Conclusions
Processing blueberries into various forms resulted in significant
losses of monomeric anthocyanins (28% to 59%) and antioxidant
capacity (53% to 71%), which most likely was due to enzymatic
polymerization and/or degradation of anthocyanins prior to
pasteurization or polymerization reactions with anthocyanins and
other phenolic compounds. Monomeric anthocyanins were extensively
degraded during storage in all thermally processed products
(canned, juices, and purees), with less than 40% of the original
total anthocyanins present in the processed products after
6 mo. In canned products, significant amounts of monomeric anthocyanins
(14% to 25%) leached out of the berries into the liquid
canning medium. Losses of monomeric anthocyanins during storage
were accompanied by increased polymeric color values, indicating
that monomeric anthocyaninswere extensively polymerized
during storage. Despite marked losses of monomeric anthocyanins
in all thermally processed products, ORACFL values changed little
during storage, suggesting that polymeric compounds formed
during storage compensated for the loss of antioxidant capacity
due to degradation of monomeric anthocyanins. More studies are
needed to identify the anthocyanin polymers and to determine
their bioavailability in vivo.