SEMINAR IN FOOD SCINCE AND BIOTECHNOLOGY
Title: Microwave Assisted Extraction (MAE) of Labile Compounds in Plant Materials
Presented by: Ying Ming Chew (周應銘) 8103043003
Hosts: 蘇雅麗、林嘉鴻
Date: 26 December, 2014 (No. 5)
Abstract
Labile compounds with bioactive or aromatic properties have been identified in
different plant material. Some of these compounds are of high demand and have
long been used in pharmaceutical and food industry. However, the thermo unstable
and oxidizable characteristics of these compounds may result in loss or degradation
of the molecules due to long time exposure to heat and oxygen in the process of
conventional extraction. Among the newly developed extraction techniques as the
alternatives to conventional extraction, MAE has attracted special interest because it
not only consumes less solvent and shorter time of extraction, but also shows higher
extraction efficiency than that carried out by conventional extraction method.
Absorption of microwave energy by plant materials may cause the build-up of
pressure within the cellular material, leading to splitting of the cellular structure with
release of its content and eventually increases the efficiency of the extraction
process.
Efficiency of MAE method has been demonstrated respectively by Liazid et al.
(2011) and Garofulic et al. (2013) in the extraction of phenolic compounds from
grape skin and sour cherry Marasca. In the study performed by Liazid et al.,
anthocyanins extraction from grape skin was carried out by MAE and conventional
maceration method respectively. The study concluded that total recoveries were
similar between the two methods used, yet the time of extraction was reduced from
5 hours to 5 minutes if MAE method was applied. On the other hand, the study by
Garofulic et. al. with regards to extraction of anthocyanin and phenolic acids from
cherry Marasca has also evidently shown that recoveries of these components
appeared to be higher than those carried out by conventional method even though
the extraction time was shorter.
In addition, data obtained by Xiao et. al. (2012) in the extraction of Vitamin C,
Beta-carotene, and Aloin A respectively from green pepper, carrot, and aloe vera
indicated that MAE is a fast and effective way for extraction of the three components
as compared to conventional solvent extractions. Especially for the extraction of
heat-labile component such as Beta-carotene and Aloin A, a more significant
improvement in yield percentage can be observed. In addition, the study also
emphasized that extraction efficiency can be further improved if a combination of
low temperature vacuum system and MAE technique is utilized.
Other than the above studies, MAE method has also been applied in the
extraction of essential oil from plant material. A method called solvent-free
microwave extraction (SFME) was successfully demonstrated by Filly et. al. (2014)
and Qi et. al. (2014) respectively from rosemary plants and pigeon pea leaves. SFME
was carried out by placing wetted (or fresh) plant material within a microwave field
connected with a condensation flask for collection of essential oil vaporized from the
plant. Both studies carried out respectively by Filly et. al. and Qi et. al. have proved
that extraction of essential oil assisted with microwave irradiation can achieve higher
extraction efficiencies than that by conventional hydrodistillation method.
In conclusion, MAE method is apparently an effective and innovative technique
of extraction especially for the labile compounds from plant materials. Data from all
the above studies have indicated that MAE method has appreciably reduced the
extraction time and meanwhile provide the extracts with higher quality than that
provided by conventional extraction method.
Reference
Garofulic, IE, Dragovic-Uzelac, V, Jambrak, AR, and Jukic, M 2013, The effect of
microwave assisted extraction on the isolation of anthocyanins and phenolic acids
from sour cherry Marasca (Prunus cerasus var. Marasca), Journal of Food
Engineering, vol. 117, pp. 437-442.
Filly, A, Fernandez, X, Minuti, M, Visinoni, F, Cravotto, G, and Chemat, F 2014,
Solvent-free microwave extraction of essential oil from aromatic herbs: From
laboratory to pilot and industrial scale, Food Chemistry, vol. 150, pp. 193-198.
Liazid, A, Guerrero, RF, Cantos, E, Palma, M, and Barroso, CG 2011, Microwave
assisted extraction of anthocyanins from grape skins, Food Chemistry, vol. 125, pp.
1238-1243.
Qi, XL, Li, TT, Wei, ZF, Guo, N, Luo, M, Wang, W, Zu, YG, Fu, YJ, and Peng, X
2014, Solvent-free microwave extraction of essential oil from pigeon pea leaves
[Cajanus cajan (L.) Millsp.] and evaluation of its antimicrobial activity, Industrial
Crops and Products, vol. 58, pp. 322-328.
Xiao, X, Song, W, Wang, J, and Li, G 2012, Microwave-assisted extraction performed
in low temperature and in vacuo for the extraction of labile compounds in food
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