## 1 Introduction  
During the production and storage of meat products, a variety of processes occur, including lipid oxidation, which can negatively affect colour, flavour, aroma, texture and nutritional value, thereby significantly reducing shelf-life. Poultry meat products are particularly susceptible to oxidative changes due to their high concentrations of unsaturated fatty acids [1, 2]. Antioxidants, usually synthetic, are used to reduce these adverse changes. However, due to consumers' aversion to synthetic additives and their search for so-called 'clean label' products, natural antioxidants derived from plant raw materials are of increasing interest among food manufacturers [3, 4, 5, 6, 7]. In the food industry, the 'clean label trend' is one of the fastest growing trends, aiming to improve the health quality of food but without compromising its safety and other characteristics [8].  
There are many substances in plants that exhibit strong antioxidant activity, and phenolic compounds are particularly valuable, including the following: phenolic acids, flavonoids, tannins, stilbenes and lignans [9, 10]. Some natural antioxidants from plants are already used in the meat industry, e.g., herbs and spices, such as oregano, rosemary, thyme, sage, ginger and mint [5, 11, 12]. A number of studies have shown that lipid oxidation in meat products could be significantly reduced by adding extracts from various plant parts, including leaves, stems, roots, fruits and seeds [1, 5, 13, 14, 15, 16, 17]. The use of extracts can facilitate standardisation of the quality of finished products and reduce the risk of microbiological contamination. It is also important that raw materials, such as hulls, skins, peels, seeds and marc, which are waste products from the fruit and vegetable, fat and cereal industries, can be used to produce extracts [7, 18, 19, 20, 21, 22].  
The production of buckwheat groats generates by-products, such as bran and husks [23]. Buckwheat hulls have already found industrial use, as pillow fillers and as ingredients in biodegradable packaging, among other uses. However, due to their contents of bioactive components, buckwheat hulls may be used as promising food ingredients. Buckwheat hulls, in addition to their high fibre content, may be a valuable source of phenolic compounds [23]. Buckwheat hulls have been shown to have higher phenolic contents and antioxidant properties in comparison to buckwheat groats. While buckwheat groats mainly contain rutin and isovitexin, buckwheat hulls contain orientin, isoorientin, vitexin and quercetin, in addition to the two flavonoids [24, 25, 26, 27]. [PERSON] et al. [28] showed that the addition of ground buckwheat hulls at a level of 1-3% improved the nutritional value of frankfurters but unfortunately also caused changes in the technological and sensory qualities of these products. The use of crushed plant materials can cause changes in sensory characteristics, especially colour and taste [5, 29]. These changes are more pronounced in poultry meat products with low natural colour intensity [3, 30]. It has been reported in the literature that plant extracts had lesser effects on the sensory qualities of meat products [14, 16]. Studies by numerous authors have described the antioxidant activities of buckwheat hull extracts [23, 26, 27, 31]. However, there are few studies in which buckwheat hull extracts have been used to reduce lipid oxidation in meat products. Therefore, the aim of the present study was to determine the influence of buckwheat hull extracts on selected quality characteristics of chicken meatballs during refrigerated storage. The novelty of these studies is the presentation of the application of buckwheat hull extracts as natural antioxidants in the production of poultry meat products. It was also checked how these additives affect the sensory and microbiological qualities of the final products, which, to the best of our knowledge, has not been the subject of a publication so far.