Encapsulation of liquid herbal extract for drying in a packed bed system

Yim, Zhi Hui (2010) Encapsulation of liquid herbal extract for drying in a packed bed system. Masters thesis, Universiti Malaysia Sabah.


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Encapsulation of aqueous herbal extract was demonstrated in the first part of this study. Two approaches were used for the encapsulation of herbal aqueous extract, i.e. through absorption with the ca-alginate hydrogel beads and the drippinggelation method. A model herbal aqueous extract, Piper sarmentosum and caalginate as the encapsulating material were used throughout this work. In the study on the absorption of extract with ca-alginate bead, the effect of process variables (i.e. alginate MIG ratio, alginate concentration, extract concentration, bead size and bead water content) on encapsulation efficiency was evaluated. The results show that the encapsulation efficiency was mainly affected by the MIG ratio and the initial beads water content. In general, the beads produced from higher MIG ratio and with lower initial water content could absorb significantly more aqueous extract. Interestingly, the lower MIG ratio beads were found to have higher antioxidant affinity. Meanwhile, in the study of encapsulation of herbal extract by dripping gelation method, it was found diffusion of the herbal antioxidants during gelation was the major setback of the method. In most cases, half of the herbal antioxidants diffused to the gelation bath within 5 minutes. The diffusion mechanism of herbal antioxidants during gelation was mainly obeying Fick's Law. The second part of this study involved drying of encapsulated extract in packed bed system, it was found that the efficiency of drying encapsulated extract and blank ca-alginate beads in packed bed system was mainly a function of increasing drying temperature, air flow rate, particle size and decreasing drying air humidity. Besides, the drying rates of encapsulated extract were generally lower than that of the blank ca-alginate beads under the same conditions. The majority of the evaluated drying models showed satisfactory goodness of fit (R-sq. values > 0.99 and the Chi-sq. values < 0.0012). However, the calculated parameters of the Midilli et at. model could not establish clear relationships with the process variables. On the other hand, the Lewis model was found to be simple and gave clear relationships between the parameter of the model and the process variables. The antioxidant contents of the final products were satisfactory preserved and ranging from 82.6 to 95.3% was retained at the end of drying. More antioxidant contents could be preserved when drying air with higher relative humidity was used. In addition, quantitative analysis revealed that the packed bed drying is more advantageous over the conventional drying methods, i.e. spray drying and freeze drying. In short, this study reveals the potential of the packed bed drying process for encapsulated herbal aqueous extract and the process could be ready for optimisation.

Item Type: Thesis (Masters)
Uncontrolled Keywords: bed system, encapsulation of liquid, herbal queous extract, ca-alginate bead, piper sarmentosum, drying method, antioxidant
Subjects: T Technology > TP Chemical technology
Divisions: SCHOOL > School of Engineering and Information Technology
Date Deposited: 15 Jul 2013 05:55
Last Modified: 11 Oct 2017 07:12
URI: http://eprints.ums.edu.my/id/eprint/6558

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