School of Biotechnology
BSc THESIS PROJECT PROPOSAL
PHYSICOCHEMICAL AND FUNCTIONAL PROPERTIES OF ANNEALING TREATED YAM&SWEET POTATO STARCHES
I/Project general information
Name of study : Physicochemical and functional properties of annealing treated sweet and yam potato starches Field of study: Food biotechnology
Supervisors: Dr. Pham Van Hung
Host institute: school of biotechnology at HCM international university Time: 1/2013-5/2013
II/- RESEARCH PROPOSAL
* Prepareration of heat-moisture treated in presentation of diferent organic acid * Deternimination of physicochemical properties of treated starch * Invesstigation of resistant starch contents of treadted starch
2.1 Literature review
2.1.1Overview of Sweet and yam potato
Sweet Potato - common name applied to a perennial, trailing herb of the bindweed family. The plant, which is native to tropical America, is cultivated on sandy or loamy soils throughout many warm regions of the world, and exists as an important food staple in a number of countries. It is planted primarily for its thick, edible roots, called sweet potatoes. The name is due to a sugar content. The process of extracting and refining the starch is similar to the potato starch process. Sweet potato starch granules vary from 4 to 40 microns with 19 micron in average. The small granules affect extraction procedures in particular the dewatering. The amylose content is 19% - 25%. Yam PotatoMost of the starch employed by food industries isproduced by extraction from corn, cassava, sweet potato,wheat or rice. Yam tubers (Dioscorea alata) are another potential starch source that could be used as food ingredient, but that has not been explored commercially (Valetudie, 1992). Several researchers have studied flour and starch obtained from yam tubers in order to find new food applications (Ciacco & DAppolonia, 1978; Ige& Akintunde, 1981; Okaka & Anajekwu, 1990; Okaka,Okorie, & Ozo, 1991; Alves, 2000). Carbohydrates of Sweet Potatoes and Yams
Yams and sweet potatoes are quite similar in carbohydrates and fiber content. One 4 oz. serving of yams contains 27 g of carbohydrates with 4 g from fiber and 0.5 g from sugars. A half-cup serving of sweet potatoes contains 21 g of carbs and 3 g of fiber, but 8 g of sugars. This combination of carbs, fiber and sugars helps determine how the food will affect your blood sugar. Sweet Potatoes, Yams and Blood Sugar
The glycemic index of sweet potatoes ranks somewhere around 61. For a yam, the glycemic index value is 37. A low glycemic index is between zero and 55, a moderate value is between 56 and 69, and a high glycemic index falls between 70 and 100. Considering these figures, a sweet potato is a moderate glycemic food while a yam is a low glycemic food. This means that a yam will have a smaller and more gradual increase on your blood sugar than a sweet potato.
2.1.2 Resistant starch
Resistant starch. The term “resistant starch” was first coined by Englyst and others (1982) to describe a small fraction of starch that was resistant to hydrolysis by exhaustive amylase and pullulanase treatment in vitro. RS is the starch not hydrolyzed after 120 min of incubation (Englyst and others 1992). However, because starch reaching the large intestine may be more or less fermentedby the gut microflora. RS is defined as the sum of starch and starch degradation products not absorbed in the small intestine of healthy individuals (EURESTA., 1992). RS in the diet can reduce the glycemic response in humans. This feature is important for people with type 2 diabetes, who suffer from an inconsistent insulin response after consuming food (Niba, 2002) It is measured chemically as the difference between total starch (TS) obtained from homogenized and chemically treated sample and the sum of RDS and SDS, generated from non-homogenized food samples...