蒸制时间对滇黄精色泽、可溶性成分及糖含量的影响

黄精炮制的关键工序是蒸制。为此研究了蒸制时间对产品色泽、可溶性成分及糖含量的影响,并模拟胃肠道环境试验了糖含量的变化。结果表明:色泽随蒸制时间的延长而加深;蒸制24 h,80%vol乙醇可溶性成分增加极显著(p<0.01),达到70.79%,而水溶性成分减少极显著(p<0.01),降至9.52%;滇黄精不含淀粉;蒸制48 h葡萄糖和还原糖含量分别增加达到4%和47.84%,变化都极显著(p<0.01);蒸制12 h粗多糖含量最高,达到9.73%,继续蒸制到24 h粗多糖含量下降到4.26%,变化极显著(p<0.01);模拟胃肠道环境后,葡萄糖、粗多糖含量变化不显著(p>0.05),还原糖含量变化显著(p<0.05)。综上,需要得到粗多糖含量高,葡萄糖含量低的黄精产品蒸制时间应小于12 h,需要得到还原糖、可溶性成分多的黄精产品应蒸制24~48 h。     

干燥方式和贮藏对甘薯可溶性糖组分组成和变化的影响

目的 探究不同干燥方式和贮藏时期对甘薯可溶性糖分组成及其变化的影响。方法 以食用型甘薯烟薯25号和普薯32号为试验材料,按不同贮藏时期取样,分别进行冷冻干燥和热风干燥处理,采用超声振荡提取-离子色谱-脉冲积分安培法对样品中10种可溶性糖组分进行提取和同时测定。结果 冷冻干燥处理,烟薯25号和普薯32号甘薯中均检出大量的葡萄糖、果糖、蔗糖和少量麦芽糖、鼠李糖、阿拉伯糖、甘露糖、半乳糖,其可溶性糖组分总量分别为151.3 g/kg和112.9 g/kg;热风干燥处理,除以上糖组分外,还检出了棉子糖和水苏糖;两个品种甘薯可溶性糖组分总量分别为203.3 g/kg和151.8 g/kg;除蔗糖外,烟薯25号甘薯各糖组分含量及其总量均显著高于冷冻干燥处理。随贮藏时间延长,两个品种甘薯中可溶性糖组分总量均呈先增加后降低的趋势,其中,烟薯25号在贮藏45 d后达到最高,普薯32号则在贮藏15 d后达到最高;烟薯25号甘薯中葡萄糖、果糖、麦芽糖和可溶性糖组分总量在各贮藏期均显著高于普薯32号,而蔗糖则在整个贮藏期间均低于普薯32号。结论 贮藏过程可使甘薯中可溶性糖含量增加,贮藏15~45 d可溶性糖含量达到最高。冷冻干燥比热风干燥更好的保持了甘薯样品可溶性糖分组成的稳定性。     

Starch Synthesis in Potato Tubers: Identification of the in vitro and the in vivo Acceptor Molecules of Soluble Starch Synthase Activity

A soluble starch synthase preparation obtained from potato tubers (Solanum tuberosum L.) was used to identify the acceptor molecules of the enzyme in vitro. Maltose was the shortest effective primer molecule, and several straight and branched glucose polymers were also able to serve as primer. Osmotically permeabilized potato tissue slices were used to identify the acceptor molecules of granule-bound and soluble starch synthases under semi in vivo conditions. Specific assay conditions were employed to differentiate between the different starch synthesizing enzyme activities. Both the granule-bound and the primed soluble starch synthases elongated amylose and amylopectin molecules which were already deposited into starch granules. Soluble malto-oligosaccharides also functioned as acceptor molecules. In the presence of 0.5 M sodium citrate, starch synthase activity was enhanced. Both amylose and amylopectin accepted more glucose units than in the absence of sodium citrate, indicating that the citrate stimulated soluble starch synthase elongated both starch components as well. The acceptor molecules of the citrate stimulated reaction are probably partly soluble. The elongation patterns of the different starch synthases are dealt with in view of some of the models explaining the side-by-side synthesis of amylose and amylopectin in higher plants.     

