After the leaf fiber was obtained, ten fiber samples in green condition weighing approximately 100 g were randomly selected. Then the samples were taken to the laboratory where they were put to dry into an oven at 103 °C for 24 h to determine the moisture content (Eq. 7.1). The moisture content of the waste from fiber extraction was also determined by means of Eq. 7.1.

, . Green weight (g)- Dry weight (g)

Moisturecontent (%)= x100 (7.1)

Green weight (g)

7.2.4 Fiber Color and Color Change

Fiber color was tested during three stages of fiber production. These were as follows: (1) after the fiber came out of the scrapping machine, when the fiber was in green condition; (2) after the application of the three bleaching treatments; and (3) after fiber drying. Color was measured with a Hunter Lab spectrophotometer, miniScan XE Plus model, to obtain parameters L*, a*, and b*. Since colorimeter diameter in its measuring area is 1 cm, fiber rolls of the appropriate thickness were prepared in order to fit the hole totally. Color change (AE*) was determined with the difference between the color of the fiber obtained with the prototype machine and the color after treatment (with water, peroxide, or hypochlorite). The value of AE* for color of the fiber obtained with the prototype machine and fiber color after drying was also obtained. To determine AE*, the ASTM D 2244 (ASTM 2012) standard was used. This standard defines AE* as the net color variation after a period and is obtained by means of Eq. 7.2.

( 7.2 )

where AE*: pineapple fiber color change; AL: L* fiber color after scrapping-L* after washing or after fiber drying; Aa: a* fiber color after scrapping-a* after wash­ing or after fiber drying; Ab: b* fiber color after scrapping-a* after washing or after fiber drying.