Varietal Diversity and Nutritional Analysis of Sago Starch (Metroxylon Sago Rottb) in Kainui, Papua

2.1 Material

The material used during the research was sago trees which were inventoried as trees that were ready to be harvested. The sago tree will then be cut into several sections 1 meter long to be used as sago starch samples.

2.2 Research procedure

Primary data collection was carried out in the research area using the quadratic method. The quadratic method is a method that uses sample plots [9]. The sample plot with a size of 100 m × 100 m (1 Ha) consists of 1 (one) observation plot (with a total observation area in the field of 1 Ha). In one sample plot, the plot is divided into sub-plots which aim to make it easier to make observations in the field, with a size of 25 m × 25 m. The number of observation subplots in the field is 16 plots which are further divided into observation radius based on growth phase. The layout of the observation procedure (inventory and identification of sago varieties) as shown in Figure 1.

1. Sago trees are inventoried based on their growth rate, including height, diameter, healthy stems, leaf sheaths that are short when compared to the previous sheaths, the shoots do not form midribs but form fruit, the sago trees start to produce flowers and the average age is 9 years to be ready harvest.

2. Sago trees are selected randomly and then identified based on their thorns, leaves, bark and roots.

3. Sago trees that are found based on their qualifications are then cut down. After that, the length of the tree stem, stem diameter, base, middle and tip were measured at 1 meter. Then the tree stem is cut in the middle and ends, then skinned and the pith is grated. After grating, the pith is squeezed and the starch is taken, then put into 650 ml aqua bottles, 3 bottles per variety, closed tightly and stored, then the sago starch samples are analyzed in the laboratory.

1.png

Figure 1. Layout of the sago variety observation plot

2.3 Data analysis

a. Water content [10]

The sago starch sample was weighed at 200-205 mg on a zinc plate which was known to have an initial weight. Starch samples were baked at 200℃ for 6 hours. The zinc plate was cooled in a desiccator for 30 minutes. The sample is weighed until a constant weight is obtained. Water content can be calculated using the formula:

Humidity level $=\frac{\mathrm{w} 2-\mathrm{w} 1}{\mathrm{w} 0} \times 100 \%$

where,

w1 = Final weight (Sample and dry cup)

w2 = Weight of empty cup

w0 = Sample weight

b. Ash content [10]

The sago starch sample was weighed at 200-205 mg in a porcelain glass. The sample in porcelain is then put into an electric furnace. The furnace is stirred for 6 hours with temperature increments of 120℃-550℃. Samples in porcelain cups were cooled in a desiccator for 1 hour. The sample is then weighed and repeated until a constant weight is obtained. Ash content is obtained by the formula:

Ash content $=\frac{\mathrm{w} 1-\mathrm{w} 2}{\mathrm{w} 0} \times 100 \%$

where,

w1 = Final weight (Sample and dry cup)

w2 = Weight of empty cup

w0 = sample weight

c. Amylose content [10]

An 80-mesh sago starch sample is required for amylose analysis. The purity of sago starch will indicate the level of amylose contained in the starch. The sample was weighed 100 mg into a 100 ml volumetric flask, then added 1 ml each of 95% ethanol and 9 ml of 1 N NaOH. The measuring flask was heated in 95℃ water bath for 10 minutes. The measuring flask is removed and cooled for 20-30 minutes. The sample was diluted with distilled water to a volume of 100 ml. The samples in the diluted volumetric flask were pipetted 5 ml each into a 100 ml volumetric flask and added 2 ml of iodine solution (0.2 g of iodine and 2.0 g of iodine pot in 100 ml of distilled water solution) and 1 ml of acetic acid solution 1 N. The solution is diluted again with distilled water to 100 ml.

The color of amylose was measured using a 620 nm spectrophotometer. A standard curve was prepared in the same way, but with standard amylose. Next, the amylose concentration in the sample is determined with the help of a standard curve.

The identification of species diversity found in Kainui natural forest found five varieties (Table 1) where each variety is found with its growth forming clumps and each variety of sago found has a different number of tillers according to its growth phase. This is as explained by study [6], that the sago found grows in clumps with different growth phases naturally. The five varieties found have in common that all are categorized as spiny sago varieties.

The crown shape of the five sago varieties found in Kainui is quite varied. Most varieties have a straight and upright crown shape. This is explained by study [11], that the crown shape of sago accessions found in South Sorong Regency varies and the accession has an upright crown shape. This can be seen from the difference in leaf shape of the five different varieties, namely the number of leaflets and leaflet width (Table 2).

Table 5 shows that the wewa variety has better stem height (13 m - 15 m and diameter 67cm - 80cm) than other varieties. However, not always the height and diameter of the stem is better for producing sago protein, but in terms of producing more sago starch than other varieties, as produced by this research, one variety, namely Wewa, with a height of 15 cm, a diameter of 50 cm produces as much wet sago starch. 430 kg. In the Kainui natural forest, the wewa variety is dominated, followed by the blight variety and other varieties. In line with the research of [11] that in the natural forest of West Papua found the average stem height is 13.3 m and a diameter of 40.4 cm. This is because there has been a change in the ecosystem with human intervention with a silviculture system, namely intensive maintenance.

