# Evaluation of Hazelnut Cake Flour for Use as a Milk Powder Replacer in Ice Cream
## 1 Introduction  
Dairy products are an important element of the daily diet of the vast majority of people. In this food category, consumers of all ages choose ice cream as a sweet and cooling food. Usually, ice cream comprises the following ingredient categories: fat, milk solids non-fat, sweeteners, stabilizers, waste, and flavours. In addition to its beneficial sensory properties, ice cream is a good source of milk fat, proteins, and carbohydrates [1, 2]. On the other hand, this milk dessert is low in bioactive substances and fibres. Therefore, the need to enrich ice cream with compounds that are naturally rich in these valuable substances has been the subject of several researches [3, 4, 5, 6, 7]. There are various methods used for obtaining oils from different materials, such as pressing (mechanical) extraction, solvent extraction, supercritical fluid extraction, microwave, enzyme, and ultrasound assisted extraction [8], and each of them provides some advantages and disadvantages regarding oil quality and extraction yield. The solvent-free method, known as the pressing extraction method, involves the application of pressure (using presses) and can be divided into two types--cold and hot extraction. Although it has a lower extraction yield, the cold pressing method is considered preferable since the investment costs are low and the processing temperature during the oil extraction lies below 50 \({}^{\circ}\)C, so the obtained oil has a superior quality due to retained bioactive compoundssuch as tocopherols, phospholipids, phytosterols, phenolic compounds, pigments, flavour, and aroma components [8; 9]. In addition, cold-pressed by-products, i.e., cakes, also contain some bioactive compounds. They are rich in proteins, carbohydrates, residual oils, and fibres which allows their further utilization in food and other industries [10]. In the food market, there are various cold-pressed oils and their by-products with different nutritional compositions, which, in addition to the oilseed type, depend on growth conditions and extraction parameters [11; 12]. The hazelnut (_Corylus_ spp.) is a nut with oil as a predominant component [13], mostly cultivated in Europe, Asia, and continental America [14]. According to Maximize Market Research forecast [15], the hazelnut market size in 2023 was 10.93 billion USD and it is projected to grow to 19.60 billion USD by 2030. In addition, it is anticipated that the global hazelnut oil market will reach 19.15 billion USD in 2030, reflecting a growth of about 8.6% from 2023 [16]. Given that increased cold-pressed oil consumption brings increased by-product generation, different studies investigated the composition of hazelnut oil cakes. Namely, it is reported that moisture, protein, fat, carbohydrate, and ash contents in hazelnut press cake were in ranges of 7.55-8.30%, 36.95-38.68%, 8.90-18.35%, 31.91-48.00%, and 5.50-7.41%, respectively [17; 18; 19]. In addition, many studies highlighted the health-promoting properties of nut consumption, including hazelnuts, such as their abilities of lowering the risk of CVD, cancer, and type 2 diabetes [20]. For the reasons above, many studies examined the possibilities of hazelnut press cake utilization in the food industry. Few attempts have been made to explore the possibility of hazelnut beverage preparation, appropriate for a vegan diet [17; 18; 21]. In addition, the study reported by [PERSON] et al. [22] created a yoghurt-like product from a hazelnut beverage, while [PERSON] [23] used this beverage for kefir production. Hazelnut press cake can be valorised in the production of many other products, such as chocolate spread [19], extruded snack products [24], wheat dough [25], and meatballs [26]. Although in many cases the sensory features of products with the addition of hazelnut flour are impaired, because of the improved nutritional composition (especially the polyphenolic composition), it is worth focusing on optimizing the recipes to obtain a functional product with delightful sensory properties.