## 8 Bromelain, Ficin, and Papain Peels By-Products-Based Cosmetic Applications
Ultimately, proteolytic enzymes can be found in several cosmetic products, each serving a different purpose. Enzyme-based formulations could be a key ingredient in future cosmetic and cosmeceutical treatments [17, 22, 27, 94, 163]. Methods of Incorporation of Bromelain, Ficin, and Papain Peel By-Products-Based Cosmetic Applications  
In order to discuss, bromelain-, ficin-, and papain-related methods of incorporation in cosmetic products, their solubility must be discussed. Bromelain and papain are highly water-soluble (Table 1) [46, 117], while fiction is less soluble, but is still viable in buffered or aqueous solutions. Thus, organic solvents reduce the solubility of all three enzymes [70]. Furthermore, it must be noted that \(\alpha\) or \(\beta\)-hydroxy acids (AHAs and BHAs, respectively) and some surfactants in cleansers or emulsifiers may denature enzymes and reduce their activity [5; 8; 13; 14; 15; 16]. Therefore, pH buffering, encapsulation techniques, the use of stabilizers, and formulation type selection (leave-on products like masks or serums, wash-off products like cleansers and scrubs or dry formulations, i.e., powder exfoliants), may be the key answer to preventing enzyme deactivation and enhancing the product's overall efficacy [17]. The creation of lyophilized enzyme powders follows a process that involves freeze-drying the enzyme to preserve its activity and stability. A lyophilized powder can easily be incorporated into dry formulations or rehydrated for use in liquid cosme [129]. Lyophilized enzymes reportedly have a longer shelf-life and are less prone to degradation during storage, while they can be activated by being mixed with a liquid component, ensuring maximum activity at the time of application [44; 57; 161; 164]. Moreover, enzyme powders can be incorporated into anhydrous (water-free) formulations like oils, balms, and powders, which minimize the risk of enzyme degradation due to hydrolysis. On the other hand, for water-based products like gels, creams, and lotions, enzymes are often added in the final stages of formulation, and pH adjusters are used to maintain optimal conditions for preserving efficacious enzyme activity [165; 166]. The utilization of encapsulation with a view to effectively protecting enzymes from harsh formulation conditions and ensuring controlled release, as aforementioned, is of great importance. Encapsulation involves encapsulating the enzyme in a protective coating to boost its stability and control its release, while common encapsulating agents include liposomes, polymers, silica particles, etc. Encapsulation shields the enzyme from external factors like pH, temperature, and UV radiation [167; 168]. Liposomes are phospholipid vesicles that encapsulate enzymes, ensure their gradual release, enhance their penetration capability, and promote product efficiency during skin delivery [169; 170; 171; 33; 160; 172]. Similarly, polymeric nanoparticles, with materials like chitosan or alginate-enclosing proteolytic enzymes, also enhance prolonged cosmetic product shelf-life [169; 173; 174; 175; 93; 161; 165; 167; 176; 177; 178]. Microencapsulation, for instance using microspheres, is ideal for powdered cosme that prevent premature activation [176; 177; 178]. There is great importance in controlling release formulations to prevent over-exfoliation and ensure prolonged enzymatic product activity; thus, delivery systems that enhance enzyme skin penetration have been examined. Nanoencapsulation by using nanocarriers (i.e., nanoemulsions, nanomotors) which improve enzymatic bioavailability and enhance product efficacy [179; 170; 171; 173; 174; 175; 176; 177; 178; 179; 180; 181; 57; 182; 57; 183] has resulted in several beneficial skin outcomes. Finally, hydrogel formulation may provide a moisture-rich medium for preserving enzyme stability and enabling skin hydration [184; 185; 186; 187; 188].