氧化铁粉中氯离子含量的测定

用硝酸银滴定氧化铁粉溶液时,氯离子的浓度会发生突变,指示电极的电位发生相应突跃,以此确定滴定终点,可以准确测定氧化铁粉中氯离子的含量。通过对不同浸取时间、温度等实验,找出最佳实验条件,进行检测下限、回收率等实验,证实此方法快速、准确。     

烘丝过程中碳酸钾对烟草香味成分含量的影响

为探讨碳酸钾(K2CO3)对烟丝中挥发性、半挥发性香味成分含量的影响,采用实验室模拟烘丝,按烟丝质量0.5％,0.9％,1.3％,1.7％和2.1％的用量将K2CO3水溶液均匀施加于烟丝,平衡48 h后,于设定条件(温度110℃,风速1.57 m/s和转速12 r/min)下烘丝至含水率为12％～13％,再用甲基叔丁基醚萃取烟丝并进行GC/MS检测.结果表明:①K2CO3对烟丝的外观有显著影响,当施加比例超过烟丝质量的1.3％时,部分烟丝变黑;②加入K2CO3后,烟丝中酯类、酸类组分含量呈规律性降低趋势;醇类组分和巨豆三烯酮类组分含量增加.     

无机水合氧化物对磷酸根的吸附行为

制备出一种新型的无机水合氧化物吸附荆，并用该氧化物对磷酸根水溶液进行吸附试验。实验分析了pH值、吸附温度和吸附时间对吸附容量的影响，同时也讨论了吸附过程相关的动力学、热力学和扩散速率。结果表明：该吸附过程为吸热吸附，它主要是以离子交换形式进行的。高温吸附与Langmuir等温吸附方程的拟合要优于低温吸附，高温下的吸附速率为一级动力学而低温吸附更趋于抛物扩散方程。     

粒状复合镁铝氧化物对碘离子的吸附性能

将层状氢氧化镁铝粉末成型、焙烧得到粒状复合镁铝氧化物,该复合材料具有230.59 m2/g的比表面积和14.87 nm的平均孔径.考察了碘离子溶液初始浓度,pH值,流速和吸附剂床层高度对其动态吸附性能的影响.在碘离子溶液初始浓度为200 mg/L,pH=7,流速为5 mL/min,吸附剂床层高度为10 cm的动态吸附条件下,饱和吸附量为217.09mg/g,明显优于粉状复合镁铝氧化物(25.61 mg/s).     

Adsorption of Tannins on Lipid Membrane in the Presence of Peptides as Related to Astringency

ABSTRACT: stringent reception mechanism of tannins, which has not been fully elucidated, was studied using a lipid-coated quartz-crystal microbalance. We found that the adsorption of astringent tannins on the lipid membrane significantly increased in the presence of peptides, while NaCl, tartaric acid, quinine-sulfite, sucrose, and glutamic acid had no effect. The adsorption of tannin-peptide complexes showed a linear relationship with tannin concentration and had an optimum concentration of peptides. The adsorption of red wines on the lipid membrane in the presence of bovine serum albumin agreed with astringent intensity in sensory evaluation. It seems that adsorption of tannin-peptide complexes on the oral lipid membrane could be important to the astringent sensation.     

无机水合氧化物对磷酸根的吸附行为

制备出一种新型的无机水合氧化物吸附剂,并用该氧化物对磷酸根水溶液进行吸附试验.实验分析了pH值、吸附温度和吸附时间对吸附容量的影响,同时也讨论了吸附过程相关的动力学、热力学和扩散速率.结果表明:该吸附过程为吸热吸附,它主要是以离子交换形式进行的.高温吸附与Langmuir等温吸附方程的拟合要优于低温吸附,高温下的吸附速率为一级动力学而低温吸附更趋于抛物扩散方程.     

