燕麦发芽过程中淀粉及其相关酶活性的动态变化

研究了裸燕麦发芽过程中淀粉及其相关酶活性的动态变化。结果表明,发芽过程中,燕麦还原糖和可溶性糖含量及α-淀粉酶、β-淀粉酶和总淀粉酶活力明显地先增加后降低;直链淀粉、支链淀粉和总淀粉的含量均随着发芽的进行呈下降趋势,发芽72 h分别降低了25.86%、11.08%和17.31%。相关性分析表明,燕麦发芽期间还原糖、可溶性糖含量分别与α-淀粉酶、β-淀粉酶及总淀粉酶活力呈显著正相关,而直链淀粉、支链淀粉及总淀粉含量均与淀粉酶活力呈显著负相关。     

玉米发芽过程中碳水化合物代谢变化的研究

以苏玉24号玉米品种为试材,研究不同发芽阶段玉米的主要生理生化变化和碳水化合物组成变化。结果显示：随着发芽时间的延长,干物质含量减少,芽长和发芽率均呈现不同程度的增加,呼吸强度整体呈上升的趋势,可溶性蛋白在发芽60h达到最低,与未发芽相比降低了39.47%;淀粉酶活力逐渐增大,α-淀粉酶、β-淀粉酶和总淀粉酶活力在发芽60h时分别是未发芽玉米的4.74、16.82倍和14.41倍,在发芽108h时分别是未发芽玉米的18.33、69.77倍和59.58倍;在淀粉酶的作用下,淀粉含量总体呈下降的趋势,60h达到最小值,比未发芽玉米降低了12.62%;直链淀粉含量总体也呈下降的趋势,发芽60h后比未发芽降低了3.19%,而还原糖、可溶性糖逐渐增大,在发芽72h达到最大值,分别是未发芽玉米的4.69倍和6.88倍;同时DE值(dextrose equivalent value)先增大后减小,在发芽36h后变化显著(P＜0.05),并在发芽84h达到最大值,是未发芽玉米的13.71倍。各指标相关性表明玉米发芽过程中主要生理变化对碳水化合物的组成有很大影响。     

精白保胚米发芽过程中淀粉酶及相关营养成分的变化

研究精白保胚米发芽过程中α-淀粉酶、β-淀粉酶和葡聚糖内切酶活力的变化,同时测定其中还原糖、总糖、淀粉及热水溶性直链淀粉的含量变化,并以发芽糙米作为对照。结果表明:精白保胚米和糙米发芽过程中α-淀粉酶和β-淀粉酶的活性先由低变高,再由高变低,精白保胚米在发芽16h时淀粉酶的活性最高,而糙米在发芽时淀粉酶活性达到最高点时间较长;葡聚糖内切酶活力随发芽时间的增加活性逐渐升高,糙米在发芽过程中葡聚糖内切酶活力高于精白保胚米。还原糖、总糖的含量随着时间的增加而升高,在20～24h后逐渐降低,精白保胚米在发芽过程中还原糖的含量高于糙米。淀粉含量随发芽时间的延长而逐渐降低,热水溶性直链淀粉的含量则不断增加。     

发芽对不同品种糙米碳水化合物组成及其相关酶活性的影响

4个不同品种的糙米样品在35℃下发芽60 h,每间隔12 h取样分析其碳水化合物组成及相关酶活性的变化。结果表明,发芽使不同品种糙米的淀粉、直链淀粉及支链淀粉含量降低;还原糖和可溶性糖含量先增加、后降低;总淀粉酶活力和α-淀粉酶活力先上升、后下降。其中,籼稻糙米发芽36 h时,还原糖和可溶性糖含量以及总淀粉酶和α-淀粉酶活力达到高峰;而粳稻糙米和糯稻糙米的高峰值则出现在发芽48 h时。     

糙米发芽过程中主要营养成分变化的研究

探究糙米的主要营养成分在发芽过程中的变化。对糙米中各营养成分发芽前后含量进行测定。淀粉含量72 h时比发芽前下降28.8%,且淀粉含量随着α-淀粉酶活力的升高而下降;还原糖含量相比发芽前增加了6.46倍;可溶性蛋白先增加后减少;谷胱甘肽含量由3.74 mg/100 g上升到9.58 mg/100 g;游离氨基酸72 h时含量最高达881.45μg/g;γ-氨基丁酸含量呈现急剧增长趋势;主要内源酶活力均呈现逐渐上升趋势;VB6不断增加;VC24 h时含量达最高3.25 mg/100 g;植酸含量呈现持续降低趋势。糙米发芽24 h~48 h的营养价值最高。     

