响应面法优化仙茅多糖的酶解工艺及其抗氧化活性研究

为开发运用仙茅多糖提供科学依据,使用纤维素酶优化仙茅多糖的提取工艺,并探讨多糖体外抗氧化活性。对影响酶解工艺的酶添加量、温度、时间和p H值,运用响应面法进行优化;通过多糖对二苯代苦味酰基自由基(DPPH·)、Fe~(3+)和羟基自由基(·OH)的消除作用来评价其抗氧化活性。结果显示:在酶添加量1.3%、酶解温度58℃、酶解时间110 min和p H5.7时,仙茅多糖提取率达到最大值,为20.52%;分别比超声提取法和热水浸提法所得多糖增多了129.8%和54.9%。且酶解法所得多糖对DPPH·、Fe~(3+)和·OH的消除率分别可达56%、30%、90%,相比于超声提取法和热水浸提法,对Fe~(3+)的还原能力更好,但是热水浸提法所得多糖对DPPH·和·OH的清除效果更好。表明酶解法在提高多糖得率的同时,还具有较好的抗氧化活性。     

杏鲍菇多糖的酶法提取及其保湿和抗氧化活性评价

利用纤维素酶提取杏鲍菇中多糖,基于单因素和正交试验优化提取工艺条件,并探讨了多糖提取物的保湿性和抗氧化活性。结果表明,酶法提取的最佳工艺条件为纤维素酶用量0.7%,料液比1∶15（g∶mL）,酶解温度50 ℃,酶解时间120 min。在此条件下,杏鲍菇多糖的提取率为2.42%。同时,1%杏鲍菇多糖的保湿性在2 h内优于5%甘油,总抗氧化能力相当于VC的90.8%～96.7%,对羟基自由基清除能力可达到VC的82.2%,表明所提取的杏鲍菇多糖具有良好的保湿性和抗氧化活性。     

白及多糖的超声-微波协同提取工艺及其抗氧化活性研究

目的:研究白及多糖的超声-微波协同提取工艺优化及其抗氧化活性。方法:以多糖得率为考察指标,通过单因素实验对料液比、浸泡时间、微波功率和协同提取时间4个影响因素进行考察,采用正交实验设计对超声波-微波协同提取白及多糖的工艺条件进行优化,并研究白及多糖对羟基自由基（·OH）、超氧阴离子（O₂^-·）和1,1-二苯基-2-苦肼基自由基（DPPH·）的清除率以评价其体外抗氧化活性。结果:最佳提取工艺条件为:液料比20∶1 m L/g,浸泡时间6 min,微波功率200 W,协同提取时间5 min,该工艺条件下多糖得率达6.98%±0.19%。单独超声波提取法和单独微波提取法的多糖得率仅为超声-微波协同提取法的46.28%和87.96%,表明超声-微波协同提取优于单独超声波提取和单独微波提取。抗氧化活性研究表明在实验范围内,白及多糖对O-2·无明显清除作用,但对·OH和DPPH·具有明显的清除作用,采用超声-微波协同提取法提取的白及多糖较微波提取法具有更高的·OH和DPPH·清除活性,当多糖浓度为0.5 mg/m L时,对·OH和DPPH·清除率分别为92.82%和74.21%。结论:超声-微波协同提取具有省时高效的特点,特别适用于多糖类物质的提取。      

巴戟天药渣中多糖的提取工艺研究

巴戟天废弃药渣含有丰富的多糖,故此研究巴戟天药渣中多糖热水提取的最佳工艺条件,为巴戟天废弃药渣的综合利用提供依据。以多糖得率为指标,通过单因素实验研究4个因素:提取温度、提取时间、料液比、提取次数对巴戟天药渣中多糖提取效率的影响。在单因素实验的基础上,通过正交试验对巴戟天热水提取工艺条件进行优化。结果表明,提取温度及提取次数是影响巴戟天多糖提取效率的关键因素,料液比及提取时间是次要因素。最佳工艺条件为:巴戟天药渣在100℃水浴中用7倍量的蒸馏水提取2次,每次1 h,在此条件下,巴戟天多糖的得率为15.67%。该工艺条件可重复,多糖得率较高。     