The quality of sago starch is determined based on the color of the starch produced, this, as produced in this study, is white, meaning that the sago starch results are very good and contains high carbohydrates, namely 92.3%, a higher value according to study [1] that the results of research from the Institute of Nutrition, Mahidol University (2014) and the United States Department of Agriculture (2018) show that the carbohydrate value obtained is 86.3, thus it will be a reference to be used as a basis for decision making by farmers and local governments for the development of sago varieties in the future. When the pith was opened, most of the sago cores observed were pink in color. It was explained by study [12] that the higher the sulfur content in the soil, the lower the L value (color brightness) and the darker the starch color. The results of this study indicate that the value of Sulphur in the soil where sago is planted is lower, so the color of sago starch is white. The analysis showed that the best sago starch content in the sago hawar variety was 99.34% and the lowest in the sago wewa variety was 98.94% (Figure 3).

The blighted sago variety grows in a low-density environment and is influenced by its growing location, as explained by study [13] that plant density greatly affects the growth and productivity of sago plants. The growing environment will supply a variety of organic and mineral materials that are transported by the roots of the breath will make the composition of the carbohydrate content in sago even higher. This is in accordance with the opinion of study [14] that the suitable environment for planting sago is a muddy area where the breath roots are not submerged, rich in minerals and organic matter.

The study [15] state that the water content in food will affect the appearance, texture and taste of food. Moisture content is the water content contained in the material, expressed in percent. Water is very influential on good or bad food. Water content affects the stability of an ingredient when stored. Water content also greatly affects food quality [15], such as texture, odor and appearance. High water content has the potential to be attacked by microorganisms. The lower the water content in starch, the better the quality of sago starch. By study [16], the moisture content of sago starch through conventional drying method was 13.69%. This means that the water content is higher than the results of laboratory analysis (Figure 4 and Figure 9) highest 12.22%. The research results from study [17] explain that the water content of sago starch produced in the Sukabumi area is higher, namely 15.07%. This means that the water content obtained in the Kainui natural forest is better because it meets SNI standards. The habit of sago farmers in Papua after harvesting sago, starch that is still wet is only placed in tumang, a container made of sago leaf fronds. This is what makes sago starch quickly damaged by microorganisms.

The amount of ash content in the six treatments has met the quality standard of sago starch (SNI 3729: 2008), which is a maximum of 0.5%. The difference in ash content of the sago starch produced is not too significant. This happens because the ash content in a material comes from the material itself. The results of the sample analysis of the five sago varieties (Figure 5) show the lowest ash content in the manoari sago variety of 0.07% and the highest in the hawar sago variety of 0.8%. This is different from the research results from study [17] which obtained an ash content of 0.15%. Also, by study [18], the ash content obtained from Bengkali was 0.437% and from Inhil was 0.116%. Also, according to study [19] the ash content produced from Merbau District is 0.408%. Study [18] stated that ash content in food generally comes from the food itself. The composition of sago flour is strongly influenced by the physical conditions of the soil where sago grows and develops.

Based on study [18], sago (Metroxylon sp.) growing on waterlogged land, in acidic conditions and containing high concentrations of sulfur will produce starch with high ash content. Based on study [10], the condition of South Sorong sago, precisely Sayal Village, generally grows on mineral soil with flooded land, both temporarily and permanently waterlogged.

Starch content is the amount of starch contained in the material expressed in percent. Starch is a polysaccharide synthesized from green plants through photosynthesis. Starch has a granular crystalline form that has a size and shape depending on the type of plant. Starch is used as a thickener and stabilizer in food. The analysis shows that the highest sago starch produced from the tested varieties is the hawar variety with an average value of 99.34% and the lowest in the wewa variety which is 98.94% (Figure 6). This is due to differences in starch content in various varieties and affected sago trees [19] based on the productivity activity of each tree. High lighting in the blight variety habitat compared to the wewa habitat.

Crude fiber is part of food that cannot be hydrolyzed by chemicals. Based on study [19], crude fiber is part of food that cannot be hydrolyzed by strong acids or bases, the chemicals used to determine crude fiber content are sulfuric acid (H₂SO₄ 1.25%) and sodium hydroxide (NaOH 3.25%). The results in Figure 7 show that the value of crude fiber produced from various varieties of sago is not hydrolyzed properly so that the value is still higher than the quality standard of sago starch (SNI 3729: 2008), which is a maximum of 0.5%.

The results of the analysis (Figure 8) show that the highest amylose content is in the blight variety and amylopectin in the makbom variety. Based on study [16], the amylose component is related to water absorption and the perfection of the product gelatinization process, while the amylopectin component will determine the swelling power (ability of starch to expand) and starch solubility. Based on study [20], sago starch contains about 27% amylose and 73% amylopectin. Study [16] reported that high amylose content causes the development of starch granules to occur at higher temperatures, so that starch with a high amylose content has a lower developmental power than starch that has a lower amylose content.