壳聚糖铁(Ⅲ)配合物吸附动力学研究

采用非均相吸附法制备了壳聚糖铁(Ⅲ)配合物,用紫外光谱(UV)、红外光谱(IR)对配合物的结构进行了表征;研究了壳聚糖对Fe³⁺ 的吸附动力学特性。实验结果表明,壳聚糖与Fe³⁺之间发生了配位作用,壳聚糖分子中参与配位反应的主要是-NH_²、-OH及少量的-NHCOCH₃;壳聚糖对Fe³⁺的吸附行为可用Langmuir单分子层吸附机理解释,且求得吸附表观活化能为3.6476kJ/mol。     

磷酸预水解对竹柳主要组分含量的影响

预水解是基于硫酸盐法生产溶解浆过程中的关键一步,主要目的是在原料进行制浆之前尽可能多地从植物纤维原料中去除半纤维素。本研究探索了预水解段添加磷酸对竹柳原料中组分含量的影响。结果表明,在竹柳预水解段添加磷酸和增大液比、增加保温时间均有助于竹柳原料中聚戊糖的脱除,但不利于α-纤维素的保留;当磷酸用量为3%(相对于绝干原料),保温时间为60 min时,液比为6∶1时,预水解后竹柳中聚戊糖去除率为71.8%,α-纤维素含保留率为93.4%。     

基于主成分分析法分析一氧化氮对绿芦笋贮藏品质的影响

为探明NO处理对绿芦笋贮藏品质的影响,以硝普钠(SNP)为一氧化氮(NO)供体,研究NO对采后绿芦笋叶绿素、VC、总糖、木质素、总黄酮含量,膜透性及抗氧化能力的影响,并结合主成分分析法分析NO处理对绿芦笋综合品质的影响。结果表明:NO处理可减缓采后绿芦笋叶绿素、VC、总糖、总黄酮含量的下降,延缓木质素、膜透性的增加,提高总抗氧化能力。主成分分析表明,贮藏12d之后,对照绿芦笋的综合品质急剧下降,而NO处理可使绿芦笋贮藏期限延长4d左右。因此,NO处理可作为一种维持采后绿芦笋品质的理想措施。     

铁离子水解对白兰地酯酸平衡的影响

研究了白兰地酒中铁离子水解对酯酸平衡的影响。试验结果表明,在Ｆｅ含量微量超标、酸度偏低的情况下,适当提高白兰地的酸度,可抑制Ｆｅ＾３＋水解对酯酸平衡的破坏,防止沉淀生成,增强白兰地的稳定性。     

Short communication: Addition of sodium bicarbonate to maternal colostrum: Effects on immunoglobuling absorption and hematocrit in neonatal calves

Twenty-six Holstein bull calves born from primiparous and multiparous cows without dystocia were assigned in a randomized complete block design to 1 of 2 treatments: pooled maternal colostrum (PMC) or PMC supplemented with 30g of sodium bicarbonate (NaHCO(3)). Calves were fed PMC from 9 different batches containing (mean ± SD) 82.05±8.45g/L of IgG. Calves were fed 2.68L of PMC at birth (referred to as 0h) and 1.32L of PMC 6h later. The total amount of IgG fed was 329.89±34.56g. Calves were fed 2L of milk replacer at 24, 36, and 48h postpartum. The addition of NaHCO(3) had no effect on IgG absorption. Serum IgG concentrations at 0, 6, 12, 24, and 48h postpartum were not different between calves supplemented with or without 30g of NaHCO(3) to colostrum. Area under the curve, apparent efficiency of absorption, and hematocrit were not affected by the NaHCO(3) treatment.     

Coffee Antioxidant Properties: Effects of Milk Addition and Processing Conditions

ABSTRACT: In the human diet, coffee is the major source of caffeoyl-quinic acids known as powerful antioxidants. The aim of this study was to assess the effect of usual coffee consumption, such as the addition of milk, and of processing conditions, such as spray-drying, on beverage antioxidant power and potential polyphenol bioavailability impairments. When 25% milk was added to coffee, up to 40% of coffee chlorogenic acid were found to be bound to dairy proteins, using an ultrafiltration technique. However, neither milk addition nor spray-drying had a significant effect on beverage antioxidant power, evaluated using 2,2-diphenyl-1-pycrylhydrazyl (DPPH), 2-2'-azobis (2-amidinopropane) dihydrochloride (AAPH), and total antioxidant capacity (TAC) tests. Moreover, these interactions tended to decrease during in vitro gastric and intestinal digestion, thus suggesting that interactions between chlorogenic acid and milk proteins in coffee and milk beverage may not have any significant effect on coffee antioxidant power before and after consumption.     