羽衣甘蓝叶片色素的基本特性及其稳定性研究

在提取纯化的基础上分析羽衣甘蓝叶片色素的基本特性及其稳定性。结果表明：羽衣甘蓝叶片色素为紫红色,极易溶于水等极性溶剂,在pH2.0 的水溶液中于540nm 波长下有最大吸收峰值。羽衣甘蓝叶片色素的颜色和吸光度受溶液pH 值变化的影响。在pH2.0 的水溶液中,羽衣甘蓝叶片色素的耐光性较好,但不耐受50℃以上的温度。酸味剂柠檬酸、苹果酸、乳酸,糖类物质蔗糖、葡萄糖、乳糖和表面活性剂SDS 对羽衣甘蓝叶片色素均有非常明显的增色与护色作用,使该色素的稳定性增强。但糖类物质会随着时间的延长(6d 以后),对色素的增色、护色作用逐渐减弱,并又逐渐出现减色作用。     

The effect of overwintering on the chemical composition of nine varieties of swede

The compositions of the roots of nine varieties of swede of high, medium or low dry matter content and winter-hardiness have been compared in samples harvested in November 1982 or March 1983. There was between 52 and 63% of root dry matter as soluble glucose, fructose and sucrose, 18 to 22% as cell wall polymers, 10 to 12% as soluble phenolic material and 3 to 5% inorganic nutrients. The chemical composition and so, presumably, nutritive value of the low and medium winterhardiness varieties were unchanged over the sampling period, whereas the high winter-hardiness varieties increased their soluble sugar levels (particularly glucose) by 20% over the winter.     

Carbohydrate Composition of Winged Bean (Psophocarpus tetragonolobus)

The carbohydrate composition of winged bean has been studied. The seeds contain about 42.2% total carbohydrates of which starch alone accounts for 36.2%. The total monosaccharides constituted 2.7% and were identified as glucose (1.17%) and fructose (1.5%); oligosaccharides amounted to only 0.61% and were identified as sucrose, raffinose, stachyose, and verbascose, on a dry defatted basis. The cold water soluble gum of winged bean contains glucose and xylose as the major sugars together with a small amount of arabinose while hot water soluble gum was found to be a glucantype polymer. Hemicellulose A consisted of glucose, xylose, and arabinose (15.5:9:1) whereas hemicellulose B consisted exclusively of glucose indicating that it is also a glucan-type polymer.     

桑葚果实不同发育期品质测定及其相关性分析

本研究对湛江地区7个桑葚品种青果期、转色期、成熟期三个时期桑葚果的单果重、可溶性固形物、可滴定酸含量及糖和有机酸组成和含量进行了测定,并进行了相关性分析。结果表明,在成熟过程中桑葚果实的可溶性固形物和糖含量呈增加的趋势,而酸则呈降低的趋势;在桑葚果实品种中检测出柠檬酸、苹果酸、奎宁酸、琥珀酸、酒石酸、酮戊二酸、抗坏血酸、草酸共8种有机酸,其中柠檬酸的含量最高,其在不同品种不同发育期含量为44.84%~80.86%,其次为奎宁酸和苹果酸;果糖和葡萄糖是桑葚重要的糖组成,其含量在成熟期的台湾长果桑的含量分别达到57.79 mg/g和66.72 mg/g,并且只有在台湾长果桑中检测到蔗糖;通过相关性分析,可滴定酸与可溶性固形物、果糖、葡萄糖、果重呈负相关,且可溶性固形物、果糖含量、葡萄糖含量三者之间呈极正相关。     

面粉中戊聚糖含量测定方法的探讨

对测定面粉中戊聚糖含量的地衣酚 -盐酸法进行了研究 ,得到如下结论 :面粉中存在的己糖干扰可通过双波长 (670、580 nm)下吸光度的差值消除 ;利用酵母发酵去除葡萄糖会带来更多干扰 ;对地衣酚 -盐酸法和间苯三酚法进行了比较 ,二者所得可溶性戊聚糖含量相似 ,但后种方法测得总戊聚糖含量略低。     

动态高压微射流对刺梨果渣膳食纤维及其抑制淀粉消化和葡萄糖扩散的影响

本实验以刺梨果渣为原料,采用酶法制备可溶性膳食纤维（soluble dietary fiber,SDF）、不可溶性膳食纤维（insoluble dietary fiber,IDF）和全膳食纤维（total dietary fiber,TDF）,并采用动态高压微射流（dynamic high pressure microfluidization,DHPM）对刺梨果渣SDF进行改性处理,初步探索了刺梨果渣膳食纤维及DHPM处理SDF（DHPM-SDF）的理化特性及其对淀粉酶活力和葡萄糖扩散的影响。结果表明,IDF和SDF都能通过吸附葡萄糖、抑制葡萄糖扩散以及改变胰淀粉酶二级结构来减缓葡萄糖的流动进程和淀粉消化速率,其中,IDF对葡萄糖的吸附能力和抑制葡萄糖扩散能力分别是SDF的1.28 倍和1.99 倍,而SDF的胰淀粉酶活力抑制率是IDF的1.73 倍,并且,SDF对胰淀粉酶活力的抑制作用主要通过改变胰淀粉酶的α-螺旋和无规卷曲结构。TDF表现出与IDF相似的葡萄糖吸附能力和抑制淀粉酶活力的能力。与SDF相比,DHPM-SDF平均粒径增加了2.08 倍,使得其葡萄糖吸附能力和抑制葡萄糖扩散能力分别提高了28.13%和62.09%,并且DHPM-SDF能显著减少胰淀粉酶的α-螺旋和无规卷曲结构相对含量（P＜0.05）,其对淀粉酶活力的抑制能力是SDF的1.44 倍。因此,刺梨果渣膳食纤维,尤其是SDF可作为降血糖产品开发的潜在优良资源,并且DHPM是提高刺梨果渣可溶性膳食纤维降血糖活性的有效改性处理手段。     

