## 2 Materials and Methods  
A systematic method was employed in this review in order to compile and synthesize the relevant scientific literature on the proteolytic activity of bromelain, ficin, and papain and their applications in cosmetics. A detailed review of the relevant scientific literature was conducted, focusing on the biochemical properties, efficacy in exfoliation, and comparative performance of such useful and efficacious enzymes. The review specifically focuses on the biochemical properties, exfoliation efficacy, and comparative analysis of bromelain, ficin, and papain, highlighting their relevance in cosmetic applications. During the literature review, all references were publicly accessible through valid scientific databases including MDPI, Google Scholar, Scopus, PubMed, Science Direct, Google Scholar, and Research Gate. The following combination of keywords was used during the data collection phase: \"proteolytic enzymes\", \"bromelain\", \"ficin\", \"papain\", \"enzyme peels\", \"exfoliants\", \"skin exfoliation\", \"physical exfoliation\", \"chemical exfoliation\", \"natural products\", \"fig\", \"pineapple\", \"papaya\", \"extraction\", \"purification\", \"molecular structure\", \"chemical properties\", \"stability\", \"chemical activity\", \"inhibitors\", \"stabilizers\", \"mechanism of action\", \"biochemical enzyme properties\", \"anti-inflammatory\", anti-melanoma\", \"antimicrobial\", \"antioxidant\", \"soothing effect\", \"wound healing\", \"tissue repair\", \"cosmetics\", \"cosmetic applications\", \"cosmetic formulations\", \"incorporation methods\", \"sustainability\", and \"circular economy\", employing different keyword combinations with the Boolean operators AND/OR. The selection criteria ensured that only high-quality, peer-reviewed studies related to enzymatic exfoliation, enzyme stabilization techniques, and cosmetic formulations were included. To ensure the incorporation of up-to-date information, only publications from 2015 onwards were considered. The literature review process was carried out between February 2024 and January 2025, with a view to reflecting the latest advancements and trends in the field of cosmetic enzyme research and to compare them with past relevant information, considering all limitations and suggesting future development aspects. All total of 207 references were included in this study, which were meticulously selected using pre-established criteria, such as being exclusively research-based articles, peer-reviewed in the English language, and published between 2015 and 2025. A few important articles published prior to 2015 with relevant information, which have not been included in more recent publications, were also included. All articles cited in our manuscript were credible research papers, reviews, peer-reviewed journals, scientific books, academic publications, reports from research institutes and universities, valid clinical trials, or even meta-analyses, and they were all evaluated for their quality according to their title, abstract, keywords, and included data. The references were thoroughly screened with Zotero \"6.0.36\", a reference management tool, to identify and remove duplicate entries, verifying the uniqueness and reliability of the cited sources. Studies with no relevant experimental/review data, articles retrieved from non-valid databases, duplications, and non-English publications were excluded. Conference papers, book chapters, theses, short surveys, old reviews, blog articles, etc., were also excluded from our review, along with low impact factor/relevance score publications. The references for each enzyme are distributed as follows:  
* Bromelain: approximately 31% of the references, focusing on its source (pineapple), its biochemical properties, purification techniques, and cosmetic applications. * Ficin: approximately 20% of the references, focusing on the extraction of ficin from the fig latex, the unique substrate specificity, and its gentle exfoliating properties.