Determination of Rutin in Black Tea by Adsorption Voltammetry (AdV) in the Presence of Morin and Quercetin

This paper presents a sensitive method to rutin determination on a screen-printed multi-walled carbon nanotube electrode modified with poly(3,4-ethylenedioxythiophene) and ionic liquid (SMWCNT-PEDOT-IL). Several studies show that rutin may be absorbed onto the surface of electrodes modified with PEDOT. On the other hand, the presence of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF₄) on the surface of the modified electrode increased the oxidation current by nearly 30 % and facilitates the oxidation of rutin to values less positive potential compared with the modified electrode only with PEDOT. Cyclic voltammetry was used to quantify and characterize the modified electrode. pH and electrochemical parameters, potential adsorption, time adsorption, and scan rate were optimized based on the oxidation of rutin to obtain the following values: pH 6.0; Eads, ?0.10 V; tads, 80 s; and scan rate 50 mV s^?1. The detection limit (3σ) was 7.7?×?10^?8 mol L^?1 and the RSD was 1.5 %. The new method was used to quantify rutin in black tea samples in the presence of others flavones with consistent results.     

Addition of straw to the early-lactation diet: Effects on feed intake,milk yield,and subclinical ketosis in Holstein cows

This study evaluated feed intake, milk yield, and subclinical ketosis in dairy cows in early lactation fed 2 different diets postpartum. Cows are typically offered a high-energy ration immediately after calving. We compared a conventional high-energy total mixed ration (TMR) with a transition ration that contained chopped straw. We predicted that adding chopped straw would increase dry matter intake, milk production, and indicators of energy metabolism during the first 3 wk of lactation compared to cows fed a conventional high-energy TMR. We also predicted that carryover effects would be likely for at least 2 wk after treatment ended. A total of 68 mixed-age Holstein cows were enrolled in the study 3 wk before their expected calving. All cows were managed on a single high-forage diet during the dry period. At calving, cows were allocated to 1 of the 2 diets: half to the conventional high-energy TMR (CTMR; n = 34; net energy for lactation = 1.61 Mcal/kg; neutral detergent fiber = 31.7%), and the other half to a high-forage TMR containing chopped wheat straw, equivalent to 4.27% dry matter (STMR; n = 34; net energy for lactation = 1.59 Mcal/kg; neutral detergent fiber = 33.7%) for 3 wk after calving. Cows on STMR were then shifted to CTMR for the next 2 wk to study short-term residual effects on the performance of cows. Treatments were balanced for parity, body condition score, and body weight. Feed intake was measured daily from 2 wk before to 5 wk after calving using automatic feed bins. Blood was sampled twice weekly from 2 wk before to 5 wk after calving, and β-hydroxybutyrate and glucose were measured in serum samples. Subclinical ketosis was identified using a threshold of β-hydroxybutyrate ≥1.0 mmol/L in wk 1 after calving and ≥1.2 mmol/L in wk 2 to 5 after calving. Cows were milked twice daily, and weekly samples (composite samples of morning and afternoon milkings) were analyzed to determine total solids, fat, protein, lactose, and somatic cell count. Data were analyzed in 2 separate periods: the treatment phase (wk +1, +2, and +3) and the post-treatment phase (wk +4 and +5). The addition of straw to the TMR negatively affected the dry matter intake of STMR cows during wk 2 and 3 of lactation. Daily milk yield during the first 5 wk of lactation was lower in STMR cows than in CTMR cows. Concentrations of β-hydroxybutyrate were higher in CTMR cows than in STMR cows during wk 1, but this effect was reversed during wk 2 and 3 of lactation. By 21 d in milk, STMR cows had a greater risk of developing subclinical ketosis than CTMR cows. Adding chopped wheat straw to the TMR during the first 21 d after calving lowered dry matter intake and provided no metabolic or production benefits to lactating dairy cattle.     

水分添加量对肉粉肠品质特性的影响

本文探究了不同加工工艺条件下肉粉肠中淀粉糊化度(Degree of Starch Gelatinization,DSG)的变化及对其产品品质特性的影响.结果表明,随着水分添加量的增加,肉粉肠的DSG和乳化稳定性显著增加(P<0.05),而蒸煮损失显著降低(P<0.05),肉粉肠中水分分布也证实了上述结果.与此同时,随着...