非纯糖液中蔗糖分解机理的研究

研究多种非糖物质同时存在时的蔗糖分解问题。结果表明，在酸性条件下，影响蔗糖分解反应速度常数Ｋ的显著因素是ＰＨ、温度以及二者的交互作用，非糖组分的影响作用不显著；而在碱性条件下，蔗糖的分解反应速度很小，主要是还原糖破坏，产生有机酸和色素，论文还对这些研究结果进行了机理探讨。     

不同培养条件对黄栀子愈伤的生长和绿原酸类物质积累的影响

本文以生长指数、绿原酸类物质含量和每升培养基中绿原酸的产量为评价标准,研究了培养基种类、碳源、蔗糖浓度、光照条件及水解酪蛋白(CH)浓度对黄栀子愈伤组织的生长及其次级代谢产物绿原酸类物质积累的影响,旨在为生产绿原酸类物质提供依据。研究显示,培养条件对黄栀子愈伤组织生长状况和绿原酸类物质积累有显著影响,适合生长的培养条件与适合绿原酸类物质积累的条件并不一致;适合黄栀子愈伤组织生长的最佳培养条件为:以MS为基础培养基,麦芽糖+蔗糖为碳源、糖浓度为3%、半光照条件下鲜重增长指数最大,达到47.11%。适合绿原酸类物质积累使得总产量达到最大的最佳培养条件为:MS培养基、蔗糖为碳源、蔗糖浓度为5%、不添加水解酪蛋白、半光照条件下培养,最高产量达每升培养基含35.55 mg绿原酸类物质。     

Novel transglucosylating reaction of sucrose phosphorylase to carboxylic compounds such as benzoic acid

We examined the synthesis of benzoyl glucoside using the transglucosylation reaction of sucrose phosphorylase. Sucrose phosphorylase from Streptococcus mutans showed marked transglucosylating activity, particularly under acidic conditions. On the other hand, sucrose phosphorylase from Leuconostoc mesenteroides showed very weak transglucosylating activity. Three main products were detected from the reaction mixture using benzoic acid as an acceptor molecule and sucrose as a donor molecule. These compounds were identified as 1-O-benzoyl alpha-D-glucopyranoside, 2-O-benzoyl alpha-D-glucopyranose and 2-O-benzoyl beta-D-glucopyranose on the basis of their isolation and the isolation of their acetylated products and subsequent analysis using 1D- and 2D-NMR analyses. From the results of the time-course analyses of the enzyme reaction and the degradation of 1-O-benzoyl alpha-D-glucopyranoside, 1-O-benzoyl alpha-D-glucopyranoside was considered to be initially produced by the transglucosylation reaction of the enzyme, and 2-O-benzoyl alpha-D-glucopyranose and 2-O-benzoyl beta-D-glucopyranose were produced from 1-O-benzoyl alpha-D-glucopyranoside by intramolecular acyl migration reaction. The acceptor specificity in the glucosylation reaction of S. mutans sucrose phosphorylase was also investigated. This sucrose phosphorylase could transglucosylate toward various carboxylic compounds. Short-chain fatty acids, hydroxy acids and dicarboxylic acids were also glucosylated with this sucrose phosphorylase.     

海藻糖对荔枝罐头非酶褐变特性的影响

在糖水荔枝罐头中添加不同糖液,通过测定贮藏期间罐头果肉色差值、糖液中5-HMF(5-羟甲基糠醛)、总糖、总氨基酸含量的变化,探讨海藻糖对糖水荔枝(桂味)罐头果肉的护色效果。结果表明:贮藏结束时,糖液为100%海藻糖的荔枝果肉褐变程度较低,色差值比100%蔗糖液组和50%蔗糖+50%海藻糖液组分别低14.0%和13.9%;5-HMF含量仅增加0.4倍,而100%蔗糖液组和50%蔗糖+50%海藻糖液组分别增加1.2倍和1.6倍;100%海藻糖组的氨基酸含量分别比100%蔗糖液组及50%蔗糖+50%海藻糖液组高13.5%和4.4%。说明海藻糖能够有效降低糖水荔枝罐头的美拉德反应程度,护色效果明显。     

