Betung Bamboo Research Articles

Physical and Mechanical Properties of Laminated Board from Betung Bamboo (Dendrocalamus asper)

Physical and Mechanical Properties of Laminated Board from Betung Bamboo (Dendrocalamus asper)

Eksplorasi Mikroflora Alami Produk Fermentasi Tradisional Cangkuak Berbasis Daging di Kecamatan Kuantan Mudik Kabupaten Kuantan Singingi

Cangkuak is a fermented food made from meat with betung bamboo shoots or kluwak, salt and rice. The fermentation process is carried out without adding microbial cultures (spontaneous) for one to three weeks in a tightly closed container. cangkuak's manufacturing technique, ingredient formulation and constituent ingredients are unique, resulting in a final product with different characteristics. Research on the presence of microbes in fermented food products (fish, milk, vegetables) has been widely conducted, but information on exploring the presence of natural microflora and the in vitro potential of fermenting bacteria in cangkuak has never been reported. This research was conducted using a survey method and the resulting data were presented descriptively. It was found that the natural microflora found in the three samples of cangkuak in Kuantan Mudik was dominated by bacteria, with the highest proportion of bacterial groups in the three cangkuak samples being fermentative bacteria (2.0 - 6.30x105 cfu/g), cellulolytic bacteria (3.30 - 5.90x105 cfu/g), amylolytic bacteria (1.70 - 4.40x105 cfu/g), proteolytic bacteria (0.12 - 7.90x105 cfu/g), lipolytic bacteria (0.08 - 0.12x105 cfu/g). Six potential fermentative isolates were obtained as evidenced by the calculation of index values, namely DK-I1 (1.59), DR-I1 (1.36), DR-I2 (2.49), DR-I3 (1.19), DKR-I1 (2.41), and DKR-I2 (2.96).

Identification of The Antioxidant Activity of Bamboo Shoots a Raw Material for Manufacturing Lemea

Purpose: This research aims to determine the antioxidant activity of bamboo shoots used as raw material for making lemea, a local fermented food. Methodology: The antioxidant activity of bamboo shoots was tested using the DPPH method. The research involved creating ethanol extracts from bamboo shoots of Mayan bamboo (Gigantochloa robusta), Betung bamboo (Dendrocalamus asper), and yellow bamboo (Bambusa vulgaris). The extracts were analyzed using a spectrophotometer at a wavelength of 517 nm after 30 minutes of incubation. Results: The study found that bamboo shoots used as raw material for lemea exhibited weak to very weak antioxidant activity. The IC50 values were 387.608 ppm for yellow bamboo shoots, 666.907 ppm for Betung bamboo shoots, and 799.593 ppm for Mayan bamboo shoots. Findings: The antioxidant activity of the bamboo shoots varied, with yellow bamboo shoots showing the highest antioxidant activity among the three types tested. Novelty: This research provides new insights into the antioxidant properties of bamboo shoots, specifically those used in making lemea. Originality: The study offers a detailed analysis of the antioxidant activity of different bamboo shoots, contributing to the understanding of their potential health benefits. Conclusions: Bamboo shoots, the raw material for making lemea, have weak antioxidant activity, with yellow bamboo shoots exhibiting the highest activity. Type of Paper: Experimental Research Article

PENGARUH MODIFIKASI PANAS OIL HEAT TREATMENT TERHADAP PERUBAHAN WARNA DAN BERAT PADA BAMBU BETUNG (Dendrocalamus asper) DAN BAMBU ANDONG (Gigantochloa pseudoarundinacea)

Betung bamboo (Dendrocalamus asper) and andong bamboo (Gigantochloa pseudoarundinacea) are non-timber forest products that can be used as a substitute for wood. However, both bamboos have light colors that are less aesthetic and susceptible to fungal and pest damage. Therefore, it is necessary to modify the bamboo. One of the modification methods used is oil heat treatment (OHT). This research aims to determine the effect of OHT on the color of betung and andong bamboo. This research was carried out the OHT using palm oil at temperatures of 180°C, 200°C, 220°C and 240°C for 2 hours. Color parameter measurements were observed using a colorimeter that implemented the CIE-Lab color system. The color parameters measured include brightness (L*), red/green chromaticity (a*), yellow/blue chromaticity (b*), and overall color change (∆E*). The percentage of bamboo weight loss after OHT was also observed. The research results show that the brightness value (L*) of betung bamboo and andong bamboo has decreased, so that the color becomes darker as the temperature increased. The a* and b* values decreased at all temperatures and durations. In addition, the value of ∆E* increased at all temperatures with a total change showing a value > 12. The decrease in weight of betung bamboo occurred at all temperatures. This heat treatment can make the bamboo color darker and more exotic, thereby increasing the added value of the product and improving the quality of bamboo from fungi and pests due to cellulose degradation.

