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Title:	Optomization of pectin extraction from dragon fruit peel using microwave assisted extraction
Authors:	Shahrooz Rahmati (P54232)
Supervisor:	Aminah Abdullah, Professor Dr.
Issue Date:	10-Sep-2013
Description:	Microwave-assisted extraction (MAE) was applied to extract pectin from dried dragon fruit peels (Hylocereus costaricensis). The extracted pectin has been identified using Fourier transform infrared spectroscopy (FT-IR), degree of esterification and galacturonic acid content. Optimization was carried out using central composite design (CCD) based on four different levels of microwave power (300, 450, 600 and 800 W). Three independent variables in terms of pH of HCl solution, X1 (1, 1.5, 2, 2.5, 3), extraction time, X2 (20, 35, 50, 65, 80 s) and volume of HCl solution, X3 (30, 50, 70, 90,110 ml) were investigated to optimize the highest yield of pectin. Analysis of variance (ANOVA) indicated that the extraction time was the most significant factor affecting response values. Besides, the extraction rate of pectin from the dried dragon fruit peel was affected by pH of HCl solution and microwave power levels. The optimal conditions of three independent variables were as: ; . The optimal predicted extraction yields were 11.83, 14.92, 17.22 and 18.53% respectively. The verification tests indicated close agreement between experimental and predicted values for each condition which were 11.8, 14.9, 17.2 and 18.50% respectively. The extracted pectins from the optimum condition were selected for further analysis. The physico-chemical properties of pectins which were monitored in this study included ash, moisture and protein content, degree of esterification, galacturonic acid content, intrinsic viscosity, texture profile analysis (TPA), color measurement, microscopic examination by using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed that with increasing microwave power from 300 W to 800 W, the mean ash content of extracted pectin decreased from 10.8 to 8.7% while, the moisture content also showed a significant decrease (p≤ 0.05) from 9.5 to 4.1%. The protein content increased from 2.6 to 5.5%. The degree of esterification of the pectin was between 45% to 48.6% which was less than 50 which indicated the presence of low methoxyl pectin in dragon fruit peels. The galacturonic acid content of pectin was in the range from 56.9 to 69.7%. The TPA results had showed a good gelling properties of pectin extract by using microwave assisted extraction. The SEM images demonstrated the effects of microwave radiation on dragon fruit peel's tissues which facilitated the interaction between solvent and material. The pectin extracted with microwave power levels of 800 W was more crystalline in nature because its XRD pattern showed sharper peaks than other extracted pectin. The FTIR spectra confirmed the presence of pectin in dragon fruit peels and detected that there was no significant structural differences among pectin samples. The galacturonic acid content of pectin was 56.9% using conventional method but increased up to 69% in microwave assisted extraction method. In conclusion, the microwave extraction technique gave better results compared to conventional method based on the quality and yield of the pectin. The results also suggested that dragon fruit peel had high potential as a new source of pectin.,Master/Sarjana
Pages:	145
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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