The Best Ways to Winnow Blueberries

History

• The "separating the wheat from the chaff" principle was behind the first winnowing system. In an effort to increase blueberry harvest productivity, winnowing machines were developed in the 1940s. A series of wheels and pulleys operated a blower inside the machine, and a set of shakers separated the fruit from any debris. The basic procedure has remained the same in the blueberry growing regions of Maine and Canada, where a significant portion of Maine wild blueberries are still picked by hand to reduce the incidence of damage to the fruit. Hand-harvesting causes stems and leaves to remain on the berries.

Time is of the Essence

• The biggest issue in blueberry harvesting is time. Harvest should be delayed until 90 percent or more of the fruit is ripe. Winnowing the blueberries as soon as possible after raking--which is the process of picking the berries from their bushes--ensures that the berries are at their driest state. Dry berries stick less to conveyor belts. According to the Wild Blueberries website, "Ninety-nine percent of the wild blueberry crop is frozen, using the individually quick freezing method (IQF), which allows for the fast preservation of taste, nutrition and antioxidant power."

Cam System Winnowing Machines

• The North American blueberry harvest consists of raking and winnowing. The harvest traditionally begins in late July through early August. The blueberries are either winnowed in the field, or sent to a processing facility. The cam winnowing system employs an offset cam vibration mechanism to bounce the blueberries down a slight incline. Cam system winnowers were developed around the 1970s in response to a need for a winnower that could be moved by one person, so it may be the better system for an individual.

Go Back to a Throwback

• A largely wooden, Emil Rivers machine gets power from a small gas engine. The raked blueberries are poured onto a moving horizontal belt, which drops them through an air current produced by wooden paddles onto another moving belt inclined at 45 degrees. The air current blows everything that is not too dense--grass and blueberry leaves--up and out of the winnower. The whole berries then roll down the descending belt into a box at the bottom of a chute. Whatever does not roll--crushed berries, insects, small stones, twigs, other debris too heavy to blow away--is carried up the inclined belt and dumped on the ground. For organic artisan growers, this may be the gentlest winnowing method.