Rowth of Betung Bamboo (Dendrocalamus asper) and Food Crop Production Under Agroforestry Bamboo Systems

One of the main species in community forests is betung bamboo (Dendrocalamus asper). Optimizing land use under bamboo can be achieved by cultivating food crops. This research aimed to determine the growth of betung bamboo and the production of food crops. The experimental design used a split plot design with four cultivation patterns as the main plots: agroforestry bamboo pattern i.e. agroforestry bamboo + rice (P1), agroforestry bamboo + rice + cassava (P2), agroforestry bamboo + rice + taro (P3), and mixed food crops (rice + cassava + taro) (P4), while the subplots were rice varieties: rindang 2 (V1), protani (V2), and unsoed (V3). The observed parameters were bamboo growth, soil fertility, and food crop production. The results showed that seven-year-old betung bamboo had an average of 6.01 mature stems per clump, an average plant height of 7.23 m, and a stem diameter of 7.12 cm. The numbers of young stems and shoots per clump was 1.45 and 3.71. The highest betung bamboo growth was in the agroforestry pattern (length: 8,49 m, diameter: 7.17 cm, thickness: 1.95, total weight: 21.31 kg). The highest rice yield was observed in the P2V1 treatment (4.17 kg). The highest cassava tuber yield per plant was observed in P4 (2.12 kg). The taro tuber yield was relatively higher in the agroforestry pattern with a distance of >1 m from the bamboo clump (0.52 kg plant-1). The land equivalent ratio (LER) and area time equivalent ratio (ATER) of bamboo and food crop agroforestry have a value above 1, so it is more efficient in land.

Organoleptic Analysis of Egyptian Martabak with the Addition of Betung Bamboo Shoots (Dendrocalamus asper)

Betung bamboo shoots (Dencrocalamus asper) is a plant derived from the shoots of bamboo betung processed into additional stuffing in Egyptian martabak. Betung bamboo shoots contain 59 gm of phosphorus and 13 mg of calcium, so they are good sources of natural nutrients for the body. The purpose of the study was to determine the organoleptic characteristics of the Egyptian martabak from bamboo betung shoots and to determine consumer acceptance of the Egyptian martabak from bamboo betung shoots. This study used an experimental method with three treatments and 3 repetitions using a completely randomized design (CRD). Data collection techniques used observation tests conducted by 5 sources, and acceptance tests were carried out by 30 consumers. The results of the observation test were analyzed by calculating the average value obtained from the sources, while the acceptance test was analyzed using a one-way analysis of variance (ANAVA). The results of the observation by the interviewees chose the Egyptian martabak, bamboo shoots, treatment 3 with the code MM3 with the addition of 70 gm of bamboo shoots, the average value was 23.31. The results of the research acceptance test consumers like the color, texture, taste of the Egyptian martabak bamboo shoots betung treatment 1 (MM1) with the addition of 50 gm of bamboo shoots (25%), for the aroma consumers like Egyptian martabak bamboo betung shoots treatment 2 (MM2) with the addition of bamboo shoots bamboo betung 60 gm (30%). The resource person chose the Egyptian martabak, bamboo shoots, treatment 3 with the code MM3 in terms of color, aroma, texture, and taste. Consumers choose the Egyptian martabak bamboo shoots with treatment 1 (MM1) in terms of color, texture, and taste. Meanwhile, in terms of aroma, consumers chose the Egyptian martabak, bamboo shoots, and treatment 2 (MM2).
 Keywords: organoleptic, Egyptian martabak, bamboo shoots.

