Skin extracted pineapple juice as pulping and bleaching agent in papermaking process

Abstract

Pineapple has been known for a number of beneficial biological activities such as antioxidative and anti-browning. Some of these bioactivities are considered to be contributed by bromelain, the enzymatic complex in pineapple. This bromelain enzyme is found mainly in the skin extracted pineapple juice. Thus, it has been used to study the effect of the juice as a pulping and bleaching agent in the process of papermaking. During pulping of pineapple leaf fiber, the mixture of pineapple juice/water was added together with a constant amount of 3% NaOH at various concentrations of pineapple juice (0%, 20%, 40%, 60%, and 80%). Several soaking time have been utilized in both pulping and bleaching process in order to get the optimum time for a fiber to be pulped and bleached by the mixture. The mechanical and physical properties of paper sheet have been studied by performing tensile strength, tear resistance and water absorption test. The optical property such as brightening test was done by employing the instrument of spectrophotometer. The morphological property was observed by using the microscope at 50X magnification. Comparatively, paper sheet produced from NaOH pulping shows better mechanical and physical properties than pulping with the mixture of NaOH and pineapple juice. Pulping with higher concentration of pineapple juice tends to give long fiber rather than short fiber and it is not really favorable in papermaking process. Meanwhile, bleached sample gives the best brightening value but it shows poor mechanical and physical properties. Overall, pulping and bleaching with skin extracted pineapple juice can be added as an alternative way in the production of paper due to its low cost and environmental friendliness. It also opens a door to utilize wisely the waste residue of pineapple.