## 1 Introduction  
### Importance of Proteins, Amino Acids, and Biogenic Amines to Food Quality  
The consumption of high-quality protein is vital to optimal nutrition. EFSA recommendations specify the daily intake of well-balanced essential amino acids for an average adult in mg per kg of body weight per day. Histidine is recommended at 10 mg/kg, isoleucine at 20 mg/kg, leucine at 39 mg/kg, lysine at 30 mg/kg, and combined methionine and cysteine at 15 mg/kg. Similarly, phenylalanine and tyrosine together are recommended at 25 mg/kg, threonine at 15 mg/kg, tryptophan at 4 mg/kg, and valine at 26 mg/kg [1]. Most proteins derived from animal sources have high bioavailability, ensuring efficient absorption and utilization by the body [2]. In contrast, proteins derived from plant sources typically have lower bioavailability due to the presence of antinutritive factors such as tannins, lectins, and protease inhibitors, which necessitate varying degrees of food processing to mitigate their adverse effects. Moreover, plant proteins are less accessible because their cell walls are only partially digestible in the human gastrointestinal tract [3]. While some plant-based foods provide a complete source of protein (such as quinoa and soybeans), many are deficient or limited in one or more essential amino acids, particularly methionine and lysine. A beneficial approach when designing a meat alternative would be to combine different protein sources to ensure a complete amino acid profile [4]. On the other hand, most meat substitutes are cholesterol-free and typically low in saturated fat and calories. They also provide a good source of fiber, folate, and manganese. However, to match the nutritional quality of meat products, their nutritional profiles should be enhanced by adding iron, calcium, zinc, and B12 vitamins [5]. The protein content of edible mushroom ranges from 19% to 40% on a dry basis; however, this can vary significantly depending on the mushroom species and the conditions under which they are grown [6]. The amino acid profile of mushroom proteins is comparable to that of animal proteins, offering a valuable alternative to reduce the reliance on animal-based food sources, particularly in developed countries [7; 8]. Edible mushroom proteins offer a full spectrum of amino acids, with the eight essential amino acids making up 25-45% of the total. Research has shown that edible fungi are particularly rich in lysine and leucine, in contrast to their lower levels in grains [9; 10]. Besides amino acids, their derivatives such as biogenic amines are also common constituents of high-protein foods. Mushrooms should be considered as food products that may contain high levels of biogenic amines (BAs). The most significant biogenic amines found in foods include tyramine (precursor: tyrosine), histamine (precursor: histidine), spermidine and spermine (derived from putrescine), putrescine (precursors: arginine and agmatine), agmatine (precursor: arginine), and cadaverine (precursor: lysine) [11]. Their main origin is the decarboxylation of free amino acids during processes like fermentation, spoilage, or putrefraction [12]. BA accumulation in food is influenced by precursor availability, the presence of decarboxylase-positive microorganisms and free amino acids, and a variety of intrinsic, technological, and environmental factors that facilitate microbial growth and enzyme production [13]. The presence of biogenic amines not only poses a risk but also serves as an indicator of food quality. Specifically, cadaverine and putrescine are regarded as markers of freshness and overall food quality. Histamine and tyramine are among the most physiologically active components, and both are vasoactive substances. Histamine, commonly referred to as scombroid poisoning, occurs from consuming spoiled fish, whereas tyramine is linked to the \"cheese reaction\", originally attributed to the intake of aged cheeses [11; 14]. The Good Manufacturing Practice sets the histamine limit for fish and fish products at 100-200 mg/kg.