This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.
Rev. Fac. Agron. (LUZ). 2024, 41(3): e244128 July-September. ISSN 2477-9407.
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Resumen
El estudio cinético de la extracción sólido-líquido de cafeína
en Ilex guayusa Loes aborda una etapa crítica en el aislamiento
de alcaloides como la cafeína. La extracción sólido-líquido, una
técnica ampliamente utilizada, desempeña un papel fundamental en
la obtención de estos compuestos. El estudio tuvo como objetivo
evaluar la aplicabilidad de la ecuación de Peleg para modelar la
extracción sólido-líquido de cafeína en hojas de Ilex guayusa Loes.
El contenido de cafeína se determinó por espectroscopía de absorción
UV-visible. La cinética de extracción se estimó utilizando la ecuación
de Peleg de dos parámetros. La correspondencia de los resultados
experimentales y los predichos por el modelo se estableció mediante
el cálculo de correlación de Pearson. Los resultados indicaron efectos
signicativos de la temperatura y el tiempo de extracción en el
contenido de cafeína, con concentraciones que variaron desde 0,24
hasta 1,52 g.100 g
-1
a diferentes temperaturas de extracción (30, 40
y 50 °C). La ecuación de Peleg modeló ecazmente la cinética de
extracción de cafeína, con altos coecientes de correlación de Pearson
(0,96895 a 0,99685) que conrmaron su idoneidad para predecir la
concentración de cafeína. Estos resultados resaltan la importancia de
comprender la cinética de extracción para optimizar los procesos de
extracción de cafeína, ofreciendo ideas valiosas para las industrias
que utilizan extractos de Ilex guayusa Loes.
Palabras clave: cinética, ecuación de Peleg, extracto acuoso, modelo
matemático.
Resumo
O estudo cinético da extracção sólido-líquido da cafeína em Ilex
guayusa Loes aborda uma etapa crítica no isolamento de alcalóides
como a cafeína. A extração sólido-líquido, técnica muito utilizada,
desempenha um papel fundamental na obtenção destes compostos. O
estudo teve como objetivo avaliar a aplicabilidade da equação de Peleg
para modelar a extração sólido-líquido de cafeína em folhas de Ilex
guayusa Loes. O teor de cafeína foi determinado por espectroscopia
de absorção UV-visível. A cinética de extração foi estimada através
da equação de Peleg de dois parâmetros. A correspondência entre os
resultados experimentais e os previstos pelo modelo foi estabelecida
pelo cálculo da correlação de Pearson. Os resultados indicaram
efeitos signicativos da temperatura e do tempo de extração no teor
de cafeína, com concentrações que variaram entre 0,24 a 1,52 g.100
g
-1
a diferentes temperaturas de extração (30, 40 e 50 °C). A equação
de Peleg modelou ecazmente a cinética de extração de cafeína, com
elevados coecientes de correlação de Pearson (0,96895 a 0,99685)
conrmando a sua adequação para prever a concentração de cafeína.
Estes resultados realçam a importância de compreender a cinética de
extração para otimizar os processos de extração de cafeína, oferecendo
informações valiosas para as indústrias que utilizam extratos de Ilex
guayusa Loes.
Palavras-chave: cinética, equação de Peleg, extrato aquoso, modelo
matemático.
Introduction
Caeine, a methylxanthine naturally present in several plants, has
been the subject of extensive research due to its stimulant eects on
the human central nervous system (Mahoney et al., 2019). Among
these plants, Ilex guayusa Loes, a shrubby species in the family
Aquifoliaceae, has emerged as a promising source of caeine,
especially in the Amazon of South America (Kelebek et al., 2024).
The solid-liquid extraction of caeine in I. guayusa represents a
fascinating and relevant eld of study in the current scientic context.
The extraction of bioactive compounds represents a fundamental
step in the isolation and identication of alkaloids such as caeine
(Rajput, 2022), and there is no single method that guarantees its
eciency. Among the most commonly used extraction techniques
for alkaloid isolation is solid-liquid extraction (Vandeponseele et
al., 2021), which plays a key role in obtaining these compounds. To
describe the mechanism underlying this process, Fick’s second law of
diusion is commonly employed, oering an in-depth understanding
of the matter transfer processes involved (Li et al., 2020; Hashim et
al., 2023).
Recent research has reported the caeine content in I. guayusa
(Paladines-Santacruz et al., 2021; Carvalho et al., 2021). However,
bibliographic data on the extraction kinetics of the solid-liquid
process are scarce. This lack of specic information highlights the
need to develop mathematical models that facilitate the simulation,
design, and control of extraction processes, thus contributing to the
ecient use of resources such as energy, time, and solvent.
On the other hand, mathematical models have an important role
in describing sorption processes, such as dehydration (Korniyenko
and Ladieva, 2021) and rehydration of food products (Tepe, 2024).
Among these models, the non-exponential Peleg model (Lalji et al.,
2022), which consists of two parameters, has proven to be particularly
useful. Given the similarity between extraction kinetics and sorption,
the study aimed to evaluate the applicability of Peleg's equation to
model the solid-liquid extraction of caeine in the leaves of Ilex
guayusa Loes.
Materials and methods
Experiment location and sample preparation
This study was carried out at the Bromatology Laboratory of the
Amazonian State University, located at km 2 ½ on the road to Tena,
in the canton and province of Pastaza, with an altitude of 940 meters
above sea level, 00° 59 ́-1” latitude and 77° 49 ́0” west longitude.
The leaves of
I. guayusa were purchased in the market of the city
of Puyo, Pastaza-Ecuador, at coordinates 1.4837° S 78.0026° W.
The leaves were washed with deionized water and then dried under
shade at room temperature. Subsequently, they were placed in a stove
(Memmert brand, SFE700 model) at 40 °C for 72 h, and the humidity
present in the leaves was calculated by mass dierence (Yu et al.,
2022). The result was used to express the initial mass of the leaves
based on the dry matter. The plant material was crushed in a mill
(KitchenAid brand, BCG111OB model), with a nominal frequency of
60 Hz. They were then sieved to obtain particles smaller than 0.5 mm.
Preparation of the extracts
For the solid-liquid extraction of caeine, the ultrasound-
assisted extraction technique (UAE) was performed using Wisd.23
equipment, WUC-DO6H model according to the procedure described
by Peñael-Bonilla et al. (2023). In each experiment, 5 ± 0.1 g of
ground I. guayusa was weighed into round-bottom asks, and 100
mL of distilled water was added. Each extraction was performed
in triplicate at 30, 40, and 50 °C for periods ranging from 10 to 90
minutes, with 5 intervals for each temperature. The obtained extracts
were ltered using Whatman No. 4 lter paper and the caeine
analyses were carried out immediately.