固相萃取-高效液相色谱法测定酱油专用焦糖中5-羟甲基糠醛和糠醛

建立了固相萃取-高效液相色谱(SPE-HPLC)法测定酱油专用焦糖中5-羟甲基糠醛和糠醛的方法。样品经水稀释,亲水亲油平衡(HLB)固相萃取柱净化,洗脱液静置沉淀后,用水稀释并过0.45μm滤膜。流动相为水和乙腈梯度洗脱,经Symmetry Shield RP18色谱柱分离,在紫外检测器280nm波长条件下进行测定。该方法在0.5~100μg/mL范围内线性关系良好,R2均大于0.999,相对标准偏差(n=6)在2.5%~4.6%之间,加标回收率在87.1%~99.2%之间。5-羟甲基糠醛和糠醛的方法检出限分别为0.039mg/kg和0.041mg/kg。     

草莓、黑莓、蓝莓中多酚类物质及其抗氧化活性研究

研究草莓、黑莓、蓝莓3种小浆果的总酚、总黄酮、原花青素含量及其总抗氧化能力。结果表明:蓝莓全果的总酚、总黄酮、原花青素含量在所测3种浆果全果中最高,分别为9.44mg没食子酸/g干质量、36.08mg芦丁/g干质量、24.38mg儿茶素/g干质量;其总抗氧化能力也最强,达14.98mmol Trolox/100g干质量。草莓的总酚、总黄酮、原花青素含量则最低,抗氧化能力也最弱。此外,3种浆果果渣中的总酚、总黄酮、原花青素含量以及总抗氧化能力均高于全果和果汁,即果渣>全果>果汁。总酚含量、总黄酮含量以及原花青素含量与总抗氧化能力之间的相关性分析表明,总酚含量与总抗氧化能力之间存在显著线性相关,相关系数r达到0.9704,表明酚类物质是其抗氧化作用的主要物质基础。     

Ultrasound-assisted extraction and antioxidant activity of phenolic and flavonoid compounds and ascorbic acid from rugosa rose (<Emphasis Type="Italic">Rosa rugosa</Emphasis> Thunb.) fruit

The present study aimed to extract total phenolic compounds (TPC), total flavonoid compounds (TFC), and ascorbic acid (AA) from the fruit of rugosa rose (Rosa rugosa Thunb.) by ultrasound-assisted extraction (UAE), and to evaluate their antioxidant activities. UAE significantly increased the extract yield compared with that obtained using the conventional method. TPC, TFC, and AA were extracted, depending on the extraction conditions (temperature, time, and ethanol concentration), in the range of 50.73–96.69, 15.93–31.88, and 3.06–6.08 mg/g, respectively. TPC and TFC were effectively extracted at a relatively high temperature (50 °C) than AA was (30 °C). The solvent condition used to extract TPC, TFC, and AA was 50% ethanol. The UAE condition for the highest antioxidant activity was obtained 30 °C, 30 min, and 50% ethanol, which were the same condition for the highest AA extraction. Among the extracts, AA showed a strong correlation with antioxidant activity at p-value of 0.001.     

Effect of Subcritical Water on the Extraction of Bioactive Compounds from Carrot Leaves

Carrot leaves, which are generally considered as agricultural residue, are rich in bioactive compounds, such as polyphenols. This study investigates the extraction of polyphenols and luteolin (flavonoid) from freeze-dried and ground carrot leaves (d?<?100 μm) using subcritical water (SCW). Water at elevated temperatures and at high pressure (40 bar) could behave as low-polar solvent to enhance extraction of organic compounds. SCW was investigated at different temperatures (110–230 °C), time (0–114 min), and solid-liquid ratio (15 and 35 g/L). Accordingly, it was revealed that total phenolic content (TPC) from carrot leaves using SCW has an increasing trend with temperature and resulted in 42.83 ± 1.85 mg per g of dry weight in gallic acid equivalent at 210 °C/113.5 min. However, luteolin content using SCW extraction behaved differently, where increase of temperature adversely affected its content. Hot water extraction studies revealed the presence of optimum luteolin content (0.768 ± 0.009-mg/g dry weight) at 120 °C for 10 min. In conclusion, it was shown that carrot leaves are a promising feedstock to extract polyphenols that has high content of luteolin.     

