Comparative evaluation of the efficacy of cereal and microbial phytases in growing pigs fed diets with marginal phosphorus supply

Two experiments with a total of 76 growing pigs (average initial body weight 16.6 kg) were conducted to compare the efficacy of cereal phytases (wheat and rye) and supplemented microbial phytase (Natuphos®). Using the slope ratio technique, the dose–response relationship between five levels of phytase (0, 50, 100, 150 and 200 U kg^?1) and the apparent absorption of phosphorus (P) within each source of phytase was calculated. Graded phytase levels in the diets were obtained by adding increasing amounts of microbial phytase or phytase‐containing wheat (Exp 1) or rye (Exp 2) to phytase‐inactivated basal diets at the expense of phytase‐inactivated wheat (Exp 1) or rye (Exp 2). Except for wheat phytase, addition of phytase to the basal diets increased (P < 0.05) apparent P absorption, with microbial phytase being more efficient (P < 0.05) than cereal phytase. There were no significant differences in apparent P absorption between the wheat‐ or rye‐based diets when either microbial or cereal phytases were supplemented from 0 to 200 U kg^?1. It could be derived from the results of this study, by means of regression analysis, that the efficacy of cereal phytases was 40% compared to microbial phytase. © 2002 Society of Chemical Industry     

微波辐射水解植酸快速制备肌醇的研究

采用微波辐射法水解植酸制备肌醇，缩短了水解时间和获得了较好的产率。用正交实验法确定了制备肌醇的最佳水解条件。提出了分析水解度的方法和探讨了植酸微波水解机理。     

鸭骨泥酶解条件优化及游离氨基酸组成分析

以鸭骨泥为原料,预处理后经定向酶解得到富含氨基酸的酶解液,从而为制备热反应型肉味香精提供底物。主要研究了预处理温度和时间对鸭骨泥酶解作用的影响,通过正交实验优化了酶法水解的条件,并对酶解液的游离氨基酸组成进行了测定。实验结果表明:鸭骨泥最佳预处理温度和时间为80℃,40min;鸭骨泥最佳酶解条件为胰蛋白酶用量10000IU/g,酶解温度45℃、pH7.5,料液比1:30,酶解时间5h,在此最佳酶解条件下,鸭骨泥水解度达63.18%,平均肽链长度1.58%,氮回收率59.43%;鸭骨泥酶解液含有16种氨基酸,其中必需氨基酸有7种,必需氨基酸占氨基酸总量的56.26%。     

Pellicle formation,microbial succession and lactic acid utilisation during the aerobic deteriorating process of Sichuan pickle

The pellicles formation, microbial changes and lactic acid utilisation during the aerobic deterioration of Sichuan pickle were discussed in this study. By plate counting, chemical detection and HPLC analysis, the aerobic deterioration of Sichuan pickle was featured by microbial growth, pellicle formation, lactic acid decrease and pH elevation. Bacteria dominated in pellicles and the pellicles present morphological change from smooth to wrinkly along with the aerobic deteriorating process. Nine species of bacteria were identified and responsible for the pellicle formation. Combined with Lactobacillus plantarum, eight pellicle‐forming bacteria were the dominant lactic acid consuming organisms in deteriorating Sichuan pickle. Especially under the harsh acid condition of the early deteriorating period, Lb. plantarum, pellicle‐forming bacteria Bacillus amyloliquefaciens, B. subtilis and Citrobacter freundii participated in the pellicles, utilised lactic acid and increased the brine pH effectively. Sequence analysis of 16S rDNA libraries suggested that the resulting pH of 4.8–5.0 initiated the growth of more undesirable organisms, and the pellicle bacterial diversity changed greatly compared with that in the early deteriorating period. The study indicated the important role of pellicles in the initiation of Sichuan pickle's aerobic deterioration and enhanced our ability to understand and potentially control the aerobic deterioration.     

