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The World Bamboo Congress VIII. Protection of bamboo by environment-friendly chemicals against short-term molding. TangThi Kim Hong 1,2 , Olaf Schmidt 1 ,Walter Liese 1 1 Center of Wood Science, University of Hamburg, Germany 2 Nong Lam University of Ho Chi Minh City, Vietnam. - PowerPoint PPT Presentation
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Protection of bamboo by environment-friendly chemicals
against short-term molding
TangThi Kim Hong1,2, Olaf Schmidt1,Walter Liese1
1 Center of Wood Science, University of Hamburg, Germany
2 Nong Lam University of Ho Chi Minh City, Vietnam
The World Bamboo Congress VIII
Background
Especially, exposed bamboo material during storage, processing, transport in container and its final use is affected by molds
Molds can grow on the surface and at the cross-ends of culms in a humid atmosphere as they require high relative humidity above 70%
Fig. 1a Moulded bamboo culms and materials at a Bamboo factory, Vietnam
Molded fresh culms five days after haversting Molded dried culms during storage
Surface of a table exposed by moldsMolded dried culms during processing
Fig 1b. Molded bamboo culms at arrival in Hamburg after container transport from Vietnam
For protection of wood and bamboo against molds and other fungi, pentachlorophenol had been widely usedPentachlorophenol is banned due to its high toxicity in many parts of the world as well as in Vietnam
Bamboo manufacturers have pressing problems to protect bamboo for home use and export
Manufacturers greatly need cost-effective but also environment-friendly treatment methods
Background
Objective
the preventing effect of organic acids (applied
for food and as antiseptica)
the additional protective effect of their low pH-value against microorganisms +
for bamboo short-term protection against molding
Material and Methods
Samples preparation
From the fresh culms with MC 100 to 120%, samples of 70 mm length were taken halfway between the internodes and longwise split.
Bamboo SpecimensBamboo speciesBambusa stenostachya Hackel and Thyrostachys siamensis Gamble (two of the important species of Vietnam) were selected for testing
Chemicals
The molds used were isolated from bamboo at the Nong Lam University of Ho chi Minh City, Vietnam.
Traditional identification and DNA-ITS sequencing revealed: Aspergillus niger, A. flavus, A. oryzae, Aspergillus sp., Paecilomyces variotii and Penicillium sp.
Fungi
Fig. 2 Specimens in plastic basins for mold protection test
Two specimens of the two bamboo species were dipped 5 min. in the respective treatment solution and placed in a small plastic basin
Treatment
Incubation and Inoculation
Test series 1: artificial infection with a water-based mixture of conidia of the molds was performed with a small brush (`artificial infection´)
Test series 2: contained the molds from the natural flora of the bamboo plants and from the sample processing (`natural mold flora´)
Assessment of Mold Growth
Results
Fig. 3 View on the artificially infected and differently treated bamboo specimens after 8 weeks of incubation
10% acetic acid
7%propionic acid
the mixture of3% boric acid + 7% propionic acid
10%propionic acid
.
prevented mold growth
totally over the whole incubation period of
8 weeks
The treatmentswith
• The effective formulations
Results
• The ineffective formulations
all other treatments allowed
severe (rating 3) or very severe (rating 4) mold growth after the first week and
very severely overgrown after the two weeks.
Results
10% Na-acetate
7% Na-propionate
10% Na-propionate
8.5
8.0
8.5
ineffective
efficacy of anti-mold pH value formulation
10% acetic acid
7% propionic acid
10% propionic acid
2.8
2.9
2.8
effective
• aicd pH value, alkaline pH value
Results
• No significant differences in final molding (after 8 weeks) between the test series `artificial infection´ and `natural mold flora´
• Both bamboo species behaved rather similar regarding mold susceptibility and prevention
Further results
Conclusions
The laboratory experiments have shown that molding of bamboo can be prevented by simple treatment with environment-friendly chemicals
Treatment of bamboo samples with acetic acid, propionic acid and a mixture with boric acid prevented mold growth for 8 weeks
The other chemicals were less effective or ineffective
The protection was related to the pH value of the treatment solution. The acetic and propionic acid had protective effect, their salts did not
• Experiments with the effective formulations will be continued under field conditions in Vietnam with larger bamboo dimensions as culms, round and split, as well as handicrafts and commodities
• Since molding of bamboo is a serious devaluation in trade, corresponding experiments are recommended for other bamboo countries with their respective species
Recommendations
Acknowledgments
Bamboo Nature LTD. Company, Vietnam
Thank you for your attention!