The present study investigated the effect of active and modified packaging as well as packaging material
oxygen permeability on quality retention of dark chocolate with hazelnuts. Dark chocolate was packaged in:
a) polyethylene terephthalate//low density polyethylene (PET//LDPE), and b) polyethylene terephthalate
coated with SiOx//low density polyethylene (PET-SiOx//LDPE). Samples were packaged either under, vacuum
or N2 or with an oxygen absorber and stored in the dark at 20 °C for a period of 12 months. “Commercial”
control samples for comparison purposes consisted of chocolate packaged in aluminum foil in air while
“model” control samples used for sensory evaluation consisted of chocolate packaged in glass jars and stored
at −18 °C. Quality parameters monitored were: peroxide value, hexanal content, color, fatty acid
composition and volatile compounds. Of the sensory attributes color, texture, odor and taste were evaluated.
PV ranged between 0.80 for fresh dark chocolate with hazelnuts and 6.51 meq O2/kg chocolate fat for
commercially packaged samples after 12 months of storage. Respective values for hexanal were 0.53 and
7.56 mg/kg. % Saturated fatty acids (SFA) increased with a parallel decrease in monounsaturated fatty acids
(MFA) and polyunsaturated fatty acids (PUFA) after 12 months of storage mainly in least protected samples
(commercial package). Likewise, after 12 months of storage an increase in concentration of aldehydes,
ketones, alcohols and alkanes (pb0.05) with a parallel decrease in pyrazines where observed especially in
case of least protected products after 6 and 12 months of storage. In general after 12 months of storage
chocolate showed whitening of the surface resulting to an increase in L* and a* values (pb0.05) and a
decrease in b* value. Dark chocolate with hazelnuts retained acceptable quality for ca. 8 months in
commercial packages. For samples packaged in PET//LDPE irrespective of storage atmosphere the shelf life
was 8 to 9 months and for samples packaged in PET-SiOx//LDPE irrespective of storage atmosphere the shelf
life was 11 months. Finally for samples packaged with an oxygen absorber irrespective of packaging material
the shelf life was at least 12 months.
Industrial relevance: Chocolate packaged with an oxygen absorber in a barrier packaging material will
maintain its aroma, taste and nutritional quality substantially longer than other packaging methods.