谷芽多糖的提取工艺及其抗氧化活性研究

优化超声法提取谷芽多糖,研究谷芽多糖的体外抗氧化活性。通过单因素试验和正交试验,研究料液比、超声功率、超声提取温度和超声作用时间对谷芽多糖提取效果的影响。分别采用紫外分光光度法和邻苯三酚自氧化法测定其清除DPPH·和O_2~-·的作用进行试验,根据试验结果评价其体外抗氧化活性。得出优化工艺条件为料液比1:35(g/mL,),提取温度70℃,超声功率180 W,作用时间20 min。谷芽多糖的得率为20.85%优选谷芽多糖的超声提取工艺,省时、高效、可靠、重现性好;体外抗氧化性试验显示谷芽多糖对DPPH·和O_2~-·具有较强的清除能力,且在一定范围内其抗氧化作用与浓度呈现良好的量效关系。     

复合酶法提取云芝多糖及其抗氧化活性

目的:优化复合酶解法辅助提取云芝多糖的提取工艺,并研究其抗氧化活性。方法:在单因素实验基础上,利用Box-Behnken方法进行酶浓度、p H、酶解时间和酶解温度四因素三水平实验设计,以多糖得率为响应值,采用响应面分析优化云芝多糖的提取条件。采用对云芝多糖清除DPPH自由基能力、清除羟自由基（·OH）能力和清除超氧阴离子（O₂^-·）能力的测定评价云芝多糖的抗氧化活性。结果:最佳提取条件为p H5.50,酶解时间37 min,酶解温度52℃,酶浓度2.50%,理论上云芝多糖的提取率为9.87%,验证实验的实际提取率为9.58%,与传统的热水浸提法提取率相比较,提高了43.63%。云芝多糖清除·OH、O₂^-·和DPPH自由基的IC₅₀分别为0.80、0.75、0.75 mg/m L,抗氧化活性研究中云芝多糖的各抗氧化活性均随多糖浓度的增加而上升。结论:复合酶解法辅助提取条件温和,方法简单,效率高,可在云芝多糖实际提取工艺中得到应用,得到的云芝多糖具有良好的抗氧化能力,可进一步的开发利用。      

莲藕多糖的碱法提取工艺优化与抗氧化活性评价

目的 优化莲藕多糖的碱法提取工艺并评价其抗氧化活性。方法 以多糖提取率为指标,以料液比、NaOH浓度、提取时间和提取温度为考察因素进行单因素实验,结合响应面法对提取工艺进行优化,并分析所得莲藕多糖的纯度、相对分子质量和自由基清除能力。结果 响应面优化结果显示,除料液比以外,NaOH浓度、提取时间和提取温度对莲藕多糖提取率均具有显著影响(P<0.05)。确定最佳工艺条件为:料液比1:16(g/mL)、NaOH浓度0.04 mol/L、提取时间1.3 h、提取温度57℃,此条件下的多糖提取率达13.07%,与预测值13.52%相近。该碱法提取多糖的纯度达73.66%,平均相对分子质量为1.727×10⁵Da。抗氧化活性评价结果显示,莲藕多糖具有清除1,1-二苯基-2-三硝基苯自由基和羟基自由基的能力,且清除率与多糖浓度成正比。结论 优化了碱提莲藕多糖的提取工艺,且提取得到的多糖具有较好的抗氧化活性,为莲藕资源的开发利用提供了理论依据。     