玉米种子发芽动态及生理变化研究

该研究以普通玉米(湘农玉27号)、甜玉米(湘农甜玉3号)和糯玉米(湘农白糯3号)为试验材料,研究不同发芽时间(0～72 h)玉米种子胚芽长、胚根长的变化动态,测定清蛋白、球蛋白、醇溶蛋白、谷蛋白、总蛋白、还原糖、总糖、支链淀粉、直链淀粉、总淀粉和赖氨酸含量等生理指标的变化,同时进行相关性分析,探索玉米种子发芽过程中的生理变化规律。结果表明,胚芽、胚根的长度随着种子发芽时间的延长而不断增加;发芽过程中,不同类型玉米的生理指标的变化趋势相同,但变化幅度存在差异,其中醇溶蛋白、谷蛋白、总蛋白、直链淀粉、总淀粉和总糖含量呈下降趋势,清蛋白、球蛋白、还原糖和赖氨酸含量则呈现上升趋势,清蛋白含量分别增加1.37%、0.31%和0.76%,球蛋白含量分别增加0.53%、0.21%和0.58%;还原糖含量最高分别达4.12%、5.82%和4.05%,赖氨酸含量分别提高1.64、2.00和1.71倍。相关性分析表明,玉米种子发芽过程中胚芽、胚根长分别与清蛋白、球蛋白呈显著、极显著正相关,与还原糖呈极显著、显著正相关,与直链淀粉极显著负相关。     

温度处理对发芽糙米中淀粉酶活力的影响

研究了温度处理对发芽糙米中淀粉酶活力的影响。结果表明 :在 1 6～ 2 8℃温度范围内 ,较低的温度能提高发芽糙米中α 淀粉酶和总淀粉酶活力 ,较高的温度使酶活力高峰提前出现 ,糙米最适发芽温度为 2 2℃。发芽糙米中 β 淀粉酶活力受发芽温度的影响较小。在发芽期间 ,糙米中淀粉含量随淀粉酶活力升高而降低 ,还原糖含量先升后降。     

实验室模拟越夏贮藏条件对玉米籽粒中淀粉及淀粉酶活性的影响

选用2013年收获的"农大709"玉米籽粒,将其分别贮藏于室温和恒温恒湿培养箱(35℃,RH75%)中,并测定玉米籽粒淀粉酶活性、淀粉和可溶性糖含量的变化,分析了高温高湿(35℃,RH75%)条件下淀粉酶与可溶性糖代谢之间的关系。试验结果表明:常温条件下总淀粉酶和α-淀粉酶活性在贮藏初期仍继续上升,而后不再发生显著变化;除蔗糖含量降低外,总淀粉和直链淀粉以及果糖、葡萄糖、麦芽糖均无显著变化。高温高湿贮藏条件下,总淀粉酶和α-淀粉酶活性均显著下降;玉米总淀粉含量无明显变化而直链淀粉含量上升;葡萄糖和果糖变化一致,均先上升后下降;而麦芽糖和蔗糖含量均为先下降后上升。     

兰州百合鳞茎冷藏保鲜过程中碳水化合物含量及淀粉酶活性的变化

以兰州百合为试材,采用紫外-可见分光光度法测定了-2 ℃冷藏保鲜过程中百合鳞茎内可溶性糖、还原糖、淀粉的含量与淀粉酶活性的动态变化,分析了碳水化合物含量与淀粉酶活性之间的关系。结果表明,在-2 ℃、60 d的冷藏保鲜期内,随着冷藏时间的延长,兰州百合鳞茎内淀粉含量明显下降,其下降幅度达62.29%,可溶性糖与还原糖含量呈上升趋势,分别上升了2.22%和1.39%。β-淀粉酶是兰州百合鳞茎中的主要淀粉酶,其活性随冷藏时间的延长而有所降低,α-淀粉酶的活性随冷藏时间的延长先降低后升高,总淀粉酶在高活性的基础上整体呈现降低的趋势。相关性分析表明,鳞茎中碳水化合物含量及淀粉酶活性之间的相关性差异水平有所不同。总淀粉酶、β-淀粉酶活性与可溶性糖、还原糖含量具有极显著负相关性,而与淀粉含量具有极显著正相关性。可溶性糖和还原糖含量的增加与低温诱导下淀粉在β-淀粉酶的作用下分解有关。     

