Rapeeporn Ruangchuay, Chokchai Lueangthuwapranit and Suthon Kongrueang

DOI: 10.14456/sjst-psu.2021.116

pp. 881 - 888

Abstract

The agarophytic seaweed Gracilaria fisheri is used as food and also for agar extraction. This study investigated the use
of a novel cleaning method to improve the quality of seaweed products. Dried seaweed was sampled from seaweed farms in
Pattani province of southern Thailand during the dry and wet seasons and from seaweed sold in souvenir shops in the area, to
determine the level of contamination and to assess quality and appearance before and after cleaning. A whirlpool washing
machine was used for the cleaning. The concentrations of the heavy metals Mn, Fe, Cr, Cd, Zn, Ni, Cu, and Pb were investigated
in the seaweed, and in the seawater and sediment in which it was grown. The sensory and external qualities were evaluated by 30
testers. The results showed that the concentrations of heavy metals in the seaweed were similar to those in the seawater and that
most of the external contamination in the seaweed during the dry and wet seasons, as well as in the purchased samples was from
mollusks and epiphytes. Nine cycles of cleaning in the washing machine produced the lowest heavy metal concentrations and
external contamination in the dried G. fisheri. The sensory evaluation showed that the color, smell, texture, and extent of
contamination were superior in the seaweed subjected to nine washing cycles. The cleaning method adopted in this study for G.
fisheri was able to effectively reduce the heavy metal concentrations by scraping off the cell walls, and to cleaning the seaweeds.
Using a washing machine is therefore recommended prior to preparing the product for sale. 

Keywords

• Gracilaria fisheri
• edible seaweed
• heavy metal
• contamination
• post-harvest