Evaluation of staining betung bamboo (Dendrocalamus asper) using natural and synthetic dyes with and without the addition of preservatives

Bamboo is a widely utilized product. The use of dyes in coloring is now becoming important in bamboo dyeing as color can provide consumer appeal and improve aesthetics. Unlike wood, bamboo has a relatively uniform color, which is beige on the inside and green on the outside. Another important step in bamboo processing is preservation. This research examines bamboo colored using synthetic dyes using textile dyes which are azo group, natural dyes derived from the extraction of sappan wood, and examines the addition of borax boric preservatives. There are four treatments: natural dyes with preservatives, natural dyes only, synthetic dyes with preservative, and synthetic dyes only. Several tests were carried out, namely retention, penetration, staining evaluation using the CIELab method, and color change tests. It was found that natural dyes exhibited higher retention than synthetic ones, and both dyes without preservatives surpassed those with preservatives. Penetration was higher in natural dyes and those with preservatives. In comparison to the natural dyes, the color produced from synthetic dyes has a higher red intensity and a darker brightness level. While the addition of preservatives produces a lighter color with a higher brightness value. All treatments showed discoloration due to UV light exposure.

Drying Efficiency of Betung Bamboo Strips (Dendrocalamus asper) Based on Different Solar Drying Oven Designs

Drying Efficiency of Betung Bamboo Strips (Dendrocalamus asper) Based on Different Solar Drying Oven Designs

REGENERASI ALAMIAH BAMBU DI AREAL GARAPAN KELOMPOK TANI HUTAN KARYA MAKMUR II DALAM TAMAN HUTAN RAYA WAN ABDUL RACHMAN

The existence of bamboo in forest areas is very important because the strong root structure of rhizomes allows bamboo to bind soil and water properly, and this is no exception in Wan Abdul Rachman Grand Forest Park. Bamboo growth is closely related to the influence of environmental conditions where bamboo grows. Fertile soil affects the growth of bamboo because the nutrients for bamboo growth are met. The objectives of this research are to determine the regeneration rate of bamboo and the ecological conditions of each species of bamboo. This research was conducted in the area at the cultivated area of Karya Makmur II Forest Farmers Group in Wan Abdul Rachman Grand Forest Park on January 2023. The method used was the exploration method which is carried out by exploring areas that are often overgrown with bamboo. The results of the research were observed that 5 species of bamboo each had a youth percentage of 17.4% for betung bamboo, 24.3% for andong bamboo, 23.9% for mayan bamboo, 12.7% for tali bamboo, and 15.8% for black bamboo. The bamboo grows at an altitude of 150--304 m above sea level, slope of 25--60%, soil acidity of 5.0--6.5, air temperature of 27.6--29.7oC, and humidity of 60--85% and has a soil texture in the form of loamy loam, clay and loam. The conclusion of this reaserch is, although bamboo can grow in a humid or dry environment, however bamboo's regeneration rate is higher in a humid environment.

Physical Properties of Bioplastic Composite Synthesized from Sago Waste and Betung Bamboo Activated Carbon

Physical Properties of Bioplastic Composite Synthesized from Sago Waste and Betung Bamboo Activated Carbon

RESPON STEK CABANG BAMBU BETUNG (Dendrocalamus asper) TERHADAP PEMBERIAN ZPT ALAMI

Betung bamboo is widely used for building construction materials, furniture, and has ecological benefits because it is hard and strong. Bamboo propagation can be done generatively and vegetatively. Generative propagation has weaknesses, namely bamboo seeds are very difficult to obtain, seed viability is low, seeds cannot be stored for long, are susceptible to pests and diseases, and require a very long time to reach the age of the first harvest. Regulatory substances that can be used to encourage the growth of bamboo branch cuttings are shallots and banana weevils. The study was arranged in a completely randomized design (CRD) with 9 treatments namely A0 (control), A1 (25% banana weevil), A2 (50% banana weevil), A3 (75% banana weevil). banana), A4 (100% banana weevil), A5 (25% shallot), A6 (50% shallot), A7 (75% shallot), A8 (100% shallot). The results showed that natural ZPT (banana and shallot weevils) had no significant effect on the growth of betung bamboo branch cuttings. Although no treatment had a significant effect, when viewed from the average value of each parameter, it can be said that the treatment of natural ZPT concentrations on bamboo betung branch cuttings was in treatment A8 (100% shallot concentration) for the parameter of the period of shoot emergence, treatment A6 (50% shallot concentration) for the number of leaves parameter, treatment A0 (control) for the root length parameter and for the parameter living percentage of bamboo betung branch cuttings showed the highest average for all treatments.

