# Active Biodegradable Packaging Films Based on the
## 1 Introduction  
The by-products generated in the production of olive oil (OO) represent a great challenge for the food industry; though they contain significant amounts of compounds with important biological activities, at the same time, they are polluting materials for the environment if its revaluation is not considered [1]. From the by-products generated annually in oil mills around the world, an enormous amount of phenolic compounds (PCs), such as oleupropein, hydroxytyrosol, and tyrosol, which have antioxidant, anti-inflammatory, antibacterial, and antiviral functions, are wasted, which may be beneficial for human consumption but whose consequences for the environment are devastating due to high concentrations of PCs that can decolorize rivers and inhibit water oxygenation and plant seed germination [2, 3]. For these reasons, alternative OO extraction processes are necessary to eliminate water use, minimize environmental impact, increase the total amount of PC in the oil,and preserve the food quality of the pomace for other applications in the food industry. One way to achieve this is by the sequential extraction of olive oil (OO) from dehydrated olives, combining expeller press extraction in which obtained oil is of similar quality to that obtained by conventional methods [4; 5], and supercritical CO2 is used to remove oil from the press cake, yielding a completely defatted pomace or flour [6]. The oil extracted from the press cake has proven to have quality indexes within those established by legislation and a much higher PC content than conventional extra virgin olive oil (EVOO) [7]. The result of these processes is a dry pomace with a high PC content, whose food quality remains intact because it has not been in contact with organic solvents. Therefore, the possible application of this flour is its incorporation in food to increase its nutritional value or by combining it with biodegradable packaging to produce bioactive packaging. Recent studies have shown that films made from agricultural waste extracts, such as peanut skin, pink pepper, coffee, wine, or OO industries, plays an important part in active packaging technology, resulting in novel methods for extending shelf life and maintaining or monitoring the quality of foods [8; 9]. Food packaging has undergone significant changes in recent years due to a number of reasons, not only to preserve the environment, but also to save energy, reduce manufacturing costs, extend the shelf life of foods, and protect their sensory and nutritional quality, as well as the health of consumers [10]. However, concerns have been raised about the potential adverse health effects of certain plastics used in packaging since the ingestion of harmful chemicals leached from them can disrupt endocrine function, while their accumulation in adipose tissue poses long-term health risks to humans [11]. Potentially, a biodegradable packaging can be made from polylactic acid (PLA), polyhydroxyalkonates (PHAs), polyesters, and starch blends [12]. Recently, interest in cellulose-derived materials has increased. Carboxymethyl cellulose (CMC), a water-soluble anionic polysaccharide, has emerged as a potential material for developing active packaging due to its film-forming properties, such as mechanical strength, barrier properties, transparency, and thermal stability [13; 14]. The addition of by-products or aqueous plant extracts to CMC films can reduce gas permeability and also protect against light [15], which initiates lipid oxidation in various foods, especially those containing large amounts of polyunsaturated fatty acids (PUFAs). In the present work, the elaboration of bioactive and environmentally friendly packaging biofilms based on carboxymethylcellulose by adding as functional ingredients the by-products obtained from the production of olive oil, such as the defatted flour and its aqueous extract, was carried out.