Recovery and fractionation of major apple and grape polyphenols from model solutions and crude plant extracts using ion exchange and adsorbent resins

Model systems composed of phenolic compounds, amino acids and mixtures thereof mimicking apple pomace and grape skin extracts were used to examine adsorption and ion exchange behaviour of one adsorbent as well as four anion and four cation exchange resins in a column system at pH 1, 5 and 7. Furthermore, apple pomace and grape skin extracts were loaded onto the resins to evaluate the transferability of the results obtained in the model experiments. In addition, different eluents were applied for the successive recovery of phenolic compounds from the resins. The results provide valuable information on highly complex adsorption and exchange systems. The data indicate both enhanced and decreased polyphenol binding rates as a result of amino acid addition depending on the composition of the solutions applied to the resins. The application of appropriate process parameters during adsorption and desorption was shown to allow selective recovery of compound classes or even individual compounds. As the model experiments did not allow complete prediction of polyphenol binding behaviour, further extract compounds not investigated in the present study presumably also interfere with polyphenol recovery. The results help to systematically optimise industrial processes, thus improving cost‐efficiency and selectivity of polyphenol recovery.     

Ion exchange and adsorbent resins for removal of acids and bitter principles from citrus juices

A further 20 commercially available ion exchange and adsorbent resins were screened for their affinities for titratable acid and citrus bitter principles. Two anion exchange resins offer the prospect of simultaneous acid reduction and debittering; two cation exchange and five adsorbent resins were moderate to powerful adsorbers of the bitter principles. The food regulation status of these resins is discussed.     

纯水生产中离子交换柱混床再生冲洗终点的控制

分析了纯水电导率与离子含量的关系,结合离子交换树脂混床再生冲洗电导率的变化趋势,确定了以电导率为指标的混床再生冲洗终点的控制值,以电导率控制冲洗终点效果良好,比pH值控制更准确、灵敏。同时还分析了终点控制不准确,可能造成氯化钠污染树脂的情况。     

Enrichment and fractionation of major apple flavonoids, phenolic acids and dihydrochalcones using anion exchange resins

In the present study model solutions containing isolated apple polyphenols were employed to systematically study their interaction with two strong anion exchangers differing in the structure of their polymeric matrix. Equimolar concentrations of catechin, caffeic acid, 5-O-caffeoylquinic acid (chlorogenic acid), phloridzin and rutin were used in single compound, binary, ternary, quaternary and pentenary model systems to investigate their ion exchange and adsorption behavior when brought into contact with a polystyrene-divinylbenzene-based and a polyacrylamide-based ion exchanger resin in a column system. To enhance differentiation between adsorption phenomena involving the lipophilic backbone of the exchanger resin and ion exchange processes, experiments were performed at pH 1 and 7. The results of this study allow a deeper insight into the complex processes occurring upon ion exchange. Significant differences were found using the two ion exchangers with the polystyrene resin showing higher recovery rates indicating that the polymeric backbone also markedly contributes to polyphenol binding through hydrophobic interactions. Furthermore, resin selectivity with regard to the binding of phenolic compounds was also shown to be dependent on the structure of the exchanger matrix. These results may further contribute to improve industrial processes for the cost-efficient and selective recovery of secondary plant metabolites, thus allowing to systematically manipulate the biofunctional properties of plant extracts.     

Adsorption isotherm,thermodynamics and kinetics studies of polyphenols separation from kiwifruit juice using adsorbent resin

In this study, the adsorption characteristics of polyphenols in kiwifruit juice were investigated using AB-8 resin, with the aim to separate the polyphenols from kiwifruit juice to prevent astringency and browning during processing and storage. Results showed that the adsorption ability (q_e) of the resin increased with an increase in temperature. The adsorption equilibrium was best described by the Freundlich isotherm (R² > 0.98). Thermodynamic parameters including the changes of enthalpy (ΔH), free energy (ΔG), and entropy (ΔS) were evaluated at 25, 30 and 35 °C. From the enthalpy change (0 < ΔH < 5), the adsorption was endothermic in nature and involved physical adsorption. The result of free energy change (ΔG < 0) demonstrated a spontaneous adsorption process. The pseudo first-order model was found to describe the kinetic data satisfactory. The adsorption mechanism was not limited solely by intra-particle diffusion as shown by the Weber and Morris model.     