Termite and decay resistances of Sumatran elephant dung-based particleboard modified with wood shavings and bamboo layering

Elephant dung (ED) particleboard (PB) still has subpar physical and mechanical qualities. In earlier research, adding wood shavings and bamboo layers to ED-derived PB successfully enhanced its physical and mechanical qualities. However, the resistance to termites and decay of this PB is still unknown. Therefore, this study examines the resistances to termites and decay of the PBs from ED fiber-modified with wood shavings and bamboo layering. ED and wood shavings were distributed throughout the PB in ratios of 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 (w/w %). Meanwhile, tali bamboo (Gigantochloa apus), talang bamboo (Schizostachyum brachycladum), kuning bamboo (Bambusa vulgaris), belangke bamboo (Gigantochloa pruriens), and betung bamboo (Dendrocalamus asper) were the materials used in this study. These findings demonstrated that adding wood shavings could improve PB’s resistance to termite and decay attacks. However, in this investigation, the layering of bamboo diminishes the PB’s resistance to termite and decay attack. A 50/50 ratio between ED and wood shavings achieved slightly higher termite mortality and lower weight loss than others. Meanwhile, kuning bamboo had lower termite mortality and higher weight loss than others.

Thermal Properties of Acetylated Betung Bamboo (Dendrocalamus asper) Pulp – Polypropylene Biocomposites

Thermal properties are important factors to determine the proper manufacturing, processing, and storing of biocomposites. Therefore, the thermal properties of the biocomposite made from acetylated betung bamboo pulp and polypropylene (PP) were investigated. The biocomposite was manufactured by hot pressing at 180 oC for 2 minutes and the fiber contents of the acetylated bamboo pulp used were 10 and 20% according to PP weight. The influence of acetylation and fiber content of bamboo pulp on the thermal properties of the biocomposite were investigated by using differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA). The results showed that acetylated bamboo pulp-PP biocomposite’s were higher than its pure and untreated biocomposites. The rate of crystallization growth of the acetylated bamboo pulp-PP biocomposites was faster up to 4.5 fold than pure PP composite. In addition, its acetylated bamboo pulp-PP had higher onset and maximum decomposition temperature than its untreated fiber-PP biocomposites but lower than PP. According to the results, the best thermal properties of biocomposite were obtained by acetylation of bamboo pulp with 10% fiber content.

The effect of heating temperature on the physical and mechanical characteristics of plybamboo prepared from betung bamboo (Dendrocalamus asper)

This research was conducted to evaluate the effect of heating temperature on the physical and mechanical characteristics of plybamboo boards as an effort to reduce the use of wood and develop composite products as a wood substitute material. The material used was betung bamboo (Dendrocalamus asper) processed using PVAc adhesive. Hygrothermal treatment was carried out at 150 °C, 160 °C, and 170 °C for one hour on bamboo strips. Subsequently, the bamboo strips were assembled into three layers perpendicular to the fibers, and adhesive was applied and compressed using cold pressing. The physical and mechanical properties of plybamboo boards were evaluated according to JAS 234: 2003 standards. The test results showed that hygrothermal treatment tended to affect the physical and mechanical properties of plybamboo boards. The hygrothermal treatment at 160 °C had the best impact, producing values closest to JAS: 234 standards, resulting in reduced moisture content, water absorption, thickness expansion, and delamination. Additionally, the heat treatment at 160 °C also provided the best improvement in density, MOR, and MOE of plybamboo boards. According to JAS:003 (2003) standards, the properties of plyboard did not yet meet the criteria as a wood substitute material.

Physical and Mechanical Properties of Oriented Flattened Bamboo Boards from Ater (Gigantochloa atter) and Betung (Dendrocalamus asper) Bamboos

