Autores
Canzi, F.A. (FEDERAL UNIVERSITY OF LATIN AMERICAN INTEGRATION) ; Meireles, D.A.L. (FEDERAL UNIVERSITY OF UBERLÂNDIA) ; Valdez, A.S.B. (FEDERAL UNIVERSITY OF LATIN AMERICAN INTEGRATION) ; Abrantes, L.S. (FEDERAL UNIVERSITY OF LATIN AMERICAN INTEGRATION) ; Augusto, S.C. (FEDERAL UNIVERSITY OF UBERLÂNDIA) ; Valderrama, P. (FEDERAL TECHNOLOGICAL UNIVERSITY OF PARANÁ) ; Toci, A.T. (FEDERAL UNIVERSITY OF LATIN AMERICAN INTEGRATION) ; Boroski, M. (FEDERAL UNIVERSITY OF LATIN AMERICAN INTEGRATION)
Resumo
The importance of pollination by bees is recognized worldwide. This study
investigates the influence of biotic pollination on the chemical composition of
coffee (Coffea arabica L.) cultivated in the municipalities of Araguari and
Monte Carmelo, in southern Minas Gerais state, Brazil. Twenty samples were
analyzed, of which 10 were obtained from crops with bees as pollinators (P),
while 10 were from crops without pollinators (NP). Analyses were made of
bioactive compounds, antioxidant capacity, and proximate composition of the
coffees. The results revealed chemical differences between the biotically
pollinated and non-biotically pollinated samples, with significantly higher
levels of the bioactive compounds caffeine, trigonelline, and chlorogenic acids
in the biotically pollinated samples.
Palavras chaves
Pollination; Sustainability; Coffee Quality
Introdução
Pollination is one of the factors influencing the chemical composition of seeds.
Pollination by bees has recognized importance in economically relevant crops
such as cotton, coffee, orange, apple, and soybean, where it has been shown to
increase productivity (WITTER et al., 2014). Pollination is crucial in
ecosystems, with almost 90% of flowering plants requiring insects or other
animals to provide this service. In coffee plantations, observations showed that
Apis mellifera bees were most prevalent (73.7% frequency), followed by the bee
species Trigona spinipes (14.5%) and Tetragonisca angustula (9.5%). The fruiting
percentage was found to be higher when the bees were able to access coffee
branches, with bean production decreasing by 55.2% when access was denied
(MALERBO and SILVA, 2011). Therefore, the interest of rural producers in using
bees to increase productivity has grown in recent years.
Given the scarcity of information concerning the effect of pollination on the
chemical composition of coffee beans, together with the importance of the
bioactive compounds present in coffee, the main objective of this work was to
evaluate the effect of biotic pollination (P), compared to its absence (NP), on
the composition of major compounds (precursors of volatiles) and bioactive
compounds (chlorogenic acids, caffeine, and trigonelline) in Arabica coffee.
Evaluation was also made of the effects on total phenolic compounds and
antioxidant capacity.
Material e métodos
This study was undertaken in two municipalities (Araguari and Monte Carmelo) in
the Triângulo Mineiro region of Minas Gerais state (Brazil), at 10 coffee
plantations notable for their size and productivity. The municipality of Monte
Carmelo, is characterized by mainly undulating relief (60%), annual average
temperature of 21.2 oC, and annual average precipitation of 1444 mm. The
municipality of Araguari has predominantly flat relief (50%), average
temperature similar to that of Monte Carmelo, and annual average
precipitation of 1566 mm.
Moisture contents and total protein of the coffee samples were determined
according to AOAC (1984). The lipids content was determined gravimetrically, as
described by Toci et al. (2013). The total carbohydrates content was determined
according to the method described by Dubois et al. (1956).
Caffeine, trigonelline and Chlorogenic acids (CGAs) were extracted as described
by Trugo and Macrae (1984). They were quantified by high performance liquid
chromatography (HPLC).
Total phenolic compounds were evaluated according to the method of Singleton and
Rossi (1965). The antioxidant activity was determined using the method based on
deoxidation of the 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH•), as described
by El-Massry et al. (2002). The determination of reducing power was performed as
described by Oyaizu (1986), with adaptations (BOROSKI et al., 2015).
Chemometric evaluation employing principal component analysis (PCA) was
performed to identify parameters (variables) responsible for differentiation
between the P and NP samples.
Resultado e discussão
The PCA analysis provides informative graphs showing the similarities and
differences among samples, using scores, and how the scores pattern can be
explained using the loadings.
Based on the scores plot, differences between samples were observed for the same
municipality, depending on the procedure (P or NP). For Araguari, this
distinction was observed in PC6 (7.24% of explained variance), while for Monte
Carmelo, a tendency for separation was observed in PC5 (9.01% of explained
variance). Although these PCs did not present the highest explained variance, it
has been reported in previous studies that the main information existing within
a dataset is sometimes not observed in the PC that shows the highest explained
variance (MOREIRA and SCARMINIO, 2013; ALMEIDA et al., 2018). In the present
case, based on the scores plots, the P samples were separated on the PC negative
side, while the NP samples were on the positive side.
The loadings plot shows the crucial variables (parameters) that explain the
pattern observed in the scores. In the case of the P samples from Araguari,
caffeine, trigonelline, 3-CQA, 4-CQA, 5-CQA, 5-FQA, and reduction were the main
variables responsible for the observed behavior. Trigonelline was the most
influential parameter, due to the high concentrations in the P samples. The
other parameters for Araguari showed slightly higher values for P, compared to
NP. On the other hand, for the Araguari NP samples, the lipids content had the
greatest influence, followed by moisture, carbohydrates, proteins, 3,4-diCQA,
3,5-diCQA, 4,5-diCQA, phenolics, and DPPH•.
A difference was observed between the behaviors of the samples obtained from
Araguari and Monte Carmelo.
Conclusões
The results revealed chemical differences between the samples with and without
biotic pollination. The concentrations of the bioactive compounds caffeine,
trigonelline, and chlorogenic acids were generally significantly higher in the
biotically pollinated samples (P). This evidenced that the pollination of coffee
plants (Coffea arabica) by bees makes the beans more suitable for germination and
less liable to attack by external agents. In terms of proximate composition, the
NP samples showed the highest values.
Agradecimentos
The authors are grateful for the financial support provided by CAPES, CNPq (grant
#310776/2018-0), CNPq/MCTI/IBAMA/Associação A.B.E.L.H.A, PELD/TMSG (grants
#441225/2016-0 and #441142/2020-6), UNILA (#105/2020/PRPPG) and FAPEMIG.
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