Blueberries are perennial flowering plants with blue or purple berries. They are classified in the section Cyanococcus within the genus Vaccinium. Vaccinium also includes cranberries, bilberries, huckleberries and Madeira blueberries.Commercial blueberries—both wild (lowbush) and cultivated (highbush)—are all native to North America. The highbush varieties were introduced into Europe during the 1930s.
Blueberries are usually prostrate shrubs that can vary in size from 10 centimeters (3.9 in) to 4 meters (13 ft) in height. In commercial production of blueberries, the species with small, pea-size berries growing on low-level bushes are known as “lowbush blueberries” (synonymous with “wild”), while the species with larger berries growing on taller cultivated bushes are known as “highbush blueberries”. Canada is the leading producer of lowbush blueberries, while the United States produces some 40% of the world supply of highbush blueberries.
Proven Health Benefits of Blueberries
Many studies have suggested that increasing consumption of plant foods such as blueberries decreases the risk of obesity, diabetes, heart disease, and overall mortality. Plant foods may also promote hair and skin health, increased energy, and overall lower weight.
Freezing blueberries is often discussed by experts. It is often said that the freezing process can diminish the potency of the blueberry’s health benefits. One study showed that over the course of 6 months in storage, the anthocyanin degraded by 59 percent.
However, this is not confirmed, and different sources take different stances on whether freezing blueberries reduces their impact on health. When in doubt, buy fresh, organic blueberries.
Although more research is needed, blueberries are strongly linked to various different elements of healthful living.
1) Maintaining healthy bones
Blueberries contain iron, phosphorous, calcium, magnesium, manganese, zinc, and vitamin K. Each of these is a component of bone. Adequate intake of these minerals and vitamins contributes to building and maintaining bone structure and strength.
Iron and zinc fulfil crucial roles in maintaining the strength and elasticity of bones and joints.
Low intakes of vitamin K have been linked to a higher risk of bone fracture. However, adequate vitamin K intake improves calcium absorption and may reduce calcium loss.
2) Skin health
Collagen is the support system of the skin. It relies on vitamin C as an essential nutrient, and works to help prevent skin damage caused by the sun, pollution, and smoke. Vitamin C may also improve collagen’s ability to smooth wrinkles and enhance overall skin texture.
One cup of blueberries provides 24 percent of the recommended daily allowance of vitamin C.
3) Lowering blood pressure
Maintaining low sodium levels is essential to keeping blood pressure at a healthful level. Blueberries are free of sodium.
They contain potassium, calcium, and magnesium. Some studies have shown that diets low in these minerals are associated with higher blood pressure. Adequate dietary intake of these minerals is thought to help reduce blood pressure.
However, other studies have counteracted these findings. For example, a 2015 study of people with metabolic syndrome found that daily blueberry consumption for 6 weeks did not affect blood pressure levels.
4) Managing diabetes
Studies have found that people with type 1 diabetes who consume high-fiber diets have low blood glucose levels, and people with type 2 diabetes who consume the same may have improved blood sugar, lipid, and insulin levels. One cup of blueberries contributes 3.6 grams (g) of fiber.
A large 2013 cohort study published in the BMJ suggested that certain fruits may reduce the risk of type 2 diabetes in adults.
Over the course of the study, 6.5 percent of the participants developed diabetes. However, the researchers found that consuming three servings per week of blueberries, grapes, raisins, apples or pears reduced the risk of type 2 diabetes by 7 percent.
5) Protecting against heart disease
The fiber, potassium, folate, vitamin C, vitamin B6, and phytonutrient content in blueberries supports heart health. The absence of cholesterol from blueberries is also beneficial to the heart. Fiber content helps to reduce the total amount of cholesterol in the blood and decrease the risk of heart disease.
Vitamin B6 and folate prevent the buildup of a compound known as homocysteine. Excessive buildup of homocysteine in the body can damage blood vessels and lead to heart problems.
According to a study from the Harvard School of Public Health and the University of East Anglia, in the United Kingdom (U.K.) regular consumption of anthocyanins can reduce the risk of heart attack by 32 percent in young and middle-aged women.
The study found that women who consumed at least three servings of blueberries or strawberries per week showed the best results.
6) Preventing cancer
Vitamin C, vitamin A, and the various phytonutrients in blueberries function as powerful antioxidants that may help protect cells against damage from disease-linked free radicals.
