contact prevents the over moisturisation while the apricots are drying. This is important to preserve high quality taste. If the apricots are drying on a tarp and sweating, the taste is more likely to turn really sour and unpleasant for consumers.

Once they reach a certain consistency after being exposed to sunlight, their seeds/pits should be removed. This process also requires great delicacy because if the apricots have dried too much, they become hard in texture, making it difficult to take the pit out. Trying to take the kernel out is a good indicator. If it comes out quickly, it means that they are ready for this process. On the other hand, if they are too soft, the pulp tends to stick to the seed and come out with it, making the process difficult and decreasing the sellable weight of the dried fruit. This task alone requires serious attention and experience. After removing the pit, apricots are left to dry for 2-3 days longer (total process takes around 5-6 days), and when they are sufficiently dry, they are stored in a cool and dry place.

Consumption and Storage Conditions of Dried Apricots

Dried apricots must be washed before consumption to soften the texture and clean the fruit (e.g., from soil and dust). After drying for a certain period, they become hard and are not very suitable/pleasant for direct consumption. Therefore, they should be washed and softened before consumption. Especially, if the fruits are kept under the sun too long, they become very dry and hard in texture and difficult to eat. The washing process should be done one or two days before the time of consumption. If the washed and stored fruits are kept too long, they lose their natural color and become darker, and if the sun-dried apricots are not stored in cold storage after washing, they become vulnerable to worms. Unwashed fruit will last longer than washed fruit under normal weather conditions without deterioration, and worming is late. After washing them, they should be consumed in a short period. Dried apricots should generally be stored in a cool and dry place. However, if this is not possible, you can store them dry in the refrigerator at 4°C (remember to wash them).

Packaging

Packaging is a crucial aspect of apricot processing, as it protects the fruit and prevents the evaporation of sulfur. The quality and shape of the packaging are important factors in dried apricot exports. The most common packaging method is inner packaging combined with a 12.5 kg cardboard box. However, there is a global trend towards smaller packaging sizes. Some countries import dried apricots in larger packages and repackage them into smaller ones, earning higher profits.

The Reason for the Price Range in Dried Apricots

There is a price range between sulfur-dried apricots supplied to the Turkish and Malatya markets. The reason for this difference is mainly the quality of the product. The price may be higher in distant cities as transportation costs are added.

Unlike other products in the market, if there is a significant downward difference in the price of a product, it is due to a defect in one or more of the fruits' three important quality factors (color, smell, taste). In short, the cheaper products may have a deficient taste or smell and a darker color.

Another reason for price variation is the difference in product size—the number of pieces per kilogram. A common misconception is that large apricots taste better than small apricots.

References

Çatı, K., & Yıldız, S. (2007). TÜRKİYE’DE KURU KAYISI ÜRETİM VE PAZARLAMA PROBLEMLERİ VE ÇÖZÜM ÖNERİLERİ. Atatürk Üniversitesi İktisadi ve İdari Bilimler Dergisi, 21(1), 337-360.
Kešelj, K., Babić, M., Pavkov, I., Radojčin, M., Stamenković, Z., Tekić, D., & Ivanišević, M. (2019). Effects of storage and sulfurization with sulfur dioxide of different concentration on changes in the color of dried apricots. Journal on Processing and Energy in Agriculture, 23(4), 190-194.