# Valorization of Cassava By-Products: Cyanide Content and Quality Characteristics of Leaves and Peel  
[PERSON]  
Cassava production generates significant amounts of by-products such as leaves and tuber peel. Instead of considering them as waste, valorization aims to find sustainable ways to utilize them. However, the presence of cyanide and insoluble fibers poses a major obstacle to their conversion into valuable products. Therefore, the objective of this study is to investigate the changes in cyanide concentration and quality of cassava leaves after mechanical pressing and in tuber peel after treatment with an enzyme solution. Frozen leaves were screw-pressed into their fractions: juice, and press cake. The results show that the cyanide level in the press cake was reduced to 73.56% and was concentrated by 97.48% in the juice compared to the frozen leaves. However, the crude protein values of the frozen leaves, juice, and press cake did not differ significantly (\(p>0.05\)), and were 27.09%, 25.47%, and 23.82%, respectively. In addition, the results for the peel revealed that pretreatment with Viscozyme(r) L, which assists in the mechanical peeling of cassava tubers, also contributed to a reduction in cyanide and insoluble fiber in the peel. Cyanide content was lowered by 53.89-58.94% in enzyme-treated peel from all three runs (ETP1-3) when compared to fresh peel (FP), while the reduction was only 8.63% in the control peel (CP) treated with hot water without enzyme solution. The insoluble fibers in cassava peel, such as neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and crude fiber (CF), were also degraded more effectively after treatment with an enzyme solution than with hot water. animal feed, in paper production, and as biodegradable packaging. In addition, cassava peel can also be processed to produce ethanol as a renewable energy source, which can help reduce reliance on fossil fuels and promote sustainable development. Thus, the efficient utilization of cassava by-products can help reduce waste and improve the sustainability of cassava production. Despite the great potential of cassava leaves and peel, their use is limited due to their high levels of antinutritional components, such as cyanogenic glycosides, which can be harmful to human health if not properly detoxified [15]. Cyanogenic glycosides occur in cassava tissue in three forms, linamarin and lotaustralin, cyanohydrin, and free cyanide. Linamarin is the predominant form, accounting for 93% of the total cyanogenic glycosides present in cassava [16]. Linamarin is hydrolyzed to glucose and acetone cyanohydrin in the presence of linamarase. Acetone cyanohydrin is then spontaneously degraded to HCN and acetone by hydroxynitrill lyase (HNL) [17]. Linamarin is usually located in the vacuole, while linamarase and HNL are localized in the cell wall [18]. Various processing methods such as drying [19; 20; 21], cooking [20; 22; 23], fermentation [2; 10; 19], enzyme and ultrasonic treatment [24], and membrane filtration or coagulation [25] have been well studied in relation to the removal of cyanide from cassava tissues of different varieties. However, most detoxification methods usually require 15 min of bounding followed by 10 to 120 min of boiling and washing with tap water. Undoubtedly, the proposed methods can reduce cyanide levels in cassava tissue to well below the FAO/WHO safe limit of 10 ppm [26]. However, these methods require long processing times, and a lot of water is wasted during washing, resulting in the loss of valuable nutrients. Considering the previous efforts, a mechanical screw press was used for this study to separate the cassava leaves into their fractions: juice and press cake. The processing of cassava leaves by screw presses not only helps to obtain a press cake with concentrated protein but also reduces the cyanide content by leaching the cyanide with the juice fraction [3].