Phenolic Profiles and Antioxidant Capacities of Chinese Unifloral Honeys from Different Botanical and Geographical Sources

Honey has been acknowledged worldwide as a good source of natural antioxidants. Chemical properties of total phenolics and flavonoids of 33 Chinese unifloral honeys from nine different floral sources were investigated. Antioxidant activities including 1, 1-diphenyl-2- picrylhydrazyl radical (DPPH·) scavenging, superoxide anion radical (O₂ ^?·) scavenging, hydroxyl radical (·OH)-scavenging activities, and reducing powers were evaluated. The results indicated that total phenolic content (TPC) ranged from 10.43 to 149.6 mg of PCE/100 g, while total flavonoid content (TFC) ranged from 9.41 to 102.1 mg QE/100 g. Positive correlations between radical-scavenging activities and, respectively, TPC values and TFC values were found. Remarkable variations in antioxidant properties, TPC, and TFC values were demonstrated in hydrophilic extracts of honeys from different botanic and/or geographic sources. The current findings will provide useful information for evaluating the food quality of Chinese honey and for educating consumers to choose specific honey lines for their specific health-promoting effects.     

Spent espresso coffee grounds as a source of anti-proliferative and antioxidant compounds

Disposal of spent espresso coffee grounds (SCG) is costly and leads to the loss of bioactive compounds that could be fractionated, in several applications. This work aimed to investigate phenolic profile, tocopherols, and antioxidant and anti-proliferative activities of SCGs ethanolic extracts from coffee powders differing in coffee provenience and composition (arabica/robusta). Tyrosol, detected for the first time in SCGs, was the most abundant phenolic measured (121–1084 mg/kg in the extract), along with 4-hydroxybenzoic acid and vanillin (885–1813 and 340–1103 mg/kg, respectively). Extract derived from 100% robusta from Guatemala (S7-R) showed the highest α- to β-tocopherol ratio of 1.2 and the highest antioxidant potential as evidenced by RACI and GAS values of −0.43 and 0.20, respectively. Moreover, S7-R showed a promising anti-proliferative activity toward human lung carcinoma cells (A549), with IC₅₀ value of 61.2 μg/mL comparable to that given by the positive control vinblastine (IC₅₀ value of 67.3 μg/mL).     

Impact of different solvents on the recovery of bioactive compounds and antioxidant properties from lemon (<Emphasis Type="Italic">Citrus limon</Emphasis> L.) pomace waste

The effects of different solvents on the recovery of (i) extractable solids (ES), (ii) total phenolic compounds (TPC), (iii) total flavonoid content (TFC), (iv) vitamin C, and (v) antioxidant activity from lemon pomace waste were investigated. The results revealed that solvents significantly affected the recovery of ES, TPC, TFC, and antioxidant properties. Absolute methanol and 50% acetone resulted in the highest extraction yields of TPC, whereas absolute methanol resulted in the highest extraction of TFC, and water had the highest recovery of vitamin C. 50% ethanol, and 50% acetone had higher extraction yields for TPC, and TFC, as well as higher antioxidant activity compared with their absolute solvents and water. TPC and TFC were shown to be the major components contributing to the antioxidant activity of lemon pomace.     

Physicochemical properties,antioxidant activity and cellular protective effects of honeys from southern Africa

The southern Africa region is a region of unique floral biodiversity; this study was undertaken to address the limited knowledge regarding the physiochemical, antioxidant activity and the ability of these honeys to protect biomolecules and cells against oxidative damage. The physicochemical properties, total polyphenolic and flavonoid content (TPC and TFC), catalase and antioxidant activity (DPPH, TEAC, and ORAC assays) of 13 representative honey samples was determined. Biological and cellular protection was investigated using the erythrocyte haemolysis, the pBR322 plasmid, as well as the dichlorofluorescein diacetate (DCFH-DA) assays in SC-1 and Caco-2 cells. High TPC, TFC, catalase and antioxidant activity was obtained, and all honeys protected DNA, erythrocytes and cells in vitro. Colour, TPC, TFC and antioxidant activity correlated well but no correlation was seen between these parameters and catalase activity, biological and cellular effects. Nevertheless, honeys with high catalase activity and/or are dark in colour with high TPC, TFC and/or antioxidant activity did show the highest degree of biological and cellular protection.     