Coupling speciation and isotope dilution techniques to study arsenic mobilization in the environment

We have developed an approach to isolate mechanisms controlling mobility and speciation of As in soil-water systems. The approach uses a combination of isotopic exchange and chromatographic/mass spectrometric As speciation techniques. We used this approach to identify mechanisms responsible for changes in the concentration of soluble As in two contaminated soils (Eaglehawk and Tavistock) subjected to different redox conditions and microbial activity. A high proportion of the total As in both soils was present in a nonlabile form. Incubation of the soils under anaerobic conditions led to changes in the concentration of soluble As in each soil but did not change the As speciation or the proportion of total As in labile forms in the soils. Hence, a decrease in soluble As in the Eaglehawk soil was the result of an Eh-induced pH decrease, enhancing the solid-phase sorption of As(V). An increase in soluble As in the Tavistock soil was due to an Eh-induced pH increase, decreasing solid-phase sorption of As(V). Incubation of the soils under aerobic conditions with microbial activity stimulated by addition of glucose resulted in no change in the solution concentration or speciation of As in the Eaglehawk soil, but led to a large increase in the concentration of soluble As in the Tavistock soil. This increase was due to conversion of exchangeable forms of As(V) into less strongly sorbed As(III) species. Incubation under anaerobic conditions in the presence of glucose resulted in a large increase in the concentration of soluble As in both soils; however, different mechanisms were found to be responsible for the increase in each soil. In the Eaglehawk soil higher concentrations of As were again due to conversion of exchangeable forms of As(V) into less strongly sorbed As(III) species. In contrast in the Tavistock soil, the increased As in solution was the result of release of As(V) from the large reservoir of nonlabile soil As.     

不同品种膳食纤维影响小鼠糖耐量结果的比较

本文选择多功能大豆纤维（MSF）、小麦纤维、纤维素、果胶和瓜儿胶等5种膳食纤维，对其影响小鼠葡萄糖耐量结果作了比较与分析。结果显示，1.0g/kg MSF、果胶或瓜儿胶可使葡萄糖耐量曲线变得尤为平缓，而同剂量纤维素和小麦纤维的效果并不显著。水溶性、粘性膳食纤维具有明显的稳定餐后血糖的作用，原因可能在于它能增加小肠内容物粘性，增加肠内非搅动层（unstirred layer）的厚度，并能使胃的排空速率降低，从而显著降低葡萄糖吸收速度。     

Variability in the content of soluble sugars and cell wall polysaccharides in red‐ripe cherry and high‐pigment tomato cultivars

BACKGROUND: Soluble sugars and cell wall polysaccharides are well known for contributing to a range of ‘quality’ characteristics of fresh vegetables such as flavour, texture and healthy properties. Red‐ripe berries of 14 cultivars of cherry tomatoes and four cultivars of high‐pigment tomato hybrids, cultivated in the south of Italy, were analysed for their content of these important qualitative parameters. RESULTS: Sakura appeared to be the cultivar with the highest amount of soluble sugars (53 g kg^?1 fresh weight (f.w.)), mainly glucose and fructose, and, hence the ‘sweetest’ among cherry tomatoes. High‐pigment tomatoes, especially HLY02 and HLY13, showed a soluble sugar content much lower than cherry tomatoes, as expected for industrial, normal‐size tomatoes. Variations in the fructose/glucose ratio, of between 0.68 and 1.48, were evidenced among the different tomato cultivars. Cell wall polysaccharides isolated from whole fresh red‐ripe berries of each cultivar were analysed chemically. The amount of matrix polysaccharides (0.9–3.4 g kg^?1 f.w.) and cellulose (0.16–1.86 g kg^?1 f.w.), as well as their glycosidic composition, showed significant differences among the different cultivars. Cellulose to matrix polysaccharide ratio was highly variable and ranged between 0.06–1.44 and 0.17–0.77 in cherry and high‐pigment tomato cultivars, respectively. CONCLUSION: The differences evidenced in the total soluble sugar and cell wall polysaccharide composition, not only among different types of tomatoes but also different cultivars within the same typology, may play a fundamental role in the quality of tomatoes and deserve further investigations. Copyright © 2008 Society of Chemical Industry     

