Nutrient loss in dried foods
Raw, fresh food at the moment it is harvested contains the highest content of nutrients and begins to decline post-harvest as it is exposed to light and air during handling. Additional nutrient loss occurs when the food undergoes preparation (peeling, slicing, chopping), and declines further once exposed to heat for preservation and storage. Thus, maximum retention occurs when food is dried right after it is picked. A few important points –
- The moment fresh food is cut open and exposed to the elements, nutrient loss occurs. For instance, beta-carotene (a precursor to vitamin A) and vitamin C (Ascorbic acid) both diminish when food is dried.
- The nutrient loss for commercially-dried foods varies between 30 – 80% for vitamin C and 10 – 50% for vitamin A. The amount of loss is dependent on many factors, including storage time, drying temperature, and dry time. The variation is much greater for fresh food purchased from the store and preserved at home.
- Pre-treatments before the drying process can help retain some vitamins, but destroy others. Chemical pre-treatments, such as sulfur dioxide, helps protect vitamins A and C but destroys vitamin B1 (thiamine), a nutrient needed for converting carbohydrates into energy. Note: organic food does not allow the use of sulfur.
- A natural method of pre-treatment includes hot water blanching, which helps preserve carotene and thiamine, but causes loss of vitamin C. Dipping foods in citrus juice or citric acid can counteract some of the vitamin C loss.
The amount of nutrient loss also depends on the drying technology; however, regardless of the type of technology employed for drying food – solar, controlled air dehydration, or freeze-drying – each method involves heat and air, which will deplete the nutritive value of the food.
- Sun drying causes the most nutrient loss while indoor dehydration using low heat causes the least amount of loss.
- No method of drying can prevent nutrient loss in food. This is why it is important to supplement with a multi-vitamin (especially one that contains vitamin C) if you plan to rely on dried food products for an extended period of time.
Why is vitamin C so important?
Did you know? The citric acid naturally found in citrus fruits bonds to metals present in the body, a process called chelation. This helps to detoxify poisonous metal agents, such as mercury, arsenic, cadmium, and lead that are often present in water or food sources by converting them to a chemically inert form. The metals can then be excreted without impairing the body.
How to supplement with Vitamin C on the Trail
- Add a powdered form of vitamin C or citric acid, such as Emergen-C, to your daily water. The original formula of Emergen-C is vegan; a few of the specialty products contain animal-derived ingredients.
- Look for dried foods that contain a rich source of vitamin C ingredients. Lemon and other citrus fruits are a commonly recognized source but are not the highest source. Chili peppers, red bell pepper, and parsley are some of the highest food sources of vitamin C. Also look for dried food seasoned with spices such as garlic and various peppers (paprika, chili powder, and cayenne). Outdoor Herbivore incorporates many of these herbs, including powdered organic lemon zest, to replace the lost vitamin C content from drying. 1 tsp of dried organic lemon peel contains 70 % of DV for vitamin C!
- If you forage for food, look for foods high in vitamin C, such as wild garlic, dandelion greens and rose hips. Also, sprouting (especially alfalfa and red clover) are a good source of vitamins & minerals, including vitamin C.
Further exploring the importance of Vitamin A & Vitamin C
Beta-carotene (precursor to Vitamin A) is the red-orange pigment found in many plants and is a member of the carotenoid family of plant nutrients. It is believed that carotenoids interact with other nutrients – such as phytochemicals – to prevent disease and promote health. In particular, beta-carotene is a provitamin A carotenoid: it converts into vitamin A by the liver. Vitamin A plays a role in a variety of functions throughout the body, such as: vision to prevent night blindness and other eye problems; immune function to protect against colds, flu and infections of the kidney, bladder, and lungs; embryonic development and reproduction; the formation of bones and teeth; to help prevent acne, reduce wrinkles & lighten skin if applied topically; metabolize protein.
- Plant sources of vitamin A include sweet potato, carrot, and spinach.
Vitamin C, or ascorbic acid, is a water-soluble vitamin needed by the body for at least 300 metabolic functions, including tissue repair and growth, healthy gums, adrenal gland function, and immune system function. Vitamin C acts as an antioxidant in the body, protecting cells from damaging effects of free radicals. Free radicals are molecules that contain an unshared electron and appear to promote heart disease and cancer. We are exposed to free radicals in the environment from air pollution, cigarette smoke, and UV radiation from the sun. In addition, vitamin C is needed to make collagen, a protein required to help wounds heal. It also improves the absorption of iron from plant-based foods.