## 1 Introduction  
Intolerance to gliadin, which is the main component of wheat gluten, can lead to serious health problems, such as celiac disease and other forms of gluten intolerance [1]. In order to prevent such problems, it is advisable to consume gluten-free food products such as rice. Rice (_Oryza sativa_ L.) is one of the important crops that plays a role in providing food for the majority of the world's population. Rice is one of the main dietary staples of South Asians and the main food crop preferred by most people around the world [2]. It is one of the main forms of nutrition of people in many countries and it is the world's most important basic cereal [3]. Rice contains carbohydrates, fats, proteins (low concentrations) and B complex vitamins, including niacin, thiamine and riboflavin [4]. Black chokeberry (_Aronia melanocarpa_) is rich in polyphenols, vitamins, minerals and fiber. Polyphenols in chokeberry include anthocyanins, flavonoids and proximaidines [5]. These compounds are responsible for the dark purple color of the grains and their antioxidant properties. Aronia berries have a very high antioxidant activity when compared to most fruits and vegetables. They also secrete free radicals, reduce oxidative stress and prevent cell damage [6]. Besides polyphenols, fruits are a good source of vitamins,especially vitamin C and vitamin K. Aronia berries are also rich in minerals, including potassium, calcium, iron and manganese [7]. All these bioactive compounds explain their health benefits (antioxidative, anticancer, anti-inflammatory, hypotensive, antiviral, antidiabetic, antiplatelet, and anti-atherosclerotic), as well as their popularity and use in food and biotechnological production [8]. Pomace is a by-product of the fruit and vegetable industry. In order to reduce its detrimental effects on the environment and costs associated with the requirement for disposal, new opportunities for the use of pomace have recently been the subject of extensive research [9]. Bioactive compound-rich by-products have the potential to serve as useful ingredients in the food and pharmaceutical industries. Pomace can be used in many different ways, but extruded products appear to have great potential. The addition of fruit and vegetable by-products to cereal-based extrudates will enhance their nutritional value because they are high in easily digested carbohydrates [10]. Extrusion is a technological process used to develop new food products with special textures, shapes and functional properties. It is a combination of high temperature, pressure and moisture content applied to grain raw materials or mixtures of grain raw materials [11]. Extrusion technology is becoming popular in the global food industry, using mixing, shaping, texturing and cooking to create new food products. This process leads to gelatinization and heat treatment of ingredients, resulting in a change in the shape, texture, structure and nutritional value of the products [12]. This makes extrusion a useful and innovative technology for developing new food products, which meet the specific needs and preferences of consumers. The main advantage of extrusion in food production is the ability to create products with a longer shelf life, better stability and better functional properties. The extruded products increase the metabolic availability of proteins and starches, the retention of nutrients, digestibility, as well as the incorporation of various inexpensive bioactive compounds with health benefits located in fruit and vegetable by-products. Other advantages are diversity of textures, preservation of biologically active substances, inclusion of various additives and ingredients, better food safety, production optimization, standardization of products, possibility of innovative food products, etc. [13; 14; 15].