Bamboo-based composite has been used widely for building components and furniture. Oriented flattened bamboo board (OFBB) is a composite board consisting of oriented structure sheets of flattening bamboo. This study aimed to analyze the physical and mechanical properties of the OFBB from ater (Gigantochloa atter) and betung (Dendrocalamus asper) bamboo. A three-layer flattened bamboo board using the isocyanate resin with a density target of 0.6 g/cm3 was applied. The characteristics of raw bamboo, the contact angle of OFBB, and board properties of density, moisture content, thickness swelling, and water absorption, as well as bending, internal bonding (IB), and compressive strength properties were determined to evaluate the quality of the OFBB. Based on the findings, the thin wall thickness of ater bamboo enhanced the physical and mechanical properties of the OFBB compared to the higher wall thickness of betung bamboo. Therefore, further development in bamboo composite products with those anatomical properties seems promising. The dimensional stability and bending properties of OFBB from ater bamboo met the quality of first grade of the Canadian Standard for OSB and waferboard, except for the IB strength. Keywords: Bamboo wall thickness, contact angle, Dendrocalamus asper, Gigantochloa atter, oriented flattened bamboo board

Fiber Quality of Betung Bamboo (Dendrocalamus asper) from Forest Area with Special Purpose (FASP) Pondok Buluh, Simalungun, North Sumatera

The FASP Pondok Buluh is located in Dolok Panribuan District, Simalungan Regency, Sumatera Utara, which has uniqueness due to the number of bamboo species found in this area, such as Betung Bamboo. This bamboo has a long fiber and is suitable for pulp and paper materials. This research aims to measure the dimension of Betung Bamboo and its fiber derivatives value for the eligibility of pulp and paper material. A total of 3 stems of Betung Bamboo were cut, and samples were taken in the form of a disc with a length of 5 cm at heights of 1, 3, 5, 7, 9, 11, 13, and 15 meters. Then the sample was cut into sticks, and separated fibers were made using the maceration process. Furthermore, the dimensions of the sample were measured using a light microscope, namely fiber length, fiber diameter, and fiber wall thickness, and then the measurement for the fiber derivatives value of the bamboo fiber. The results of this research obtained the average dimension of bamboo fiber is 2402 μm for fiber length, fiber diameter is 18.18 μm, lumen diameter is 8.73 μm, and fiber wall thickness is 4.91 μm. The fiber length graph shows the decreased fiber length along the bottom to the top of the bamboo culm and the wavy trend for the fiber diameter on some bamboo heights. The measurement of the fiber derivatives values obtained the average Runkle ratio 1.15, felting power 133.63, mulhsteph ratio 76.91%, rigidity coefficient 0.27, and flexibility ratio 0.48. Then the quality class of bamboo fiber was determined. A score of 275-325 was obtained with quality class II, meaning that Betung Bamboo is grown in the Pondok Buluh area. It is suitable for use as raw material for pulp and paper because it has long fibers, is easy to flatten when milled, and has good fiber bonds.

The Effect Of Potassium Permanganate On Betung Bamboo (Dendrocalamus Asper) Epoxy Fiber Compositesusing Hand Lay Up Method

The application of natural fiber composites in the modern world is often overlooked due to the rise of new synthetic fibers. The BetungBamboo is one type of natural fiber that has been used for many generations in the Indonesian archipelago. The fiber can be used to produce composites, however the choice of matrix and fiber treatment has an effect on determining the strength properties of the composite. In this study using epoxy resin as a matrix and Betung Bamboo fiber as a filler. Permanganate treatment of Betung bamboo fiber was conducted using KMnO4 solution. With variations in KMnO4 concentrations of 3%, 5%, and 7% for 15 minutes of immersion. The fabrication was carried out by hand lay-up method with silicone rubber molds. Tensile tests are then carried out to determine the tensile strength of the composite. Digital microscopy was observed to see the fracture pattern of the composite. The initial hypothesis of this study was the treatment of KMnO4 solution which aims to improve the interfacial properties of strength and resistance of Betung bamboo fiber and matrix, so that the mechanical properties of the composite are stronger. The highest tensile strength was at 5% KMnO4 content of 33.55 MPa and the lowest was at the specimen without KMnO4 content of 28.06 MPa. The highest strain was on specimens without KMnO4 content with 2.645% and the lowest on 7% KMnO4 content with 1.513%. The highest elastic modulus value was at 7% KMnO4 content of 20.84 MPa and the lowest was for specimens without KMnO4 content of 10.6 MPa. In the tensile test specimen without KMnO4 content, there are pullout fracture patterns, and in the tensile test specimen with 5% KMnO4 content there are indications of overload fracture pattern.

Physical, Chemical, and Mechanical Properties of Six Bamboo from Sumatera Island Indonesia and Its Potential Applications for Composite Materials.