Effects of replacing dietary starch with sucrose on ruminal fermentation and nitrogen metabolism in continuous culture

A dual-effluent continuous-culture system was used to evaluate the effects of partially replacing cornstarch with sucrose in a total mixed ration on ruminal fermentation and N metabolism. The 4 treatments were 0 (control), 2.5, 5.0, and 7.5% sucrose and, respectively, 7.5 (control), 5.0, 2.5, and 0% cornstarch in a total mixed ration containing 20% corn silage and 40% alfalfa silage. Fermenters were fed 4 times a day during four 9-d periods with sampling beginning on d 6. Replacing cornstarch with sucrose did not alter ruminal pH (5.97), total volatile fatty acids (VFA) (104.4 mmol/L), or the acetate to propionate ratio (2.16); however, branched-chain volatile fatty acids were higher for the control treatment compared with the 7.5% sucrose treatment. Five hours postfeeding, sucrose treatments significantly altered molar proportions of all volatile fatty acids, and acetate-to-propionate and glucogenic-to-lipogenic ratios. Digestibility of dry matter and N were not affected by treatment, but digestibility of total non-structural carbohydrates was increased with sucrose treatments. A quadratic effect was noted for neutral detergent fiber (NDF) digestibility as sucrose replaced starch. A higher NDF digestibility (66.1 vs. 59.9%) was observed for the 7.5% sucrose treatment compared with the other 2 sucrose treatments. Levels of ammonia N were within an acceptable range to support microbial protein synthesis and did not differ among treatments (mean=9.23 mg/dL). Sucrose inclusion in the total mixed ration did not affect bacterial N synthesis. Results indicate that (at the levels tested in this study) inclusion of sucrose in the diet when rumen-degradable protein is adequate does not affect ruminal fermentation.     

硫酸-甲醇衍生化对烟草中乙酰丙酸质量分数测定的影响

为考察采用硫酸-甲醇衍生化方法测定烟草中乙酰丙酸质量分数的可靠性,分析了硫酸-甲醇衍生化时间和温度对烟草中乙酰丙酸质量分数测定的影响,探索了5种糖类成分在硫酸-甲醇衍生化条件下是否产生乙酰丙酸甲酯,比较了263个烟草实际样品中果糖和蔗糖质量分数与乙酰丙酸质量分数的关系。结果表明:①硫酸-甲醇衍生化时间和温度对烟草样品甲酯化产物中乙酰丙酸甲酯响应的影响不同于其他有机酸甲酯,且这种不同与烟草基质有关;②果糖和蔗糖在硫酸-甲醇衍生化条件下能产生乙酰丙酸甲酯,而葡萄糖、麦芽糖和肌醇在衍生化过程中不产生乙酰丙酸甲酯;③蔗糖在硫酸-甲醇衍生化条件下产生的乙酰丙酸甲酯的质量仅为相同质量果糖产生的1/2;④利用硫酸-甲醇衍生化法测定得到的烟草中乙酰丙酸的质量分数受烟草中果糖和蔗糖的影响。      

Changes in the volatile compounds and chemical and physical properties of Yali pear (Pyrus bertschneideri Reld) during storage

Volatiles from stored Yali pear (Pyrus bertschneideri Reld) were studied using high-resolution gas chromatography and the solid-phase microextraction (SPME) method of gas chromatography/mass spectrometry (GC/MS). The dominant components were ethyl butanoate, ethyl hexanoate, α-farnesene, hexanal, ethyl acetate, hexyl acetate, ethanol and so on. By using GC-olfactometry, it was demonstrated that the volatile compounds from SPME were responsible for the aroma of Yali pear. The levels of sugars, organic acids, and phenolic acids in Yali pear were investigated using high-performance liquid chromatography. Fructose was the dominant sugar, followed by glucose and sucrose. With increasing storage time, sucrose levels decreased, however fructose and glucose levels did not changed remarkably. There was a slight decrease in flesh firmness during storage. The general soluble solids concentration, slightly decreased after 5 months storage. Some aroma volatile components increased during storage, while others decreased, especially the esters. The organic acids and phenolic acids also changed. Yali pear flavor was affected by changes in the levels of volatile compounds, and chemical and physical properties.     