澳洲金鲈鱼种肌肉中氨基酸与脂肪酸组成的分析

目的研究澳洲金鲈肌肉中营养成分组成。方法采用色谱法和常规分析化学法检测出澳洲金鲈鱼种肌肉中蛋白质、脂肪、氨基酸和脂肪酸等含量,并对肌肉中氨基酸与脂肪酸组成进行分析和评价。结果澳洲金鲈鱼种肌肉中含有17种氨基酸(未测色氨酸),在必需氨基酸中含量最高的是赖氨酸,含量最低的是蛋氨酸,必需氨基酸占氨基酸总量的39.67%;第一限制性氨基酸是蛋氨酸和胱氨酸;氨基酸比值系数分为78.55%;必需氨基酸指数为89.64%;澳洲金鲈的蛋白质营养符合E/T应为40%左右和E/NT应为60%以上的参考蛋白质模式标准。澳洲金鲈含有22种脂肪酸,含量最高的是油酸,亚油酸次之;不饱和脂肪总量为64.4%。结论澳洲金鲈具有营养价值高、味道鲜美等特点,可以作为我国优良品种引进及产业化开发的淡水鱼。     

Use of weak cation exchange resin Lewatit S 8528 as alternative to strong ion exchange resins for calcium salt removal

Softening of beet sugar juices using the weak cation exchange resin Lewatit® S 8528, both in hydrogen and sodium form has been studied. After analyzing the influence of the main operating parameters on decalcification efficiencies through a Taguchi approach, experimental runs were carried out at 40 BV/h and 80 °C to determine operation time, breakthrough point and resin capacity. The performance of the Lewatit S 8528 resin was compared with that of the industrially used Amberlite SR1L Na, a strong cation exchange resin. The experimental results showed that the use of Lewatit S 8528 in the acidic form is a feasible alternative to the classical strong cation exchange resins, providing calcium removal efficiencies higher than 80%. The mean calcium concentration in the softened thin juice was lower than 18 mg CaO/L. The breakthrough point corresponding to weak resin Lewatit S 8528 in H⁺ form, 700 bed volume, was considerable higher than that obtained for the strong resin Amberlite (300 BV). No considerably increase in the concentration of reducing sugars in the softened juice was observed. The consumption of chemical reagents in the regeneration stage was 3.2 ± 0.5 kg H₂SO₄/m³, considerably lower than the consumption of sodium chloride, 44 ± 1 kg NaCl/m³ when the strong Amberlite resin was used.     

Developmental changes of carbohydrates,organic acids,amino acids,and phenolic compounds in ‘Honeycrisp’ apple flesh

The developmental changes of carbohydrates, organic acids, amino acids and phenolic compounds in ‘Honeycrisp’ apple flesh were investigated using GC–MS and HPLC. A total of 12 carbohydrates, 8 organic acids, 20 amino acids, and 18 phenolic compounds were identified and quantified. Each metabolite showed characteristic changes during fruit development, but in general, concentrations of most sugars and sugar alcohols either increased or remained unchanged whereas concentrations of most organic acids, amino acids and phenolic compounds decreased with fruit development, indicating that most sugars and sugar alcohols are synthesised and/or accumulate at a faster or similar rate relative to fruit growth whereas organic acids, amino acids and phenolics are synthesised and/or accumulate at a slower rate relative to fruit growth. On a whole fruit basis, the content of most metabolites increased with fruit development. In the flesh of mature ‘Honeycrisp’ apple, fructose and sucrose and sorbitol are the major sugars and sugar alcohol; malic acid is the major organic acid; aspartic acid, asparagine, glutamic acid, proline, threonine and γ-aminobutyric acid are the major amino acids; and procyanidin B1, procyanidin B2, chlorogenic acid, catechin and epicatechin are the major phenolic compounds, respectively.     

游离氨基酸检测方法及其应用

游离氨基酸是动植物体中重要的活性成分和风味物质,随着现代科学技术的进步,游离氨基酸的检测方法多样且应用研究进展迅速,汇总整理各类检测方法及其相关应用不可或缺。综述了常用于检测分析游离氨基酸的分光光度法、离子色谱-积分脉冲安培法、氨基酸分析仪法、高效液相色谱法和液相色谱-串联质谱法5种方法,以及2种新技术,分析了各检测方法的原理及优缺点,并对各检测方法列举了相关应用研究。现代新型技术的发展和推广,多元化离子化方式、高分辨质谱、多级串联质谱等技术将会使游离氨基酸分析的灵敏度、准确度、分析速度及自动化程度均提高到一个崭新的水平,选择性好、准确度高、前处理简便的检测手段将是游离氨基酸检测分析技术的未来发展趋势。     

