A study published in the journal, Innovative Food Science & Emerging Technologies, investigated the effect of active and modified atmosphere packaging (MAP) as well as packaging material oxygen permeability on quality retention of dark chocolate with hazelnuts.
According to the authors, nuts with chocolate coatings show higher oxidation than those stored uncoated under the same storage conditions, with a referenced study suggesting that the chocolate coating blocks the passage of air and moisture to the nuts' tissue, resulting in a decrease in relative humidity and therefore increased oxidation rates.
The researchers said that their study was motivated by the fact that there were no previous findings published on the use of active and MAP for the preservation of chocolate, and they evaluated the use of an oxygen absorber as well as MAP and a vacuum packaging material barrier to oxygen on shelf life extension of dark chocolate with whole hazelnuts.
According to the researchers, dark chocolate was packaged in a polyethylene terephthalate//low density polyethylene (PET//LDPE), as well as a polyethylene terephthalate coated with SiOx//low density polyethylene (PET-SiOx//LDPE).
They said that 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 aluminium foil in air while ‘model’ control samples used for sensory evaluation consisted of chocolate packaged in glass jars and stored at −18 °C, added the authors.
After 12 months in the case of the least protected samples (commercially packaged in air) the authors found an increase in the total saturated fatty acids (SFA) at 53.68 per cent, and a parallel decrease in the monounsaturated fatty acids (MUFA) (42.44 per cent) and polyunsaturated fatty acids (PUFA) (3.88 per cent).
While in the case of the most protected samples (PET-SiOx//LDPE with the oxygen absorber) they found the SFA, MUFA and PUFA were 43.49, 50.68 and 5.83 per cent, respectively.
The researchers noted an increase in concentration of aldehydes, ketones, alcohols and alkanes with a parallel decrease in pyrazines where observed especially in case of least protected products after 6 and 12 months of storage.
According to the team, after 12 months of storage, the least odour changes were in products packaged with the oxygen absorber irrespective of packaging material permeability with the lowest scores being recorded for dark chocolate commercially packaged at 20°C.
The authors reported that in samples with the oxygen absorber significant changes in taste were observed after four months of storage at 20°C while in all other samples significant changes were observed starting from the second month of storage. But they found colour changes were the least in samples packaged under vacuum.
And the researchers concluded that in samples packaged with an oxygen absorber, irrespective of packaging material, the shelf life was at least 12 months.
Source: Innovative Food Science & Emerging Technologies Volume 11, Issue 1, January 2010
Title: Effect of active and modified atmosphere packaging on quality retention of dark chocolate with hazelnuts
Authors: S.F. Mexis, AV Badeka, K.A. Riganakos and M.G. Kontominas