Biohydrogenation of fatty acids and digestibility of fresh alfalfa or alfalfa hay plus sucrose in continuous culture

The pattern of biohydrogenation of fatty acids from fresh alfalfa or alfalfa hay supplemented with 3 concentrations (0, 4, and 8%) of sucrose was studied at a constant pH of 6.2. Four continuous culture fermenters were used in a 4 × 4 Latin square design to test the hypothesis that fresh forage would increase flow of vaccenic acid (VA) from the fermenters compared with the same forage in hay form and that this difference would be diminished by adding sucrose to the hay diet by changing the bacterial community profile. Effluent was collected from each of the 4 fermenters during the last 3 d of each 10-d period. Nutrient digestibility, volatile fatty acids (VFA), and fatty acids in the effluent were measured. Flow of bacterial organic matter (OM) and neutral and acid detergent fiber and acid detergent fiber digestibilities were higher for fresh alfalfa than alfalfa hay. True OM digestibility of alfalfa hay tended to linearly decrease with sucrose supplementation. However, microbial efficiency and flow of bacterial OM (g/d) linearly increased with sucrose addition. There was no change in total VFA concentration; however, proportion of acetate linearly decreased and proportion of butyrate linearly increased with sucrose addition. Fresh alfalfa increased total biohydrogenation of fatty acids compared with than hay. Vaccenic acid flow (mg/d) was much higher for fresh alfalfa compared with alfalfa hay (216 vs. 41) and VA was the predominant 18:1 isomer, followed by trans-13 18:1; however, sucrose had no effect on VA flow. The percentage of VA (of total trans-18:1) was not different between fresh alfalfa and hay, whereas percentage of trans-10 18:1 was much lower for fresh alfalfa. Therefore, the ratio of VA to trans-10 18:1 was higher for fresh alfalfa. Flow of trans-12 18:1 linearly increased, whereas flows of cis-12 and total cis-18:1 had quadratic responses to sucrose supplementation. Total biohydrogenation and biohydrogenation of linoleic and linolenic acids linearly decreased with sucrose; however, there was no effect of sucrose on total trans fatty acid flow. Sucrose may be more detrimental to the last step of biohydrogenation of VA. The effects of sucrose on biohydrogenation and concentration of VFA may have been caused by a shift in microbial population by mechanisms that are independent of pH.     

蔗糖癸酸酯对沙门氏菌的抗菌作用及其机理初探

本文研究了蔗糖癸酸酯对沙门氏菌的体外抗菌作用及其机理。采用肉汤稀释法测定了不同p H值下蔗糖癸酸酯对沙门氏菌的最小抑菌浓度(MIC)和最小杀菌浓度(MBC)。通过测定菌体渗漏物、SDS-聚丙烯酰胺凝胶电泳分析、扫描电镜观察、DNA结合试验等,初步研究了蔗糖癸酸酯对沙门氏菌的抗菌机理。结果表明:蔗糖癸酸酯在p H 7.0时对沙门氏菌的MIC为20 m M,在酸性条件下抗菌效果更为显著。蔗糖癸酸酯能够使菌体细胞内核酸、蛋白质和还原糖等外泄,影响细胞膜结构完整性和菌体正常形态;对菌体细胞蛋白(尤其是大分子量蛋白)的合成与积累有干扰作用;同时糖酯的亲水性头基可与DNA磷酸基团以氢键的方式结合,使DNA骨架收缩。因此,可将蔗糖癸酸酯作为兼具乳化和防腐作用的多功能食品添加剂,应用于动物源性食品的加工和储藏过程中。     