Physico-chemical changes in sugarcane (Saccharum officinarum var yellow cane) and the extracted juice at different portions of the stem during development and maturation

A study was conducted to determine the physicochemical differences between portions (top, middle, and bottom) of sugarcane at different maturation stages (between 3 and 10 months from planting). The variety used was Saccharum officinarum var. Yellow cane. The parameters analysed were weight, diameter, yield, total soluble solids (TSS), pH, titratable acidity, sugar content (sucrose, glucose, fructose). The weight, diameter, total soluble solids (TSS) and sucrose content increased significantly (P<0.01) in all portions (top, middle and bottom) up to the end of maturity. On the other hand, titratable acidity (TA), pH, juice yield, glucose and fructose contents decreased significantly (P<0.01) during maturation. However, significant differences were also detected in weight, diameter, TSS, sugar content, pH, TA and juice yield between the different portions during maturation. Sucrose content, juice yield and TSS were found to be the most suitable indicators of maturity, while TA, glucose and fructose contents were found to be poor maturity indicators. A suitable harvesting stage was found to be between 7 and 8 months after planting.     

冠突散囊菌与茶叶生物碱共培养液态发酵体系的构建及特性

选取茶叶中三种主要生物碱咖啡碱(Caffeine)、可可碱(Theobromine)、茶碱(Theophylline)作为构建单体-冠突散囊菌共培养液态发酵体系(10 d)的添加底物,考察了冠突散囊菌对茶叶中主要生物碱的发酵特性。结果表明,与对照组相比,咖啡碱(0.2mg/mL)的添加可刺激冠突散囊菌的生长与繁殖,发酵液中葡萄糖的含量下降更为迅速,pH值随着发酵时间的增加持续下降直至第9 d趋于稳定,可溶性蛋白含量呈现先增加后下降的趋势,但在发酵过程中,冠突散囊菌既不能将其作为碳源、氮源消耗来维持生长,也不能代谢分解咖啡碱;可可碱与茶碱(0.08 mg/mL)在发酵体系中的发酵情况与咖啡碱基本相似,两者均能刺激冠突散囊菌的生长与繁殖,但均不能将其作为碳、氮源消耗,且发酵结束后在各自发酵体系中分别检测到0.00091 mg/mL、0.00109 mg/mL的咖啡碱,这说明冠突散囊菌可能具有以可可碱、茶碱作为前体合成咖啡碱的能力。     

Synthesis and testing of glucose derivatives for feeding to ruminants

Glucose compounds were synthesized and tested for resistance in a 48-h in vitro rumen fermentation. Glucose complexed with formaldehyde, acetaldehyde, and acetone was resistant. When complexed with propionic and succinic acids, the products readily fermented. The resistant compounds also withstood acid hydrolysis at a pH similar to that of the abomasum. This suggests that these products would have little value as a dietary source of glucose for ruminants if the release of glucose to the animal depended on acid hydrolysis in the abomasum. The possibility of enzymatic hydrolysis of glucose-formaldehyde compound was studied in a feeding trial with sheep. Eight Finncross wethers were fed the formaldehyde product in three quantities in their diet. Blood and urine glucose plus blood, urine, and fecal total soluble carbohydrate were measured. It appears that this glucose-formaldehyde product resists rumen fermentation but does not become metabolically available to sheep as indicated by large quantities of product excreted in urine and feces.     

Respiratory inhibitors affect incorporation of glucose into Saccharomyces cerevisiae cells,but not the activity of glucose transport

Incubation of starved galactose-grown S. cerevisiae cells with cyanide reduced glucose uptake as measured over a 5-s period. The V_max for glucose uptake was decreased by over a factor of two but the apparent affinity for glucose doubled. When measured in the sub-second time scale, however, there was no significant inhibition of glucose uptake, by cyanide, up to 200-ms, clearly demonstrating that, in cyanide treated cells, glucose uptake was not linear for the first 5-s. After a 200-ms exposure of untreated cells to radio-labelled glucose, less than 10% of the intracellular label resided in soluble uncharged compounds. In cyanide-treated cells up to 43% of the labelled compounds were uncharged, with a concurrent reduction of intracellular label residing in anionic compounds. The results suggest that, in the presence of 10 mM cyanide when respiration is inhibited, a reduction in the cellular ATP concentration causes a reduction in hexose-kinase activity which results in an accumulation of internal free glucose, which in turn causes a reduction in net glucose transport.     

