The bloom is a layer of natural wax that naturally coats the fruit produced by blueberry plants. Its function is to protect the blueberries against disease and external factors.
Furthermore, bloom is essential for extending the shelf life of blueberries once harvested; therefore, it is best not to wash them before storing them in the fridge, but rather just before eating them, if necessary.
Bloom acts as a barrier against moisture and certain external pathogens that can damage the berries. Consequently, this natural wax coating is vital for producing high-quality blueberries and serves as an indicator of their freshness, as overripe blueberries typically begin to lose this coating and turn black.
Prepared and written by Adrián García Villar, Agricultural Engineer from the Polytechnic University of Madrid (UPM). Membership No. 215, Official Association of Agricultural Engineers of the Principality of Asturias (COIASTUR)
References:
Juan Carlos García, Guillermo García González de Lena, Marta Ciordia Ara, (2018).