Dried fruit is a good choice when you need a healthy snack or even as a sweet addition to a recipe.While many fruits may be considered lower in vitamin K, does the process of drying different fruits affect their vitamin K content? For example, raw spinach alone is already quite high in vitamin K but once cooked, the vitamin K content grows even higher. This is in part due to the serving size. Fresh spinach has a lower number of leaves by volume than cooked spinach.
The Process of Drying Fruit
Many different fruits can successfully be dried, but some of the more common fruits include apples, apricots, bananas, cherries, citrus peel, coconuts, currants, dates, figs, grapes, nectarines, papayas, peaches, pears, pineapple, plums and rhubarb.1 When dried successfully, the snack produced should be safe and flavorful. Should you decide to dry fruit in your own home, it is important to follow proper preparations for drying.
Choose fruit that is high quality without decay, bruises or mold. Drying fruit does not improve the quality of the fruit.1 Once the fruit is thoroughly washed and cleaned, cut the fruit into slices ranging in size from about 1/8 inch to 1/2 inch. A good rule to follow is the higher the water content in the fruit, the larger the slice should be.1 Once sliced, the fruit will need to be pretreated before drying.
Pretreating the fruit is an important step for both the quality of your snack as well as for the safety of the fruit. Pretreating is usually done by soaking the sliced fruit in an acidic solution, preserving both the color and texture as well as destroying potentially harmful bacteria.1 There are three different types of pretreatment solutions that are normally used: ascorbic acid pretreatment, citric acid pretreatment and lemon juice pretreatment.1 Both citric acid and lemon juice have had no reported interactions with warfarin and are low in vitamin K.2 It is a good idea to check with your physician before relying on this ingredient if you take warfarin or another blood thinner. Interactions with ascorbic acid are rare, but have been reported.3
Drying your own fruit is not an exact science and the amount of drying time each piece takes can depend on what you are using as well as the moisture content of the fruit and the humidity in the air. Drying can either be done in an oven or with a food dehydrator.1When drying is complete, make sure to condition the fruit to minimize the chances of mold growth and spoiling.1 This can be done by placing the dried fruit loosely in glass or plastic containers, to see if moisture condenses in the jar. If it does, further drying may be necessary.
Dried Fruit and Vitamin K
Many of the fruits that are already low in vitamin K are still considered low when they are dried. For example, 1 fresh apricot contains around 1.2 micrograms of vitamin K while 10 dried apricots contain around 1.1 micrograms. Also, 1 fresh apple contains around 3.0 micrograms of vitamin K while 5 dried apple rings contain around 1.0 micrograms. Fruits that are already high in vitamin K content appear to still be high when dried. One cup of fresh blueberries contains about 28 micrograms of vitamin K while a similar number of dried blueberries, approximately 1/4 cup, still contain around 23.8 micrograms of vitamin K. Whether you want to dry the fruits yourself or if you would rather buy them from the grocery store, it is still a good idea to be aware of the different foods you eat that may affect your INR level. If you do want to dry your own fruit, it is a good idea to consult your physician if you are unsure about the type of pretreatment you should use while on warfarin.
- 1. Garden-Robinson, J. Ph.D., R.D., L.R.D. Drying Fruits. NDSU Extension Service. September 2012. Retrieved from the website: https://www.ag.ndsu.edu/pubs/yf/foods/fn1587.pdf.
- 2. Drugs.com. Drug Interactions Between Citric Acid/Potassium Citrate and Coumadin. 2016. Retrieved from the website: http://www.drugs.com/drug-interactions/citric-acid-potassium-citrate-with-coumadin-681-0-2311-1529.html.
- 3. Ehrlich, S.T., N.M.D. Possible Interactions with: Vitamin C (Ascorbic Acid). University of Maryland Medical Center. September 27, 2007. Retrieved from the website: http://umm.edu/health/medical/altmed/supplement-interaction/possible-interactions-with-vitamin-c-ascorbic-acid.