水分对微波辐射玉米淀粉性质的影响

用微波辐射不同水分含量的玉米淀粉,并对微波改性后淀粉的性质进行研究,结果发现其黏度下降,糊化温度提高,热稳定性提高;晶体结构仍为A-型晶,但是微晶减少,亚微晶略有增加,总的结晶度变化不明显;随着水分的增大,淀粉颗粒的偏光十字逐渐减弱,当水分达40%时,多数淀粉偏光十字已经消失.     

水分对微波变性木薯淀粉颗粒物态性质的影响

本文研究了不同水分含量对微波变性的影响,发现微波辐射导致淀粉颗粒内部产生的由内向外的瞬间膨胀压力使原木薯淀粉微孔孔径进一步增大而形成大小不同孔径的爆裂孔,脐点处的爆裂孔孔径最大,微波变性时原淀粉的水分含量应当小于35％。孔结构的改变对提高淀粉的反应活性具有重要意义,微波处理的结果为酶的作用提供了通道。     

木薯淀粉纳米颗粒的制备及载药性能的研究

以木薯淀粉为原料,用微波-超声波辅助沉降法制备淀粉纳米颗粒,通过扫描电镜、粒度仪等对淀粉纳米颗粒进行了表征。以姜黄素为载药模型,考察了药物初始质量浓度、无水乙醇质量分数、载药温度、载药时间对载药量的影响,并探究了木薯淀粉纳米颗粒对姜黄素的缓释作用。结果表明,药物初始质量浓度为40μg/m L、无水乙醇质量分数为30%、载药温度为30℃、载药时间25 min时,木薯淀粉纳米颗粒对姜黄素的吸附量最大,可达81.14 mg/g。姜黄素原料药5 h释放率为95%,而木薯淀粉纳米颗粒透析5 h后,药物释放率仅为15%。由此可知,微波-超声波辅助沉降法制备的木薯淀粉纳米颗粒具有较好的载药性能,并对药物具有较好的缓释效果。     

马铃薯淀粉颗粒在微细化过程中结晶结构的变化

采用偏光显微镜、X光衍射及差热分析等测试手段 ,探讨了马铃薯淀粉颗粒在用机械球磨微细粉碎过程中结晶结构变化的特征及规律。结果表明 ,机械力化学效应使得淀粉颗粒结晶结构受到破坏 ,结晶程度降低 ,最终由多晶态转变成非晶态。马铃薯淀粉的糊化温度也随粉磨时间的延长而降低 ,糊化相变吸热峰逐渐消失 ,水分相变吸热峰增强。     

微波变性淀粉水解规律的研究

利用α-淀粉酶和葡萄糖苷酶作用于微波变性木薯淀粉，并与原木薯淀粉进行比较，考察微波变性木薯淀粉在α-淀粉酶和葡萄糖苷酶作用下的降解规律。结果表明在相同水解条件下，微波变性淀粉更易于被水解。     

微波辅助复合氧化法合成氧化玉米淀粉

以玉米淀粉为原料、以过氧化氢和过硫酸钾为复合氧化剂、以Fe2＋为催化剂,在酸性条件下采用微波辅助复合氧化法合成氧化玉米淀粉。以反应温度、微波催化合成/萃取仪功率、催化剂质量分数（占干淀粉总量,下同）、复合氧化剂质量分数（占干淀粉总量,下同）、淀粉乳浓度、体系pH值、反应时间等因素为变量,以氧化度为衡量指标,采用单因素实验和正交实验确定微波辅助复合氧化法合成氧化玉米淀粉的最佳工艺条件为：反应温度55℃、微波催化合成/萃取仪功率400 W、催化剂质量分数0.3%、复合氧化剂质量分数8%、淀粉乳浓度45%、体系pH值4.00、反应时间21min,在此条件下,可以制得氧化度为0.140%的氧化玉米淀粉。     