糙米与发芽糙米主要品质性状的比较研究

试验以8份水稻品种的糙米和发芽糙米为供试材料,对糙米发芽前后的稻米理化性状、总糖和还原糖含量、可溶性蛋白含量、氨基丁酸含量及稻米食味和稻米RVA谱进行测定比较。结果表明,糙米在发芽后其直链淀粉含量和总糖含量均有不同程度下降;发芽糙米的还原糖含量、总蛋白质含量、可溶性蛋白含量及γ-氨基丁酸含量较糙米有不同程度增加;供试发芽糙米的食味值和RVA特征值均低于相应的糙米。总体来说,发芽糙米的营养价值高于糙米,而发芽糙米饭食味品质的提升还有待进一步研究。     

Optimization of Malting Conditions for Two Black Rice Varieties,Black Non‐Waxy Rice and Black Waxy Rice (Oryza sativa L. Indica)

Two black rice varieties, “black non‐waxy” and “black waxy”, were investigated as possible raw materials for the production of malt. The malting conditions were optimised using response surface methodology. The three process parameters were steeping, germination time and temperature. Each parameter was tested at three levels: adjustment degrees of steeping were 38, 41, and 44%, germination times were 6, 7, and 8 days, and the temperatures were 20, 25 and 30°C. At the end of the germination process, all samples were kilned at 50°C for 24 h, and shoot/rootlets were removed before a detailed quality assessment was performed. Data analysis was performed using the Design Expert Statistic Program. The optimal conditions found for both rice varieties were as follows: germination time of 8 days at 30°C and 44% grain moisture. Although the extract yield, and a‐amylase and β‐amylase activities of both rice malts were lower than barley malt, the higher activity of limit‐dextrinase enzyme and apparent attenuation limit (AAL), which was higher than 80%, suggests that rice malt has potential for use in brewing.     

Effects of germination on the activities of amylases and phenolic enzymes in sorghum varieties grouped according to food end‐use properties

Fifty sorghum varieties were screened to determine the effects of germination on levels of starch, α‐amylase, β‐amylase, phenylalanine ammonia lyase (PAL), peroxidase (POX) and polyphenol oxidase (PPO). Germination decreased starch content, with amylose being more degraded than amylopectin. In germinated grain, α‐amylase activity increased several‐fold in all varieties, whereas β‐amylase activity did not increase uniformly and even decreased in some varieties. Activity of the key enzyme in phenolic biosynthesis, PAL, was detected in only half of the varieties before germination but in all of them after germination. PPO was not activated in germinated sorghum grains, whereas POX activity increased up to tenfold in some varieties. Zymography revealed that germination induced de novo synthesis of several POX isoenzymes, among which an anionic POX isoenzyme (pI 3.1) was ubiquitously present. Amylase and phenolic enzyme activities could be correlated with grain and plant agronomic characteristics. The use of sorghum varieties for local dishes such as ‘tô’, ‘dolo’, couscous and thin porridge could be correlated with amylase and phenolic enzyme activities and the contents of their substrates. The biochemical constituents determined are useful markers for selection of varieties for food utilisation with special emphasis on infant porridges. Copyright © 2006 Society of Chemical Industry     

Effect of Ultrasonic Treatment on the Physicochemical Properties of Maize Starches Differing in Amylose Content

Normal maize, waxy maize and amylomaize V starches were treated at a moisture content of 70% by ultrasonic treatment. The results showed that the surface of normal and waxy maize starches was porous after treatment and a fissure could be clearly observed in the surface of amylomaize V starch. Ultrasonic treatment did not change the X‐ray pattern of the three maize starches. The swelling power (amylomaize V (B‐type) > normal maize > waxy maize (A‐type)) and solubility (amylomaize V > normal maize > waxy maize), the syneresis of amylomaize V starch and the gelatinization transition temperatures of the three starches increased on this treatment. Ultrasonic treatment decreased the syneresis of normal and waxy maize starches, the enthalpy of gelatinization (amylomaize V > waxy maize ≈︂ normal maize) and the gelatinization temperature range (amylomaize V > normal maize ≈︂ waxy maize) of all starches. A drop in viscosity of all three starches was observed and the viscosity patterns of three starches remained unchanged after ultrasonic treatment. The data showed that ultrasonic treatment degraded preferentially the amorphous regions and more easily attacked linear amylose than highly branched amylopectin.     

