# Hake Fish Preservation Using Plant-Based Impregnated Polylactic Acid Food Films as Active Packaging
## 1 Introduction  
Over the past decades, global fish consumption has steadily increased, driven by economic growth and improved living standards [1]. Reflecting this trend, the 2024 edition of _The State of World Fisheries and Aquaculture_ reported that the global fisheries and aquaculture production reached 223.2 million tons in 2022, a 4.4% increase from 2020. This included 185.4 million tons of aquatic animals, with a global per capita consumption of 20.7 kg, two times higher over the last 60 years [2]. This rise underscores the growing demand for fish as a vital source of high-quality proteins and essential nutrients including omega-3 fatty acids, minerals, and vitamins [3]. However, preserving fishery products presents a significant challenge due to rapid microbial, enzymatic, and chemical reactions during storage, which degrade the quality, flavor, texture, and nutritional value [4]. These challenges underscore the need for innovative approaches, such as active packaging, to mitigate spoilage and enhance shelf life. As aconsequence, advanced preservation techniques have been developed [5], among which active packaging (AP) has emerged as a promising solution. According to the European Union Guidance to Commission Regulation No. 450/2009, AP provides an extra function, in addition to a protective barrier against external altering factors. This type of packaging can absorb food-derived chemicals from the food or its environment (absorbers), or it can release substances into the food or the environment surrounding the food such as preservatives, antioxidants, and flavorings (emitters) [6]. In this sense, AP may not only extend the shelf life of perishable foods more efficiently than traditional packaging, but can also align with modern food safety standards by integrating active components that can absorb or release substances to enhance food preservation [7; 8]. In recent years, there has been growing interest in incorporating natural antioxidants, such as polyphenols, tocopherols, essential oils, and plant extracts, to replace synthetic ones like butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA), which have raised health concerns [9]. The addition of polyphosphates is another controversial point in food safety [10]. Among these natural sources, plant extracts have gained attention for their bioactive properties and their potential to valorize agro-industrial by-products [11]. Among the agri-food residues, those derived from the production of olive oil from _Olea europaea_ L. tree are of particular interest. The Mediterranean region produces about 60% of the world's olive output, generating large amounts of by-products like olive pomace and olive leaves [12]. It is well-known that olive leaves are rich in phenolic compounds including simple phenols, flavonoids, and secoiridoids [13]. These bioactive compounds can be extracted using conventional extraction techniques such as Soxhlet and heat-reflux extraction or by using alternative techniques such as microwave, ultrasound, and high-pressure assisted extraction [14]. Olive leaf extracts have shown potential in active packaging applications such as loaded polyethylene terephthalate/polpropylene films (PET/PP) for vegetables (e.g., cherry tomatoes and sunflower seed preservation) [15; 16], and in meat (e.g., the development of biodegradable carrageenan films for lamb meat preservation) [17]. Parallel to these developments, the food packaging industry is increasingly adopting biodegradable polymers to minimize the environmental impact. Polymers in food packaging have distinct advantages such as their adequation to food properties and composition to increase their preservation, which makes the commercialization of packaged food the strategy most often used by supermarkets to provide a wide variety of fresh and frozen products. Nowadays, the major focus on polymer-based packaging is to minimize the environmental impact by utilizing biodegradable polymers as sustainable alternatives to conventional materials derived from fossil fuels [18].