非晶颗粒态马铃薯淀粉结构特征

用扫描电子显微镜、偏光显微镜、X -射线衍射法等分析测试方法 ,以原淀粉为参照 ,对非晶颗粒态马铃薯淀粉的颗粒形貌、颗粒大小和结晶程度进行了详尽观察 ,结果发现 ,在非晶化处理过程中发生了从内向外爆裂式膨胀而形成大小、深度、位置不同的爆裂孔 ,并有少量的淀粉颗粒碎片粘附在颗粒的表面上 ,非晶颗粒态淀粉仍然能够保持颗粒外形 ,颗粒大小比原淀粉有所增加 ,不再具有原淀粉颗粒结晶性 ,整个颗粒呈现无定形结构     

赤铁矿反浮选抑制剂变性淀粉的制备及应用性能

本文采用干法工艺,以木薯淀粉为原料,在固相中与酯化剂磷酸二氢钠、氧化剂过氧化氢进行反应,制备复合变性淀粉。讨论了酯化剂、氧化剂、催化剂、反应温度、反应时间、反应体系水的质量分数、反应pH值等因素对反应的影响。实验结果表明,当酯化剂NaH_2PO_4用量为淀粉质量的4.0%,氧化剂过氧化氢用量为淀粉质量的1.0%,催化剂用量为淀粉质量的2.0%,反应pH值为6.0,体系水分含量为25%时,低温60℃反应3h,高温135℃反应2h,制备所得产品的指标为:酯化取代度DS为0.0545,羧基含量为0.0862%,在赤铁矿反浮选中作为抑制剂,效果显著。     

高交联非晶颗粒态玉米淀粉制备方法研究

报道了高交联、水分散体系高温溶胀、高交联碱糊化协同作用非晶颗粒态玉米淀粉的制备方法 ,采用偏光显微镜对其由多晶态向非晶态的变化进行了确认 ,提出在一定条件下 ,高交联玉米淀粉可以由原淀粉多晶颗粒态制备成只含无定形结构的非晶颗粒态淀粉     

微波场对小麦淀粉性质的影响

研究了微波辐射前后小麦淀粉物化性质的变化。采用微波对水分含量30％的小麦淀粉进行处理。结果表明微波处理淀粉颗粒表面出现小孔,微波处理增强了对应X射线衍射峰的强度,降低了膨胀度、溶解度、析水率以及焓值,提高了糊化转变温度、转变温度范围。小麦淀粉经处理后糊化起始温度升高、黏度降低,但其黏度曲线不改变。以上数据表明在淀粉颗粒内无定形区和结晶区的直链淀粉与直链淀粉、直链淀粉与支链淀粉发生交互作用,产生了新的不同稳定性的结晶体,从而导致微波处理淀粉内部更加有序的结晶排列。     

氧化/交联双重改性淀粉胶粘剂的制备

以玉米淀粉为原料、过硫酸铵(APS)为氧化剂和三聚氰胺为交联剂,采用氧化/交联双重改性法制备淀粉胶粘剂。研究了反应时间、反应温度、氧化剂和交联剂用量等因素对改性淀粉胶粘剂耐水性和流动性能的影响。结果表明:当反应时间为2.5 h、反应温度为65℃、w(APS)=4.0%、w(甲醛)=1.00%和w(三聚氰胺)=2.5%时,改性淀粉胶粘剂的耐水性(耐水时间96 h)和流动性能(黏度750 mPa·s)均较好。     

DRYING OF SLICED RAW POTATOES IN SUPERHEATED STEAM AND HOT AIR

Drying experiments were conducted on raw potato slices, using atmospheric pressure superheated steam and hot air as drying media at 170 and 240°C. Mass changes of the material were continuously measured, the conditions of cross section near the surfaces were observed with an electron microscope, also color changes of their surface were measured during drying. The respective drying methods and temperature conditions were compared and it was found that, in the case of superheated steam drying, moisture content temporarily increases due to steam condensation in the initial stage of drying, therewith, as well as starch gelatinization rapidly develops. Meanwhile, in case of hot air drying, starch gelatinization occurs more slowly than with superheated steam drying and that non-gelatinized starch granules remain on the surface when drying was completed. Furthermore, surface color measurements showed that samples dried by superheated steam were more reddish than ones dried by hot air and the surfaces were more glossy, because no starch granules remain on the surface in case of superheated steam drying.     

