Determination of soluble persimmon tannin by high performance gel permeation chromatography

Condensed tannins present in persimmon fruits are responsible for the astringent taste. This paper describes an assay method for the determination of soluble persimmon tannin by high-performance gel permeation chromatography (HPGPC) which could be linked to a post column reaction system for the on line identification of phenolic compounds. The 80% acetone extract of crude persimmon tannin was purified using a Microcon® centrifugal filter device to remove small molecules. The purified extracts were analyzed by HPGPC, using a TSK G4000 PWXL column and eluted with 10% methanol at a flow rate of 0.3 ml/min at 40 °C. The recovery of 21.7 mg added soluble persimmon tannin standard from 2 g of persimmon paste was 80%. This assay method was used to determine the soluble tannin content during persimmon dehydration. The persimmon tannin content was decreased during dehydration and became undetectable before completion of the process. An on-line post column reaction system was developed with Folin-Ciocalteu’s reagent for the confirmation of the presence of phenolic compounds.     

Effect of high temperature on condensed tannin accumulation in leaf tissues of big trefoil (Lotus uliginosus Schkuhr)

Plants from three clones of big trefoil (Lotus uliginosus Schkuhr) having low, medium and high concentrations of tannin in their leaves were subjected to growing conditions with normal (20°C) and high (30°C) temperature regimes. Plants were tested every 3 weeks for foliar condensed tannin content using the vanillin-HCl and the butanol-HCl assays. Plants from clones growing under high temperatures matured more quickly and by 14 days had condensed tannin levels substantially greater than plants from the same clones grown under normal temperatures. Clones remained consistent with respect to their parental tannin levels throughout two trials. Leaves from high-temperature clones suffering additional nutrient stress symptoms had very low levels of foliar condensed tannins and cross-sections of chlorotic leaves revealed an absence of large tannin vacuoles. It is concluded that high-temperature stress can induce the formation of additional condensed tannin in the leaves of this species.     

高温及高温水处理对兔绒性能的影响

兔绒经过高温、高温水处理后,其强度、断裂伸长率、色泽都发生了变化.经实验对比和分析得出,高温、高温水处理对兔绒性能的影响相似于羊绒,高温处理对兔绒的强度、断裂伸长率的损伤要小,在高温140℃处理50 min后,兔绒的强度、断裂伸长率分别损失15.4%和10.5%.但高温水处理对兔绒性能影响较大,高温水140℃处理50 min后,兔绒的强度、断裂伸长率的性能损失为64.1%和80.9%.同时高温处理对兔绒色泽影响较小,但高温水处理对兔绒色泽有严重的影响.     

高温及高温水处理对狗毛性能的影响

分析狗毛经过高温、高温水处理后对其强度、断裂伸长率、色泽的影响.经实验数据分析和对比得出:高温、高温水处理对狗毛的性能有破坏作用,高温处理对狗毛的强度、断裂伸长率的损伤小于相同温度高温水处理对狗毛强度、断裂伸长率的损伤.并随着处理温度的升高,狗毛的相应物理性能进一步下降.在处理过程中,对狗毛的色泽也产生了影响,但高温处理的影响小于高温水处理对狗毛色泽的影响.     

L-异亮氨酸高效液相色谱检测方法的研究

L-异亮氨酸在紫外光区无吸收峰,需将其进行衍生后才能测定.通过对比两种柱前衍生方法,建立高效液相色谱法柱前衍生检测L-异亮氨酸质量分数的方法.OPA自动衍生法检测耗时15 min,R=1,加标回收率99%~100.1%,RSD<1.0%;PITC手动衍生法检测耗时30 min,加标回收率96%~98%,RSD<1%.O PA自动衍生法在检测的时效性和准确性方面均具有明显优势,可用来高效地检测L-异亮氨酸的质量分数,在生物发酵、饲料添加剂、食品添加剂和制药等领域具有较高的应用价值.     

