3.3. Effects of juice processing on monomeric anthocyanins and
polymeric color
Throughout juice processing, the changes in total monomeric
anthocyanins (TMA) and polymeric color (PC) were evaluated.
While the milling step did not change the TMA level found in the
black mulberry fruit (p > 0.05), significant increases were observed
following the mashing (137.7% increase), pressing (28.7% increase),
and pasteurization (9.0% increase) steps in comparison to the
amounts present in the previous steps. As a result, juice processing
resulted in an overall significant increase (213.8% increase) in the
original TMA concentration giving a final TMA concentration of 681 mg C3GE/100 g DW in the final juice sample (p < 0.05)
(Table 1).
The increases/decreases observed in TMA levels following the
different steps of juice processing coincided with corresponding
decreases/increases in percent PC. The percent PC decreased by
22.6% – from 33.6% in fresh fruit to 26.0% in final pasteurized juice
– during juice processing. This could be the result of the removal of
the polymeric anthocyanins with the press cake waste (58.5% polymeric
color) (Table 1).