Blueberry production and consumption continue to increase worldwide, despite unfavorable weather conditions in some countries and rising production costs worldwide. There is strong demand, in particular, for blueberries.

Given the high demand for this fruit, there is a clear need, from an economic point of view, to optimize its harvest and storage. In fact, the blueberry presents some difficulties in the management of the supply chain, which all too often results in poor quality. Among them is the difficulty of harvesting at the appropriate degree of maturity, which must take place when the berry it is completely rotated, while the insertion area of ​​the peduncle may still have a pink color.

"The tendency to harvest the fruit ahead of time causes batches of products with a non-uniform color, with possible deterioration during the storage period, due to the decrease in bioactive components, such as anthocyanins and polyphenols," explains the professor. Giovanna Giacalone, from the Department of Agricultural, Forestry and Food Sciences (Disafa) at the University of Turin. «The presence of molds and yeasts, naturally present on the surface of the fruit, is then another cause of deterioration of blueberries during storage.

In view of the above, and in order to solve the problems mentioned, Disafa, in collaboration with Pro.Lux and Move2Web, Piedmontese companies specialized in the field of UV-C led lamps, is studying a new post-harvest treatment. Specifically, the researchers are evaluating the possibility of using UV-B and UV-C radiation to irradiate blueberries before cold storage and stimulate the production of polyphenolic components.

As a result of a collaboration with Disafa, it was agreed that Pro.Lux and Move2Web would be willing to build a prototype “UV Test Box” (in the image on the right, provided by Giovanna Giacalone) intended to test the effects of UV-B and UV-C radiation in blueberries.

«The objective pursued is to bring to the market a visually uniform product with superior organoleptic qualities, which is achieved by improving the nutraceutical characteristics of the fruit. At the same time, the UV treatment will reduce the microbial load, promoting a better shelf life,” explains Giacalone. «Thanks to the UV Test Box provided by Pro.Lux, experimentation has begun to outline an operating method applicable to small fruit packaging lines.

As Professor Giacalone explains to FreshPlaza, «the box is experimental and the objective is not to treat a large amount of product at a time, but to verify if the treatment works and, if so, transfer the methodology to the blueberry processing lines. In each test we treat about 500 g of product, which is placed directly on the rack with which the box is equipped.

«Irradiation is only from above, so the blueberries have to be arranged in a single layer, which is what also happens on the processing lines. The trial is currently testing different irradiation powers and treatment durations. "It is also being evaluated which part of the processed product should be subsequently conditioned at room temperature, so that the polyphenol synthesis processes are stimulated."

«Promising results have been obtained, in terms of increasing the content of polyphenols and total anthocyanins, with treatments of between 10 and 25 minutes and with adaptation times of about 24 hours, but we are also evaluating shorter times. We use an irradiation power of about 1800 µW/cm² and doses of between 600 and 3200 mJ/cm² depending on the duration of the treatment," concludes Giacalone.