Effect of protein-xanthophylls (PX) concentrate of alfalfa supplementation on physico-chemical properties of turkey breast and thigh muscles during ageing

The objective was to evaluate the effects of a dietary protein-xanthophylls (PX) concentrate of alfalfa to turkey diets (at 15 and 30 g kg^− 1 feed) on the physico-chemical properties of breast and thigh muscles during ageing. The experiment involved 120 turkeys (Big-6 type) allotted to 3 groups (group I—control group; group II—with 1.5% supplementation of the protein-xanthophylls (PX) concentrate; group III—with 3% supplementation of the protein-xanthophylls (PX) concentrate). Measurements of pH, water holding capacity, color, oxymyoglobin content, TBARS and oxidation–reduction potential showed that the addition of protein-xanthophylls (PX) concentrate of alfalfa to a turkey diet did not cause deterioration of breast and thigh meat quality. In addition, changes in color, oxymyoglobin content, TBARS and oxidation–reduction potential values suggested that the inclusion of the concentrate to turkey diets acts as an antioxidant in the raw meat.     

苜蓿黄酮的分离及其生物转化研究进展

苜蓿属植物资源丰富,并且含有大量的黄酮类物质。黄酮类物质具有多种生物活性及药理作用。本文对苜蓿黄酮的分离、结构鉴定以及黄酮苷的生物转化的最新进展等进行了总结,并对苜蓿黄酮的发展方向进行了探讨。     

紫花苜蓿生物活性与应用的研究现状

紫花苜蓿的茎、叶中含有多种营养素及未知生长因子,紫花苜蓿次生代谢物具有多种独特的生物活性,如抗氧化、抑菌等。本文简述了紫花苜蓿叶蛋白、皂苷、类黄酮、膳食纤维等主要活性成分及其营养保健作用,并谈及紫花苜蓿活性成分营养保健的应用前景。     

紫花苜蓿中单宁的提取工艺优化及体外抗氧化作用研究

采用正交实验法研究紫花苜蓿中单宁的最佳提取工艺条件,探讨了乙醇浓度、乙醇中盐酸的浓度、提取温度及提取时间四因素对紫花苜蓿中单宁提取量的影响。确立了紫花苜蓿中单宁最佳提取条件为:盐酸浓度2.5%,乙醇浓度70%,提取温度50℃,提取时间5h,测得紫花苜蓿中单宁提取量为2.15mg/g。并采用邻苯三酚自氧化体系、Feton体系对紫花苜蓿中单宁的抗氧化活性进行了研究,并同VC进行了比较。结果表明:紫花苜蓿中单宁对邻苯三酚自氧化有抑制作用,对羟基自由基有良好的清除作用。     

新疆紫花苜蓿挥发油化学成分的分析

采用水蒸气蒸馏法提取新疆紫花苜蓿中的挥发油,通过气相色谱-质谱联用技术,结合计算机质谱图库检索,对分离的化合物进行结构分析。从紫花苜蓿挥发油中初步确定了53种化合物,占挥发性物质含量的95.6%,并用峰面积归一化法得出各化学成分在挥发油中的含量。紫花苜蓿挥发油主要组分为6,10,14-三甲基-2-十五酮（10.28%）、叶绿醇（8.23%）、反-2-烯基-己醛(5.46%)、3-甲基丁醛(3.61%)和沉香醇（3.17%）等。     

响应曲面法优化紫花苜蓿中香豆雌酚的提取工艺

采用响应曲面法对紫花苜蓿中香豆雌酚的提取工艺进行优化。在单因素试验基础上,建立影响香豆雌酚粗提取物得率的3 个主要因素即液料比、提取温度和提取时间与提取率之间的数学模型。利用SAS V8.0 软件分析表明：在液料比27.28:1(mL/g)、提取温度67.7℃和提取时间13.77h 时,香豆雌酚粗提取物得率较高,最佳提取率为2.64‰,与预测值基本相符。     

Inactivation of Escherichia coli O157:H7 and Salmonella spp. on alfalfa seeds by caprylic acid and monocaprylin