糖碳源和氨基酸氮源对苍白杆菌属发酵产生物表面活性剂的影响

该实验为优化苍白杆菌（Ochrobactrum sp.）产生物表面活性剂的发酵条件,比较了不同糖碳源（蔗糖、乳糖、甘油、木糖、果糖）、氨基酸氮源（谷氨酸、天冬氨酸、赖氨酸、精氨酸和缬氨酸）、碳氮比（C/N）（1、10、20、30、40）对生物表面活性剂发酵的影响。结果表明,最优碳源为蔗糖,发酵5 d达最大乳化活性56.30%;最优氮源为天冬氨酸,发酵4 d达最大乳化活性54.00%;最优C/N为10,发酵4 d达最大乳化活性55.75%。     

Production of zearalenone in vitro and in corn grains stored under modified atmospheres

The production of zearalenone by an isolate of Fusarium equiseti was studied in chemically defined medium and in corn grains stored under modified atmospheres. An increase in the concentrations of sucrose or xylose in Czapek's medium resulted in increased toxin production, while no toxin was produced when lactose was present in the medium. Methionine (10(-2) and 10(-3) M) and cystine (10(-3) M) added to Czapek's medium inhibited zearalenone production. When amino acids or nitrogen salts were added as the sole nitrogen source, only alanine, tryptophan and NH4Cl totally inhibited zearalenone production. Zearalenone production was inhibited almost completely in high-moisture corn grains (27%) kept under atmospheres enriched with high CO2 levels (60%, 40% or 20%) with either 20% or 5% O2. However, a lower amount of CO2 was needed to inhibit fungal development and toxin formation when a reduced O2 level was applied.     

Sugars and organic acids in Japanese plums (Prunus salicinaLindell) as influenced by maturation, harvest date, storage temperature and period

The effects of fruit maturation, harvest date, storage temperature, storage period and shelf life, on the concentrations of individual sugars and organic acids in Japanese plums were investigated. During fruit maturation in 'Amber Jewel' plums, sucrose concentration increased significantly from 101 days after full bloom (DAFB) to 1 week after commercial maturity (136 DAFB) with a non-significant change in the concentration of total organic acids and malic acid, the major organic acid. The changes in concentrations of sugars and organic acids during cold storage of 'Amber Jewel' plums harvested on 129 and 136 DAFB appeared to be independent of harvest date. Storage of 'Amber Jewel' plums at 5 °C accelerated the loss of sucrose and increased the concentrations of fructose and glucose from the 4^th week of storage compared with those stored at 0 °C. 'Blackamber' plums did not undergo any significant increase in the total and individual sugars during 5 weeks storage and subsequent shelf-life of 8 days at 20 °C. Malic acid concentrations declined during storage from 3 weeks onwards with a further substantial loss during ripening at 20 °C. Maturation, harvest date, storage temperature, storage period and shelf-life affect the concentrations of sugars and organic acids in Japanese plums.     

Improvement of nutritive value in corn for human nutrition

Corn was steam cooked at a pressure of 5 psig (108·3°C) for 15, 30 and 60 min and the cooked grain was dried, ground and analysed chemically. Reducing sugars, sucrose, starch, lysine and niacin were altered by the cooking procedure.The same corn variety was germinated at 25°C for 5 days. Germinated and non-germinated seeds were not separated but were dried and analysed together. Protein, ether extract, free fatty acids, crude fibre, starch, sucrose, reducing sugars, thiamin, riboflavin, niacin, lysine and tryptophan were altered significantly. Germination improved the nutritional quality of corn and is less expensive than heat treatment.     

