Ferulic acid (FA) is well known for its variety of biological activities. However, FA has low water solubility, which limits its potential applications in the food and pharmaceutical industries. In this study, FA was encapsulated by spray drying with maltodextrin (MD) and hydroxypropyl methylcellulose (HPMC) under optimal ratios to address this limitation. The FA/MD complex was effectively formed at FA 8%:MD 20% and the FA/HPMC complex at FA 10%:HPMC 25%. Encapsulation efficiency, solubility, and stability were evaluated by high-performance liquid chromatography. The characteristics and morphology of each material and complex were analyzed by an X-ray diffractometry, Fourier transform infrared spectrometry, differential scanning calorimetry and scanning electron microscopy. All these analyses indicated that FA was well encapsulated with MD and HPMC. Moreover, encapsulated FA had enhanced water solubility and stability. Thus, FA may be a promising ingredient for the food and pharmaceutical industries.
Bibliographical noteFunding Information:
This work was supported by School of Life Sciences and Biotechnology for BK21PLUS, Korea University and a grant from the Institute of Biomedical Science & Food Safety, Korea University and Noksibchoaloe .
The experiment was carried out to find the optimal FA encapsulation ratio with MD and HPMC; thus, an FA/MD complex and FA/HPMC complex were formed. The modification was based on the method by Higuchi-Connors (Higuchi, 1965). A solution containing FA and biopolymers is required for encapsulation by spray drying. The ratio of FA and biopolymers is a factor that determines the encapsulation efficiency, so their optimum conditions were investigated. The criterion for optimal conditions is the maximum acceptance of FA, and excess FA was added to the various concentrations of biopolymer to determine the concentration to satisfy this criterion (Fig. 1A). The experimental results revealed that FA bound the most in MD 20% and HPMC 25%. At these concentrations, the FA content showed relatively higher results than other concentrations and it showed a significant difference. In Fig. 1A, the initial increasing portion of the curve indicates the formation of new complexes as the concentration increases with biopolymers concentration. However, the graph starts to decrease at too high concentrations. In high-concentration biopolymers, there are many hydroxy groups in MD and hydroxypropoxy in HPMC, so interactions occur between them instead of FA. Since the formation of complexes between FA and biopolymers is relatively reduced, it means that the concentration just before the decrease is the concentration of biopolymers that can accommodate FA to the maximum (Mathew & Abraham, 2008). Fig. 1B shows the exact FA concentrations that can be combined with the biopolymers concentrations obtained in Fig. 1A (MD 20% and HPMC 25%). Statistical differences are observed at each concentration and the graph shows that equilibrium begins at FA 8% in the MD group and at FA 10% in the HPMC group. Reaching equilibrium means that there are no more biopolymers to form complexes because most biopolymers have already joined with FA to form new complexes. Therefore, the point that equilibrium begins is the optimum ratio at which the substances are bound to each other at the maximum. Additionally, sediment was observed at higher FA concentrations because there were no more biopolymers to bind to FA, which supports the evidence that this result is the optimal ratio. In summary, the optimal ratio of the FA/MD complex was FA 8%:MD 20% and of the FA/HPMC complex was FA 10%:HPMC 25% to produce effective encapsulation complexes. The proportions were selected to produce FA encapsulation complex powder by a spray drier and these were used in all following steps.This work was supported by School of Life Sciences and Biotechnology for BK21PLUS, Korea University and a grant from the Institute of Biomedical Science & Food Safety, Korea University and Noksibchoaloe.
© 2020 Elsevier Ltd
- Encapsulation complex
- Ferulic acid
- Water solubility
ASJC Scopus subject areas
- Food Science
- Chemical Engineering(all)