Perspectives Newsletter Winter 2020
Vol. 42, no.4 / Posted on March 19, 2020

It all started in 2007 when I moved to Nova Scotia to take my first faculty job in Nova Scotia Agricultural College. It did not take too long to realize that Nova Scotia is the center of wild blueberry empire with this small fruit, bringing almost $150M in province budget. Wild blueberry is considered as a queen of berries with multiple health benefits (https://www.nswildblueberries.com). However, Nova Scotians did not enjoy wild blueberries, since most of harvested wild blueberries exported in other provinces or overseas frozen. The opportunity was clear, but the challenge was the lack of technology for wild blueberries 0processing into food product.

blueberry 1in December 2008 we started to test novel hydrodynamic cavitation technology for blueberry whole fruit processing into nutritional food products. The small-scale machine we ordered just arrived from Ukraine. The first samples we tested with our kids and friends were successful, kids loved it (see picture). Finally, blueberry farmer from Prince Edward Island decided to build large-scale processing facility for the delicious berry.

The larger-scale equipment came in 2011. The assembling and tuning of the new technology required efforts of international engineering team and took 6 months. Finally, by the end of the year we started small runs with hot filling of product in the glass bottles. That was the time when we met face-to-face with our biggest enemy -mold. 3-8 bottles from the batch of 1000 ended up with mold growth, but this was enough to reject sales. The product clearly was not marketable from food safety prospective. Extensive sanitation of facility and equipment, recommended by food safety specialists, did not help. Mold seemed to like to grow in blueberry puree.

After extensive research of literature, we realized that Japanese food scientists had similar problems with our wild blueberries. Kikoku, Tagashira and Nakano (2008). [Heat resistance of fungi isolated from frozen blueberries. Journal of Food Protection, 71(10), 2030–2035] identified rare heat-resistant mold, which extremely stable to thermal treatment, surviving even at 110oC. Due to the current technology of blueberry growing, when weeds burned with propane flame, this mold is abundant in the blueberry field soil.

Fortunately for us, a group of microbiologists in AAFC Research Center in Nova Scotia worked with heat-resistant mold for years. Dr. Lihua Fan and associates agreed to support industry research with their methodology as a part of a large cluster project “Effect of Novel Cavitation Technology on Quality and Safety of Food”.

The one-year study ended up with unexpected results. Hydrodynamic cavitation added up to thermal sterilization effect, so our product was completely sterile at temperatures significantly lower than it was established by Japanese researchers. Finally, this study was published in 2018 in the Journal of Food Science (Fan et al., 2018).

On the other hand, microbiological analysis showed that our contaminated bottles did not contain heat-resistant mold. It immediately led us to the conclusion that contamination occurs after product filling. Together with talented Ukrainian engineer Sergey Tarasenko we have developed operational procedure for after-filling handling of bottles, which stopped mold contamination and opened the market for retail and wholesale of innovative food product.

blueberry 2This team effort of engineers and microbiologists was instrumental to understand and eliminate food safety problem. Now you can find the product in Sobeys food distribution chain under the trademark name “Pure-E”. Finally, Nova Scotians could enjoy rich flavor of blueberries, grown in their own home.

Dr. Alex Martynenko, P. Eng.
Associate Professor,
Department of Engineering
Faculty of Agriculture
Dalhousie University