II. LITERATURE REVIEW
2.1 BAMBOO SHOOTS
Bamboo shoot is one of non-wood forest products in Thailand. It is also one of important raw materials for making traditional delicacy of many countries in Eastern Asia. Bamboo shoot, as
shown in Figure 1, is edible portion of bamboo plant that have emerged from the ground and harvested before significant fibre development. Bamboo shoot is protected by many sheaths of
overlapping, brown husk covered in fine, and sharp hairs. Freshly harvested shoot has conical shape, creamy color inside, a strong smell, sweet taste, and crunchy texture. It also has a length of
20-30 cm and weighs almost to a pound. However, the size and the weight depend on its growth location; depth, fertility, pH, and nutrition of the soil; temperature; watering and drainage
conditions Winarno 1992; ERG 2004.
Figure 1. Freshly harvested bamboo shoots
Based on climate, bamboo is categorized into two groups, i.e. monopodial sub-tropical bamboos and sympodial tropical bamboos. Sub-tropical bamboos produce three types of shoots,
i.e. spring or summer shoots, winter shoots, and rhizome shoots, while tropical bamboos produce only summer shoots. Thailand has sympodial bamboos that produce shoots from May to October
with most productions in July to August every year INBAR 2006. There are many species of bamboo shoots growing in Thailand, such as Bambusa edulis, Bambusa oldhamii, Bambusa
pallida, Dendrocalamus asper, Thryrsostachys siamensis, Dendrocalamus giganteus, Dendrocalamus merrillianus, and Dendrocalamus membranaceus Munro Winarno 1992;
Scurlock et al. 2000; ERG 2004. Dendrocalamus membranaceus Munro or white bamboo grows well in Doi Tung, Northen Thailand. It is one of the most promising species for bamboo shoots in
Doi Tung. It is smooth and easy to handle. It also has a hole at the center and a lighter weight. Bamboo shoots are very nutritious food. Nutritional content of bamboo shoots,
Dendrocalamus membranaceus, was shown in Table 1. They are rich in protein that produces eight essential amino acids. They are also low in cholesterol and saturated fat contents, and high in
dietary fibers. Although the fat content is comparatively low, it is still higher than many other vegetables and the shoots contain rich essential fatty acids. They also contain active materials,
such as antioxidants flavones, phenols, and steroids. They are valuable in pharmaceutical and food processing industries and can be processed either into beverages, medicines, additives, or
health foods. Bamboo shoots also contain flavones and glycosides which have excellent anti-
4 microbial property; dietary flavonoids which have anti-proliferative activity; lysine which is
known as a limited amino acid; and Germaclinum which is known to carry anti-aging properties Middleton et al. 2000; Zagrobelny et al. 2004; NMBA
b
2009.
Table 1. Macronutrients of Dendrocalamus membranaceus Chongtham et al. 2011
Nutrient Content g100 g fresh weight
Moisture 89.30 ± 1.34
Carbohydrate 5.40 ± 0.03
Protein 3.38 ± 0.10
Amino acids 3.46 ± 0.02
Ash 0.63 ± 0.04
Dietary fibre 2.91 ± 0.06
Fat 0.43 ± 0.05
Starch 0.23 ± 0.04
Vitamin C 1.58 ± 0.06
Vitamin E 0.65 ± 0.10
Despite its benefits, many tropical shoots contain high level of anti-nutrient as cyanogens FAO 2012. A survey 2008-2009 that has been conducted in Thailand by Bureau of Quality and
Safety of Food cooperated with Regional Medical Sciences Centers and Provincial Public Health Offices reported that the highest mean level of cyanide was found in fresh bamboo shoot at the
level of 167 mgkg and the lower quantity was detected in fermented bamboo shoot and boiled bamboo shoot at the levels of 41.1 mgkg and 19.2 mgkg, respectively Teerapapthamkul et al.
2011. The results showed that cyanide content may be reduced by boiling or fermentation process. Some studies have also reported that cyanide content from bamboo shoots as Taxiphyllin
can be reduced by boiling, steaming, soaking in water, superheated steam drying, or fermentation Ferreira et al. 1995; Tripathi 1998; Bhargava et al. 1996; Wongsakpairod 2000; Bhatt et al.
2003.
2.2 DEHYDRATION 2.2.1 Drying
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