Forced Air Cooling for Moisture Control on Fresh Wild Blueberries

Commodities

• Fruits: berries (blueberries)

Practices

• Crop Production: food product quality/safety, postharvest treatment
• Education and Training: extension, farmer to farmer, on-farm/ranch research, technical assistance

Wild Blueberries harvested during their very short harvest window often are damp due to dew, fog or rain which typically has been fine for harvest destined for the freezer. With historic low prices paid by processors, more growers are entering the fresh market and are finding these conditions are the limiting factor for growth. This project will provide a unique and cost effective method to allow market growth and improved quality.

The objective is to design an economic forced air cooling system that will draw cooled and dehumidified air through new ventilated harvest boxes overnight and thus condition them for packing the following day. Forced-air cooling systems are a well known method of cooling produce but we aim to see if we can also dry our produce using this method. Measurements before and after treatment will be recorded to verify success.

There are around 500 wild blueberry growers in Maine. The small and medium size farms are increasing the volume of berries sold to diversified markets, especially fresh pack. Many receive two different newsletters and an annual report of activity in the wild blueberry growing community. About 400 people attend the annual conference and summer field day, all of which will be utilized to share progress and results of this project. At Brodis Blueberries, we host several educational events each year at our farm for wild blueberry growers and this project will be a focus of each one.

The primary objective is to reduce moisture levels on the exterior of the wild blueberry to improve fruit quality and reduce food safety hazards.

Measurement of success will include measuring a variety of variables:

•     Weight of berries going into the system and their weight coming out. This would be collected throughout the season with particular focus on extreme conditions to see how this project could lead growers to expand their best harvest windows into conditions with more berry dampness.
•     Shelf life of berries that have gone through the tunnel (dry) will be compared to that of berries that have not gone through the tunnel.  This study will help guide growers in assessing whether utilizing it would open up markets requiring longer time between harvest and consumer consumption which is a major hurdle for wild blueberry growers.
•     Finally and also as a berry quality consideration, we would take before and after pulp/bulk temperature readings to see how much evaporative cooling we may achieve. This would impact both shelf life but also possibly reduce energy consumption to cool the berries along the cold chain from farm to consumer.