Microwave-assisted extraction of phenolics from pineapple (Ananas comosus) peel for green zero-valent iron production

Date of Publication


Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Chemical Engineering


Gokongwei College of Engineering


Chemical Engineering


Outstanding undergraduate thesis in Chemical Engineering, 2016

Thesis Adviser

Cynthia F. Madrazo
Marylou M. Uy

Defense Panel Chair

Susan A. Roces

Defense Panel Member

Luis F. Razon
Vergel C. Bungay
Nathaniel P. Dugos
Jonathan R. Dungca


This study focused on the optimization of the microwave-assisted extraction (MAE) of phenolic compounds, from pineapple peel. Pineapple peels were used because of the high pineapple production in the country which means that large amounts of pineapple waste are also available. Furthermore, pineapple contains high amounts of phenolic compounds.

An efficient way of extracting phenolic compounds in plant matrices is by MAE. In this study, MAE was done to optimize the extraction with parameters of extraction time (1 to 5 min), solvent-to-solid ratio (SSR) (10:1 to 50:1), and microwave power (100W, 300W, 500W) with 95% (v/v) ethanol as the solvent. The phenolic yield was determined by the use of Folin-Ciocalteu method in terms of gallic acid equivalents (GAE). The range of the yield was from 0.6479 to 3.7466 mg GAE/g dry peel. Using the parameters of the maximum value, the optimum was found to be at 300W, 50 SSR and 5 min.

It is important to extract these phenolics because of its many beneficial properties and uses. One of its possible applications is a reducing agent for zero-valent iron (ZVI) production.

After optimization for maximum yield using response surface methodology, the optimum sample extract was obtained and was reacted with an iron (III) chloride solution to form the ZVI particles. An electron scanning microscopy was done to optically confirm ZVI particles, while an energy-dispersive x-ray spectroscopy was utilized to elementally determine the presence of iron.

It was concluded that microwave-assisted extraction is effective for extracting phenolics from pineapple peels. The optimal phenolics yield was also enough to produce the ZVI particles. However, the yield may still be increased further. Thus, it is recommended to vary the extraction parameter settings to improve phenolics yield.

Abstract Format




Accession Number


Shelf Location

Archives, The Learning Commons, 12F Henry Sy Sr. Hall

Physical Description

ix, 82 leaves : illustrations (some color) ; 28 cm. + 1 computer disc 4 3/4 in.


Microwaves; Phenols; Carbon dioxide; Carbon compounds

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