Fiber morphology and recovery chemical composition and pulp properties of abaca (Musa textilis Nee) cv. Inosa harvested at different stages of stalk maturity

The morphological, chemical and physical properties of abaca fibers cv. Inosa harvested at different stages of stalk maturity was investigated to determine the suitability of the fibers in the production of pulp and paper products, establish the interrelationships between fiber morphological and chemical properties on pulp yield and quality, and explore the possibility of getting maximum extractable fibers from abaca leafsheaths using different stripping methods. Abaca cv. Inosa at 8-10 months old already possess the inherent desirable characteristics of fibers for pulp and paper such as extremely long fiber cells (over 3 mm), thin cell walls, low runkel ratio (less than 0.70), high flexibility coefficient and high slenderness ratio. The morphological dimensions of fibers taken from 8-10 and 12-14 months old stalks were already comparable to mature fibers derived from 18-24 months old stalks. Fibers derived from 8-10 months old (young) abaca cv. Inosa already possess the desirable chemical properties for pulping as shown by the characteristic low lignin and ash content, high alpha-cellulose, holocellulose and hemicelluloses contents; comparable with those from intermediate and mature stalks. The average pulp recovery of fibers from abaca cv. Inosa was higher in all three stages of stalk maturity compared to Laylay and Linawaan cultivars. The Kappa number and viscosity of 'Inosa', in all three, stages of stalk maturity, were also high compared to 'Laylay' and 'Linawaan'. The maximum fiber yield potential of abaca cv. Inosa is not yet attained at early stage of maturity. Fiber yield of 8-10 months old abaca stalks was only 21% to 32% of those obtained from mature stalks, but usage wise, the fibers are already suitable for pulp and paper production. Fiber recovery was significantly increased to almost 100% using the modified spindle stripping method resulting to 64% increase in net income compared to the standard stripping method.