Abstract
Antioxidant films based on poly(ε-caprolactone) (PCL) containing almond skin extract (ASE) were developed for food packaging applications. The effect of ASE incorporation on the morphological, structural, colour, mechanical, thermal, barrier and antioxidant properties of the prepared films were evaluated. The structural, tensile and thermal properties of the films were not altered due to ASE addition. Although no significant differences were observed for the oxygen permeability of samples, some increase in water absorption and water vapour permeability was observed for active films due to the hydrophilic character of ASE phenolic compounds, suggesting the suitability of this novel packaging for fatty foods conservation. ASE conferred antioxidant properties to PCL films as determined by the DPPH radical scavenging activity. The efficiency of the developed films was evaluated by the real packaging application of fried almonds at different ASE contents (0, 3, 6 wt.%) up to 56 days at 40 °C. The evolution of peroxide and p-anisidine values, hexanal content, fatty acid profile and characteristic spectroscopy bands showed that active films improved fried almonds stability. The results suggested the potential of PCL/ASE films as sustainable and antioxidant food packaging systems to offer protection against lipid oxidation in foods.
Highlights
Lipid oxidation is considered to be the main factor limiting the shelf-life and quality of almonds due to their high content in polyunsaturated fatty acids, mainly linoleic acid [1]
It was considered that almond skin extract (ASE) compounds considered that ASE compounds added at the studied concentrations by melting at 80 °C followed added at the studied concentrations by melting at 80 ◦ C followed by a compression-moulding at 120 ◦ C, by a compression-moulding at 120 °C, as previously described, were dispersed in the polymer matrix as previously described, were dispersed in the polymer matrix uniformly without any significant uniformly without any significant particles aggregation resulting in homogeneous films with particles aggregation resulting in homogeneous films with uniform thickness and good appearance
Antioxidant films based on PCL and natural antioxidants extracted from almond skin by-products were successfully developed
Summary
Lipid oxidation is considered to be the main factor limiting the shelf-life and quality of almonds due to their high content in polyunsaturated fatty acids, mainly linoleic acid [1]. The initial linoleic acid content in almonds subjected to frying processes has been reported to be higher than in raw ones, due to oil frying medium migration to the sample, causing a more severe food degradation [3]. To overcome this problem, special attention has been paid in recent years to the use of agri-food by-products as new sources of natural antioxidant agents [4]. This new strategy is aligned with the circular economy action plan to reduce food waste implemented by the European Union since around 1/3 of the total food produced worldwide is estimated to be lost or wasted [5]
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