Development of agricultural waste-based antioxidant films and their application on olive oil protection
摘要
The aim of this study was to investigate the effects of agricultural waste extracts (AWEs) incorporation on the physicochemical characteristics of corn zein-based active films and the activity of the films against extra virgin olive oil oxidation. The effect of the incorporation of olive and artichoke leaves, pomegranate peel, black and purple grape pulp extracts (at concentrations of 4, 6, and 10% v/v) on the mechanical and optical properties of zein-based active films was studied. Parameters such as peroxide, free acidity, and color were determined to evaluate the oxidation status of extra virgin olive oil samples stored for 60 days at room conditions at 25 ◦C, open to the atmosphere. The moisture contents of the all zein-AWEs films except for zein-purple grape pulp extract films decreased significantly compared with the zein control film. Similar to zein control film, all studied films incorporated with different AWEs had low light transmittance. The addition of AWEs caused a reduction in tensile strength. At the end of the storage period of 60 days, the free fatty acidities (FFA) and peroxide values (PV) of the extra virgin olive oils did not reach the maximum limit allowed by the current legislation. Moreover, the films had an inhibitory effect on the oxidation of olive oil. The addition of the AWEs into the zein films significantly reduced the FFA and PV of olive oil samples. At the end of storage, the sample containing 10% artichoke leaf extract had the lowest FFA value (0.501% oleic acid) and the sample containing 10% black grape pomace extract had the lowest PV (1.749 meqO2/kg). Therefore, this study demonstrated the effectiveness of AWEs incorporated zein films as a packaging material to minimize the oxidation of extra virgin olive oil.