20 



POSTHARVEST HANDLING OF BLUEBERRIES 



Wesley R. Autio 



Department of Plant and Soil Sciences 



University of Massachusetts 



Blueberries ( Vaccinium corymbosum ) are very perishable once harvested and 

 must be handled carefully to maintain quality and reduce postharvest losses. 

 The primary quality factors, as outlined by the U.S. grade standards, are 

 maturity, color, size, and freedom from defect and decay (7). In a 3-year 

 study of blueberries at retail stores Cappellini et al. (3) determined the 

 reasons for postharvest berry losses (Table 1). Of the 15.2% of berries lost, 



Table 1. Sources of blueberry losses in retail outlets. From Cappellini et 

 al. (3). 



Percentage 

 Defect lost 



Decay 10.7 



Overripe or dehydrated 3.3 



Mechanical or insect injury 0.2 



Immaturity 1 .0 



TOTAL 15.2 



over two-thirds were lost to decay, so efforts to improve postharvest handling 

 of blueberries must reduce the incidence of decay to be successful. In this 

 discussion I will present general changes which occur during blueberry 

 ripening, factors which affect decay, and means for reducing decay and 

 increasing postharvest life and fruit quality. 



Ripening 



Blueberries are a climacteric fruit, meaning that they exhibit a rapid 

 rise and fall in respiration during the course of ripening. Throughout this 

 period many other changes occur, including a reduction in acidity, an increase 

 in sugar content, and a dramatic increase in anthocyanin content (the source of 

 the blue coloration). Table 2 depicts the timing of the major changes that 

 occur during ripening. 



It is interesting to note that blueberries do not attain their full flavor 

 when they first become blue, but actually require an additional 1 to 2 days to 

 develop full flavor (8). This is reflected in Table 2 by a sharp decline in 

 acids (and rise in pH) and rise in sugars after the fruit become blue, both 

 changes improving flavor. The sugar/acid ratio reflects both of these changes, 

 and is what we perceive when we taste the fruit. 



