Yields and Properties of Sago Flour (Metroxylon sagu Rottb.) on the Different Stages of Sago Palm Tree in Nakhon Si Thammarat Province ผลผลิตและคุณสมบัติของแป้งสาคูระยะต่าง ๆ ในจังหวัดนครศรีธรรมราช

Abstract

The objective of this research is to know the utilization of sago palm tree from Nakhon Si Thammarat province, southern Thailand. Our aim is to investigate the production of sago flour from palm trees of different growth stages. This research also identifies the physicochemical properties of sago flour produced from three different growth staged palm trees; 1^st stage: the plants aged from 6-7 years, 2^nd stage: the plants before starting of flowering period and 3^rd stage: starting from flowering stage to antler shape period. Sago was collected from stem base, central trunk, and stem end. The whole body weight (mean ± standard deviation) of 1^st, 2^nd and 3^rd staged plants were 654.45±72.81, 780.70±92.53 and 922.00±152.62 kg/tree, respectively, and debarked parts weight were 525.46±55.49, 628.40±34.50 and 714.61±40.53 kg/tree, respectively. During comparing the sago production from three staged plants, 3^rd staged plants produced the highest percentage of sago (19.77± 0.68%). When phenolic compound and antioxidant activity of sago flour were compared, it was observed that 2^nd staged plants produced the highest amount of phenolic compound (133.57±22.89 mg GAE/100 g) and highest percentage of antioxidant (62.60±11.21%). Antioxidant was measured in terms of % radical scavenging activity at 100 mg/ml. Color values (CIE L*, a*, b*) of sago flour  produced from different staged plants were different. Sago flour found from 1^st and 2^nd staged plants were more white (L*-1^st stage: 90.17±0.80, 2^nd stage: 89.86±0.69; a*-1^st stage: 1.49±0.87, 2^nd stage: 2.10±1.48; b*-1^st stage: 7.03±0.83, 2^nd stage: 7.36±1.23), while sago flour produced from 3^rd staged plants were pinkish-white (L* 89.12±1.16, a* 4.30±1.90, and b* 6.35±1.76). Study of the shape and size of sago starch granules with field emission scanning electron microscope found that sago flour had smooth surface and oval shape. During measuring the particle sizes of flour granules (found from 1^st, 2^nd and 3^rd staged plants) the sizes were observed about 12-42, 6-37 and 15-47 micrometer, respectively. This study confirms that during sago harvesting, people should choose 2^nd and 3^rd staged plants due to higher sago yield, as well as due to higher phenolic compound and antioxidant activity in sago flour which could be beneficial for cosmetic production and for the people who are health-conscious.