DRYING OF SLICED RAW POTATOES IN SUPERHEATED STEAM AND HOT AIR

Drying experiments were conducted on raw potato slices, using atmospheric pressure superheated steam and hot air as drying media at 170 and 240°C. Mass changes of the material were continuously measured, the conditions of cross section near the surfaces were observed with an electron microscope, also color changes of their surface were measured during drying. The respective drying methods and temperature conditions were compared and it was found that, in the case of superheated steam drying, moisture content temporarily increases due to steam condensation in the initial stage of drying, therewith, as well as starch gelatinization rapidly develops. Meanwhile, in case of hot air drying, starch gelatinization occurs more slowly than with superheated steam drying and that non-gelatinized starch granules remain on the surface when drying was completed. Furthermore, surface color measurements showed that samples dried by superheated steam were more reddish than ones dried by hot air and the surfaces were more glossy, because no starch granules remain on the surface in case of superheated steam drying.     

微波辐射对木薯淀粉结构的影响

考察了不同含水量的木薯淀粉经不同形式（敞口和封口形式）微波辐射的温度变化曲线及其多层次结构.结果表明：无论以那种形式辐射,木薯淀粉样品含水量越低,样品温度升高幅度越大,且都会出现等温转换,含水量越高等温转换时间越长,敞口辐射较封口辐射的等温转换更显著; FTIR结果显示,微波辐射不破坏木薯淀粉分子的化学键,没有新的化合物产生,红外结晶指数略有降低;偏光显微镜和光学显微镜的结果显示,木薯淀粉的结晶结构有所变化,而其形态结构没有变化.这些结果表明,经微波加工的木薯淀粉食品对人或其他生物是安全的.     

微波条件下水分含量对淀粉醚化反应的影响

以木薯淀粉为原料,3-氯-2-羟丙基三甲基氯化铵为阳离子醚化剂,自制碱性复合催化剂为醚化催化剂,采用微波法制备阳离子淀粉。研究探讨不同醚化剂用量、不同微波功率、不同微波时间条件下,反应体系水分含量对阳离子醚化反应效率的影响。结果表明,不同的醚化剂用量、不同的微波功率及不同的微波时间组合,获得最佳醚化反应效率所需的反应体系水分含量各有不同。醚化剂用量较高时,选用较高的体系水分含量以及较高的微波功率和较长的微波时间,可获得较高的醚化反应效率;醚化剂用量较低时,选用中等的体系水分含量以及中等的微波功率和较长的微波时间,可获得较高的醚化反应效率。     

Effects of germination time and drying temperature on drying characteristics and quality of germinated paddy

Germination time and drying temperature are very important parameters affecting the quality of the germinated paddy (GP) since the microstructure of starch granules is modified during germination. The experimental results showed that the germination time increasing from 60 to 68 h provided more loosely-packed starch granules, lower hardness of cooked GP, higher γ-aminobutyric acid content (GABA) and larger number of fissured GP after drying. However, the modified microstructure did not cause a difference between drying curves at each germination time. Prediction results of the moisture content from the two-layer model were in good agreement with the experimental results and also showed that the effective moisture diffusion coefficient values of husk were significantly lower than those of germinated brown rice. Drying at a higher drying temperature could reduce the number of fissured GP more significantly. The hardness of cooked GP samples and their GABA contents obtained from drying temperatures changed insignificantly from that of the shade-dried GP. The sensory analysis results revealed that the texture of GP was better than that of the rice without germination and the longer germination time provided the adverse effect on the fermentation odour and texture.     