酶解鸡汤熬制过程中蛋白质和氨基酸的变化

利用木瓜蛋白酶适度酶解,进行常压和高压熬制,探讨鸡汤蛋白质和氨基酸的变化。结果显示:酶解鸡汤熬制过程中粗蛋白逐渐增加,30 min后呈显著性增加(p<0.05),常压熬制90 min、高压熬制30 min分别为0.848%、0.921%。可溶性蛋白逐渐增加,但常压熬制120 min仍然较低,仅为5.45 mg/g;高压熬制20 min的可溶性蛋白为6.546 mg/g,熬制70 min后高达8.372 mg/g。酶解鸡汤常压熬制过程中胶原蛋白呈显著增加(p<0.05),熬制120 min后仅为4.208%;高压熬制60 min后显著增加(p<0.05),熬制90 min后高达7.827%。酶解常压熬制和高压熬制鸡汤的氨基酸总量分别增加了13.64%、42.94%,苦味氨基酸分别增加了14.59%、53.95%。表明适度酶解和高压熬制能加快蛋白质类物质的溶出,缩短鸡汤熬制时间,但鸡汤苦味物质也有所增加。      

水解工艺对苦荞提取物中槲皮素含量的影响及其药代动力学研究

目的:以苦荞提取物为研究对象,通过正交实验设计优化苦荞提取物中芦丁被酸水解为槲皮素的工艺条件,并结合药代动力学研究探讨酸水解工艺对苦荞提取物中芦丁和槲皮素吸收的影响。方法:以盐酸百分含量、水解时间、乙醇百分含量、水解温度作为因素设计四因素三水平正交实验优化苦荞提取物中芦丁酸水解为槲皮素的工艺条件,以该工艺进行苦荞提取物酸水解,并在水解第1、2、4、6 h取样得到不同槲皮素含量的水解产物1、2、3、4。分别灌胃大鼠200 mg/kg的苦荞提取物及各水解产物,并在不同时间点采血,以黄芩素为内标,高效液相色谱(HPLC)测定血浆中槲皮素的浓度,DAS 2.0计算主要药代动力学参数。结果:苦荞提取物芦丁酸水解的最佳工艺参数为盐酸百分含量0.91%、水解时间6 h、乙醇百分含量50%、水解温度70 ℃,在该工艺条件下64.11%芦丁转化为槲皮素。苦荞提取物、水解产物1、2、3、4槲皮素的AUC_0-t分别为(17.604±5.422)、(42.175±9.435)、(87.917±19.347)、(116.706±46.256)、(178.509±49.478) mg/L·h,C_max分别为(2.743±1.217)、(7.109±2.603)、(12.438±3.197)、(15.727±4.68)、(20.044±5.736) mg/L。与苦荞提取物相比,其水解产物1、2、3、4的药代动力学参数AUC_0-t、C_max具有显著性差异(p<0.05)。结论:苦荞提取物经酸水解后部分芦丁转化为槲皮素,芦丁和槲皮素在大鼠体内的累计吸收量也相应提高。     

应用植酸、活性炭去除白酒中固形物

由于白酒贮存于铝质容器中，致使酒中固形物增高。应用植酸降固处理后，再选用专用活性炭吸附除浊处理。实践证明，植酸活性炭结合除浊降固，能有效降低酒中固形物(氧化铝)，使产品质量达标，并且不影响酒的风味质量。(陶然)     

晋西北酸粥发酵过程中微生物基因组DNA提取方法的比较

为了找到一种简单高效的晋西北酸粥发酵过程中微生物基因组DNA提取方法,本文采取对提取的微生物基因组DNA进行浓度测定的方法,比较了溶菌酶-SDS-蛋白酶K法、改良CTAB法和改良CTAB-溶菌酶法三种方法的提取效果。结果表明:溶菌酶-SDS-蛋白酶K法效果最好,可以获得质量较高的微生物基因组DNA,DNA浓度为1657.53 ng/μL;改良CTAB-溶菌酶法比溶菌酶-SDS-蛋白酶K法效果差,DNA浓度为1308.08 ng/μL;改良CTAB法对微生物基因组DNA的提取效果比溶菌酶-SDS-蛋白酶K法更差,DNA浓度为1098.36 ng/μL。以提取到的微生物基因组总DNA为模板,进行16S r DNA基因的PCR扩增,在回收产物中目的条带清晰,表明提取到的微生物基因组DNA含量高、结构完整。整体实验结果表明,溶菌酶-SDS-蛋白酶K法对于提取晋西北酸粥发酵过程中微生物基因组DNA效果最好。      