草莓汁中糖酸组成分析及其在掺假鉴别中的应用

为了解草莓汁的糖酸组成特点并探索其在掺假鉴别中的应用,采用高效液相色谱法对10个品种草莓果汁中可溶性糖、有机酸组成与含量进行分析,结合化学计量学方法探索其在草莓汁掺假鉴别中的应用。结果表明,草莓汁中可溶性糖主要由蔗糖、葡萄糖和果糖组成,有机酸主要是柠檬酸和苹果酸。不同品种草莓果汁中各种可溶性糖和有机酸的含量存在较大差异,但葡萄糖与果糖的比值受品种影响较小,柠檬酸占检测到总有机酸含量的62.39%~82.73%。通过分析草莓原汁及其掺假样品中可溶性糖和有机酸组成,结合主成分分析和线性辨别分析等模式识别方法,可以实现对草莓果汁与掺加梨汁、苹果汁、杏汁和桃汁等掺假样品的区分,而且掺假量越大,区分效果越好。草莓果汁可溶性糖和有机酸组成特征结合化学计量学分析能够对掺假草莓果汁进行较好地区分,可用于草莓果汁掺假鉴定和质量控制。     

多糖和添加剂对菠萝茎蛋白酶活力的影响

以相对酶活力及热失活动力学为指标,研究不同类型的添加剂对菠萝茎蛋白酶活力的影响,并探讨作用机理,以提供菠萝茎蛋白酶存放和应用过程中的有效保护方法。结果表明：葡萄糖、海藻糖和可溶性淀粉对菠萝茎蛋白酶热稳定作用由高到低分别为：海藻糖＞葡萄糖＞可溶性淀粉;金属离子螯合剂(EDTA-2Na、多聚磷酸钠)、防腐剂(苯甲酸钠)和还原剂(焦亚硫酸钠、β-巯基乙醇)对菠萝茎蛋白酶活力保护机理不同,但适量使用都能使其酶活力得到提高,其中还原剂的激活效果最好;焦亚硫酸钠在质量分数为0.05%时,能显著提高菠萝茎蛋白酶活力,相对酶活力达3.68,且在存放3d后酶活力才降至原酶液水平。     

金丝小枣在生长成熟过程中理化特性的变化规律

本文研究了6个不同生长成熟期(S1~S6)金丝小枣果实的色泽、叶绿素、可溶性糖及其代谢酶活性、有机酸及氨基酸的动态变化,以明确其代谢规律。研究结果表明:枣果生长成熟过程中,叶绿素含量降低,枣果由绿变红;葡萄糖、果糖均逐步积累,而山梨醇含量逐渐降低,蔗糖则在生长发育初期未被检出,其积累主要发生在枣果成熟后期,且其含量最高,金丝小枣为蔗糖积累型果实,蔗糖磷酸合成酶是蔗糖积累的关键酶;金丝小枣为苹果酸型果实,苹果酸随枣果的成熟而积累,而柠檬酸含量先上升后降低;Pro和Asp在枣果成熟过程中被大量合成,是成熟枣果中最主要的两种氨基酸。全红枣的可溶性总糖、糖酸比以及游离氨基酸总量最高,可作为金丝小枣鲜食的最佳采收时期。     

Celery by-products as a source of mannitol

Vegetable by-products have mainly been utilized as a source of dietary fiber and natural antioxidants, but residual vegetables could also be used as a raw material for soluble sugar and polyol extraction. Therefore, two celery residues from the food industry, composed either of stalks alone or stalks plus leaves, were extracted with hot 85% ethanol to solubilize soluble sugars and mannitol. Low-molecular-weight carbohydrates in the extracts were identified and quantified by high-performance liquid chromatography. Both celery residues contained similar amounts of sucrose (5.7-5.9%), but different ratios of hexose (glucose and fructose) to mannitol. Total sugar content and mannitol were higher in the stalks (45.5% and 15.2%, respectively) than in the stalk plus leaf residues (33.9% and 13.3%, respectively). Mannitol represented 33.5-39.3% of the total carbohydrate in celery wastes. The alcoholic extracts from celery residues are proposed as a natural source of mannitol and soluble sugars, which might be used by the food industry. The alcohol-insoluble residue from celery by-products could be further used for the preparation of dietary fiber-rich food supplements.