## 1 Introduction  
The exploration of solid residue (a byproduct left after extracting oil from seeds) as a resource began only a few decades ago due to the increasing scarcity of natural resources across the globe from the impact of different factors, including population growth, overexploitation, climate change, and global warming, since before the oil seeds were valued only for their oil content [1; 2; 3]. Subsequently, researchers have focused on several oil seed plants to understand the possible utilization of their solid residue. One of them is _Nigella sativa_ L., a small annual flowering oil seed plant belonging to the Ranunculaceae family, which is highly recognized due to its nutritional and medicinal value. _Nigella_ has multiple names across the world. For example, it is known as Al-habbah, Al-Sawda, Habet el-Baraka, and Kamounaswad in Arabic countries; jintan hitan in Indonesia; Shoniaiz in Iran; black cumin in English; and kalonji in Pakistan and India [4; 5; 6]. _Nigella_ seed contains not only protein, carbohydrate, dietary fiber, vitamins, and minerals--which have nutrient value--but is also a source of several bioactive phytoconstituents belonging to the different groups, such as phenolics, alkaloids, terpen, sterols, tools, and fatty acids, that have therapeutic properties [7; 8; 9]. However, thymoquinone (TQ), which is a monoterpene and is one of the major bioactive compounds in _Nigella_ seed, is responsible for much of this. For example, pharmaceutical companies use it in the treatment of a variety of microbial, wound, inflammation, and skin pigmentation diseases, and cosmetic industries use it to prepare different cosmetic items such as soap, shampoo, and cream [10]. Since _Nigella_ seed contains only 28-40% \(w/w\) oil, with the remaining mass being the solid residue (seedcake and sludge) [11], a large quantity of _Nigella_ seeds needs to be processed to meet the oil demand of the world. As a result of this, a large quantity of solid residue is produced as a byproduct of oil extraction. Since _Nigella_ seed is a source of many important phytoconstituents, the solid residue might also hold a potential quantity of these compounds. A considerable amount of research has been carried out on the seeds and oil; however, there is limited information on _Nigella_ solid residue. More particularly, fewer researchers have reported the physicochemical properties of its solid residue, yet their reports support the presence of many important macronutrients (protein, carbohydrate, and fibers) and micronutrients (vitamins and minerals) in pressed _Nigella_ solid residue [12; 13; 14; 15]. These phytochemicals are essential for the growth and development of both plants and animals. It has been reported that amending soil with _Nigella_ solid residue and priming seeds with microbial antagonists can effectively control root rot fungi in both leguminous and non-leguminous crops [16]. [PERSON] [13] investigated the viability of _Nigella_ solid residue as a component of fish feed, comparing its crude protein content with that of soybean solid residue and demonstrating its potential to substitute soybean solid residue in fish feed formulations. This underscores the multiple applications of _Nigella_ solid residue. However, many aspects of _Nigella_ solid residue are unknown yet. For example, there is a scarcity of information on the health-benefiting bioactive phytoconstituents present in _Nigella_ solid residue. Given that _Nigella_ seeds contain bioactive compounds such as antioxidants, phenolics, TQ, and unsaturated fatty acids, which have significant health-benefiting properties, researching the presence and concentration of these compounds in _Nigella_ solid residue has the potential to improve nutrition, reduce waste, and create new opportunities in various industries, including agriculture, food production, and health and nutrition.