不同链淀粉含量玉米微晶淀粉理化性质研究

分别以蜡质玉米淀粉、玉米淀粉及高直链玉米淀粉为原料,在酸醇介质中制备不同水解率微晶淀粉,测定不同微晶淀粉水解性能并研究其颗粒形貌、结晶结构、溶解度及消化性。结果表明:淀粉颗粒内部结构致密性依次减弱,支链淀粉含量高的淀粉较易被试剂进攻;经酸醇处理后,三种微晶淀粉均保留原来晶型,颗粒形态没明显变化,没破碎和膨胀出现,但颗粒表面变粗糙;随直链淀粉含量增加,相似条件(水解率和温度)淀粉溶解度逐渐降低;in-vitro消化体系中三种淀粉及其微晶淀粉消化速度依次降低。     

不同发芽阶段高粱粉理化及功能特性的变化

该实验以白高粱为原料,研究不同发芽时间对高粱粉淀粉组分及含量、淀粉酶活力、热力学、糊化、流变以及功能特性的影响。结果表明,发芽后高粱淀粉酶活力显著上升;总淀粉、直链淀粉和支链淀粉含量显著下降;热力学性质测定结果表明,发芽使糊化焓增加,提高了其稳定性和结晶度,起始糊化温度上升,峰值和终止糊化温度无显著变化;随着发芽时间的延长,高粱粉体系黏度下降,热糊稳定性及冷糊稳定性提高;储能模量和损耗模量低,高粱粉糊的流动性增强;发芽改善了高粱粉的乳化和乳化稳定性、起泡和泡沫稳定性,持油性提高、持水性降低。综上所述,发芽在一定程度上改善了高粱粉的理化及功能特性。     

发芽对普通玉米和糯玉米淀粉理化特性的影响

以普通玉米和糯玉米种子为材料,进行不同发芽时间处理,分析发芽对其淀粉理化特性的影响。结果表明,与CK（未发芽处理）相比,两种类型玉米发芽后淀粉溶解度和淀粉糊透光率增大,且随着发芽时间的延长而升高;蓝值、碘结合力和膨润力减小,且随着发芽时间的延长而降低。普通玉米发芽36 h时淀粉胶凝化和回生参数最高;发芽后糯玉米淀粉的胶凝化温度降低,胶凝化焓值、回生焓值和回生值随发芽时间的延长先升高后降低,在发芽48 h时最高。发芽提高了两种类型玉米淀粉的结晶度,普通玉米淀粉结晶度和尖峰强度在发芽60 h时最高,糯玉米在48 h最高。因此,发芽可以作为改变淀粉理化特性的手段,为玉米的加工利用提供参考。     

Preparation and properties of RS III from waxy maize starch with pullulanase

Waxy maize starch was treated by pullulanase debranching and retrogradation at room temperature to produce resistant starch (RS). Physicochemical properties, crystalline structure and in-vitro digestibility of starch samples with different RS content were investigated. Compared with native starch, apparent amylose content of RS products increased. Based on Gel Permeation Chromatography (GPC) the Molecular Weight Distribution (MWD) of resistant starches significantly changed. Scanning Electron Microscopy (SEM) showed that upon pullulanase debranching and retrogradation treatment the granular structure of native starch was destroyed and all RS samples exhibited irregular shaped fragments. Crystal structure of samples changed from A–type to a mixture of B and V–type. The crystallinity of resistant starch also improved as compared with native starch. Moreover, samples with higher resistant starch showed higher relative crystallinity. Differential Scanning Calorimetry (DSC) determination showed that To、Tp、Tc and ΔH all increased which was in agreement with RS content. The resistance of waxy maize starch with Pullulanase treatment to α-amylase digestibility also increased, while the in-vitro digestibility of products decreased.     

Milling and flour pasting properties of waxy endosperm mutant lines of bread wheat (Triticum aestivum L)

Two waxy endosperm mutant lines, K107Wx1 and K107Wx2, derived from a bread wheat cultivar, Kanto 107, had a lower flour yield in test milling and a lower peak temperature in flour pasting measurement than their parent. Starch content in the kernel of waxy mutants was low, while fat and (1→3),(1→4)‐β‐D‐glucan content was high compared with cv Kanto 107, but protein content was similar for all of them. Waxy mutants had less α‐amylase activity than their non‐waxy parent, and had lower peak viscosity of flour paste in the pasting medium of water. A pasting test in silver nitrate solution increased peak viscosity in both waxy and non‐waxy flours. The viscosity of waxy flour paste rapidly increased above 60°C, while that of non‐waxy flour paste increased gradually at 60–80°C. The difference in pasting behaviour was attributed to the presence of amylose in starch granules. © 1999 Society of Chemical Industry