## 1 Introduction  
Rapeseed oil, commonly used edible oil, is ranked as the second largest oil crop with an annual production of approximately 12 million tons [1, 2]. Rapeseed oil is enriched in numerous bioactive components, including tocopherols, phytosteorols, and squalene that are beneficial in preventing coronary heart disease, diabetes, hypertension, etc. [3, 4, 5, 6]. However, the high temperature, light exposure, and humidity air during oil extraction, storage, and processing can accelerate the hydrolysis of triglycerides, causing the generation of free fatty acids (FFAs) which is reflected by the increased acid values and rancid smell [7, 8]. The rancid oils not only diminish their economic values but also pose threats to public health [9, 10]. Currently, high-acid oils are only used as cheap raw materials for industrial production, or even simply discarded to cause huge resource waste and environmental pollution [11, 12]. Hence, deacidification is a primary and essential step to improve the quality and applicability of edible oils. Traditional oil deacidification primarily relies on alkali refining, which uses sodium hydroxide to saponify free fatty acids and reduce the acid value of crude oil [13]. However, a large amount of crude oil is entrapped in the soap micelles and removed with the soap during centrifugation, resulting in the fact that the loss of neutral oil and micronutrients such astocopherol, gamma oryzanol, and phytosterols. Moreover, a large amount of wastewater will be generated, which will cause serious pollution to the environment. Other deacidification methods include distillation and solvent extraction, where distillation can be inefficient due to high temperatures and energy consumption, and solvent extraction may pose risks of solvent residue [14; 15; 16; 17; 18; 19]. Furthermore, oils extracted and deacidified by solvents require additional separation and purification, consuming more resources. Hence, a cleaner and greener approach to improve oil deacidification is highly required. Enzymatic deacidification relies on lipases to catalyze the esterification between free fatty acids (FFAs) and specific acyl acceptors such as glycerol, monoglycerides, and phytosterol to reduce the acid value of oils. Compared to chemical methods, the enzymatic approach not only reaches the oil deacidification in greener and cleaner ways but also simultaneously generates functional lipids such as monoglycerides (MAGs), diacylglycerol-erol (DAG), and phytosterol esters (PEs) [20; 21]. To improve the catalytic stability and reusability of free enzymes, researchers have attempted various enzyme immobilization techniques including physical adsorption, encapsulation, chemical cross-linking, and covalent to bind or restrict enzyme molecules to solid carriers [22; 23]. Based on this concept, commercialized immobilized lipases such as Nozoyme 435, Lipozyme TL IM, and RM IM have been developed and widely used in oil processing [24; 25; 26]. However, the high cost of commercialized immobilized lipases is the main reason to suspend their industrial application. Moreover, the carriers including microporous resins or silica gels are easily deformed or fragile at extreme conditions with high temperatures, fierce agitation, and polar solvents [27]. Hence, the selection of robust carriers is the key step for the preparation of stable and efficient immobilized lipases. Recently, different porous solids such as porous carbon materials (PCMs), organic-inorganic hybrid porous material (KCS-2), hollow multihulled solids, and magnetic nanoparticles have been reported for enzyme immobilization [28; 29; 30; 31]. However, these carriers are constrained by the long preparation period, complex preparation procedures, and high cost; therefore, these particles were only used for lab-scale research instead of for industrial application.