油炸高温处理对淀粉结构与性质的影响

油炸加工技术已广泛应用于食品加工中,了解淀粉在油炸过程中的结构与理化性质的变化,有利于淀粉类食品在实际生产中品质的调控与改进。本文主要综述了油炸加工工艺对淀粉的结构(颗粒结构、晶体结构、分子结构等)以及理化性质(糊化特性、热特性、消化特性等)的影响,以期为淀粉类食品的深加工提供理论依据。     

高浓高温对啤酒酵母发酵性能的影响

以啤酒酵母S-6为实验菌株,研究了主发酵温度和原麦汁浓度对啤酒发酵的残糖、酒精度、风味物质和絮凝性等性能指标的影响。结果表明,原麦汁浓度一定时,主发酵温度对高级醇和乙酸酯的含量影响较大,主发酵温度由10 ℃提高至16 ℃时,高级醇含量提高了10%～20%,乙酸酯含量提高了8%～16%,但CO2累积质量损失、残糖、酒精度和絮凝性基本不受温度的影响;主发酵温度一定时,原麦汁浓度对酵母絮凝性影响较大,原麦汁浓度越高,酵母絮凝性越低,将高浓（18 °Bx）发酵液稀释50%至常浓（12 °Bx）,残糖、酒精度和高级醇的含量与常浓发酵液基本相同。该研究为选育高温高浓发酵低产高级醇同时强絮凝性酵母菌株提供了重要依据。     

高效液相色谱法测定高温加工食品中丙烯酰胺

目的 建立一种快速、简便、可靠的液相色谱法测定高温加工食品中丙烯酰胺含量的分析方法。方法 样品粉碎后经超纯水提取、正己烷脱脂、C18固相萃取柱萃取、流动相洗脱后得到样品净化液,经液相色谱仪,以乙腈-水(体积比2:98)作为流动相,流速为0.8mL/min,测定波长205nm,柱温20℃的色谱条件测定,外标法定量。结果 在该条件下,丙烯酰胺在0.1μg/mL-2.0μg/mL内具有良好的线性关系(R²=0.9987),检出限14μg/kg,定量限40μg/kg,加标回收率在91.5%~95.0%之间,1.0μg/mL丙烯酰胺标准溶液重复6次进样的相对标准偏差为(RSD)为0.16%。结论 液相色谱法可以准确、快速测定高温加工食品中的丙烯酰胺含量。     

高温条件下多酚对茶油挥发性成分的影响

研究加热过程中多酚对茶油挥发性成分的影响,选取茶油和5组添加了0.02%多酚的茶油(没食子酸、儿茶素、槲皮素、没食子酸丙酯、3,4-二羟基苯乙酸)为材料,采用顶空固相萃取-气质联用法(HS-SPME-GC-MS)对6组样品在180℃下加热不同时间后挥发性风味成分进行分析。结果表明,在加热过程中添加多酚减缓了茶油挥发物数量的降低,但能抑制挥发物总量的生成;对挥发性物质种类的影响而言,添加多酚能有效减缓正构醛含量的减少,但对不饱和醛和其他不良挥发性成分如挥发性短链脂肪酸的生成具有抑制作用。因此,添加多酚能使高温下茶油的风味有所改善。     

酶高温轧蒸退浆工艺

对棉织物的酶高温轧蒸工艺进行研究，讨论了酶浓度、轧余率、轧酶温度、酶液pH值和汽蒸时间等因素对退浆效果的影响，初步确定淀粉酶退浆工艺为：淀粉酶L401．5-2g／L，轧余率100％～110％，室温轧酶（轧前先浸轧60℃热水），酶液pH值约6．5，汽蒸时间15min，汽蒸温度100—102℃。比较碱轧蒸退浆工艺发现，酶退浆工艺退浆率较高，可达7级以上，但毛效、润湿性和白度稍低。     