糠醛类化合物的制备及其在鞣制中的应用

利用农业生物质资源,提取制备糠醛和5－羟甲基糠醛（5－HMF）,是绿色化学品研究开发的重要内容之一。糠醛结构中含有活泼的醛基,故很早以前就有人将其用于皮革的鞣制。本文综述了糠醛和5－羟甲基糠醛的制备方法及研究进展。总结了糠醛鞣革特点,并着重就糠醛和5－羟甲基糠醛的改性及其鞣革前景进行了分析讨论。     

离子交换固相萃取高效液相色谱联用法检测食品中5-羟甲基糠醛

为提高分析方法的准确性,优化建立一种定量检测各类食品中5- 羟甲基糠醛含量的高效液相色谱方法。采用离子交换固相萃取柱代替传统的C18 固相萃取柱进行前处理,与高效液相色谱联用,提高了方法的回收率和精密度。在0.01～12mg/L 质量浓度范围内,5- 羟甲基糠醛质量浓度和色谱峰面积线性关系好(R2=0.9998),方法检出限(RSN=3)为3.42μg/L。在0.1、0.5、1mg/kg 3 种质量浓度添加水平内,5- 羟甲基糠醛的添加回收率为85%～103%,RSD 为0.31%～3.83%。采用该方法对13 种样品进行测定,结果表明该方法能够用于食品中5- 羟甲基糠醛含量测定。     

Polyphenols content and antioxidant capacity of thirteen faba bean (Vicia faba L.) genotypes cultivated in Tunisia

In vitro antioxidant capacity of thirteen genotypes of faba bean (Vicia faba L.) collected during three different growing stages (vegetative, reproductive and maturity) have been evaluated. For the vegetative stage (VS) and reproductive stage (RS) the whole plant (WP) has been used for the analysis while for the maturity stage (MS) the plant was divided and analyzed in different parts, the whole seed (WS), seed coat (SC), cotyledons (Cot) and pod (Pod). The antioxidant capacity has been evaluated by means of the total phenolic and total flavonoid contents (TPC and TFC respectively), the ferric-reducing/antioxidant power (FRAP) and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assays. The results showed different antioxidant properties for the same genotype when considering the different parts or stages of the plant. High content of both total phenolics (> 92.85 mg as gallic acid equivalent (GAE)/g of dried plant) and flavonoids contents (> 11.87 mg as rutin equivalent (RE)/g of dried plant) were found for all genotypes during the vegetative and the reproductive stages, which also showed the highest antioxidant activity (FRAP value ≥ 1.157 mmol/g and DPPH radical-scavenging capacity > 43.49%), indicating their potential as natural sources of antioxidant foods. For the maturity stage, the highest values for the TPC, TFC, FRAP and DPPH scavenging capacity were observed for the pods and the lowest for the cotyledons.The results of this study indicate that faba beans are a good source of natural antioxidants independently to their genotype. The quantification of the antioxidant capacity according to the stage and the plant part could be suitable for applications on the food industry in relation to production and preservation of faba bean food products.     

Simultaneous separation and determination of sugars,ascorbic acid and furanic compounds by HPLC—dual detection

An HPLC method was developed for the simultaneous separation and determination of sugars, ascorbic acid, 5-HMF (5-hydroxymethylfurfural), furfural and four other furanic compounds as the possible degradation products of sugars and ascorbic acid on heating and by Maillard reaction. Sucrose, glucose, fructose, ascorbic acid, dehydroascorbic acid, 5-HMF, furfural, DMHF (2,5-dimethyl-4-hydroxy-3(2H)-furanone), 2-furoic acid, 2-acetylfuran and furfuryl alcohol were separated on an Aminex HPX-87H column (300×7.8 mm). The mobile phase consisted of acetonitrile and 0.005 mol l⁻¹ sulfuric acid aqueous solution (16:84, v/v). Two detectors, a refractive index detector and a photodiode array detector, were used to detect these compounds. Several fruit juice and drink samples were analyzed using this HPLC method. For alcoholic beverages, the content of alcohol was also simultaneously determined by refractive index detector.     