银柴胡多糖超声辅助提取工艺优化及抗氧化活性分析

目的：为了提高银柴胡多糖得率，对银柴胡多糖提取工艺参数进行优化，并评价其体外抗氧化活性。方法：采用超声辅助提取银柴胡多糖，在单因素实验基础上结合响应面法（Box–Behnken Response Surface）对提取工艺参数进行优化，并采用Sevag法除蛋白得银柴胡粗多糖，进一步对其抗氧化活性进行分析。结果：优化后银柴胡多糖最佳提取工艺参数为超声温度50℃、时间3.20 h、提取次数2次，在此条件下多糖得率最高，为28.24%±0.10%，多糖含量为59.13%；体外抗氧化测定结果显示，银柴胡粗多糖清除DPPH自由基、OH自由基、ABTS+自由基的IC50分别是5.47、2.40和1.44 mg/mL，表明其具有一定的抗氧化能力。结论：本研究经优化得到的银柴胡多糖提取工艺切实可行，可为银柴胡资源的开发利用提供理论依据。     

微波-超声波协同辅助优化阳荷多糖提取工艺及抗氧化性分析

以野生阳荷为原料,采用微波-超声协同辅助提取阳荷中的多糖并优化其提取工艺,借助体外抗氧化模型对阳荷多糖进行抗氧化分析。响应面分析法优化得到阳荷多糖的最优提取工艺为:超声功率454 W,提取时间15 min,提取温度67℃,料液比1∶26(g/mL)。在此工艺条件下,阳荷多糖的最优得率为(10.40±0.35)%。体外抗氧化活性分析表明,阳荷多糖具有较强的清除DPPH·、ABTS+·、超氧阴离子自由基(O2-·)和羟基自由基(·OH)能力,其自由基清除活性随阳荷多糖浓度的增加而增强,证明阳荷多糖是一类优异的自由基清除剂。     

米糠多糖提取工艺优化及抗氧化活性研究

以米糠为原料提取多糖,在单因素试验的基础上,利用响应面分析法优化多糖提取工艺,并建立回归模型,同时探究其体外抗氧化活性。结果表明：米糠多糖的最佳提取工艺为提取温度85℃,提取时间3 h,乙醇体积分数80%,液料比25∶1 (mL/g),在此条件下,多糖得率为17.31%。提取的米糠多糖对·OH、DPPH·和O^-₂·清除作用明显,因此其具有较高的抗氧化活性,是一种良好的天然抗氧化剂,且其质量浓度与抗氧化活性呈现一定的量效关系。     

Ovarian structures and circulating steroids in heifers and lactating cows in summer and lactating and dry cows in winter

Two experiments compared follicular and luteal development and circulating steroid concentrations from induced luteolysis to ovulation in lactating Holstein cows (n = 27; 40.0 +/- 1.5 kg milk/day) vs. nulliparous heifers (n = 28; 11 to 17 mo-old) during summer (Experiment 1), and in lactating (n = 27; 45.9 +/- 1.4 kg milk/d) vs. dry cows (n = 26) during winter (experiment 2). All females received PGF2,, 6 d after ovulation and were monitored until next ovulation by daily ultrasound and assay of serum progesterone (P4) and estradiol (E2). Every female was used two or three times. In Experiment 1, lactating cows had high incidence of multiple ovulation (63.5%) compared with heifers (1.3%). Among single ovulators, there was no difference in maximal size of ovulatory follicles between lactating cows and heifers (15.8 vs. 16.5 mm, respectively). However, lactating cows had lower peak serum E2 (8.6 vs. 12.1 pg/ml), took longer to ovulate after luteolysis (4.6 vs. 3.8 d), developed more luteal tissue volume (7,293.6 vs. 5,515.2 mm3), and had lower serum P4 on d 6 after ovulation (2.0 vs. 3.0 ng/ml) than heifers (data included multiple ovulators). In experiment 2, multiple ovulations were similar between lactating and dry cows (17.9 vs. 17.2%, respectively). Peak serum E2 was also similar between lactating and dry cows (7.6 vs. 8.5 pg/ml) although lactating cows had larger ovulatory follicles (18.6 vs. 16.2 +/- 0.4 mm). Lactating cows took longer to ovulate (4.8 vs. 4.2 d), developed more luteal tissue (7,599 vs. 5,139 +/- 468 mm3), but had similar serum P4 (2.2 vs. 1.9 ng/ ml) compared with dry cows. Therefore, lactating cows had similar or lower circulating steroid concentrations than dry cows or heifers, respectively, despite having larger ovarian structures.     

