Potential of local k-carrageenan extracted from red seaweed (Eucheuma cottonii) as food packaging material

Interest in renewable packaging materials over the synthetic petroleum-based packaging has been rose recently. κ-carrageenan from local red seaweeds (Eucheuma cottonii) has great potential as the renewable sources and was not explored extensively. Therefore, this research was focused on the development and properties of the κ- carrageenan films extracted from Malaysia’s E. cottonii. In the first objective, physical properties of κ-carrageenan films with different concentration (10-60%) and type (glycerol, sorbitol, and polyethylene glycol (PEG)) of plasticizers were studied. The overall observations revealed that films contained sorbitol showed the best properties than films contained glycerol and PEG, especially in water barrier properties. Sorbitol-plasticized films had lowest (p<0.05) water vapor permeability (WVP) (4.2 x 10⁻¹⁰ g mm s⁻¹ m⁻² Pa⁻¹) and water uptake ratio (WUR) (2278.1%) at the 30% concentration of plasticizer. Concentration of plasticizers did influence (p<0.05) the κ-carrageenan films except for the films that contained sorbitol (p>0.05). The tensile strength (TS) and elongation at break (EAB) of films was decreased and increased (p<0.05), respectively with the increasing of plasticizers. The addition of plasticizers reduced the opacity of films (p<0.05) while the color of films was not affected (p>0.05). In the second objective, the effects of palm oil at different levels (0.5-2%) on the properties of local (C1: Lucky Frontier, Malaysia) and commercial (C2: Tacara, Malaysia; C3: MSC Co., Korea; C4: Rico Co., Philippines) κ-carrageenan films were studied. The water barrier properties of κ-carrageenan films were improved along with the increasing of palm oil concentrations (p<0.05), irrespective of the κ-carrageenan sources. The addition of palm oil produced thicker and more opaque films (p<0.05), decreased the TS and thermal properties (p<0.05), but increased the EAB (p<0.05) and the contact angle (p<0.05). The C4 films showed the best in overall properties including lowest WVP (3.2 x 10⁻¹⁰ g mm s⁻¹ m⁻² Pa⁻¹), WUR (22.48.1%), and film solubility (FS) (61.1%) (p<0.05). In the third objective, the potential of κ-carrageenan coatings to protect and maintain the quality of fresh-cut pineapples was investigated for 9 days. The C1 and C4 κ- carrageenan with and without 2% of palm oil were used as the formulation of coatings. κ-carrageenan coatings had protected the fresh-cut pineapples from weight loss and microbes and maintained their firmness (p