梭子蟹下脚料酶法制取蛋白水解物最佳工艺的研究

采用酶法从梭子蟹下脚料中制取蛋白水解物,并利用单因素试验和正交试验对最佳酶解条件进行研究。结果表明,梭子蟹下脚料最适的水解蛋白酶为碱性蛋白酶;在液料比3:1 时,最适酶解条件为温度55℃、时间3.0h、pH8.5、加酶量(E/S)1000U/g,此时水解度为26.68%,其中温度对水解度的影响最大,其次为加酶量;蛋白水解物的分子量小于10kD,蛋白水解呈味氨基酸含量为412.6mg/L,占氨基酸总量的39.42%,具有很高的营养价值和应用前景。     

Continuous ultrasound and pulsed ultrasound: Selective extraction tools to obtain enriched antioxidants extracts from cocoa beans (Theobroma cacao L.)

In this study, the effect of continuous assisted extraction (CUAE) and pulsed ultrasound assisted extraction (PUAE) of phenolic compounds from cocoa beans was evaluated. Frequency (25/45 kHz) and extraction time (15/30 min) were varied. Phenolic acids were identified as catechin-(+), epicatechin-(+), procyanidin B1 and procyanidin B2 were quantified on each extract by HPLC-DAD. Then, total phenolic content (TPC), total flavonoids content (TFC), flavan-3-ols, non-flavonoids content (NF) and proanthocyanidins (PAC) were determined. The experimental findings indicated the highest extraction yields of TPC and flavonoids subclasses when prolonged PUAE was used. Additionally, an increase of 282% in epicatechin yield was obtained compared with CUAE. However, the prolonged use of continuous sonication increased the non-flavonoids extraction yield in 23% compared with pulsed sonication. The scavenging and iron chelating activity depended on the chemical composition of each extract and was not correlated directly to TPC.     

通过测定啤酒中5-羟甲基糠醛评价啤酒老化程度

由于5-羟甲基糠醛对啤酒老化所具有的指示作用。通过研究啤酒中5-羟甲基糠醛水平的高低与啤酒存储期间老化程度之间存在的相关性，利用高效液相色谱法，测定啤酒中5-羟甲基糠醛含量，来评价啤酒风味老化的程度。     

Optimization of the extraction of phenolic compounds from red grape marc (Vitis vinifera L.) using response surface methodology

Optimization of the extraction of total polyphenols (TPC), flavanols (FL), total anthocyanins (TA) and total tannins (TT) from grape marc by the response surface methodology is important to improve the recovery of these high-value phytochemicals. The independent variables studied were ethanol concentration (% EtOH), extraction time (h) and liquid-to-solvent ratio (L/S). TPC, FL, TT and TA showed different patterns of extractability, with significant variation in the linear, quadratic and interaction effects of the independent variables. The optimal extraction conditions were determined and the quadratic response surfaces were drawn from the mathematical models. The optimal extraction conditions were: 57% EtOH, 17?h, 50:1 L/S for TPC; 57% EtOH, 13?h, 50:1 L/S for FL; 62% EtOH, 16?h, 50:1 L/S for TT and 52% EtOH, 6?h, 10:1 L/S for TA. These optimum conditions yielded: 24?mg GAE/g DM of TPC; 1.5?mg quercetin/g DM of FL; 18?mg catechin/g DM of TT and 6?mg malvidin/g DM of TA.     

Effects of different pretreatment methods on drying kinetics,three-dimensional deformation,quality characteristics and microstructure of dried apple slices

The purpose of this study was to evaluate the effects of different pretreatment methods including blanching (30, 60 and 90 s), ultrasound (10, 30 and 60 min), pectinase treatment (15, 30 and 60 min), and osmotic dehydration treatment (0.5, 1.0 and 4.5 h) on the drying characteristics, three-dimensional (3D) deformation, color, total polyphenol content (TPC), antioxidant activity and microstructure of apple slices during drying. The shrinkage and height standard deviation (HSD) were calculated to evaluate the 3D deformation such as surface curl and flatness of the apple slices. The results showed that blanching, pectinase and osmotic dehydration treatment could increase the shrinkage and reduce the surface curl of the samples. Blanching, ultrasound and osmotic dehydration pretreatment could inhibit the color changes of dried apple slices, while pectinase treatment could aggravate the color deterioration of the samples. The apple slices pretreated with blanching for 60 s contained the highest TPC of 4.86 mg/g, and the samples also had the highest antioxidant activity. In addition, microstructure of the pretreated samples was significantly different from those of untreated samples. Therefore, pretreatment technology before drying is of great significance to improve the appearance and quality of products.     

