PDF《American Journal of Applied》

30 min using Kjeldahl digester (Tecator Kjeltec System, Germany) at minimum temperature 400°C. After that,

50 mL distilled water was added for distillation using Kjeldahl distillation. Then, the sample was titrated with hydrochloric acid (0.20 N) to calculate the amount of HCL present in NaOH solution (40%). The boric acid solution (4%) was used for the catalyst reagent. The percentages of nitrogen were converted to protein by multiplying by 6.25. Water activity: The powder was placed inside the plastic placing sample. It was measured using Aw sprint (Swiss made NOVASINA TH-500) water activity equipment. Crude fiber: Two gram of sample was put into

250 mL conical flask and 1.25% Sulfuric acid solution was added. The sample was heated about

30 min and was filtered using vacuum filter (today'

s vacuum filtration VF 100) and washed until traces of acid was undetected using pH paper. The Whatman paper 5B which pore size

125 micrometer was placed in the Buchner flask. After that the acid extracted was transferred into

250 mL conical flask and 1.25% NaOH solution was added. The sample was heated again for

30 min and was filtered using vacuum filter and washed with water until base was undetected. The whole material was transferred into crucible and dried for

12 h at 120°C. After that the crucible was placed into muffle oven at 550°C for

12 h and weight of crucible was recorded. Am. J. Applied Sci.,

6 (7): 1341-1346,

2009 1343 Ascorbic acid: Five gram of fresh pitaya stem was cut and homogenized using warring blender. The sample was filtrated using Muslin cloth. The filtrate will used to determine the ascorbic acid content using reflectometer (Merck KGaA,

64271 Darmstadt,........