Alfalfa and other seed sprouts have been implicated in several Escherichia coli O157:H7 and Salmonella spp. human illness outbreaks in the U.S. Continuing food safety issues with alfalfa seeds necessitate the need for discovery and use of novel and effective antimicrobials. The potential use of caprylic acid (CA) and monocaprylin (MC) for reducing E. coli O157:H7 and Salmonella spp. populations on alfalfa seeds was evaluated. The effectiveness of three concentrations of CA and MC (25, 50, and 75 mM) to reduce E. coli O157:H7 and Salmonella spp. populations in 0.1% peptone water and on alfalfa seeds was evaluated. Surviving populations of E. coli O157:H7 and Salmonella spp. were enumerated by direct plating on tryptic soy agar (TSA). Non-inoculated alfalfa seeds were soaked for up to 120 min to evaluate the effect of CA and MC solutions on seed germination rate. For planktonic cells, the efficacy of the treatments was: 75 MC > 50 MC > 25 MC > 75 CA > 50 CA > 25 CA. Both E. coli O157:H7 and Salmonella spp. were reduced to below the detection limit (0.6 log CFU/ml) within 10 min of exposure to 75 MC from initial populations of 7.65 ± 0.10 log CFU/ml and 7.71 ± 0.11 log CFU/ml, respectively. Maximum reductions of 1.56 ± 0.25 and 2.56 ± 0.17 log CFU/g for E. coli O157:H7 and Salmonella spp., respectively, were achieved on inoculated alfalfa seeds (from initial populations of 4.74 ± 0.62 log CFU/g and 5.27 ± 0.20 log CFU/g, respectively) when treated with 75 MC for 90 min. Germination rates of CA or MC treated seeds ranged from 84% to 99%. The germination rates of CA or MC soaked seeds and water soaked seeds (control) were similar (P > 0.05) for soaking times of ≤ 90 min. Monocaprylin (75 mM) can be used to reduce E. coli O157:H7 and Salmonella spp. on alfalfa seeds without compromising seed viability.     

Temperature Adjustment for Reference Evapotranspiration Calculation in Central Arizona

A key component in the calculation of reference crop evapotranspiration (ETr) is the weather data. If the weather data have been collected from a station under nonreference conditions, the data itself may contain errors, which will in turn yield inaccurate ETr estimates. It was proposed by Allen in 1996 that data used for evapotranspiration be scrutinized by comparing daily minimum temperature (Tmin) and the daily average dew point temperature (Tdew). If the difference between Tmin and Tdew is greater than 3°C, then the site is considered to be arid (nonreference) and adjustments are recommended for temperature and dew point data. In Arizona, normal weather conditions often occur where Tmin and Tdew do not approach each other. This study examined the appropriateness of applying the conditions set forth by Allen to temperature data collected in central Arizona. Two weather stations were set up in a 35.5?ha alfalfa field in central Arizona to measure dry bulb and wet bulb temperatures. Additionally, plant temperature data were collected to verify field conditions. Daily data were taken for 1.5 years at the University of Arizona’s Maricopa Agricultural Center. Of the 611 days of data collected, the difference between Tmin and Tdew was greater than 3°C on 329 days, indicating that these data were not taken under reference conditions. Among these data, 178 days were verified as nonreference but 151 were verified as actually being under reference conditions. Making adjustments for these days (151 days) resulted in a 47?mm decrease in ETr estimation, which mostly occurred during the summer.     

紫花苜蓿根系拉拔试验研究

为了研究紫花苜蓿根系的拉拔力学性质和评价其根系固土力学机制的增强效应,采用室外原位拉拔试验分析了影响苜蓿根系拉拔力的因素。试验结果表明：① 紫花苜蓿根系拉拔力随着直径、根长、根系表面积的增大而增大,抗拉力与直径增长趋势呈指数关系,根长L2（20~30 cm）比根长L1（10~20 cm）平均拉拔力增大了69.62%,根长L3（30~40 cm）比根长L2平均拉拔力增大了61.7%,根长L3平均拉拔力比根长L1增大156.16%。② 拉拔力随根系表面积的增大而增大;根长L2、L3的平均根系表面积分别是根长L1的2.28倍和5.17倍;根长L2、L3平均拉拔力分别是根长L1的1.70倍和2.66倍。③ 紫花苜蓿根系拉拔力与植物根径呈负相关,满足幂指函数关系。拉拔强度T的大小为T3 (30~40 cm)>T2 (20~30 cm)>T1 (10~20 cm),根长L2、L3的平均拉拔强度比根长L1的减小了14.70%,53.71%。     

Water footprint of beef production on Texas High Plains pasture

ABSTRACT

Depletion of the Ogallala aquifer in the U.S. Great Plains demands information on water usage in forage-fed beef production. We compared a summer grazing system for beef steers consisting of warm-season grasses vs. grasses growing with lucerne (Medicago sativa L.). The water footprint averaged 39 and 26 m³ of water kg^?1 of beef liveweight gain, respectively, when water included rainfall, irrigation, and livestock drinking. Including lucerne reduced the water footprint of beef weight gain thanks to its ability to alleviate protein deficiency in the associated grasses, thus diminishing an important source of inefficiency in converting feed to meat.