橙汁模拟体系非酶褐变产物及评价标准

以橙汁中糖、氨基酸、抗坏血酸、柠檬酸为变量构建不同的非酶褐变模拟体系,通过研究体系贮藏期间3-羟基-2-吡喃酮（3-hydroxy-2-pyrone,3OH2P）、5-羟甲基糠醛（5-hydroxymethylfurfural,5-HMF）、糠醛（furfural,2-F）3 种褐变产物的变化,确定褐变产物的可能来源;通过分析比较褐变度（A420 nm）、褐变指数（browning index,BI）、总色差值（ΔE）3 种非酶褐变评价标准的相关性,确定不同评价标准是否有一致性。结果表明：果糖降解是生成5-HMF的主要途径,3OH2P来源于抗坏血酸的降解,糖能促进2-F的生成;在含糖的模拟体系中,A420 nm、BI、ΔE相互之间均呈显著正相关（P＜0.05）,这3 种评价标准具有一致性;然而在不含糖的体系中,A420 nm与BI、ΔE均无显著相关性（P＞0.05）,这3 种评价标准存在差异性。     

活性炭吸附结合TiO2光催化分离纯化杨木预水解液中的木糖

利用活性炭吸附和TiO₂光催化降解脱除杨木预水解液中的溶解木素,探讨了不同活性炭类型（木质基磷酸活化活性炭、食品质303活性炭、煤质活性炭）、活性炭用量、吸附时间、光催化时间、TiO₂用量对预水解液中木素、总木糖、糠醛、羟甲基糠醛（5-HMF）以及乙酸等有机组分含量的影响,优化确定了活性炭吸附和TiO₂光催化降解条件。研究结果表明,木质基磷酸活化活性炭对木素的吸附脱除效果最好,在活性炭用量为1.0%和吸附时间为10 min时,总木糖得率为93.1%,木素、糠醛、5-HMF、乙酸脱除率分别为75.1%、29.3%、22.4%、3.5%。单一TiO₂光催化处理,在TiO₂用量1.0%和光催化时间10 h条件下,总木糖得率为89.0%,木素、糠醛、5-HMF、乙酸脱除率分别为40.2%、24.2%、32.1%、3.1%。活性炭协同TiO₂光催化处理预水解液的较优工艺条件为：木质基磷酸活化活性炭用量1.0%、光催化时间6 h和TiO₂用量0.1%~0.5%,此条件下预水解液中木素的脱除率为84.4%~86.7%,总木糖得率为88.2%~89.8%,糠醛脱除率为53.8%~65.1%,5-HMF脱除率为48.6%~51.7%,乙酸含量变化不明显 。     

Combined ultrasound and heat pretreatment improve the enzymatic hydrolysis of clam (Aloididae aloidi) and the flavor of hydrolysates

The effects of pretreatments with ultrasound (UP), heat (HP), and combinations of heat-ultrasound (HP-UP) and ultrasound-heat (UP-HP) on the flesh enzymolysis of clam (Aloididae aloidi) and the flavor characteristics of hydrolysates were investigated. The optimum UP pretreatment conditions for the hydrolysis were obtained at ultrasound power of 500 W, ultrasound time of 20 min, and liquid/solid (L/S) ratio of 2:1 (v/w), yielded 41.33% of hydrolysis degree (DH). Among the different pretreatments, the UP pretreatment had the highest DH value, while the HP-UP pretreatment obtained the highest soluble peptide content. The UP pretreatment efficiently enhanced the contents of taste-active components, including free amino acids, 5′-nucleotides, and succinic acid. The HP pretreatment promoted the formation of pleasant volatile compounds and reduced the content of unpleasant volatile compounds, such as 1-octen-3-ol and 2-ethyl-1-hexanol. The combined HP-UP pretreatment was an effective method for improving the enzymatic hydrolysis of clam and the flavor of hydrolysate.