Biblioteca do Café
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Item Physicochemical comparison of aqueous extracts from Peruvian coffee husks (Caturra, Catimor and Geisha) varieties(Universidade Federal de Lavras, 2023-12-19) Yance, Maciela Yoselyn Puñez; Peréz, Grover Chuquipiondo; Galdos, María Estela Ayala; Pariona-Velarde, DanielThe study aimed to determine and compare the physico-chemical characteristics of coffee husks aqueous extracts corresponding to three Peruvian varieties of Arabica coffee: Caturra, Catimor and Geisha. Each sample was dehydrated at 45 °C for 10 hours, ground, sieved and dissolved in 2.5% w/w water. Aqueous extracts were obtained and analyzed for pH, total solids (TS), whiteness index (WI), reducing sugars (RS), total phenols (TP) and reducing power (RP) for the antioxidant activity The influence of coffee varieties, particle sizes (0.097, 0.033, and 0.0139in) and extraction temperaturas (60 and 80 ºC) on the physicochemical characteristics of their corresponding extracts was determined by factorial analysis. Correlation between TP and RP was significant while RS and TP showed an inverse relationship. Cluster values indicate similarity between Geisha extracts at 60 and 80 °C and the corresponding Catimor extracts at 80 °C. Differences were observed between the Catimor extracts at 60 °C and Caturra at 60 and 80 °C. Based on these results, the extracts exhibit distinctive intrinsic characteristics. The Caturra extracts at 60 °C showed the highest antioxidant capacity, while the Catimor extracts at 60 °C or 80 °C exhibited the highest WI (water holding capacity) and pH values. Additionally, the Geisha extracts displayed the highest amount of RS (reducing sugars). These findings are of utmost significance for the development of novel products using Peruvian coffee husks, encompassing beverages, concentrated juices, and the enhancement of coffee quality offered in coffee shops. These developments can be guided by the physicochemical characteristics obtained in this study.Item Isolamento de leveduras de cavernas e avaliação do seu potencial biotecnológico para fermentar hidrolisados lignocelulósicos(Universidade Federal de Lavras, 2023-02-27) Bonett, José Eduardo Abril; Duarte, Whasley Ferreira; Ferreira, Rodrigo LopesPretendeu-se, neste trabalho, isolar, identificar e realizar uma avaliação biotecnológica de leveduras isoladas de 15 cavernas localizadas no estado de Minas Gerais. Para tal fim, usaramse amostras de solo em distintas zonas das cavernas e, para o isolamento, realizaram-se plaqueamentos usando o meio Extrato Malte. Para a identificação das leveduras, utilizou-se a técnica de MALDI-TOF. A avaliação biotecnológica das leveduras foi realizada em relação à produção de xilitol, etanol, proteína e biomassa e, para isso aplicaram-se testes de fermentação de xilose e em hidrolisados de substratos lignocelulósicos de café. A produção de etanol foi avaliada pela técnica de HPLC, e a determinação de proteína, pelo método de Kjeldahl. A produção de biomassa foi calculada por meio de uma curva de calibração. Do isolamento, obtiveram-se 236 leveduras, analisadas por MALDI-TOF. Dessa análise, encontraram-se espécies ainda não relatadas para cavernas. Quanto à avaliação biotecnológica, foi encontrado que nenhuma cepa produziu xilitol e que algumas cepas foram capazes de produzir etanol. A respeito da produção de proteína, uma cepa identificada como C. orthopsilosis apresentou maior porcentagem de proteína (35,8%). Os resultados obtidos permitiram verificar que as cavernas não são ambientes totalmente isolados do meio externo. A estrutura da caverna, a sua interação com o meio externo e as alterações do meio circundante influenciam na entrada de matéria orgânica nas cavernas. Isso influencia na presença de leveduras nas diferentes zonas das cavernas. Além disso, este é o primeiro trabalho em que é realizada a caracterização biotecnológica de leveduras de caverna. Os resultados obtidos permitiram conhecer os parâmetros-chave para melhorar a produção de etanol, proteína e biomassa dessas leveduras em hidrolisados lignocelulósicos para futuros trabalhos.Item Evaluation of aqueous coffee husks extracts as a corrosion inhibitor of 1020 carbon steel in 1 mol L-1 HCl solution(ABM, ABC, ABPol, 2019) Ramos, Samantha Alcântara Fernandes; Senna, Lilian Ferreira de; Lago, Dalva Cristina Baptista doCorrosive processes in acidic medium reduce the performance and durability of metallic materials, causing problems to several industries. Corrosion inhibitors are commonly used to decrease these effects. As these inhibitors must be ecologically friendly currently, this work evaluated the anticorrosive effect of natural extracts of coffee husks (Coffea arabica L.) in the protection of carbon steel in 1 mol L-1 HCl solution. Extractions were performed using water as the extraction solvent. The polyphenols content increased with the extraction temperature, and the extracts were produced using 100 ºC. Extract concentrations of 10, 20 and 30 % v/v were analyzed as inhibitors for carbon steel in acid medium, using weight loss and electrochemical tests, as well as scanning electron microscopy. There was an increase in the inhibition efficiency as the extract concentration increased, reaching values around 97 % using 30 %v/v of extract for the weight loss tests.Item Kinetic parameters study for the slow pyrolysis of coffee residues based on thermogravimetric analysis(Sociedade Brasileira de Química, 2020) Tibola, Fernando L.; Oliveira, Tiago J. P. de; Cerqueira, Daniel A.; Ataíde, Carlos H.; Cardoso, Cássia R.Thermal decomposition of coffee husks was investigated by thermogravimetric analyses. The proximate, ultimate and composition analyses were performed. Thermogravimetric tests were realized, the material was heated to 1173 K using five heating rates: 5, 10, 15, 20, 25 K min-1. The kinetic parameters were estimated using the methods of Kissinger-Akahira-Sunose and Friedman, the distributed activation energy model and the independent parallel reactions model. The isoconversional models of Kissinger-Akahira-Sunose and Friedman showed the dependence between determined values of activation energy and mass conversion, the activation energy values varied from 1437.39 to 199.22 kJ mol-1 for Kissinger-Akahira-Sunose and from 127.81 to 230.35 kJ mol-1 for Friedman model. The values of activation energy were determined for Miura-Maki method; varying from 137.39 to 199.22 kJ mol-1. The model of parallel and independent reactions showed the presence of six different reactions (with activation energy values varying from 42.0 to 214.2 kJ mol-1) occurring during coffee husks pyrolysis, indicating a complex reaction. Currently, works regarding the determination of kinetic parameters for coffee husks pyrolysis are not common. The present work is the first report using the model of parallel and independent reactions to estimate kinetic parameters for pyrolysis of coffee husks, a residue widely generated worldwide.