不同茶类中黄酮醇苷酸水解条件的优化及酸水解前后3种黄酮醇含量的测定

目的 建立高效液相色谱法（High performance liquid chromatography, HPLC）同时测定不同茶类中黄酮醇的含量,并优化茶叶中黄酮醇苷酸水解成黄酮醇（杨梅素、槲皮素、山柰酚）的条件,以此测定不同茶类中三种类型黄酮醇苷元的含量。方法 样品经70%甲醇水（V:V）提取后,用盐酸（16%）-甲醇溶液进行酸水解,再经乙酸乙酯萃取、浓缩、复溶至相同体积;酸水解前后的样品溶液均用HPLC对黄酮醇进行定量分析并用超高效液相色谱-串联质谱(ultra-performance liquid chromatography-tandem mass spectrometry, UPLC-MS/MS)对黄酮醇苷进行定性分析。 结果 3种黄酮醇在3.125~100 μg/mL的浓度范围内具有较好的线性关系（r2≥0.9976）,优化后的方法的重复性、稳定性、精密度较好（相对标准偏差（RSD）≤4%）。六大茶类中黄酮醇苷的最佳酸水解条件：水解时间为1 h,水解温度为80 ℃,盐酸 (16%)-甲醇溶液最佳比例为1:2 (V:V)。 结论 本研究优化了茶叶中黄酮醇苷酸水解的方法,并利用HPLC测定了六大茶类酸水解前后黄酮醇的含量。方法处理简单、结果准确可靠,适用于茶叶中黄酮醇及其苷类物质的分析。     

一种绢纺原料除油微生物菌株的获得及除油性能研究

从茧丝腐化液中筛选获得了一株脱油效率较高的菌株,经16S rDNA分子鉴定,命名为Enterobacter sp.TY-4。对脱油菌株脱油条件进行了优化,获得了最适碳源为蔗糖、最适氮源为蛋白胨,最适C/N为0.25︰1,培养基最适pH 7.0,最适浴比和接种量分别为2︰125和1%。将脱油菌株TY-4与一株脱胶菌株Aeromonas sp.TJ-5进行共培养,对比了脱胶菌和除油菌同时接种与次序接种对重油茧丝脱胶除油效率的影响。结果表明,采用共培养方式和次序接种明显提高了脱胶脱油效率,残油率和脱胶率分别达0.48%和24.1%。     

Investigation of the susceptibility of acid-deamidated wheat gluten to in vitro enzymatic hydrolysis using Raman spectra and free amino acid analysis

BACKGROUND: The number and surface nature of amino acids (AAs) in substrate proteins available to hydrolytic enzymes are critical. Among them, the micro‐environmental properties of specific AAs in substrates before hydrolysis would probably dominate the susceptibility of substrates to enzymatic hydrolysis. Fundamental knowledge concerning this regard is lacking. The objective of this work was to investigate the relationship between the exposure level of AAs in acid‐deamidated wheat gluten and their susceptibilities to in vitro enzymatic hydrolysis by pancreatin through both high‐performance liquid chromatography and Raman spectra. Wheat gluten deamidated with HCl (HDWG), citric acid (CDWG), succinic acid (SDWG) and acetic acid (ADWG) at the same degree of deamidation under the same heat treatment were chosen as the substrates. Substrate characterisations including degree of hydrolysis, surface hydrophobicity and structural characteristics before hydrolysis, together with analysis of free AAs of the corresponding hydrolysates during hydrolysis, were investigated. RESULTS: Hydrolysates from SDWG had the highest value for the degree of hydrolysis. The susceptibility of CDWG to pancreatin hydrolysis was the lowest, lower than native wheat gluten (CK) after the initial 36 h. Compared with free AAs, the mole increase profiles of CK, Arg production levelled off in HDWG after 12 h whereas it was inhibited in ADWG. For SDWG, Arg release was dramatically inhibited after 12 h and was replaced by Trp. Investigations using Raman spectra of the micro‐environment of Cys, Trp, Tyr and His and the mole increase trend of them indicated that the exposure level of these amino acids in substrates was positively related to their susceptibilities to pancreatin hydrolysis especially after 24 h of hydrolysis. CONCLUSION: Deamidation by four acids has a distinct influence on the structural characteristics of wheat gluten substrates. Although the substrates were selected at the same level of deamidation by the same heat treatment, their resultant conformational differences significantly influenced the exposure level of amino acids for binding to enzymes and the susceptibility of substrates to in vitro enzymatic hydrolysis. Therefore, it had an influence on changing enzyme cutting sites of pancreatin. This information will provide a better understanding of specific behaviour of AAs in wheat gluten during enzymatic hydrolysis from a new perspective. Copyright © 2012 Society of Chemical Industry     

