## 2 _Introduction_
After extraction, the remaining biomass is considered waste. Although its unprecedented production growth (expected to grow at a CAGR of 22.44% over the next 10 years) will inevitably lead to large amounts of defatted residual material, there has been limited research into the use of defatted hemp seed residues. [PERSON] et al., 2020 [18], investigated the potential of incorporating hemp meal as a filler in melamine urea formaldehyde (MUF) adhesives for plywood production. They found that the incorporation of 20-25 pbw (parts by weight) hemp flour facilitated the production of plywood panels with mechanical properties comparable to the reference plywood bonded with MUF adhesive mixed with rye flour. More recently, in 2024, [PERSON] et al. [19] used extracted hemp proteins, both modified and unmodified, in combination with glutaraldehyde to synthesize wood adhesives. The adhesiveness of these resins was tested on cherry wood samples of specific dimensions. The results showed that hemp protein has significant potential as a renewable and environmentally friendly alternative to plant protein-based adhesives. Regarding the olive tree, it is another crop whose cultivation produces waste that causes environmental problems and whose management entails significant economic costs. Olive growing and olive oil production processes generate significant solid residues, both from the processing of the fruit and from the waste olive leaves. An average mature olive tree can yield between 10 and 70 kg of olive oil, which is equivalent to roughly 2500 to 17,500 pieces of olive fruit, and a corresponding amount of residues [20]. It is therefore clear that a huge amount of olive leaf and fruit waste such as pomace, exhausted olive cake, pomace skins, and stones is produced every year. Of course, these residues are a source of valuable bioactive compounds such as simple phenols and phenolic acids, secorimidoids, flavonoids, lignans, and triterpene acids, which are used in several applications including pharmaceuticals, dietary supplements, biofunctional foods, and cosmetics. Their extensive use is now the focus of commercial interest in the global market, but this also creates other waste in large quantities that usually remain unused. Several scientists have investigated the use of olive residues--olive stones in particular--in various applications, such as fillers in thermoplastic resin composites [21; 22; 23], the recovery of various chemicals from them [24; 25], as ingredients in skin care formulations, as a natural muld for plants, and as a fuel [26; 27]. However, there are only a few publications on wood adhesives, and none of them used olive residues after removal of the valuable bioactive compounds. Specifically, [PERSON] et al., 2021 [28], compared cactus waste seeds and olive stones as fillers in phenol-formaldehyde (PF) to produce wood composites. The study showed that incorporation of up to 20 per cent cactus waste seeds and olive stones in PF resins resulted in higher viscosity, gel time, and solids content than the control PF, while the corresponding plywood panels had lower formaldehyde emissions than the control. [PERSON] et al., 2016 [29], used olive stone/unsaturated polyester resin compositions at various ratios to produce particleboards that were evaluated for their mechanical and physical properties according to European standards. It was found that such panels have acceptable performance. In this context, we investigated the possibility of replacing wheat flour, an edible resource, with biomass waste in the manufacture of pMDI-based adhesives for plywood panels, with the aim of producing a non-competitive and environmentally friendly product. Specifically, we examined the replacement of wheat flour with a combination of commercial defatted soybean flour and various biomass residues. The biomass residues investigated included olive leaves (OLs), exhausted olive pomace (EOP), residual olive skin (ROS), and olive stones (OSs), both with and without the removal of their bioactive compounds.