Fertilization and early embryonic development in heifers and lactating cows in summer and lactating and dry cows in winter

Two experiments in two seasons evaluated fertilization rate and embryonic development in dairy cattle. Experiment 1 (summer) compared lactating Holstein cows (n = 27; 97.3 +/- 4.1 d postpartum [dppl; 40.0 +/- 1.5 kg milk/d) to nulliparous heifers (n = 28; 11 to 17 mo old). Experiment 2 (winter) compared lactating cows (n = 27; 46.4 +/- 1.6 dpp; 45.9 +/- 1.4 kg milk/d) to dry cows (n = 26). Inseminations based on estrus included combined semen from four high-fertility bulls. Embryos and oocytes recovered 5 d after ovulation were evaluated for fertilization, embryo quality (1 = excellent to 5 = degenerate), nuclei/embryo, and accessory sperm. In experiment 1, 21 embryos and 17 unfertilized oocytes (UFO) were recovered from lactating cows versus 32 embryos and no UFO from heifers (55% vs. 100% fertilization). Embryos from lactating cows had inferior quality scores (3.8 +/- 0.4 vs. 2.2 +/- 0.3), fewer nuclei/embryo (19.3 +/- 3.7 vs. 36.8 +/- 3.0) but more accessory sperm (37.3 +/- 5.8 vs. 22.4 +/- 5.5/embryo) than embryos from heifers. Sperm were attached to 80% of UFO (17.8 +/- 12.1 sperm/UFO). In experiment 2, lactating cows yielded 36 embryos and 5 UFO versus 34 embryos and 4 UFO from dry cows (87.8 vs. 89.5% fertilization). Embryo quality from lactating cows was inferior to dry cows (3.1 +/- 0.3 vs. 2.2 +/- 0.3), but embryos had similar numbers of nuclei (27.2 +/- 2.7 vs. 30.6 +/- 2.1) and accessory sperm (42.0 +/- 9.4 vs. 36.5 +/- 6.3). From 53% of the flushings from lactating cows and 28% from dry cows, only nonviable embryos were collected. Thus, embryos of lactating dairy cows were detectably inferior to embryos from nonlactating females as early as 5 d after ovulation, with a surprisingly high percentage of nonviable embryos. In addition, fertilization rate was reduced only in summer, apparently due to an effect of heat stress on the oocyte.     

2018年深圳市售蔬菜和鸡蛋中氟虫腈及其代谢物的检测分析

目的 建立超高效液相色谱-串联质谱法同时测定蔬菜和鸡蛋中氟虫腈及其代谢物(氟甲腈、氟虫腈砜和氟虫腈亚砜), 并对深圳市售的蔬菜和鸡蛋中氟虫腈及其代谢物残留状况进行抽样检测。方法 采用QuEChERS前处理方法, 以C18色谱柱为分离柱, 以乙腈和10 mmol甲酸+6 mmol甲酸铵水溶液为流动相进行梯度洗脱, 用超高效液相色谱-串联质谱(ultra performance liquid chromatography-mass spectrometry/mass spectrometry, UPLC-MS/MS), 电喷雾电离(electrospray ionization, ESI), 多反应监测(multiple reaction monitoring, MRM)模式检测, 外标法同时定量测定氟虫腈及其代谢物。结果 方法的线性范围为0.1~2.0 μg/L, 线性相关系数均大于0.9994, 检出限0.0005 mg/kg, 定量限0.001 mg/kg; 蔬菜中3个水平的平均加标回收率88.0%~101.2%, 相对标准偏差(relative standard deviation, RSD)均小于8.5%; 鸡蛋中3个水平的平均加标回收率86.1%~104.8%, 相对标准偏差(RSD)均小于9.2%。结论 该方法具有操作简单、干扰少、快速、准确可靠等特点, 可适用于蔬菜鸡蛋中氟虫腈及其代谢物的检测。     

