# Development of Modified Gas Composition for Atmosphere Packaging of Sliced Apple Chips
## 1 Introduction  
One of the most popular and widely processed fruits is apples. A leading European country in global apple production and export is Poland. In 2023 alone, almost 3.9 million tons of apples were harvested [1]. The average monthly fruit consumption in Polish households increased from 3.46 kg/per capita in 2010 to 3.71 kg/per capita in 2023 [2]. Apples are a source of dietary fiber (2-2.4 g/100 g), vitamin C (3-23 mg/100 g), and microelements such as calcium (6 mg/100 g), potassium (107 mg/100 g), and zinc (0.04 mg/100 g [3, 4, 5]. Apples are especially rich in polyphenols (66.2-211.9 mg/100 g) [6, 7]. Moreover, these compounds exhibit antioxidant properties. Levels of particular elements differ between apple varieties and depend on cultivation conditions [8, 9, 10]. Considering the sensory and nutritional values of apples, these fruits are good materials for further processing. The shelf-life of seasonal fruits and vegetables should be prolonged using appropriate processing techniques that preserve their natural values [11, 12]. Moreover, growing consumer consciousness and nutritional knowledge drive them to search for high-quality products rich in beneficial substances. As a result, convenient and functional food is more desirable [13]. Technologies aimed at minimizing food processing while preserving its sensory, nutritional, and textural properties--ensuring both efficiency and safety--are being used. Emerging green methods are expected to be cost-effective, energy-efficient, and adaptable to different types of food and processing methods. However, many current green technologies do not fully meet these expectations, prompting the food industry to seek alternatives free from synthetic chemicals [14]. Convection drying is a basic and commonly used food shelf-life prolongation process aiming to reduce water activity. It extends the shelf-life of the product and maintains its nutritional value. However, high temperatures can damage thermolabile bioactive compounds, cause discoloration, influence the texture, appearance, etc. [15]. Most food products are heat sensitive and drying procedures should be carefully conducted. Research has shown that drying at lower temperatures contributes to lower losses of nutritional compounds [16]. Fruits are one of the most commonly dried products. An example of a dehydrated food is dried sliced apple chips, which have become a popular snack recently [17]. This form of apples is very convenient and ready to eat, as the fruit has already been washed and/or peeled before further processing. Likewise, dried apple chips are lighter than fresh fruits and can be easily transported without bruising. Due to the water evaporation during drying, the change of matrix from apples to apple chips makes the compounds share higher because of its concentration [18]. Considering product quality, one of the most important attributes is color and shrinkage [16]. These parameters are connected with food quality evaluation and decide consumer satisfaction. The product's appearance gives information about its freshness, taste, aroma, moisture content, and nutritional value [19; 20]. Apples and their processed forms, such as dried or apple chips, are particularly vulnerable to quality deterioration due to oxidation and microbial activity. The slicing process damages the cellular structure, leading to accelerated enzymatic browning and changes in texture and flavor [21; 22]. The enzymatic browning causes color changes due to the oxidase reaction of phenolic compounds with atmospheric oxygen which diffuses into fruit tissue. To prevent this negative impact, anti-browning agents such as citric acid are used [23]. During drying, either enzymatic and non-enzymatic color changes occur. These could enhance the negative effect and affect the acceptability of dried and semi-dried products [24]. Another fundamental quality determinant is texture. The drying process intensively influences the fruit's microstructure so there is a risk of receiving products of undesirable texture.