Less acceptable in terms of sensory qualities
than their fresh-cut counterparts, total polyphenol content and
antioxidant activity values in vacuum impregnated products were lower
than in fresh-cut samples. This
procedure may cause an increase in the content of polyphenolic
compounds in apple tissue, mainly anthocyanins, thus
modifying fruit color as well as vitamin C content, since black currant is agood source
of this compound. The authors investigated the effect of extract concentration,
the level of pressure and the duration of its application on both mass transfer
and nutritive value of apple cubes by applying the response surface method. In
the process of vacuum impregnation they used high fructose corn syrup with
extract content of 50° Brix and a
black currant concentrate mixed in the following proportions [%]: 90/10, 85/15,
80/20 and pressure within the range of 40–80 kPa in time
ranging from 15 to 45 min. Higher pressure and longer duration resulted in a
greater uptake of extract compounds, but not a high black currant content. A
higher antioxidant activity was obtained using medium and high concentrations
of black currant concentrate, while the highest content of vitamin C was
recorded at a medium content of black currant in the impregnating solution.
Optimal parameters of vacuum impregnation were specified based on the analyses,
promoting the introduction of such amounts of black currant concentrate, which
significantly enhanced the nutritive value of produced apple cubes. Roβle et al.
(2011) applied vacuum impregnation of fresh-cut apple wedges in order to enrich
them with honey, additionally applying an addition of browning inhibitors and
subjecting the enriched fruit to osmotic dehydration
.
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