Zinc and iron contents and their bioaccessibility in cereals and pulses consumed in India

Several cereals and pulses commonly consumed in India were screened for zinc and iron contents and their bioaccessibility in the same was determined by equilibrium dialysis employing an in vitro simulated digestion procedure. Zinc content of cereals ranged from 1.08 mg/100 g in rice to 2.24 mg/100 g in sorghum. Zinc content of pulses was between 2.03 mg/100 g (whole chickpea) and 2.68 mg/ 100 g (decorticated chickpea). Iron content of cereals ranged from 1.32 mg% in rice to 6.51 mg% in sorghum, while that of pulses ranged from 3.85 mg% in decorticated green gram to 6.46 mg% in black gram. Dialyzability of zinc from pulses (27–56%) was generally higher than that from cereals (5.5–21.4%). Dialyzabilities of iron were almost similar from both cereals and pulses examined and were 4.13–8.05% in cereals and 1.77–10.2 % in pulses. A significant negative correlation between inherent phytate content and zinc dialyzability value was inferred in the case of pulses. Phytic acid content of the cereals had a significant negative influence on iron dialyzability. Inherent calcium had a negative influence on zinc dialyzability in cereals. Tannin did not have any significant influence on zinc or iron dialyzabilities from cereals and pulses. While both insoluble and soluble fractions of the dietary fibre generally interfered with zinc dialyzability, the insoluble fraction alone had this effect on iron dialyzability. The lower collective negative influence of the inherent factors on zinc dialyzability from pulses is consistent with their higher concentrations in these grains, relative to cereals. The negative correlation of inherent phytic acid with zinc and iron dialyzabilities was supported by enhanced dialyzabilities of these minerals upon partial removal of phytate from the grains by treatment with fungal phytase.     

Fenvalerate residue level and dissipation in tea and in its infusion

Fenvalerate is a non-systemic insecticide/acaricide used in controlling a wide range of pests, including those resistant to organochlorine, organophosphorus and carbamate insecticides. The study investigated the dissipation behaviour (residue level) of fenvalerate in tea and its transfer during infusion. Fenvalerate was applied on tea crop at two dosages, 100 and 200?g a.i.?ha^?1 (recommended and double the recommended) in the dry and wet seasons under field conditions. Samples (green tea shoots, made tea, its infusion and spent leaves) were analysed for fenvalerate by high-performance liquid chromatography using diode array detection. The residue dissipated faster in the wet season than in the dry season. Seven days after the treatment (normal round of plucking) the residues observed in the green shoots at the two dosages were 0.5?±?0.01, 1.1?±?0.01 and 0.4?±?0.02, 0.9?±?0.01?mg?kg^?1 in the dry and wet seasons, respectively. During processing of green tea shoots to made tea a 30–40% loss of residue was observed. The transfer of residue from made tea to infusion was in the range 10–30% for both seasons, whereas 50–70% of the residues remained in the spent leaves. However, the degradation rate in both seasons followed first-order kinetics. The half-lives were in the range of 2–3 days for green shoots and made tea in both seasons.     

果蔬及其制品中真菌毒素的污染与检测研究进展

果蔬在生长、贮存、运输及加工等一系列过程中,极易受到各种病原菌的侵染而发生腐烂,腐烂果蔬不仅造成巨大的经济损失,而且导致果蔬积累大量的真菌毒素。真菌毒素可通过食物链的传递对人或动物的健康带来巨大威胁。本文就果蔬中常见真菌毒素的种类、产毒菌株、侵染途径、产毒条件、毒性作用、检测方法和限量标准等方面进行详细的总结,旨在为果蔬中真菌毒素的控制提供参考。     

