Sensory and physicochemical changes in gluten-free oat biscuits stored under different packaging and light conditions.

The influence of different packaging films and their thickness (polyethylene terephthalate/casting polypropylene (PET/CPP_34), biaxially oriented polypropylene (BOPP_40), polyvinylchloride (PVC_12), BOPP/CPP_50 and polyethylene/ethylene vinyl alcohol/polypropylene (PE/EVOH/PP_50) on the quality of gluten-free oat biscuits was evaluated for a storage period up to 3 months under light and darkness conditions. Periodically (day 30, 60 and 90), physical parameters, peroxide value, texture and microbiological parameters together with sensory attributes (surface colour, smell, taste, crunchiness and off-flavour) were assessed. Moisture and water activity of biscuits decreased during storage in all packages. The highest peroxide value was obtained for biscuits packed in PVC_12, while the lowest was for the PE/EVOH/PP_50, for both storage conditions. The biscuits' colour changed from yellow-brown to light yellow and the change was more pronounced in the light as compared to the dark storage conditions. The hardness value decreased (p > 0.05) during the storage period. The electronic nose system showed that the distinct volatile composition of the biscuits stored in the light was correlated with the higher scores of the off-flavour attribute and with the peroxide values. The sensory data showed that BOPP/CPP_50 preserved the colour of the biscuits, while PE/EVOH/PP_50 kept the initial crunchiness of the biscuits up to 90 days of storage in both light and dark conditions. The study suggested that BOPP/CPP_50 and PE/EVOH/PP_50 can be used for gluten-free oat biscuits' packaging and storage up to 90 days for both conditions studied, without adversely affecting their physicochemical and sensory properties.