离子交换纤维对蔗汁脱色的研究

研究了离子交换纤维和离子交换树脂对糖厂蔗汁的脱色性能,主要研究离子交换纤维对糖厂清汁脱色的效果,最佳的工艺条件,以及离子交换纤维的再生。结果表明,离子交换纤维对蔗汁脱色有很好的作用,有广泛的应用前景。     

Fungicide effects on ammonium and amino acids of Monastrell grapes

The influence of six fungicides (famoxadone, fenhexamid, fluquinconazole, kresoxim-methyl, quinoxyfen and trifloxystrobin) on the amino acids and ammonium composition of grapes (var. Monastrell) are studied. The treatments were performed under critical agricultural practices (CAP), 6 h before grape collection. The analytical determination of amino acids and ammonium were made using HPLC with a photodiode array detector (DAD), after derivatisation of the sample with diethyl (ethoxymethylene)malonate (DEEMM). The application of fungicides to the vine decreased concentrations of nitrogenous compounds in grapes. Furthermore, the qualitative and quantitative effects on the amino acids in the grapes depended on the type of fungicide used. The fungicides which affected the highest number of amino acids were famoxadone and fenhexamid, while quinoxyfen affected the lowest number of amino acids. Grapes treated with famoxadone contained the lowest concentration of total amino acids.     

HPLC-fluorimetric method for analysis of amino acids in products of the hive (honey and bee-pollen)

An optimization of the OPA method has made feasible separation and quantification of 23 amino acids, which include 5 infrequently searched for. Detection limits ranged from 0.24 to 10.1 pmol in honey and from 29.1 to 0.42 pmol in bee-pollen; reproducibility (C.V.) ranged from 5.3% to 20.4%; recoveries were above 78.8%. Forty monovarietal honey samples from ilex, oak, heather and chestnut-tree were analyzed for their free amino acid profiles. α-Aminoadipic acid and homoserine are reported for the first time in honeys. Thirty-two samples of Spanish bee-pollen, made of a majority of pellets from Cistus Ladanifer (67.1%) and Echium plantagineum (8.9%), were analyzed for their free and total amino acid profiles. Free γ-aminobutyric acid was extensively found with an average of 0.53 mg/g, while Hser and Orn were infrequent. Manually separated monofloral pellets from Cistus ladanifer and Echium plantagineum were analyzed for their free amino acid contents (including proline): 32.46 and 21.87 mg/g for the former and 22.18 and 12.23 mg/g for the latter. In contrast, the total amino acid percentage (on a dry weight basis) was 13.95% for Cistus ladanifer and 32.22% for Echium plantagineum.     

Demineralization of animal blood plasma by ion exchange and ultrafiltration

The blood waste from slaughterhouses is strictly controlled due to its high pollutant load, the treatment for its purification being of great economic interest. The separation of proteins, the most valuable components of blood, in a chromatographic column requires the use of well treated plasma, in particular the removal of inorganic salts. Accordingly, a demineralization process is usually required. In this paper, ion exchange and ultrafiltration demineralization techniques were tested and the results compared. In the ion exchange experiments, the blood plasma was treated with cationic and anionic resins in packed columns, studying the removal of the major cations and anions, protein loss and pH evolution in both the loading and elution steps. In the demineralization process by means of membranes, a 10KDa ultrafiltration membrane was used, the blood plasma being filtered to concentrate all the proteins in the retentate while removing the inorganic ions and other compounds in the permeate. The evolution of the major anions and cations in the plasma and the protein loss were studied at different volumetric concentration factors. The results obtained enable us to draw conclusions as regards the advantages and disadvantages of each technique at a laboratory scale and to offer some considerations regarding the operation at an industrial scale.     

Comparison of free amino acids and volatile components in three fermented milks

Free amino acids (FAAs) and volatile components were analysed in commercial samples of yoghurt and Actimel^® drink as well as laboratory‐made kefir. The lysine and cysteine were the principal amino acids and accounted for about 70% of the total FAAs in all the samples. However, the amino acid profiles in the different fermented milk products differed: on the whole values for most of the amino acids were observed to be significantly higher in the Actimel^® samples. A total of 50 volatile components were identified. The largest number of volatiles were found in the kefir. Ethanol, 2,3‐ butanodione and 3‐hidroxybutan‐2‐one were the most prevalent volatile components, with ethanol significantly higher in the kefir samples.     

