| Water caltrop belongs to caltrop group. Its scientific name is Trapa spp. , also called the name of caltrop, dragon horn and water chestnut. There are two main kinds which are T. quadrispinosa.Roxb and T. hispinosa. Fresh water caltrop contained up to 2:1. 96% starch, which could be a kind of better resource of starch. The starch, as an important renewable resource, because of its extensive use and potential application that has, has received the extensive attention of various countries more and more. Physical and chemical properties of starch and its function characteristics are influenced by the starch source. Developing new starch resources and furthering its physical and chemical properties and function characteristics investigation, have positive significance to the further use of starch.This topic applied two kinds of method to extract starches from water caltrop, which are water washing and acid washing, and compared their physical and chemical indexes. Modern analytical instrument and equipment such as SEM and RVA, etc. were adopted, and further investigation to the physical and chemical properties and function characteristics of the starch were carried on, at the same time the maize and potato starch were drawn as reference objects. The particles properties were determined, the content of amylose and amylopectin, gelatinization properties, solubility and swelling power, per cent transmittancy and retro-gradation properties, etc were determined as well. On the basis of the study about original starch properties, two modify starch products - phosphate starch and hydroperoxidized starch were developed. These researches made up for the study blank of water caltrop starch properties. And provided the theory foundation and basic data for the use of water caltrop.(1.) The physical and chemical indexes of water caltrop starch showed: the water content of water caltrop starch (8. 32% or 7. 75%) was higher than maize and potato starch, and its ash content (0.15% or 0.13%) was low, the protein content (0.86 % or 0.57%) was lower than maize starch, the fat content (0.07% or 0.06%)was lower as well.(2)Of the particle properties, SEM showed that the particle shapes of water caltrop were elliptical, round and polygon. Water caltrop and potato starch were with the smooth surface, but there existed some pores on the surfaces of the maize starch. The particle properties of water caltrop extracted by acid washing indicated obvious layer constitution, and grooves in the surface.(3)Of the physical and chemical properties, the amylose content of water caltrop starch is 15. 76% which was between the maize and potato starch. Amylogram characteristics of water caltrop starch indicated the characteristic values of the highest peak and the time when the highest peak arrived were between the maize and potato starch, others were all more than the the maize and potato starch. Its Pasting temperature was 80.15C which was higher than the maize and potato starch. Viscosity of gelatinized water caltrop starch increased when the concentration of starch increased. What's more, its viscosity changed largely when different salt or sucrose existed. Usually its viscosity decreased when sodium chloride, sucrose and alum existed. But on the contrary when borax existed its viscosity increased. Solubility and swelling power of water caltrop starch both increased when temperature increased. It swelled slowly at 65癈, fast between 85-95癈. There were a beginning swelling stage and a fast swelling stage, then the water caltrop starch had typical bi-swelling process, and belonged to limited-swelling starch. Per cent transmittancy was 58. 4% of the water caltrop starch. Both the water caltrop starch and the maize starch retro-graded more easily than the potato starch. The starch concentration (4%) affected their retro-gradation values much more, and at pH 6. 0 there were bigger retro-gradation values.(4) Of the phosphate modified starch, its peak time reduces. And the phosphate starch could be completely cold water-soluble, also had the certa...
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