废弃植物油亚临界水解制取混合脂肪酸及其动力学研究

以废弃植物油为原料,用亚临界水解法制备混合脂肪酸,研究混合脂肪酸的制备条件及其反应动力学。结果表明,废弃植物油在亚临界水中的适宜反应条件为:反应温度280℃,反应时间30 min,油水体积比为1:3.5,转化率最高达98.1%。废弃植物油在亚临界水中的水解反应平均反应级数为n=1.123 89,活化能E_a=70.87 kJ/mol,频率因子A=1.770 6×10~5,动力学模型为-dc_A/dt=1.770 6×10~5e~(-70.87/RT)C_A~1.123.89。     

Variation in the phytic acid content of soybeans and its effect on consistency of tofu made from soybean varieties with high protein content

The relationships of contents of phytic acid and protein to the breaking stress of tofu were examined using soybeans of three Japanese varieties with high protein content harvested in different locations from the years 2001 to 2003. The phytic acid content was more variable than protein content within different cultivating locations and years for the same variety and showed significant negative correlation to the breaking stress of tofu made with 0.25% MgCl₂ for all the varieties (P < 0.001, r = ?0.60). In particular, Sachiyutaka variety was characterized by the highest negative correlation between the breaking stress of tofu and the phytic acid content in soymilk (P < 0.001, r = ?0.73). As MgCl₂ concentration increased, the correlation between the phytic acid content and the breaking stress of tofu was reduced, and finally there was no significant correlation between them when the breaking stress reached a maximum at the particular MgCl₂ concentration which is probably concerned with varietial characteristics of soybeans. These results support the idea that the variation in the content of phytic acid, which can act as a buffer against coagulation of soy protein, accounts for the fluctuation in consistency of tofu made with lower MgCl₂ concentrations (ca. 0.25%) using soybeans of the same variety with different cultivating conditions. Copyright © 2005 Society of Chemical Industry     

绍兴腐乳发酵过程中蛋白质水解及其对成品白点影响的研究

研究了绍兴腐乳发酵过程中蛋白质水解与酪氨酸含量变化的规律,分析了不同发酵时间腐乳样品的氨基酸态氮、三氯乙酸-氮溶指数（TCA-NSI）、游离氨基酸、蛋白质水解度（DH）、酪氨酸含量及蛋白质分子量变化。结果表明:绍兴腐乳发酵过程中坯料中酪氨酸随着氨基酸态氮、TCA-NSI、游离氨基酸、DH的增加而增加;1⁴0d内主要是7S和11S蛋白质的分解,40d以后主要是小分子蛋白质的进一步分解。相关性分析表明,游离酪氨酸的含量与DH的Pearson相关系数最高。同时对成熟腐乳的研究发现有白点腐乳的TCA-NSI、DH和游离酪氨酸显著高于无白点腐乳,这表明了腐乳中白点的形成是由蛋白质过度水解造成的。本研究为绍兴腐乳白点的控制提供了参考。      

豆豉返霜过程中基本理化特性及微生物多样性差异分析

通过测定豆豉在返霜过程中水分、灰分、粗蛋白、粗脂肪、总糖、还原糖、总酸、氨基态氮含量、氨基酸组成以及返霜前后微生物的变化,研究返霜前后其基本理化特性和微生物组成的变化规律。结果表明,随着返霜的进行,豆豉中灰分和总糖含量基本保持不变,粗脂肪、还原糖、总酸含量整体呈下降趋势,水分含量先增加后基本保持稳定;氨基态氮含量在贮藏前6d内与粗蛋白含量变化趋势相反,且氨基酸评分结果显示,返霜后豆豉中蛋白质营养价值降低。Illumina Miseq测序结果表明,返霜后,豆豉的细菌和真菌OTUs都有所降低,细菌芽孢杆菌属增加,真菌曲霉属减少。因此,返霜会降低豆豉的营养价值及细菌群落多样性,增加真菌群落多样性,破坏豆豉原有的特色菌群组成结构。     