Research suggests that antioxidants may inhibit tumor growth, decrease inflammation in the body, and help ward off or slow down esophageal, lung, mouth, pharynx, endometrial, pancreatic, prostate, and colon cancers.
Blueberries also contain folate, which plays a role in DNA synthesis and repair. This can prevent the formation of cancer cells due to mutations in the DNA.
7) Improving mental health
Population-based studies have shown that consumption of blueberries is connected to slower cognitive decline in older women.
Studies have also found that in addition to reducing the risk of cognitive damage, blueberries can also improve a person’s short-term memory and motor coordination.
8) Healthy digestion, weight loss, and feeling full
Blueberries help to prevent constipation and maintain regularity for a healthful digestive tract because of their fiber content.
Dietary fiber is also commonly recognized as an important factor in weight loss and weight management by functioning as a “bulking agent” in the digestive system. High fiber foods increase satiety, or the feeling of being full, and reduce appetite.
How to freeze drying blueberries?
We will also present some other methods in freeze-drying if you don’t have a machine for it.
1. Using your freezer
This can be a substitute to the freeze-drying machine if you don’t mind the long process. This long process is estimated to be several weeks at maximum.
To start with it. First, you will need a perforated tray. In choosing the food that you want to freeze-dry, better start with small stuff like fruits. Chop the fruit into small pieces and arrange it neatly on the perforated tray.
Small pieces are preferred because the moisture can easily be removed that way. Choose the freshest ones because when they’re rehydrated, they will still be fresh in the next years.
For the next several hours, the fruit will undergo freezing. However, the long process here will be the sublimation that will take several weeks as stated.
The water will sublimate from solid form into a gas form. Your sliced pieces of fruit will then be thoroughly dried after waiting a long time.
The way to test if your freeze-dried fruit is ready is to thaw it first. If the drying process is not complete, your fruit will turn black after melting. Return it right away to your freezer and wait for a few days.
Test it again by thawing and if doesn’t turn into a black color, that would entail that the freeze-drying process is complete. Your freeze-dried fruit is then ready to be stored in an airtight bag for storing.
2. Dry Ice
Dry ice (or cardice) is carbon dioxide in the solid phase. Freeze-drying food in this method is relatively faster than putting it directly into your freezer. The way to use dry ice is to prepare a large container, twice the size of the food you’re going to freeze-dry.
The food (in this context, fruit) that you should freeze-dry should never be in contact with dry ice, so you need to place it in a sealed plastic bag.
After you placed the food in the plastic bag then into the large container (the bottom base should already have one layer of dry ice), you can now cover the whole container with dry ice. Word of caution for this method is to always wear gloves.
Dry ice should never be melted prematurely, and that’s why you will need to store it in a freezer. Dry ice can make the moisture evaporate from the food because the environment is already at zero humidity.
As the dry ice will sublime and gas will escape, you should punch holes on your large container.
Regularly check your container every 24 hours. You will know the freeze-dried fruit is ready when all the dry ice had sublimed. After that, the freeze-dried fruit is ready for storing.
3. Vacuum Chamber
This process could take one week or more depending on the water content of your fruit.
To start with this, the prepared fruit that you want to freeze-dry should be frozen isolated.
You don’t want ice crystals to form, so don’t open the freezer door until several hours had passed.
Then, removing the fruit from the freezer, place it immediately inside the vacuum chamber.
The recommended temperature and pressure of the chamber should be at least 10⁰C and 120 Torr, respectively. Sublimation process will then occur and may drag on for one week. Test if the freeze-drying is complete and then it’s ready for storage.
4. Freeze-Drying Machine
This is the most expensive method but the duration in preparing the freeze-dried food takes lesser time than all of the methods mentioned above.
A typical freeze-drying machine consists of a freezing coil attached to a compressor, shelves attached to heating units, and a vacuum pump.
To use this machine, place the fruit inside the heated shelves and through the compressor, the temperature is lowered to a freezing temperature. The frozen fruit will then begin sublimation.
This is by the vacuum pump that lowers the atmospheric pressure inside by pumping it outside. The pressure becomes very low that the ice immediately shifts into a vapor form.
The food is undergoing a long process of sublimation that could take a few days at maximum.