INHIBITION OF MICROORGANISMS IN SALAD DRESSING BY SUCROSE AND METHYLGLUCOSE FATTY ACID MONOESTERS

The antimicrobial activity of sucrose and methylglucose esters of medium to long chain fatty acids was studied with two microorganisms involved in the spoilage of salad dressings, Zygosaccharomyces bailii and Lactobacillus fructivorans. The microorganisms were inhibited to various degrees by 0.1, 0.5, and 1.0% synthesized sucrose or methylglucose monoesters using a modified broth dilution method. Sucrose monoesters were most inhibitory when the esterified fatty acid was myristic (C₁₄) or palmitic acid (C₁₆). Methylglucose monoesters with lauric (C₁₂) or myristic acid (C₁₄) exhibited greater inhibition than those with longer chain fatty acids. The least inhibition was generally observed with sucrose and methylglucose oleate (C_18:1). Sucrose monoesters were usually more inhibitory than methylglucose monoesters of the same fatty acid, especially for palmitic and stearic (C₁₈) acids. In salad dressing, 1% sucrose monoesters of lauric, myristic, or palmitic acid significantly (P < 0.05) inhibited the growth of Z. bailii and L. fructivorans, and were comparable with or more effective than 0.1% sodium benzoate. Z. bailii growth was nearly completely inhibited by sucrose laurate, myristate and palmitate by 9 days of salad dressing storage. Sucrose monoesters did not delay the lag phase of L.     

ANTIMICROBIAL ACTIVITY OF FATTY ACIDS AND THEIR ESTERS AGAINST A FILM-FORMING YEAST IN SOY SAUCE

Antimicrobial activity of fatty acids and their glycerol and sugar esters against a film-forming yeast isolated from raw soy sauce was determined in diluted soy sauce. In a series of fatty acids (alkyl chain length of 7, 9, 11 and 13) and their monglycerides, capric acid and monolaurin had the highest inhibitory activity. Two selected sugar esters (sucrose monocaprate and sucrose monolaurate) could not completely inhibit the growth of test organism throughout 3 weeks.     

Sugars and Acid Analysis and Effect of Heating on Color Stability of Northwest Concord Grape Juice

Changes during storage in color of Concord grape juice extracted after heating to different temperatures and the carbohydrate and nonvolatile acid composition of Concord grapes were studied. Heating crushed Concord grapes under pilot plant conditions to 88° and 99°C inactivated nearly all of the polyphenoloxidase, increased the extraction of anthocyanins (ACN) and reduced polymeric color in the grape juice. During storage of the juice for 8 months, the rate of ACN degradation and color density decrease was the same in all samples. Glucose, fructose and sucrose were the only sugars found in Northwest Concord grapes, while malic and tartaric acids were the major nonvolatile acids. Lesser amounts of phosphoric, citric and coumaric acids were present.     

长牡蛎肉小肽营养液的研制

研究长牡蛎肉小肽营养液制备的工艺条件。先以水解度为指标,确定长牡蛎肉中性蛋白酶、木瓜蛋白酶、菠萝蛋白酶单酶的最适水解条件,通过正交试验确定各单酶水解的最佳工艺条件;然后以此为基础进行三酶复合试验,根据水解度确定最佳工艺条件,制备长牡蛎肉水解液;最后以该水解液为原料,通过正交试验确定最佳配方,按最佳配方制备小肽营养液。在最佳工艺条件下,长牡蛎肉三酶复合水解度达52.97%,经聚丙烯酰胺凝胶垂直板电泳测定,小肽峰值相对分子质量范围在300～1 000之间;17种游离氨基酸含量500.16 mg/100 mL;小肽营养液最佳配方:水解液(mL)∶蔗糖(g)∶柠檬酸(g)∶氯化钠(g)为100∶10∶0.2∶0.2,游离氨基酸总量≥5 000mg/L。本小肽营养液营养丰富,制备工艺较简单,可应用于长牡蛎肉的高值化开发。     