高压对从苹果渣中提取酚类物质的影响

考察高压对乙醇溶液提取苹果渣中酚类物质的影响。结果表明：乙醇浓度70％（V：V）比较适宜。随着处理压力的增大，酚类物质的得率逐渐升高（400MPa除外），且在500MPa以前得率提高的幅度较大，压力达到600MPa以上后得率增幅不大。随着提取时间的延长，酚类得率先升后降，提取时间以10min为宜。酚类物质的得率先随温度升高而增大，到50℃达到最高，随后又下降。高压对乙醇溶液提取苹果渣中酚类物质有显著的促进作用。     

Addition of amino acids to grape juice of the Merlot variety: Effect on amino acid uptake and aroma generation during alcoholic fermentation

The effects of adding selected amino acids (phenylalanine, alanine, aspartic acid and threonine) to grape juice on the generation of aroma compounds and on amino acid uptake were studied. The fermentation kinetics varied according to the quantities of amino acids added. The fermentations finished more quickly in supplemented juices and their alcoholic content was significantly higher than in the control (p < 0.05). Amino acids were consumed mainly in the first quarter of fermentation. Higher alcohol formation took place at the same time as ethanol formation: with more amino acids present in the medium, more phenyl ethanol (p = 0.01) and benzyl alcohol were formed while isoamyl alcohol production decreased. The contents of isoamyl and phenylethyl acetates, ethyl hexanoate and ethyl octanoate, as well as most fatty acids increased during the fermentation, reaching a maximum for 10% of ethanol; with higher alcoholic contents, their concentrations decreased.     

Sensory aroma from Maillard reaction of individual and combinations of amino acids with glucose in acidic conditions

The aroma produced in glucose–amino acids (individual and in combination) Maillard reaction, under acidic conditions at 100 °C were determined and compared by trained panellist. Proline produced pleasant, flowery and fragrant aroma. Phenylalanine and tyrosine produced dried roses aroma. Alanine produced fruity and flowery odour, while aspartic acid and serine both produced pleasant, fruity aroma. Arginine, produced a pleasant, fruity and sour aroma at pH 5.2, but not at its natural pH. Glycine, lysine, threonine and valine produced a pleasant caramel-like odour. Isoleucine and leucine gave off a burnt caramel aroma. Methionine developed a fried potato odour. Cysteine and methionine produced savoury, meaty and soy sauce-like flavours. A combination of these amino acids produced different types of aroma, with the stronger note dominating the odour of the mixture. This study will help the prediction of flavour characteristics of hydrolysates from different protein sources.     

Comparison of amino acids,biogenic amines and ammonium ion of wines made of different types of fruits

Amino acids, biogenic amines and ammonium ion are the primary nitrogen sources in fruit wines. Compared to grape wines, our knowledge to their profile in wines made of other fruits is very lack. Fourteen wines made of nine kinds of fruits together with seven grape wines were selected to compare their nitrogen component profile. White grape wines possessed the highest level of total amino acids, followed by red grape wines and then the wines made of the other fruits. Red grape wines contained the highest level of biogenic amines, followed by white grape wines and the wines made of the other fruits. Ammonium ion was also found to be higher in the wines made of grapes. Principal component analysis revealed that the obvious separations existed among the wines made from different types of fruits, indicating that these nitrogen compounds could be served as the indicators to differentiate different types of fruit wines.     

Impact of sources and doses of potassium on biochemical and greenleaf parameters of tea

Effect of different sources and doses of K on certain biochemical parameters, such as carotenoids, chlorophyll, polyphenols, catechins, amino acids and nutrient contents, such as phosphorus, magnesium, zinc, potassium and nitrogen, in tea flush shoots comprising three leaves with a bud were studied. The relationship existing for polyphenols and carotenoids with amino acids was inversely proportional, while leaf nitrogen had a positive and significant correlation coefficient with amino acids. Even though a linear increase in the biochemical parameters was noticed against rate of potassium application, a comparatively small quantity was sufficient to improve the same parameter in the case of sulphate of potash (SOP). Neither of the two sources influenced the chlorophyll content of tea shoots, irrespective of their doses over control. The ideal N:K ratios for maximum productivity and biochemical parameters would be 1:0.83 or 1:0.62 if the source of K is muriate of potash (MOP), while it is 1:0.21 or 1:0.42 for SOP.