The suitability of bamboo's basic characteristics is very important for more specific purposes, such as composite raw materials. Anatomical, physical, mechanical, and chemical characteristics are some of bamboo's fundamental characteristics. This study analyses the basic properties, such as physical, mechanical, and chemical properties of bamboo from the Forest Area with Special Purpose (FASP) Pondok Buluh Sumatera Island, Indonesia (I); analyses the relationship between the properties of each type of bamboo (II); and chooses the type of bamboo with the best properties that have the potential to be applied to composite materials, such as laminated bamboo (III). This study used materials consisting of six species of bamboo from the FASP Pondok Buluh. The manufacture of physical and mechanical test samples refers to the ISO 22157 standard, 2004, while the chemical properties test refers to the TAPPI 1999 standard. The chemical, physical, and mechanical properties of bamboo vary widely among species. The lowest holocellulose and α-cellulose content were found in the Kuning Bamboo (B. vulgaris var. vittata). The content of holocellulose and α-cellulose causes the lowest density in Kuning Bamboo (B. vulgaris var. vittata). The Dasar Bamboo (Bambusa vulgaris) has the highest levels of lignin. The substances have an impact on moisture content, T/R ratio, and shear strength. The Dasar Bamboo (Bambusa vulgaris) has the lowest moisture content, the highest T/R ratio, and the highest shear strength. However, Betung Bamboo (Dendrocalamus asper) has the highest density in this study. The compressive strength of the Betung Bamboo (Dendrocalamus asper) has the highest value. Therefore, Betung bamboo and Dasar Bamboo in this study were potentially utilized for composite materials, such as laminated bamboo.

Effect of Alkaline 5% NaOH treatment with variations of immersion time on tensile strength and flexural strength of Betung bamboo internode

Betung bamboo has a bigger stem diameter, thicker walls, and shorter internodes than other species of bamboo, making it ideal for building materials such as bridges and interior furnishings that may also be turned into works of art. Alkaline NaOH treatment was introduced to Betung bamboo to increase its mechanical properties. The alkaline treatment used a solution consisting of 5 %NaOH. Specimens with alkaline treatment were immersed into 5%NaOH solution for one hour, two hours, and three hours, followed by two hours of drying in a furnace at 60 °C. Tensile tests (ASTM D638) and flexural tests (ASTM D790) were carried out using servo hydraulics MTS Landmark 100 kN under static loading. The tensile strength, modulus of rupture (MOR) and modulus of elasticity (MOE) were analyzed from the results tests. The average maximum tensile strength of the Betung bamboo internode immersed for two hours into 5%NaOH solution is about 195.95 MPa, whereas the average values of MOR and MOE are about 207.35 MPa and 4.56 GPa, respectively. The faults and surface conditions in the Betung bamboo internode were observed using fractographic and morphological observations.

Changes in Chemical Composition of Betung Bamboo (Dendrocalamus asper) after Alkali Immersion Treatment under Various Immersion Times

This research aimed to analyze the change in chemical composition of the betung bamboo (Dendrocalamus asper) strands after alkali immersion treatment under various immersion times. The bamboo culms were converted into strands with the target length, width, and thickness of 70, 25, and 0.5 mm, respectively. Strands were alkali immersion-treated with 1% NaOH solution for 1, 2, and 3 h. Preparation of powder for chemical component analysis refers to the Technical Association of the Pulp and Paper Industry (TAPPI) standard T 264 cm-07 regarding the preparation of wood test samples for chemical analysis. Structural and non-structural bamboo strand chemical components such as holocellulose, alpha-cellulose, hemicellulose, klason lignin, and extractives were analyzed. The results showed that alkali immersion treatment decreased the hemicellulose content from 21.55% before treatment to 20.30% after 3 h immersion. Thus, it changed the holocellulose and alpha-cellulose composition. Alkali immersion treatment also changed the extractive substances dissolved in cold water, hot water, 1% NaOH, and ethanol-benzene solution. The decrease in hemicellulose, molecular weight lignin, and extractive substances would be beneficial for bamboo-oriented strand board manufacture to improve strand adhesion, dimensional stability, mechanical properties, and durability against biological agents attack. Keywords: alkali immersion times, alkali immersion treatment, bamboo, chemical components, pre-treatment