Effect of temperature and consistency on wheat dough performance

The effects of the dough consistency (DC; 300–700 BU), temperature of mixing (16–32 °C) and temperature along fermentation (15–35 °C) on the wheat bread dough performance during mixing, proofing, cooking and cooling have been studied through a central composite experimental design. Farinograph responses revealed the significant role of DC (α < 0.001) and mixing temperature (MT) (α < 0.001) on wheat bread dough elasticity. Fermentation responses obtained from the rheofermentometer showed that the DC induces a significant positive linear effect on dough development, whereas gas development was mainly governed by the fermentation temperature. The wheat bread dough behaviour subjected to a dual mechanical shear stress and temperature constraint showed that DC had a significant linear and positive effect on the starch gelatinisation and gelling process. Therefore, breadmaking is highly governed for DC, namely dough hydration, which has a direct consequence on the mixing, fermenting, cooking and cooling performance of the wheat bread dough.     

Production of catalase by fungi growing at low pH and high temperature

More than 100 fungi were isolated from cultures at pH 1.0 or 2.5 and 42-45 degrees C, and the production of catalases was investigated. Four strains produced a catalase with high stability at pH 2.0, and three of them produced two extracellular catalases and four intracellular catalases. In these four intracellular catalases, two catalases were similar to extracellular catalases in enzymatic properties and pI. These strains belonged to Aspergillus niger.     

高温高压提取茶汤加工普洱茶膏的研究

普洱茶膏是云南独特的速饮茶叶产品,但目前采用大锅熬制的工艺提取茶汤,导致产品的香气低、滋味淡薄,亟需改进提取方法。本文应用高压灭菌锅和响应面设计,开展高温高压(121℃、103kPa)提取茶汤加工茶膏研究。优化发现在浸提温度为113℃,茶水比1∶41g/mL,时间14min的条件下,提取茶汤的茶多酚、氨基酸、水浸出物含量最高,分别为20.89%±0.81%、3.82%±0.35%和37.89%±5.35%。按优化条件提取茶汤、减压浓缩、干燥加工制成茶膏有效成分含量与感官评审得分均优于大锅熬制加工的茶膏。本研究表明高温高压提取茶汤可以改进茶膏品质,在速饮茶叶产品加工中具有一定的应用前景。      

Effect of microbial inoculant on quality of alfalfa hay baled at high moisture and lamb performance.

The effectiveness of a microbial hay inoculant in high moisture alfalfa hay was evaluated. Alfalfa (third cutting) was baled at 72% DM without or with inoculant and at 82% DM without inoculant during yr 1. In yr 2, alfalfa (second cutting) was baled at 75% DM without or with inoculant and at 82% DM without inoculant. Application rate of inoculant was 3.8 L/.98 tonne each year. At this application rate, 90 billion cfu were applied per .98 tonne of forage. Hays were core sampled at 0, 14, 30, and 60 d after baling to determine chemical composition. By d 30, all hays had DM content of 89%. In yr 2, 12 wether lambs were assigned to three treatments in a replicated 3 x 3 Latin square. Treatments were chopped, low moisture hay plus corn; chopped, inoculated high moisture hay plus corn; and chopped, high moisture hay plus corn. All diets contained 63% alfalfa hay, 35% ground corn, and 2% minerals and vitamins. In yr 1, inoculated and low moisture hays were not different in chemical composition but were higher in CP and lower in NDF than high moisture hay. Neither NDF nor CP were different among the three hays in yr 2. Average daily gain was not different on the three diets. The feed to gain ratio was lowest for the inoculated hay, intermediate for the low moisture hay, and highest for the high moisture hay diet. Daily gain and feed to gain ratio were not different for lambs fed the inoculated hay baled at 75% DM compared with lambs fed untreated hay baled at 82% DM.     

