# Edible Films Based on Ovine Second Cheese Whey with Oregon Essential Oil
###### Abstract  
The aim of this study was to produce edible films using ovine second cheese whey (SCW) powder, alone or combined with whey protein isolate (WPI). SCW is a by-product obtained in the manufacture of ovine whey cheeses. In this instance, it was dehydrated after increasing the protein concentration by ultrafiltration/daifiltration. Furthermore, the effects of the addition of oregano (_Origanum compactum_) essential oil (EO) in two proportions to the films produced with a mixture of SCW powder and WPI were studied. The water vapor permeability, solubility, color, opacity, antioxidant activity, and the mechanical properties of the films were determined. In addition, we determined the films' structure, by FTIR; thermal stability, by TGA; and microstructure and crystallinity, by XRD. SCW combined with WPI can be used to prepare edible films, but their properties were found to be affected depending on the proportion of each product. The substitution of WPI by SCW caused decreases in water solubility (from 81.44 to 66.49% D.M. ), modified the color and decreased tensile strength (from 1.57 to 0.17 MPa), and decreased the elongation at break (from 52.17 to 3.57%), the puncture strength (from 2.40 to 0.20 MPa) and the deformation (from 18.92 to 0.93%) of the films. EO addition to the SCW-WPI films increased the antioxidant activity of the films (from 0.97 to 2.19 mg DPPH/g). It also modified other characteristics of the films such as the water solubility and the tensile strength. Both SCW and EO incorporations influenced the secondary structure of proteins and the thermal stability, microstructure and crystallinity of the films. ed 2  
compounds. However, conventional packaging materials are associated with challenges related to recycling, inability to degrade after disposal, detrimental environmental and wildlife impacts, and utilization of finite fossil fuel reserves. Additionally, the presence of microplastics and the potential migration of harmful additives from plastic packaging into food pose significant health risks and concerns [2]. Regulation 2025/40 of the European Union restricts the utilization of certain single-use plastics and minimizes the weight and volume of packaging, the waste produced and the inclusion of some additives in the materials [3]. The food sector is one of the biggest contributors to global greenhouse gas emissions (approximately 26%) and, consequently, food waste contributes to the negative impact of climate change, since much of the food produced is not consumed. Therefore, to minimize these negative impacts, new packaging must be able to guarantee food quality and safety, as well as increase the shelf life of food and be edible or easily recyclable [1]. These reasons explain why we continue to develop sustainable and fully biodegradable packaging materials, including edible films and coatings, providing a long shelf life for food and thus promoting the safe integration of packaging [1]. Thus, packaging materials obtained from biopolymers such as proteins, polysaccharides and lipids are a good alternative to petroleum-derived materials (synthetic materials) since they are obtained from renewable sources or biodegradable industrial by-products and do not adversely affect the environment [2,4]. Protein-based films are a sustainable and efficient alternative for food packaging [5]. These films are produced from proteins extracted from various sources, such as cheese whey, wheat and corn [6, 7, 8]. They have advantages in terms of biodegradability, are edible, and have good barrier properties that help preserve food against moisture, oxygen and light [2]. Why protein-based edible films have become an interesting innovation in the food industry as a food packaging material, due to their sustainability and nutritional characteristics. The whey is a by-product of cheese production, and the protein is concentrated mainly by membrane processes that obtain whey protein concentrate (WPC) and whey protein isolate (WPI).