Use of a humidity adsorbent derived from cockleshell waste in Thai fried fish crackers (Keropok)

Abstract

In this research, cockleshell waste from food processing is developed into a humidity adsorbent using a simple technique. Cockleshells were first heated at 1,000°C. The crystal structure, functional group, and morphology of cockleshells before and after heat treatment were investigated. Cockleshells before heat treatment had the aragonite phase of CaCO3 compound, but it transformed into the CaO phase after heat treatment. Next, fried fish crackers, Keropok, were selected for humidity testing. The behavior of the humidity adsorbent and fried fish crackers was investigated for 0–180 days. After humidity testing, the CaO phase of the humidity adsorbent reacted with the humidity or water molecules and transformed into the Ca(OH)2 phase. The amount of crack and roughness on the humidity adsorbent surface increased with the increase in humidity testing time. The humidity adsorbent underwent a high humidity reaction and transformed into Ca(OH)2 after 30 days. The water activity, crispness, and thiobarbituric acid-reactive substances (TBARS) of fried fish crackers were analyzed. The water activity of fried fish crackers rapidly decreased, whereas the crispness slowly decreased in the range of 0–30 days. The humidity adsorbent controlled the TBARS value by increasing slowly. Based on these results, cockleshell waste can be developed as a humidity adsorbent and used to prolong the shelf-life of local food products to at least 90 days.

Keywords

• cockleshell waste
• calcium hydroxide
• humidity adsorbent
• heat treatment
• fried fish crackers