Banca de DEFESA: HEMERSON DANTAS DOS SANTOS
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.DISCENTE : HEMERSON DANTAS DOS SANTOS
DATA : 03/05/2019
HORA: 14:00
LOCAL: Instituto de Química
TÍTULO:
Chemometric analysis of NMR data of coffee from the Chapada Diamantina region (state of Bahia, Brazil)
PALAVRAS-CHAVES:
Coffee. Chapada Diamantina (State of Bahia, Brazil). NMR. Chemometrics.
PÁGINAS: 80
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Química dos Produtos Naturais
RESUMO:
The coffee from the Chapada Diamantina region, in the state of Bahia, Brazil, are considered high quality, due to the use of adequate production and processing criteria throughout the entire process. Studies about the chemical profile of coffee have correlated chemical composition, quality standards and data about geographical origin, thus contributing to antifraud methodologies. This research used Nuclear Magnetic Resonance (NMR) to study the chemical composition of coffee from Chapada Diamantina, in order to contrast them to coffee from other regions. We analyzed 37 commercial samples, which are classified, accordingly to their quality, as traditional, superior and gourmet.
1H NMR spectra were acquired on the Varian Inova 500 spectrometer of the Laboratório Baiano de Ressonância Magnética Nuclear (LABAREMN/UFBA). Analyzing the NMR data, we identified characteristic signals of chlorogenic acids (CGA), such as caffeoylquinic acids [6.74 - 6.80 m], alkaloids and xanthines as trigonelline [4.43 s] and caffeine [3.24 s, 3.41 and 3.84 s]. We also observed characteristic signals of furans (5-HMF [9.44 s]), amides and amino acids such as acrylamide [5.83 and 5.99 m] and L-alanine [1.39 d (6 Hz)]. Finally, we identified signals of organic acids, such as lactic acid [1.35 d (7 Hz)] and acetic acid [1.96 s], as well as carbohydrates and lactones, such as myo-inositol [3.27 - 3.35 m] and γ-butyrolactone [2.15 - 2.18 (m)]. The pretreatment of the
1H NMR spectra was made using alignment, autoscaling, and normalization (norm one). Then, the principal components analysis was performed. In the PCA scores plot, we observed four groups, which were denominated Chapada Diamantina, Bahia, Brazil and gourmet/superior. The coffee from Chapada Diamantina presented a characteristic chemical profile, which distinguished them from the others, mainly because they contain higher levels of aliphatic compounds. The coffee from that region which present highest commercial value and which are classified as gourmet were grouped with Colombian coffee and some national ones with similar quality standards. This group presented higher levels of chlorogenic acids and trigonelline, substances which contribute to the pleasant aroma and taste of the beverage. The chlorogenic acid signals of coffee from other regions of the state of Bahia showed very low intensities. Coffee from other Brazilian states presented higher quinine levels in comparison than those from Bahia, and lower levels of chlorogenic acids than those from Chapada Diamantina. The results show that
1H NMR, coupled with chemometrics, is a very effective tool to discriminate coffee, allowing us to obtain from the data set as much information as possible, and to highlight its most important pieces. This methodology, whose efficiency has been proved by various studies, can help us understand complex mixtures.
MEMBROS DA BANCA:
Presidente - 1756798 - ELISANGELA FABIANA BOFFO
Interno - 2422743 - GISELE ANDRE BAPTISTA CANUTO
Interno - 3768242 - PAULO ROBERTO RIBEIRO DE JESUS
Externo à Instituição - ROSILENE APARECIDA DE OLIVEIRA - UESC-BA
Externo à Instituição - LOURDES CARDOSO DE SOUZA NETA - UNEB