RESUMO A busca por proteases de origem vegetal aumenta gradualmente devido à sua diversidade e estabilidade em ampla faixa de pH e temperatura. As flores da alcachofra são uma fonte vegetal proteolítica já estudada, porém suas folhas são escassas nesse aspecto. Assim, o objetivo dessa pesquisa foi a obtenção de extratos das folhas da alcachofra com diferentes tampões e métodos de extração como fonte alternativa proteolítica e coagulante vegetal, bem como a separação e comparação do perfil proteico desses extratos. A metodologia utilizada foi baseada na extração com tampão de citrato de sódio (pH 3), acetato de sódio (pH 5) e tris-HCl (pH 7), por agitação mecânica (AM) e ultrassom (US); determinação de proteínas; atividade proteolítica (AP) e atividade específica (AE); atividade de coagulação do leite (ACL) e potencial de substituição do coalho (PSC); análise de cromatografia liquida de alta eficiência (HPLC) com detector UV-Vis e análise de componentes principais (ACP). Os extratos das folhas Cynara scolymus apresentaram resultados elevados no extrato com Citrato-US para os parâmetros AP (14,38), AE (19,71), ACL (440) e PSC (30,60) comparados aos demais tratamentos. Os extratos com citrato e acetato tiveram tempo de coagulação rápido (máx 3 min). A análise de HPLC possibilitou a separação dos diferentes compostos proteicos presentes nos extratos e picos mais expressivos nas amostras com Citrato-AM e Acetato-AM; e picos isolados para o Citrato-US. Conclui-se que os extratos das folhas da alcachofra com o tampão citrato e acetato atribuíram resultados satisfatórios para atuarem como coagulante vegetal, bem como para realização de novos estudos para purificação de enzimas proteolíticas e aplicação em queijos.

ABSTRACT The search for origin plant-based proteases increases gradually due to their diversity and stability over a wide range of pH and temperature. Artichoke (Cynara scolymus) flowers are a proteolytic vegetable source already studied, but their leaves are scarce in this respect. Thus, the objective of this research was to obtain extracts of artichoke leaves with different buffers and extraction methods as an alternative proteolytic source and plant coagulant, as well as the separation and comparison of the protein profile of these extracts. The methodology used was based on extraction with sodium citrate buffer (pH 3), sodium acetate (pH 5) and Tris-HCl (pH 7) by mechanical stirrer (MS) and ultrasound (US); protein determination; proteolytic activity (PA) and specific activity (SA); milk clotting activity (MCA) and rennet substitution potential (RSP); high- performance liquid chromatography analysis (HPLC) with UV-Vis detector and principal component analysis (PCA). Extracts of Cynara scolymus leaves showed high results with Citrate-US for the parameters PA (14.38), SA (19.71), MCA (440) and RSP (30.60) compared to other treatments. The extracts with citrate and acetate presented a quick coagulation time (max 3 min). The HPLC analysis enabled the separation of the different protein compounds present in the extracts and most expressive peaks in the samples with Citrate-MS and Acetate-MS; and isolated peaks for Citrate-US. It was concluded that extracts of artichoke leaves with citrate and acetate buffer attributed satisfactory results to act as plant coagulant, as well as to carry out further studies for the purification of proteolytic enzymes and application in cheeses.

Abstract Essential oils (EOs) are a promising alternative for food preservation and can be used instead of synthetic antimicrobial compounds such as sanitizers, as long as they are efficient and safe. In view of this possibility of use, Lippia alba (Mill) (LAEO) and Cymbopogon citratus D.C. Stapf. (CCEO) essential oils were evaluated as natural antimicrobials and applied into coriander for its biocontrol. The EOs were extracted and their physical properties, total phenolics, cytotoxicity to Artemia salina L. and antimicrobial potential in vitro and on natural coriander microbiota were determined. The EOs had a LD50 (median lethal dose - checked), are considered biologically active. MIC (Minimum Inhibitory Concentration) varied from 1.25 to 5.00 μL/ mL and from 0.62 to 5.00 μL/ mL for LAEO and CCEO, respectively, on standard strains of Staphylococcus aureus, Salmonella Thyphimurium, Salmonella Enteritidis, Escherichia coli and Listeria monocytogenes. The lowest MIC values for LAEO and CCEO were selected for application in coriander. EOs reduced the pathogenic microbial load in the coriander revealing its potential as a natural sanitizer, and thus demonstrating superior or equivalent efficacy to commercial sanitizer. By correlating the cytotoxic and antimicrobial results obtained, we have shown that these EOs present potential for application in foods.