温度对高温大曲液态培菌过程菌群结构的影响

选用高温大曲在30 ℃、37 ℃、40 ℃、43 ℃和53 ℃不同温度条件下液体培养,对培养过程中微生物菌群结构和代谢产物的变化进行了分析。结果表明,较低的培养温度有利于酵母菌和乳酸菌的生长,而较高的培养温度有利于耐高温细菌和霉菌的生长。其中,酵母菌在37 ℃培养60 h数量最多,霉菌在53 ℃培养48 h数量最多,乳酸菌在37 ℃培养24 h数量最多,总细菌在40 ℃培养24 h数量最多。从代谢产物的分析结果看,酒精度和总酸含量在37 ℃时含量最高,乙酸乙酯、总酯含量在30 ℃时最高,α-氨基酸态氮含量在53 ℃时最高。可根据增强发酵活力、提高酒度和酯含量等需求,延长不同培养温度范围的保持时间。     

用普鲁兰酶改进玉米淀粉基复合膜性能的研究

以玉米淀粉为原料,选用甘油为增塑剂,羧甲基纤维素钠与海藻酸钠复合为增强剂,采用延流法制备玉米淀粉基复合膜。研究增塑剂的种类、用量,增强剂的种类、用量,烘干温度,延流体积等对复合膜性能的影响。普鲁兰酶可使淀粉中的支链淀粉脱支而形成直链淀粉,从而提高淀粉膜的性能。利用正交实验法,以玉米淀粉基复合膜的抗拉强度为指标,研究得出普鲁兰酶对复合玉米淀粉脱支作用时的最佳工艺条件为:酶用量0.8ASPU/g,pH4.5,时间4h,温度60℃。     

钢丝绳润滑脂高低温性能研究

结合国内相关行业对钢丝绳润滑脂高低温性能的新要求,分析钢丝绳脂的结构特点,研究稠化剂、基础油和添加剂等各组分对钢丝绳润滑脂高低温性能的影响,同时提出改善钢丝绳脂高低温性能的途径:(1)在蜡膏制成的普通钢丝绳润滑脂中加入微晶蜡和聚合物,可改进稠化剂的晶粒结构,得到高滴点的钢丝绳润滑脂。(2)环烷基基础油或芳烃抽出油中的石蜡烃含量少,可获得低温下不发生脆裂的钢丝绳润滑脂。(3)聚甲基丙烯酸酯降凝剂通过改变蜡晶粒形态和聚集程度,对防止润滑脂低温脆裂起到改进作用。     

Effect of increasing oil from distillers grains or corn oil on lactation performance

The objective of this study was to evaluate production response and more specifically percentage and yield of fat in milk from dairy cows fed distillers grains with added solubles (DGS). It was hypothesized that the oil present in DGS would decrease milk fat yield. Four dietary treatments consisted of dried DGS replacing soybean meal and soybean hulls. The DGS inclusion rates as a percentage of dry matter (DM) were 0, 5, 10, and 15% DGS. To determine the role of oil in DGS, a fifth diet similar to 0% DGS with added corn oil (OIL) was included. Twenty multiparous Holsteins were assigned to a replicated, 5 × 5 Latin Square design with periods of 21 d. Diets were formulated to have similar crude protein and neutral detergent fiber (NDF) concentration. Feeding OIL or 15% DGS resulted in similar production of milk, milk protein, and milk fat. Increasing dietary DGS linearly increased milk production and milk true protein yield. Adding corn oil increased milk yield and, although milk true protein yield also tended to increase with oil, milk true protein concentration decreased. The addition of DGS or OIL did not significantly change fat yield from 0% DGS; however, fat concentration in milk was significantly decreased by DGS due to increased fluid milk production. In diets containing approximately 28% NDF, cottonseed, blood and fish meal, feeding DGS to bring total dietary fatty acids to 5% of diet DM increased milk and milk protein yield without decreasing milk fat yield. Reduced proportions of shorter chain fatty acids and increased proportions of longer chain fatty acids in milk as dietary fatty acid content increased suggests that de novo fatty acid synthesis in the mammary gland was inhibited but this was offset by increased secretion of long-chain fatty acids, presumably absorbed from the diet. Therefore, our hypothesis that feeding corn oil either as DGS or as pure corn oil would decrease milk fat yield was not correct.