Influence of the cultivar on the organic acid and sugar composition of potatoes

BACKGROUND: Citric, malic, tartaric, oxalic, ascorbic, aconitic and fumaric acids, and sucrose, fructose and glucose, were determined in ten potato cultivars (Azucena negra, Bonita, Bonita negra, Borralla, Colorada de baga, Mora, Negra, Palmera lagarteada, Peluca blanca and Terrenta) from the Canary Islands in order to differentiate them. The influence of the production zone was also considered. RESULTS: Citric acid and sucrose were the most abundant organic acid and sugar, respectively. There were significant differences in all the analysed sugars and organic acids between the potato cultivars, except for oxalic and malic acids. Differences associated with the production zone were found in the contents of organic acids for some cultivars. Linear discriminant analysis is a useful tool to differentiate the potato samples according to the cultivar and the zone of production. CONCLUSIONS: Seven organic acids (citric, oxalic, malic, tartaric, aconitic, fumaric, and ascorbic acids) were identified and quantified in potatoes. The main sugars (sucrose, glucose and fructose) were also determined. The genetic information of the cultivars determines marked differences in sugars and organic acid contents among the analysed potato cultivars. The soil and climatic conditions affect the organic acid and sugar contents of some potato cultivars. Copyright © 2010 Society of Chemical Industry     

逆相转移催化合成葵花籽油蔗糖酯

先由食用葵花籽油和甲醇在碱性催化剂条件下酯交换反应制得脂肪酸甲酯,然后脂肪酸甲酯与蔗糖通过水溶剂法,以逆相转移催化剂DMAP催化制备蔗糖脂肪酸酯.通过对酯糖摩尔比、催化剂用量、反应温度、反应时间进行考察,确定最佳合成条件为:酯糖摩尔比2.5∶1,催化剂用量4％,反应温度 85℃,反应时间7h.在最佳合成条件下,葵花籽油脂肪酸甲酯的转化率高达65.32％,所得产品具有良好的表面活性,其临界胶束质量浓度(CMC)为6.5 g/L,表面张力为27.41 mN/m,乳化力为79 s,浊点指数为7.2 mL,HLB值为10.1,碘值(Ⅰ)为126.9 g/100 g.     

Assimilate transport in grapevines -effect of phloem disruption

Assimilate translocation in mature grapevines (cv. Gewürztraminer and cv. Harslevelü) under field conditions was investigated during the growth season by quantifying individual sugars and organic acids in mature leaves, shoot bark and berries, as affected by girdling the shoot just above the bunches. Tissue was sampled at berry set, pea size, veraison and ripeness stages of the vine. Invertase activity was determined in the shoot bark at ripeness. In the leaves, malic acid concentrations reached lowest levels at pea size, but increased thereafter. Tartaric acid decreased after peaking at pea size stage. Tartaric acid concentrations increased with girdling. Despite the increase in leaf age, sucrose concentrations remained virtually stable during the season, emphasising the importance of mature leaves for nourishing bunches. Girdling resulted in a build‐up of sucrose in the leaves. In the bark, malic and tartaric acid stayed more or less the same during the growth period, but increased above the girdle. As a result of phloem disruption, sucrose also increased. The increase in glucose and tartaric acid is believed to result from catabolic cleavage of sucrose by invertase. Invertase activity was evident in the bark (of mature Harslevelü vines) at ripeness, which may indicate involvement in osmotic adjustments and gradients in the bark/phloem structure. In the berries, malic and tartaric acids reached peak concentrations at pea size. The volume increase during the ripening period, and in the case of malic acid also respiratory loss, resulted in a decrease in organic acid concentration. Malic acid continued to decrease after the initial decline, whereas tartaric acid stayed virtually stable. Girdling had no marked effect on organic acid accumulation in the berries. Sucrose concentrations were low during the first part of the season, but increased thereafter. Sucrose concentrations during ripening increased with girdling, which may represent a concentration effect and/or import from the rest of the vine. Sucrose concentrations (in mature Harslevelü vines) were indeed lower below than above the girdle. Comparison of sucrose concentrations in the leaves, bark and berries showed the existence of a decreasing concentration gradient, in line with the source:sink transport concept. An equally prominent decrease in sucrose:glucose ratio in the berries from the start of the ripening period indicates that vacuolar integrity (compartmentation) was affected in the ripening berry, most probably allowing hydrolysis of sucrose by invertase and decreasing osmotic potential within the berry. The results provide further evidence for the hypothesis of an osmotic gradient driven transport to the berry.