Blueberry Council of Missouri Newsletter

Health Benefits, Picking and Storage

Editor: Howard Thompson
June 2009

Since June is Blueberry Month in Missouri, it is only appropriate to talk about the plant and the fruit itself. The blueberry and its cousins; cranberries, huckleberry, lingonberry, bilberry all belong to the genus Vaccinium. They all like acidic soil with a high amount of organic matter. Blueberries are shrubs, native to North America, that are 2 to 8 feet high. There are four basic species grown in North America, based on the climate. The low bush is found mainly in Canada. The Northern and Southern Highbush are grown in their respective areas of North America. The last species is called rabbiteye which is native to the south. Southern Missouri/Northern Arkansas (USDA Zone 6b) is the most northern range of the two species native to the south.

Although we associate blue and purple with blueberries, the fresh fruit is actually green under the blue skin. We get the classical purple color only after cooking, when the cells break down and there is a mixture of skin and fruit pigments and chemicals.

The blueberry have been touted as a “super fruit”, not just because its nutritional content as noted below, but for other properties that do not make the required USDA listing. Starting with one of the more basic, is how the body responds when eating blueberries. Like any other fruit, blueberries naturally contain sugars which are carbohydrates. As you have seen on the TV ads by Nutri-System, there are good and bad carbs. The difference between a good and bad carb is based on that carb’s ability to raise your blood sugar(glucose) a little or a lot. This ability is measured by the Glycemic Index. Hard candy has GI of 95-100, white bread 81 and celery 0. Low GI foods have an index of less than 55. Fresh blueberries have a GI of 40 to 50 depending on the source quoted. The foods with the lower GI raise your insulin levels less since your blood glucose rise is lower. The lower your insulin response, the lower the blood fat levels. Over time, a diet with a lower glycemic index results in less body fat and less hardening of the arteries; arteriosclerosis. Recent studies done at the University of Michigan showed that old, fat, rats feed a diet that contained 2% blueberry powder for 90 days had less abdominal fat, lower cholesterol, and had improved glucose control and insulin sensitivity. This suggests that blueberries may alter fat metabolism.

The chemicals that give blueberries their characteristic color and taste also make them the “King of the Superfruits”. According to a study by Tufts university, blueberries have the highest amounts of antioxidants of the 60 fruits and vegetables measured. These antioxidants and phytochemicals( anthocyanins, Chlorogenitc acid, ellagic acid, catechins, reseratrol and pterostilbene) help destroy the free-radicals which have been associated with aging, decrease cognitive abilities and cancers. The antioxidant anthocyanin, which gives the blueberry is distinctive color, is present in a higher concentration than that found in red wine as reported in the J Agri Food Chem. This gives blueberries a cardioprotective effect. Anthocyanins, along with the tannins also in the blueberry, affect E. coli in the bladder just like its cousin, the cranberry. This gives the blueberry a protective effect against bladder infections. Because of the blueberry’s effect on vision, it is called the “vision fruit” in Japan. Bottom line, blueberries need to be part of your daily fruit and vegetable intake. From a grower’s point of view, let’s have blueberries with every meal.

As a grower of blueberries and several other fruits, the blueberry is one of the easiest fruits to care for and to pick. In Missouri, there are very few insects that attack blueberries. This allows them, for the most part, to be grown without insecticides. The biggest pest for blueberries, other than birds and Bambi, are fungi and molds. With the expectation of the gray fruit mold, Botrytis, these fungi are treated when there is NO fruit on the plant. Even if your grower finds a need to treat for Botrytis, it is usually done around bloom and before the berry starts to turn color. This gives Mother Nature more than enough time to wash the fruit. If you have any questions about your grower’s practices, just talk to them.

Blueberries start to turn color from the tip of the fruit that looks like a small flower, the blossom end. The color spreads toward the stem. Since most blueberries are in a fruit cluster, the color around the stem is often hard to see. If you have to break into the tight cluster to pick the fruit, then it is likely NOT ready. As the cluster matures, it loosens making the individual fruit easier to pick. The best tasting berry just rolls into your hand. The berry has to be in the full blue stage for 2-3 days to have the best flavor. These few extra days at the full blue stage allow the sugars in the berry to mature resulting in the sweetest berry. If you make a mistake and get a pink butt, just put in your bucket and keep going. The best pie comes for many berries of different ages and culitvars. If you are new to picking, you may need to sample as you pick to help refine your decision making. Practice makes a perfect pie, so pick often but an individual plant needs to be picked only twice a week.

Blueberries have a natural waxy coating that protects the fruit and helps retains moisture inside the fruit. This coating can be easily rinsed off. Once the coating is gone there is an increase risk of spoilage. This means, don’t wash them until you are ready to use them. To retain flavor and moisture, you want to cool them as soon as possible. They can be stored in a refrigerator for at least week if allowed to breath and there is not damaged fruit in the container.

Since blueberry picking season is shorter than the demand for blueberries, one needs to talk about longer term storage. If you are a very picky picker and you are comfortable that nothing has been sprayed on the berries, all you have to do is seal in a plastic bag and throw them into the freezer. If you are not a particularly picky picker, when you get home, dump out berries into a shallow pan and sort out the leaves, bugs and under-ripe berries before placing into a freezer bag. Which ever the type of picker you are, when you take them out of the freezer, a light thump should easily give you loose berries.

If you feel a need to rinse the berries before freezing, the berries either need to be dried before freezing or placed on a cookie sheet to freeze as a single layer of berries. After freezing, the berries can be transferred to a freezer container. Another option for washed berries is freeze them in a pie pan. Line a pie pan with aluminum foil or use a zip-top bag. Mix the berries with the ingredients for a pie filling, place in the foil or zipper bag, seal and freeze in the pan. Once frozen, the pan can be removed and the pie-shaped frozen berries stored for later use. When you want a pie for Thanksgiving or Christmas, just make a crust, add the berry filling and bake. Blueberries are NOT just for June and July.

Contact the grower nearest to you for the start of their season and for picking times. Happy picking!

Blueberry (fresh)Blueberry (frozen, unsweetened)
1 c (148 g) 1 c (155 g)
Energy kcal 84 79
Protein g 1.10 0.65
Fat g 0.49 0.99
Carbohydrate g 21.45 18.86
Fiber g 3.6 4.2
Calcium mg 9 12
Iron Mg 0.41 0.28
Magnesium Mg 9 8
Phosphorus Mg 18 17
Potassium Mg 114 84
Sodium Mg 1 2
Zinc Mg 0.24 0.11
Copper Mg 0.084 0.051
Manganese Mg 0.497 0.228
Selenium Mcg 0.1 0.2
Vitamin C Mg 14.4 3.9
Thiamin Mg 0.055 0.05
Riboflavin Mg 0.061 0.057
Niacin Mg 0.619 0.806
Pantothenic acid Mg 0.184 0.194
Vitamin B6 Mg 0.077 0.091
Folate Mcg 9 11
Vitamin B12 Mcg 0 0
Vitamin A IU 80 71
Vitamin E Mg 0.84 0.74
Vitamin K Mcg 28.6 25.4
g=grams mg=milligrams kcal=kilocalories IU=International Units ug=micrograms
ATE=alpha tocopherol equivalent

Composition by Percent:
Water 84.21%
Protein 0.74%
Ash 0.24%
Lipids 0.33%
Carbohydrates 14.49%
US Higbush Council