This complexation makes it difficult for proteins to dissolve in water and subsequently to precipitate and be purified [2; 6; 14]. Those proteins have valuable nutrition content; however, they have limited bioactive properties which can be improved by chemical or enzymatic hydrolysis that produce protein hydrolyses (as bioactive peptides) [14]. For phenolic content extraction, various solvents such as water, ethanol, methanol, isopropanol, ethyl acetate, hexane, deep eutectic solvents, and other organic solvents are used. Among the solvents, water generally gives the lowest extraction yield, and deep eutectic solvents are difficult to prepare, with relatively high cost. Although organic solvents provide higher extraction yields, they may have toxicity, cause harmful effects to environment, and need extra recovery and disposal steps [15; 16]. For a greener approach, ultrasound assistance, microwave treatment, enzymatic hydrolyzation, high pressure homogenization, and supercritical fluid extraction techniques may also be used to increase phenolic extraction yield; however, they may have some drawbacks regarding cost, industrial scale adaptability, being sophisticated, and operational difficulties [13; 15; 16; 17; 18]. Similar to protein extraction, the lignocellulosic structure in the cake prevents higher phenolic compound extraction yield due to complexation with carbohydrates and proteins. The fermentation can be regarded as a suitable solution for bioactive component extraction from oil seed cakes because microorganism may have the ability to hydrolyze the complex carbohydrates and proteins in plant tissues, resulting in free phenolic compounds, proteins, peptides, and amino acids. The microbial activity may also contribute the bioactive component and protein formation in the medium [19; 20]. Although different types of fermentation techniques have been applied to the oilseeds, the solid-state fermentation (SSF) which takes place on a solid matrix with little or no free water present is an alternative way due to being more practical and environmentally friendly technology. The formation of bioactive components by SSF depends on process conditions such as initial moisture content, incubation temperature, and incubation time, which are critical parameters [21]. Research in the SSF area is generally focused on commercial enzyme production. In addition to this, there have also been many studies seeking to increase the amount of free phenolic and protein content, to produce bioactive peptides, and to eliminate antinutritional factors from fermented products [22; 23; 24; 25; 26; 27; 28]. When black bean flour, soybean cake, peanut cake, flaxseed cake, and hazelnut cake were fermented using various microorganisms for these purposes, significant increases in the protein content of fermented products were determined [29; 30; 31] (_p_ < 0.05). In addition, in the fermentation studies of various legumes, oilseed meals, wheat, and hemp by _Bacillus_ species, _Aberggillus_ species, _Lactobacillus_ species, _Rhizopus oligoporus_, Bifidobacterium, and _Pleurotus ostractus_, significant changes occurred in soluble phenolic compounds, protein content, and antioxidant activities of the fermented products, while significant improvements were observed in the antihypertensive, antidiabetic, and anticancer activities of some of the products [29; 32; 33; 34; 20; 35; 36; 37; 22; 23; 24]. Among the SSF studies in the literature, there are limited research where fermentation of HOC was studied. In these studies, ethanol and various enzymes were produced by fermenting the outer hard and inner soft shells of hazelnut with SSF [38; 39; 40; 41; 42; 43; 44; 45; 46]. Similarly, studies on the production of alpha amylase using _Bacillus amyloliquefaciens_ and increasing the protein content of the meal for animal nutrition using _Aberggillus niger_ ATCC 9142 were also carried out [47; 48]. In these studies, it was observed that while the hemicellulose content of HOC decreased with fermentation, the protein content increased by 31% (_p_ < 0.001).