Preservation of Fruits and Vegetables through Drying
Learn the best practices and find recipes for drying fruits and vegetables. Dried foods are tasty, nutritious, lightweight, and easy to store and use. Dried fruits make high-energy snacks. The fact that dried foods are lightweight and compact makes them desirable for hiking and camping trips.
Some fruits and vegetables suitable for drying include apples, pears, peaches, plums, apricots, bananas, cantaloupe, strawberries, blueberries, carrots, celery, corn, green beans, potatoes, and tomatoes. Fruits can also be dried as fruit leathers and rolls. Meat can be dried like jerky. Herbs are one of the easiest foods to dry.
How Foods Are Dried?
Increasing the temperature of food makes its moisture evaporate, and air moving over the food carries the moisture away. A balance of temperature and humidity is needed to successfully dry foods.
Methods:
Food dehydrators, whether bought or made at home, are effective in producing high-quality dried foods. If using an oven, it's important to set the temperature between 140 to 150°F (60 to 65°C) for optimal results. To allow moisture to escape, leave the oven door slightly open, around 2 to 3 inches. A convection oven from SS Engineers is ideal as it combines gentle heat with a fan to circulate the air evenly. Room drying can work if the room temperature, humidity, and air movement are suitable, but air-conditioned homes may be too cool for efficient drying. Sun drying is effective in dry climates, but in Pennsylvania's high humidity, it is not a practical method for food drying.
Procedures:
Once you've prepared the trays with your sliced fruits or vegetables, place them inside a dehydrator that has been preheated. It's recommended to start with a temperature of 145°F (63°C) if there is still surface moisture on the produce. After one hour, lower the temperature to a range of 135 to 140°F (57 to 60°C) to continue the drying process. It's important to avoid drying the food at too high of a temperature, as this can cause the outer surface to harden, trapping moisture inside the slice. This is known as case hardening and can prevent proper drying. Keep in mind that food will shrink as it dries, so for smaller fruits and vegetables, use a fine mesh or tray to prevent them from falling through.
Pre-treating Fruits
For certain fruits like apples, pears, peaches, and apricots, it can be beneficial to pre-treat them before drying. Pre-treatment helps to preserve the color, reduce vitamin loss, and extend the shelf life of the dried fruits. Research has shown that using an acidic solution as a pre-treatment can also enhance the elimination of potentially harmful bacteria during the drying process. To pre-treat the fruits, you can soak them in a solution made by mixing 3¾ teaspoons of powdered ascorbic acid (or crushing 20 500-milligram vitamin C tablets) or ½ teaspoon of powdered citric acid in 2 cups of water. Leave the fruits in this solution for 10 minutes before transferring them to the drying trays. Alternatively, you can use a mixture of equal parts bottled lemon juice and water as a substitute for the pre-treatment solution mentioned earlier.
There are alternative methods for pre-treating fruit before drying, including syrup blanching, water blanching, and sulfating. In syrup blanching, the prepared fruit is simmered in a syrup made of 1 cup sugar, 1 cup white corn syrup, and 2 cups water for 10 minutes. After simmering, the fruit is left to soak in the hot syrup for 30 minutes before being drained, rinsed, and placed on the drying trays. Syrup-blanched fruit tends to be sweeter but also stickier compared to fruit treated with other methods.
Certain fruits & Vegetables like blueberries and cranberries, require a brief dip in boiling water to crack their skins. However, it's important not to keep them in the boiling water for too long, as it can make the fruit too soft. After cracking the skins, cool the fruit quickly and gently pat them dry. It's worth noting that homemade dried cranberries and blueberries will have a different taste compared to the sweeter commercially dried ones.
Conditioning and Storing Fruits:
When fruits & vegetables are fully dried, they should be flexible and not have any moisture when you press them between your fingers. To ensure the dried fruit stays fresh, place it loosely in an airtight container made of glass or plastic. Leave it in the container for a few days to allow any remaining moisture to spread evenly. If you notice any condensation forming inside the container, it means the fruit needs more drying time to remove excess moisture.
If you have fruits that are not peeled or covered, it's important to take steps to eliminate any insect eggs that may be present. One method is to heat the dried fruit in the oven at 160°F for 30 minutes. Alternatively, you can place the fruit in the freezer at a temperature of 0°F or below for 48 hours. Storing dried fruit in the freezer or refrigerator will help extend its shelf life and keep it fresh for a longer period of time.
Blanching Fruits & Vegetables
SS Engineers offers a cutting machine that is designed to cut leafy vegetables such as spinach, leek, celery, cabbage, and water convolvulus, as well as other vegetables like cucumber, eggplant, melons, and even fish meat. The machine comes with various blades that can be easily changed to cut vegetables into different shapes. It is suitable for use in kitchens, restaurants, schools, vegetable retailers, and food processing factories.
Testing Dryness and Storage
When vegetables are fully dried, they become tough, brittle, or crunchy, and there is no need to condition them further. To keep them fresh and prevent moisture absorption, store the dried vegetables in containers that can seal tightly. It is best to store them in a dark place as exposure to light can cause a loss of vitamins in the vegetables. By following these storage practices, you can maintain the quality and nutritional value of your dried vegetables for a longer period of time.
Leathers
Leathers are a type of dried food made from pureed fruits or vegetables, and they get their name from their texture when dried. You can make leathers using fresh, frozen, or drained canned fruit or vegetable purees. If the puree is thin, like berry puree, you can add applesauce to make it thicker. To prevent darkening, add 2 teaspoons of lemon juice or 1/8 teaspoon of ascorbic acid for every 2 cups of light-colored fruit. Usually, you don't need to add sweeteners because the natural sweetness intensifies during drying. However, if desired, you can add ¼ to ½ cup of corn syrup or honey for every 2 cups of fruit. Sugar can be used, but it may crystallize over time. Keep in mind that sweetened leathers may be slightly sticky.
Pour prepared puree about ¼ inch thick onto plastic dehydrator trays or line a cookie sheet with plastic wrap (be careful to smooth out wrinkles; tape edges to prevent sliding). Do not use waxed paper or regular aluminium foil as the leather will stick. Nonstick foil works well.
SS ENGINEERS and Consultants is an active engineering company in India, having a wide range of operational sectors, The Industrial cleaning and material handling systems are among the primary focus with increasing frequency to brainstorm on complex cleaning issues in the automotive industry. We have conceived, delivered solutions that have made great contributions in the material handling of the industry.
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