Academic literature on the topic 'Cross-linked starch'

Doctor of Philosophy<br>Department of Grain Science and Industry<br>Yong Cheng Shi<br>This study focused on in-vitro digestibility and pasting properties of cross-linked (CL) starch with different amylose contents and different cross-linking levels, as well as physicochemical properties of extruded wheat flours with different amylose contents and functionality of amylopectin and cross-linking in improving the textural and physical properties of oat flour extrudates. Starch was CL by phosphorylation using a mixture of sodium trimetaphosphate and sodium tripolyphosphate at the ratio of 99:1 under alkaline condition. The digestibility of highly CL maize starches with different amylose contents was determined by Englyst, Available Carbohydrate Dietary Fiber and Association of Official Analytical Chemists (AOAC) Method 991.43 methods. CL waxy and normal maize starch granules swelled much more at higher temperatures, resulting in significantly lower total dietary fiber content than high-amylose maize starch. The alkali treatment study on low levels of cross-linking in starch affected the ratios of total bound phosphate esters which changed the degree of starch swelling, crytallinity and pasting properties of the CL starch. The study on the mechanism of the digestive enzymes and the extent of digestion during the incubation of CL wheat starch in AOAC Method 2009.01 showed progressive digestion after 16 h of incubation, which may not reflect in-vivo response in human. Extrusion of normal and waxy wheat flours resulted in the breakdown of starch and an increase in the insoluble protein, which affected the textural and structural properties of extrudate. High energy input played a major role in radial expansion of normal hard wheat extrudate, whereas higher amylopectin in soft waxy wheat flour was a dominant factor in determining the radial expansion when compared to normal soft wheat. Inclusion of soft waxy wheat in the oat flour formulations at 18% moisture content improved the textural and structural properties of extrudates. Low cross-linking level of CL waxy maize starch in oat flour formulation increased the void fraction and reduced the breaking strength of extrudates, whereas higher cross-linking levels of CL starches improved the resistant starch level on oat flour formulation but had very poor structural and textural properties.The study offers a good insight on the properties and digestibility of CL starch, as well as using low levels of CL starch to improve textural properties of nutritional extruded products. In addition, study on the extrusion of wheat flours with different amylose and protein contents provides knowledge on the influence of chemical compositions and energy input on the physico-chemical properties of extrudates.

碩士<br>國立嘉義大學<br>食品科學系碩士班<br>90<br>Abstract In this study, the starch of both tapioca and wheat were used for antirretogradation approach. The esterification, cross-linking modification, or dual modifications by each after were employed to find out the optimal process operation for modified starch product. The data shows the esterification of starch may decreasing the gelatinization temperature (down to 51.5℃ and 46.1℃of tapioca and wheat, respectively), elevating the top viscosity (up to 922 BU and 384 BU of tapioca and wheat, respectively) and accelerating the breakdown reaction (up to 581 BU and 148 BU of tapioca and wheat, respectively). However, the cross-linking modification may inhibit the breakdown reaction, down to 1.3 BU, of cross-linking starch of tapioca. The esterificated starch shows the significant results on antiretrogradation that past transparencies were consistent in 28 days under 4℃ storage, the transparencies after 7 cycles of freeze-thaw stability assay were down to 1.05﹪ and 22.9﹪, the degree of antiretrogradation were 0.0976 and 0.180 (J/g) of tapioca and wheat, respectively. Further more, the assays results of cross-linking modification before esterification of dual modified starch in gelatinization temperature were 51.7℃ and 49.5℃, the breakdown reaction were 56 BU and 40 BU and the transparencies after 7 cycles of freeze-thaw stability were 0 and 22.9﹪of tapioca and wheat, respectively. Otherwise, cross-linking modification after esterification of dual modified starch shows the higher values in all 3 assays than cross-linking modification before esterification of dual modified starch of both tapioca and wheat. Applying the modified starch also improved the ability of antiretrogradation, but influenced the texture of the past by DSC investigation. The crystal dumplings were made from variant composition of modified or unmodified starch for sensory evaluation. The result shows the crystal dumplings made from tapioca starch with the highest acceptability is unmodified starch without applying any modified starch and the poorest is applying the cross-linking modification after esterificated starch. However, the crystal dumplings made from wheat starch with the higher acceptability is applying the dual modified starch, cross-linking modification after or before esterification, but the unmodified or applying the cross-linking modified starch got the poor acceptability. Therefore, applying the cross-linking before esterification dual modified starch may elevate the water holding capacity and improve the characteristics of antiretrogradation to the frozen food application, and under a balance with the acceptability of texture for creating the most popular food product. Keywords: Tapioca, Wheat, Esterification, cross-linking, dual modifications.

碩士<br>國立中興大學<br>食品科學系<br>88<br>Two rice varieties, waxy (TKW1), non-waxy (TNS19) and cassava were used as test samples. They were reacted by STMP (sodium trimetaphosphate) with different times form a cross-linked type and the pasting behaviors, clarity, swelling power and solubility etc. were also investigated. The cross-linked TKW1 starch showed a higher peak viscosity than native ones. Non-waxy rice (TNS19) resulted in a non-peak viscosity after 4 hours reaction. Cross-linked cassava starch showed a higher peak viscosity than native starch after 4 hours, and no peak viscosity showed. The enthalpy (H), onset temperature (To) and peak temperature (Tp) of cross-linked TKW1 starch were higher than native starch, but there were not significantly change among reaction time. The cross-linked TNS19 starch also indicated a higher enthalpy (H), onset temperature (To) and peak temperature (Tp) and it had a positively correlation with reaction time. The cross-linking cassava starch had an opposite results of the enthalpy. The clarity of three cross-linked starches was decreased significantly with reaction time. The solubility and swelling power of the cross-linked TKW1 and cassava starch were also decreased with reaction time. But the solubility and swelling power of cross-linked TNS19 starch was increased with time in 85℃ test temperature, and there were significantly different in 65℃ and 75℃ test temperature, respectively.

碩士<br>義守大學<br>生物科技學系<br>102<br>The research goal of this experiment is chemically to crosslink poly(vinyl alcohol) (PVA) and starch to form a 3D scaffold that is effective water absorbent, has a stable structure, and supports cell growth. PVA and starch can be chemically cross-linked to form a PVA-g-Starch 3D scaffold polymer, as observed by Fourier transform infrared spectroscopy (FT-IR), with an absorbency of up to 800%. Tensile testing reveals that, as the amount of starch increases, the strength of the 3D scaffold strength reaches 4 × 10^−2 MPa. Scanning electron microscope (SEM) observations of the material reveal that the 3D scaffold is highly porous formed using a homogenizer at 500 rpm. In an enzymatic degradation, the 3D scaffold was degraded by various enzymes at a rate of up to approximately 30–60% in 28 days. In vitro tests revealed that cells proliferate and grow in the 3D scaffold material. Maximum number of cells about 20 x 10^4 after 6 days of culture. Energy dispersive spectrometer (EDS) analysis further verified that the bio-compatibility of this scaffold. Finally, the experimental results suggest the degree of swelling and degradation rate are significantly different compared with using starch and chitosan as an additive of the 3D scaffold.