## 1 Introduction  
Recently, there has been a growing interest in the use of biodegradable and natural components for the production of food film. Primarily, it is used to create packaging that plays an additional role in the context of environmental protection [1]. These films can also be used as coatings applied to the surface of food products, which provide a barrier against the passage of gases and water. In addition, they create an internal atmosphere, which contributes to the product preservation [2]. Current packaging, apart from its primary function of protecting food from various types of contamination, acts as active packaging, too. They work via the release of active substances into the food, so they can improve its shelf life as well as its health quality [3]. Biopolymers include natural products made of plants, living organisms, or microorganisms [4]. The main advantages of biopolymers are their renewability, toxicity, biodegradability, and bioadhesion [4; 5]. These include cationic polysaccharides such as chitosan, proteins (collagen), anionic polysaccharide (alginate), or plants such as tapioca, cotton, or corn [5]. Functional foods are increasingly popular among consumers, due to their health-enhancing effects and their protection against environmental stressors [6; 7]. Raspberry fruit is characterized by a high content of compounds classified as functional food constituents, which include high levels of polyphenols, total dietary fiber, and vitamins (C, B\({}_{1}\), B\({}_{2}\), B\({}_{9}\), E, PP) and minerals (Fe, Cu, Ca, Mg, Mn, Cu, P, and K) [6]. Research has shown that the choice of food products is of key importance for consumers. Consumers more often accepted functional foods enriched with ingredients already present in and associated with these products [7; 8]. Moreover, the way the ingredients were introduced into the food was an important parameter in consumers' choice of specific products. Less processed and naturally enriched products were more likely preferable by shoppers [8]. The price of the food product was also an important aspect for consumers. Buyers more aware of the health benefits of functional products were ready to pay more for the product than those without this knowledge; however, the price should still not be too high [8]. According to [PERSON] et al. [9] and Menrad [10], the acceptable price for functional products should not exceed 40% (in China) and 30-50% in Europe. Therefore, the choice of the biopolymers used for the production of biocomposite films seems to be a good option, as these raw materials are inexpensive and broadly available [11]. Lack of knowledge and modern solutions referring to the use of biopolymers in food can cause some concern and uncertainty among consumers [8]. According to the U.S. Food and Drug Administration (FDA), the materials used to create films are considered as GRAS (generally recognised as safe), both chitosan and plant extracts [12; 13]. In addition, the European Union (EU) in accordance with Annex II and Annex III to Regulation (EC) No. 1333/2008 has established that sodium alginate is a safe substance and can be used as a food additive [14]. The addition of sodium alginate is due to the fact that chitosan is rarely used alone for film formation as it has poor mechanical strength, so additives in the form of other polysaccharides are used [11]. Poland has been a major raspberry producer for many years. In 2022, our country was the second largest producer of raspberries among EU countries, with 104,900 tons [15]. Raspberry fruits are characterized by high antioxidant, anti-inflammatory, and cytotoxic activity [16]. It had been shown that they have an effect on lowering blood glucose levels and reducing cholesterol and low-density lipoprotein levels. Interestingly, these properties were also exhibited by frozen raspberries [17]. In Poland, there are conventionally and organically grown as well as wild raspberries. These crops differ in the use of fertilizers and pesticides--they are not allowed in organic farming [18].