Biodegradable plates made of pineapple leaf pulp with biocoatings to improve water resistance

Abstract

A crucial property of fibrous packaging paper for food is water resistance, while strength properties are also important. To improve these properties, several bio-coating solutions were applied as coatings on paper made of pineapple leaf pulp. The effects of beeswax, chitosan, shellac, alginate/gellan gum and beeswax–chitosan (1% chitosan+4%glycerol+30%beeswax) solutions on pineapple leaf pulp paper were assessed in relation to making biodegradable paper plates. The cooking time (120–180 min) of chemical pulping and the dose of pulp by moist weight (200, 250, and 300 g) to a paper frame (40 × 40 cm2) were also studied on making the paper samples. The papers were tested for their physical and mechanical properties. The optimal cooking time and dose of pulp by moist weight found were 180 min and 300 g of pulp per frame, respectively. The bio-coatings increased average grammage and thickness of paper, but gave density reduction from that of uncoated paper. Coating paper with beeswax–chitosan solution gave the longest absorbency time, followed in rank order by alginate/gellan gum, chitosan, beeswax and shellac. The maximum 5.9 kN/m2 tensile strength was found for paper coated with beeswax–chitosan solution before hot pressing. On comparing papers bio-coated before or after hot pressing, no difference was found in the degradable time with NaAlg/gellan coating, while such difference was observed with beeswax-chitosan coating. The results suggest beeswax–chitosan solution as the best among the alternatives tested, for coating paper to make biodegradable plates.

Keywords

• Beeswax
• Biodegradable
• Bio-coating solutions
• Chitosan
• Pineapple leaf fibers