Sugar Palm LITERATURE REVIEW

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II. LITERATURE REVIEW

A. Sugar Palm

Sugar palm is used as collective term for plant species of Arenga. The genus Arenga is distributed in South China, the Ryukyu Islands and Taiwan in the north to Christmast Island in the south and from India in the west to Queensland, Australia in the east. The greatest diversity is found in Sumatra, Penninsular Malaysia, and Borneo Dransfield and Mogea 1984. In his recent revision of the genus, Mogea 1999 described 22 species, two subspecies and four varieties. Five species are distributed in Thailand Hodel 1998 of which three are arborescent, which are A. obtusifolia, A. pinnata, and A. westerhoutii. The identification of the latter two species, which are both solitary, is often confused. They both are single- stemmed palms and similar in stem diameter and have persistent leaf sheats to the ground that split in coarse Pongsattayapipat and Barfod 2005. A. pinnata and A. westerhoutii are separated based on their leaf morphological characters in the identification keys. In this research, we focused on the Arenga westerhoutii Griff. Sugar-palm or Tao Arenga westerhoutii Griff. is an economical fruit tree in the Palmaceae family of Nan Province in northern Thailand Hoare et al. 1998. In Indonesia, sugar palm is used to make wine, sugar, and starch sago, but in Thailand, sugar palm’s endosperm is processed either as a dessert syrup, called “loog tao” or “loog chid” “loog” means fruit in Thai. Moreover, the young pith in its stem makes a delicious dish Chantaraboon et al. 2010. The sugar palm seed takes about 4 to 20 months to germinate. Its germination rate is 65 percent Chantaraboon 1998. During its first to third year sugar palm grows very slowly, taking about 15 to 18 years from seeding to fruiting stage. The fallen mature seed can grow naturally into many seedlings under their mother trees, but not all grown seedlings survive because of their high density plot. A sugar palm tree produces 5 to 6 clusters. When the last cluster is senescent, the tree will die. This is known as a hapaxanthic tree Pongsattayapipat and Barford 2005. This palm has 12-30 leaves that are gathered in a rather loose crown. Leaf dimensions depend on the age of the palm varies from 6 to 15 meters. The leaflets of A. westerhoutii are regularly arranged and arised from the leaf rachis in one, rarely several planes. The color of its flower is yellow and has a wide shape. Kingdom : Plantae Phylum : Magnoliophyta Class : Angiospermae Order : Arecales Family : Arecaceae Genus : Arenga Species : westerhoutii a b Figure 1. a Infructescence of Arenga westerhoutii Griff. b individual infructescence of Arenga westerhoutii Griff., taken by Phunsiri Suthiluk 2007 3 The distribution of A. westerhoutii are widespread in evergreen and semi-evergreen forests in Penninsular Malaysia and Thailand Zakaria et al. 1999, where they occur from sea level to 900 on elevation. Very little information is available on the utilization of A. westerhoutii mainly because its identity has been confused with A. pinnata. Tao is not grown for commercial purpose in Thailand. In addition, sugar palm is valued as a non-timber forest product Chantaraboon 1998. Therefore, tao is mainly consumed troughout Thailand as a dessert or for ice cream topping. The sugar palm Arenga westehoutii Griff. seed are rounded, obovoid to oblong-turbirate, approximately 4 cm both in length and in width. They are light bluish green when immature and bluish green or dark green when ripening Pongsattayapipat and Barfod 2005. There are two or three seeds inside sugar palm fruit. The seeds young endosperms are good source of dietary fiber and calcium. According to Suthiluk et al. 2009, the nutritional composition of sugar palm seed are listed as below. Table 1. Nutritional value of sugar palm seed A. westerhoutii Griff. Composition Content Moisture 86.71 Protein 3.04 Fat 0.07 CHO 9.81 Ash 0.36 Crude Fiber 7.63 Total Dietary Fiber 8.59 Calcium 965.07 mgkg Phosphorus 270.71 mgkg Figure 2. Fruit and cross section of Arenga westerhoutii Griff., taken by Phunsiri Suthiluk 2007

B. Pectin 1. Definition and source of pectin