Health benefits of blueberries affected by processing

Blueberries’ high polyphenol content has earned them ‘superfood’ status. While they are healthy enough when raw, recent research shows that cooking or baking the fruit changes their health benefits.

Some methods of processing, such as juicing and canning, have been shown to lower polyphenol levels by 22 to 81%. However, no studies have tested whether the polyphenol content of blueberries in breads, muffins or pies is affected.

A research team led by Ana Rodriguez-Mateos sought to test the stability of these health-promoting compounds during cooking, proofing (when the dough rises before cooking) and baking. The results of their research are outlined in a paper published in the American Chemical Society’s (ACS’s) Journal of Agricultural and Food Chemistry.

The researchers found that all three processes had mixed effects on blueberries’ polyphenols including anthocyanin, procyanidin, quercetin and phenolic acids. Anthocyanin levels dropped by 10 to 21%. The levels of smaller procyanidin oligomers got a boost while those of the larger ones dipped. Phenolic acid levels increased. Other compounds such as quercetin remained constant.

According to the researchers, the good retention of polyphenols observed in the study might be due to the use of yeast, which may act as a stabilising agent during baking.

“Due to their possible health benefits, a better understanding of the impact of processing is important to maximise the retention of these phytochemicals in berry-containing products,” the researchers said.

The research was funded by the Alpro Foundation.