我国熟制坚果与籽类食品中霉菌及其毒素污染状况研究

目的 调查我国熟制坚果与籽类食品中霉菌及其毒素污染状况，掌握该类食品中霉菌及真菌毒素污染风险的关联性。方法 通过采集市售商品，检测霉菌及其毒素，采用内转录间区（ITS）测序法对样品中污染的霉菌进行属鉴定。结果 19.32%（560/2 912）的熟制坚果与籽类食品霉菌计数>25 CFU/g。单一、混合坚果超过该限值的比例分别为14.78%（322/2 178）和32.56%（239/734），差异有统计学意义（P<0.05）。单一坚果中核桃超过该限值的比例最高，为24.10%（47/195），杏仁、巴达木和花生分别为17.44%（15/86）、16.81%（20/119）和16.22%（73/450），其余种类均在15%以下。对26份霉菌计数>25 CFU/g的样品进行真菌毒素检测，1份采自云南的花生检出白僵菌素污染量为16.37 μg/kg。ITS扩增子测序发现熟制坚果与籽类食品中主要污染曲霉属、交链孢霉属、念珠菌属等，和真菌毒素检出有相关性。结论 熟制坚果与籽类食品中霉菌污染较高，检出的霉菌属有产真菌毒素的风险，提示应加强该类食品中污染霉菌的监测、种属鉴定及产毒情况研究，掌握其污染途径和产毒规律，为开展风险评估，采取有效防控措施提供科学依据。     

蛋白质组学技术及其在乳及乳制品中的应用研究进展

蛋白质组学技术是近年来生命科学研究的重要工具,在食品、医学及动植物研究领域具有独特优势。利用蛋白质组学技术研究乳及乳制品,深入阐明其中蛋白质的表达及动态变化已成为当前的研究热点。该文主要综述了蛋白质组学的概念、常用技术及应用领域,重点介绍蛋白质组学在乳及乳制品领域,特别是在乳脂肪球膜蛋白、乳清蛋白、乳及乳制品加工过程以及干酪制品中的研究应用,探讨了目前乳及乳制品蛋白质组学研究中存在的问题与局限,并对蛋白质组学及其在乳及乳制品中的应用前景进行了总结与展望,为应用蛋白质组学技术深入研究乳及乳制品提供了理论依据。     

Sweetness and aroma perceptions in dairy desserts varying in sucrose and aroma levels and in textural agent

Sweetness–aroma interactions were investigated in model dairy desserts varying in sucrose concentration, aroma concentration and in textural characteristics using different textural agents (κ-, ι-, λ-carrageenans and an equal-mix of the three). Overall intensities of sweetness and aroma perceptions were evaluated by sensory analysis and apparent partition coefficients of aroma compounds were measured by static headspace—GC.Sweetness–aroma interaction was characterised by a non-reciprocal relationship. Concentration of aroma had no impact on sweetness intensity, whatever be the sucrose concentration or textural characteristics of desserts, whereas varying texture or sucrose concentration modified aroma intensity. However, effects on aroma assessment were effective only when aroma concentration was the highest. In this condition, use of λ-carrageenan or increasing sucrose concentration from 25 to 50 g kg⁻¹ enhanced aroma intensity, but no extra enhancement was observed when sucrose concentration was 100 g kg⁻¹. As the air–dessert partition coefficient remained constant, impact of textural characteristics and sweetness variation on aroma perception did not result from physico-chemical interaction.     

冰酒中的毕赤属和汉逊属酵母菌的筛选及其在葡萄酒酿造中的应用

从冰葡萄酒自然发酵过程中分离、鉴定出10株毕赤属(Pichia)和汉逊属(Hanseniaspora)酵母,对其耐受性(酒精、糖、酸、SO2)进行研究,筛选得到4株耐受性能优良的酵母菌株,编号为"HO"和"HU"(Hanseniaspora属)、"PO"和"PK"(Pichia属).再将此4个酵母菌株与商业酿酒酵母(S...