## 1 Introduction  
The plant-based food sector is rapidly growing due to environmental, ethical, and health concerns associated with the high consumption of animal-based products. Raising animals generally results in greater environmental impacts than cultivating plants, including higher greenhouse gas emissions, increased water and land use, and nitrogen pollution [1]. Ethical considerations and the perception of plant-based diets as healthier are also driving this shift [2; 3]. Consequently, the European retail sales of plant-based foods grew by 21% between 2020 and 2022, reaching $5.8 billion [4]. The faba bean (_Vicia faba_ L.) is gaining attention in the plant-based food industry for its high protein content and functional properties [5] as well as for its ability to fix nitrogen through symbiosis with _Rhizobium_ bacteria, making it an environmentally friendly crop. Pulses like the faba bean are frequently used in products aiming to mimic animal-based foods such as milk, cheese, meat, fish, and eggs. The faba bean is increasingly incorporated into bread, pasta, snacks, and infant formulas [6; 7; 8]. Moreover, studies have shown that the faba bean protein concentrate is suitable for meat-like products [9], and fibrous textured meat analogues have been successfully produced [10]. However, consumer acceptance of faba bean-based products is hindered by \"off-flavours\", defined as an unpleasant taste and/or aroma [11]. These off-flavours are problematic in plant-based food where consumers expect flavours similar to meat, cheese, milk, etc. Off-flavours are caused by volatile (aroma) or non-volatile (taste) compounds [12]. They are described as dried pea-like, beans, bitter, and with an unpleasant fruity note in faba bean [13; 14]. Volatile compounds from lipid oxidation contribute significantly to off-flavours, especially those derived from polyunsaturated fatty acids (PUFAs) such as linoleic acid (C18:2) and linolenic acid (C18:3) [15]. PUFAs undergo enzymatic oxidation (via lipoxygenase) or autoxidation, producing volatiles with strong off-flavour properties [12]. Additionally, non-volatile PUFA-derived compounds (e.g., trihydroxy fatty acids, etc.) are bitter even at low concentrations, and PUFAs themselves are also bitter [16]. Other bitter and/or astringent compounds in legumes include polyphenols (phenolic acids, flavonoids, and tannins), saponins, amino acids, and peptides [17; 18; 19]. Tannins, in particular, contribute to bitterness or astringency in faba beans based on their degree of polymerization [20; 21]. Although saponins are bitter and/or astringent in pea, their lower concentration in faba beans makes them unlikely major contributors [22]. Recently, the alkaloids vicine and convicine have also been proposed as contributors to bitterness and mouth dryness [22]. Breeding offers an alternative for reducing off-flavours to costly post-harvest treatments (e.g., thermal, chemical, or enzymatic), which are expensive and energy-intensive [12]. Contrarily, targeting the off-flavour precursors or enzymes involved in flavour development through breeding can address the issue upstream. [PERSON] et al. [23] reviewed the challenges of breeding for reduced off-flavours in faba bean and proposed marker compounds, including volatile (e.g., hexanal) and non-volatile (e.g., 1-linoleoyl glycerol) lipid-oxidation products, phenolic acids (e.g., p-coumaric acid, ferulic acid), flavonoids (e.g., quercetin), and tannins (e.g., epicatechin, procyanidin B2). Genetic research into off-flavour traits and protein content in faba bean has been limited. Previous studies have examined volatile off-flavours [24], phenolic acids and flavonoids [25], fatty acids, total phenols, total saponins, and total tannins [26; 27]. However, these studies characterized only a limited number of samples (e.g., fewer than 50), and they lacked estimates of important genetic information such as heritability or genetic correlations across traits and/or environments.