Van Hal, M. (2000) Quality of sweet potato flour during processing and storage. Food Reviews International, 16: 1-37.
Van Soest, J.J.G., Benes, K., Dewit, D. and Vligenthart, J.F.G. (1996) The influence of starch molecular mass on the properties of extruded thermoplastic starch. Polymer, 37(16): 3543–3552.
Vasanthan, T. (2001) Overview of laboratory isolation of starch from plant materials. Food Anal Chem. Unit, E2.1.1-E2.1.6
Vignaux, N., Doehlert, D.C., Elias, E.M., McMullen, M.S., Grant, L.A. and Kianian, S.F. (2005) Quality of spaghetti made from full and partial waxy durum wheat. Cereal Chemistry, 82: 93-100.
Wang, Y.J. and Wang, L. (2003) Physicochemical properties of common and waxy corn starches oxidized by different levels of sodium hypochlorite. Carbohydrate Polymer, 52: 207–217.
Waramboi, J.G., Dennien, S., Gidley, M.J. and Sopade, P.A. (2011) Characterisation of sweetpotato from Papua New Guinea and Australia: Physicochemical, pasting and gela-tinisation properties. Food Chemistry, 126: 1759–1770.
Wickramasinghe, H.A.M., Takigawa, S., Matsuura-Endo, C., Yamauchi, H. and Noda, T. (2009) Comparative analysis of starch properties of different root and tuber crops of Sri Lanka. Food Chemistry, 112: 98-103.
Wong, R.B.K. and Lelievre, J. (1981) Viscoelastic behavior of wheat starch pastes. Rheo-logica Acta, 20: 299–307.
Woolfe, J.A. (1992) Sweet potato ― Past and present, in: Sweet Potato: An Untapped Food Resource (ed. J.A. Woolfe), Cambridge University Press, Cambridge, pp. 15–40.
Wotton, M. and Bamunuarachchi, A. (1978) Water binding capacity of commercial produced native and modified starches. Starch-Starke, 33: 159–161.
Wurzburg, O.B. (1986) Cross-linked starches, in: Modified Starches: Properties and Uses (ed. O.B. Wurzburg), CRC Press, Boca Raton, FL, pp. 41–53.
Xie, S.X., Liu, O. and Cui, S.W. (2005) Starch modification and applications, in: Food Carbohydrates (ed. S.W. Cui), CRC Press, BocaRaton, FL, pp. 357–405.
Yiu, P.H., Loh, S.L., Rajan, A., Wong, S.C. and Bong, C.F.J. (2008) Physicochemical properties of sago starch modified by acid treatment in alcohol. American Journal of Applied Science, 5: 307–311.
Zaidul, I.S.M., Yamauchi, S., Takigawa, C., Matsuura-Endo, T., Suzuki, T. and Noda, T. (2007) Correlation between the compositional and pasting properties of various sweet potato starches. Food Chemistry, 105: 164–172.
Zhang, T. and Oates, C.G. (1999) Relationship between α-amylase degradation and physico-chemical properties of sweet potato starches. Food Chemistry, 65: 157–163.
Zhou M., Robards K., Glennie-Holmes M. and Helliwell S. (1998) Structure and pasting properties of oat starch. Cereal Chemistry, 75: 276–281.
Zhu, F., Yang, X., Cai, Y-Z., Bertoft, E. and Corke, H. (2011) Physicochemical properties of sweet potato starch. Starch-Starke, 63(5): 249–259.
Zobel, H.F. (1988a) Starch crystal transmissions and their industrial importance. Starch-Starke, 40: 1–7.
Zobel, H.F. (1988b) Molecules to granules ― A comprehensive starch review. Starch, 40: 44–50.
11.2 Bakery Products and Snacks based on Sweet Potato
Tai-Hua Mu2, Peng-Gao Li3, and Hong-Nan Sun1
1 Institute of Agro-Products Processing Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-products Processing, Ministry of Agriculture, Beijing, P.R. China
2 Department of Nutrition and Food Hygiene, School of Public Health, Capital Medical University, Beijing, P.R. China
11.2.1 Introduction
Sweet potato is an abundant resource and also inexpensive as a raw material. Besides being directly used in food preparation, vigorous development of sweet potato comprehensive processing and construction of corresponding industrial chains, have strong economic and practical significance in taking full advantage of this resource, expanding product application, improving diet structure, and also increasing the income of farmers. Considering that China has many varieties of sweet potato processing products, this chapter will mainly introduce a series of processing methods of common baked sweet potato food and snacks.
11.2.2 Sweet Potato Bread
Adding a certain amount of sweet potato flour during bread processing is simple, reduces production costs and improves economic efficiency. The technological process of sweet potato bread (Peng et al., 2003) is summarized in Figure 11.2.1.
Figure 11.2.1 Technological process of sweet potato bread.
The operating procedure includes:
1. Dry yeast activation: Before using, dry yeast should be activated by first dissolving in 30 °C warm water and set aside for 30 min before use. During its use, mixing with sugar has to be avoided.
2. Primary dough preparation: Mix together 60 % of sweet potato flour, milk powder, sugar, bread improver and additives and stir well, then add eggs and the activated dry yeast. Knead the dough for approximately 10 min until it reaches the “smooth stage”.
3. Primary dough fermentation: Yeast is propagated in an effort to expand the dough as a seed dough. The fermentation temperature is controlled between 27 and 28 °C, with the relative moisture content around 75–80 %, and the fermentation time of 2 h. During fermentation, the dough needs to be punched back once or twice.
4. Secondary dough preparation: Mix the remaining flour and supplemental ingredients with the mature dough for further preparation. Sweet potato should be washed, cleaned, cooked, peeled and mashed before mixing. For the best quality bread, the percentage of sweet potato should be controlled to under 30 %.
5. Secondary dough fermentation: Seed dough is obtained from the primary fermentation, so the secondary fermentation time is shorter, approximately 1.5 h. The fermentation temperature is controlled between 28 and 30 °C, with the relative moisture content around 75–80 %. In order to achieve the stage of full fermentation and a uniform distribution of small holes in the dough, during this procedure the dough also needs to be punched back once or twice.
6. Shaping and fermenting: According to the product desired, the dough is divided into small pieces. The weight loss, 10–12 % during baking, should be considered when weighing. Fermenting temperature is 35 °C, with the relative moisture content around 85–90 %. Let the small dough naturally rise until its volume is doubled after fermenting.
7. Baking: The baking temperature is controlled between 200 and 220 °C, and needs to be baked for 10 min. The high-humidity baking method would be beneficial for bread rising.