Development of a new pre-drying method of accelerated water absorption and partial gelatinization of starch in paddy using pulsed microwave-water applications in a microwave rotary drum dryer

The present study was undertaken to develop a pre-drying process of an accelerated water absorption and partial gelatinization of starch in paddy using pulsed microwave-water applications. The experiments on microwave-assisted water absorption by paddy (var. Sworn Masuri) at five power density levels in the range 0.2–1?kW?kg^?1 were conducted in a semi-pilot-scale microwave dryer. The paddy was exposed to pre-calculated intermittent water spray and pulsed microwaves up to 100?min. The water absorption kinetics were modeled using modified Azuara’s equation of mass transfer and the process was compared with traditional hot water soaking of the paddy at 60?°C for 3.33?h. The moisture content gained by paddy during microwave-assisted water absorption was faster (30% in 1.67?h) compared to hot water soaking (30% in 3.33?h). The consumption of water, specific energy, and water absorption time during microwave processing were reduced by 70%, 39.51%, and 50%, respectively. The method of slopes was used to estimate moisture diffusivity during microwave-assisted water absorption by paddy. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) of treated paddy were done to understand the changes in the crystallinity and the microstructure of starch molecules. The microwave-assisted water absorption process was found to accelerate the moisture gain with the effect of partial gelatinization of starch in the paddy. Further, the experiment can be continued in the same microwave dryer to fully gelatinize the paddy at 30% moisture content and dry the gelatinized paddy.     

Design,Preparation and Characterization of Self‐Reinforced Starch Films through Chemical Modification

A new technique for design and preparation of self‐reinforced starch films is introduced. The films were based on a high‐amylose corn starch that was chemically modified in different ways. Hydroxypropylation was used to decrease gelatinization temperature and improve processability. The reinforcing component consisted of cross‐linked starch granules, where the crosslinking increased granule thermal stability and moisture resistance. Distribution of the cross‐linked starch was imaged by CLSM, and the matrix/particle interface was studied by SEM. Modulus and tensile properties of the starch film were increased by about 30 and 20%, respectively, after addition of rigid cross‐linked starch particles. A perfect interface between matrix and reinforce agent was obtained.

     

酯化淀粉接枝马来酸酐共聚物微球制备及对Mn2+的吸附

首先以淀粉为原料、多聚磷酸钠为酯化剂制得磷酸酯淀粉,然后采用反相乳液聚合法制备磷酸酯淀粉微球,并用马来酸酐对微球进行改性。通过单因素试验法探讨了m(淀粉)∶m(多聚磷酸钠)配比、乳化剂含量、交联剂含量和温度等因素对微球的形成和产率等影响,并对微球的结构、溶胀性和吸附性等进行了分析。结果表明:当m(淀粉+多聚磷酸钠)=10 g、m(淀粉)∶m(多聚磷酸钠)=60∶40、环氧氯丙烷(ECH)交联剂为5 g、乳化剂为0.10 g和反应时间为5.0 h时,微球产率相对最高;当Mn2+浓度为0.03 g/L时,磷酸酯淀粉微球、马来酸酐改性淀粉微球对Mn2+的常温吸附量分别为0.616、0.793 mg/g。     

改性大米淀粉胶粘剂的制备和应用

以大米淀粉为原料、丙烯酰胺(AM)为接枝改性剂、封闭型异氰酸酯为主交联剂和三羟甲基苯酚(TMP)为助交联剂,合成了一种改性大米淀粉胶粘剂。对各种影响因素进行了分析,得出了最佳的工艺参数,即当w(淀粉)≈25%(相对于主剂而言)、w(双氧水)=7%(相对于淀粉而言)、6%≤w(AM)≤8%(相对于主剂而言)、w(TMP)=5%(相对于主剂而言)、并选用乙烯/醋酸乙烯共聚乳液(VAE)作为分散剂以及采用亚硫酸氢钠对芳香族异氰酸酯预聚体进行封闭时,改性大米淀粉胶粘剂的耐水性能和胶接性能明显提高,符合Ⅱ类胶合板的使用要求。