杜仲籽油混合脂肪酸制备工艺优化及脂肪酸组成分析

以杜仲籽油为原料,在常压下皂化水解并用正己烷萃取制备杜仲籽油混合脂肪酸。在单因素超碱量、KOH-乙醇溶液/油的比例、皂化温度、皂化时间和酸化pH研究的基础上,选取超碱量、皂化温度、皂化时间和酸化pH四个因素,应用响应面设计中的Box-Behnken设计对皂化工艺进行优化并得到回归模型,通过气质联用仪分析杜仲籽油脂肪酸的组成。结果表明,制备杜仲籽油混合脂肪酸的优化工艺条件为:超量碱52%,皂化温度77℃,皂化时间82min,酸化pH2.7,在此优化条件下,测得混合脂肪酸的酸值为159.19mg KOH/g。气质联用仪分析结果显示杜仲籽油混合脂肪酸中α-亚麻酸的相对含量可达60.14%,可以作为进一步分离提取杜仲籽油α-亚麻酸的原料。      

Anti-listeria activity of poly(lactic acid)/sawdust particle biocomposite film impregnated with pediocin PA-1/AcH and its use in raw sliced pork

A novel poly(lactic acid) (PLA)/sawdust particle (SP) biocomposite film with anti-listeria activity was developed by incorporation of pediocin PA-1/AcH (Ped) using diffusion coating method. Sawdust particle played an important role in embedding pediocin into the hydrophobic PLA film. The anti-listeria activity of the PLA/SP biocomposite film incorporated with Ped (PLA/SP + Ped) was detected, while no activity against the tested pathogen was observed for the control PLA films (without SP and/or Ped). Dry-heat treatment of film before coating with Ped resulted in the highest Ped adsorption (11.63 ± 3.07 μg protein/cm²) and the highest anti-listeria activity. A model study of PLA/SP + Ped as a food-contact antimicrobial packaging on raw sliced pork suggests a potential inhibition of Listeria monocytogenes (99% of total listerial population) on raw sliced pork during the chilled storage. This study supports the feasibility of using PLA/SP + Ped film to reduce the initial load of L. monocytogenes on the surface of raw pork.     

黄酒微生物及其与风味形成关系的研究进展

黄酒是我国传统发酵食品,在其风味物质形成过程中,微生物起到了非常重要的作用。本研究综合分析了黄酒原料处理、麦曲、酒药以及酿造过程等方面对微生物群落结构,并探讨了微生物群落结构与黄酒风味形成的关系。其中,浸米过程中的微生物主要以乳酸菌为主,麦曲主要以霉菌为主,酒药主要以酵母菌为主。而在整个黄酒酿造过程中霉菌先减少后增多,并在后酵过程起到产酶糖化的作用;酵母先增加后减少,并在前主酵过程中起到产酒精增强黄酒风味的作用;细菌尤其是乳酸菌在浸米及酿造过程中起到降解大分子物质的作用从而促进黄酒呈香呈味,且对有机酸的产生即黄酒酸味起到积极作用,而其余各种细菌在黄酒不同的酿造阶段相互作用并对黄酒的风味起到积极作用。根据目前的研究现状,提出可利用多组学技术分析黄酒中主要产香微生物并通过后续的高通量筛选应用到黄酒发酵生产中,优化黄酒风味的形成过程。     

Genetic analysis of milk urea concentration and its genetic relationship with selected traits of interest in dairy cows

The aim of this study was to estimate genetic parameters of milk urea concentration (MU) and its genetic correlations with milk production traits, longevity, and functional traits in the first 3 parities in dairy cows. The edited data set consisted in 9,107,349 MU test-day records from the first 3 parities of 560,739 cows in 2,356 herds collected during the years 1994 to 2020. To estimate the genetic parameters of MU, data of 109 randomly selected herds, with a total of 770,016 MU test-day records, were used. Genetic parameters and estimated breeding values were estimated using a multiple-trait (parity) random regression model. Herd-test-day, age-year-season of calving, and days in milk classes (every 5 d as a class) were used as fixed effects, whereas effects of herd-year of calving, permanent environment, and animal were modeled using random regressions and Legendre polynomials of order 2. The average daily heritability and repeatability of MU during days in milk 5 to 365 in the first 3 parities were 0.19, 0.22, 0.20, and 0.48, 0.48, 0.47, respectively. The mean genetic correlation estimated among MU in the first 3 parities ranged from 0.96 to 0.97. The average daily estimated breeding values for MU of the selected bulls (n = 1,900) ranged from −9.09 to 7.37 mg/dL. In the last 10 yr, the genetic trend of MU has gradually increased. The genetic correlation between MU and 11 traits of interest ranged from –0.28 (milk yield) to 0.28 (somatic cell score). The findings of this study can be used as the first step for development of a routine genetic evaluation for MU and its inclusion into the genetic selection program in the Walloon Region of Belgium.