Characterisation of anthocyanin–betalain mixtures for food colouring by chromatic and HPLC-DAD-MS analyses

Anthocyanins and betalains that are mutually exclusive in nature were mixed to investigate their potential synergism for food colouring purposes. The blends obtained from four commercial anthocyanic (black carrot, elderberry, sour cherry and strawberry) and one betalainic extract (red beet) were studied with respect to colour evolution over three weeks. While new colour shades were produced by blending anthocyanins with betalains, chroma and hue angle of the mixtures changed over time. The greatest number of new colour shades with acceptable chroma was obtained at pH 4.5 and 5, the stability maxima of red beet, succeeded by pH 3.0. Interestingly, at pH 3.5 only one combination yielded an acceptable chroma, whereas at pH 7 no mixture was stable. To determine individual anthocyanins and betalains in mixtures in a single run, a HPLC method was developed and combined with a mass spectrometer for the identification of specific pseudomolecular and daughter ions.     

A review of botanical characteristics, phytochemistry, clinical relevance in efficacy and safety of Lycium barbarum fruit (Goji)

Lycium barbarum has been used as a traditional Chinese medicine (TCM) to nourish liver and kidney, and brighten the eye. The fruits are dried or freshly squeezed for their juice and concentrated for beverages. Among various constituents, a group of polysaccharides (LBP) with a Glycan-O-Ser glycopeptide structure has been most researched and considered to be important for the efficacy of L. barbarum. Studies indicate effects of L. barbarum on aging, neuroprotection, general well-being, fatigue/endurance, metabolism/energy expenditure, glucose control in diabetics, glaucoma, anti-oxidant properties, immunomodulation, anti-tumor activity and cytoprotection. In addition to TCM, L. barbarum can be sold as a dietary supplement or classified as a food based upon the long and safe traditional usage. This review is to provide background and updated information of chemical constituents and efficacies with safety including a new direction for research and current regulatory situation of L. barbarum.     

Phenolic compound profiles in selected Queensland red wines at all stages of the wine-making process

The phenolic profiles of Queensland red wines (two Cabernet Sauvignons and one Shiraz) from different stages of wine-making were studied. Samples were taken at crush, after the primary and malolactic fermentations, post-oaking, and post-bottling, and then extracted and separated into aqueous and organic fractions using liquid–liquid extraction and solid-phase extraction, and analysed by HPLC-DAD-MS. About 75% of the phenolic compounds were extracted into the aqueous fraction, with malvidin-3-glucoside and derivatives as the main components. The major non-anthocyanin phenolic compounds (∼25%) included gallic acid, syringic acid, ethyl gallate, caftaric acid, coutaric acid, caffeic acid, coumaric acid, catechin, and quercetin. The polymerisation of anthocyanins was shown to occur progressively throughout the wine-making process. Most of the 25 identified phenolic compounds had highest concentrations during the fermentation stage, and stabilised or slowly decreased thereafter. There were weak and insignificant correlations (P > 0.05) between individual phenolic compounds and the total antioxidant activities (ORAC). Four groups of phenolic compounds (anthocyanins, hydroxybenzoic acids, flavanols and hydroxycinnamic acids) each showed some correlation with the total antioxidant activity, as did the total polyphenol content, suggesting that the antioxidant properties of red wine are due to a complex mixture of phenolic compounds that vary in composition throughout the wine-making process.     

Pattern recognition of three Vitis vinifera L. red grapes varieties based on anthocyanin and flavonol profiles,with correlations between their biosynthesis pathways

The presence of anthocyanins and flavonols in three selected red grape varieties was investigated, in order to use their polyphenolic characterisation as a fingerprint. Berry skins of Gran Negro grapes were characterised by the presence of high content of malvidin- and peonidin-3-O-glucoside; Mouratón grapes, by the presence of high content of petunidin- and delphinidin-3-O-glucoside; and Brancellao grapes, by the presence of high content of cyanidin-3-O-glucoside. The main flavonols found included the 3-O-glucosides of quercetin, myricetin, kaempferol, laricitrin, isorhamnetin and syringetin. Using cluster analysis and principal components analysis, Gran Negro could be characterised by their content of isorhamnetin-3-O-glucoside and syringetin-3-O-glucoside and, along with Mouratón, by their myricetin conjugates. Flavonol profile could not provide a fingerprint of Brancellao variety. Stepwise discriminant analysis was performed in order to find the polyphenolic compounds, which characterised the selected grape varieties. Finally, anthocyanin and flavonol profiles in red grapes were compared and results confirmed that biosynthesis of flavonols is closely related to that of anthocyanins.     

Quercus ilex L.: A rich source of polyacylated flavonoid glucosides

From the methanolic extract of Quercus ilex leaves a series of acylated flavonol glucosides were identified, among them five new naturally occurring compounds. The constituents, which were all p-coumaroyl glucosides of kaempferol, were characterised either as pure compounds or as inseparable, complicated mixtures of cis and trans isomers. Their complete structure elucidation was done by 2D NMR (COSY, HSQC, HMBC, ROESY) and HPLC-DAD-MS analyses. 2D NMR spectral data allowed the discrimination between different isomers. Quantitative analysis of the methanolic extract of the plant revealed that it is a rich source of acylated flavonoid glucosides (1.22%). Under the experimental conditions chosen HPLC-DAD-MS analyses showed that cis isomers are less polar than trans isomers and their detailed identification, the first in the literature so far, could serve as a tool for the detailed characterisation of analogous isomers by HPLC-DAD-MS in other complicated plant extracts.     

榆树叶中类胡萝卜素的组成和含量

目的：分析榆树叶中类胡萝卜素主要组分的结构和含量。方法：丙酮提取榆树叶类胡萝卜素,采用高效液相色谱与二极管阵列检测器和质谱联用技术分析类胡萝卜素组分,依据其光谱和质谱信息并与标准品和文献相比较,确定主要类胡萝卜素的结构;采用高效液相色谱法测定不同采集时间的榆树叶中主要类胡萝卜素的含量。结果：叶黄素和β-胡萝卜素为榆树叶中主要的类胡萝卜素组分,其含量因采集时间不同而异：叶黄素含量范围为880.2～1 385.4 μg/g干样,平均含量为1 098.3 μg/g干样;β-胡萝卜素含量范围为142.8～364.2 μg/g干样,平均含量为297.7 μg/g干样。结论：榆树叶有望成为叶黄素开发的食品新资源。     

进口西拉葡萄酒的HPLC-DAD-MS特征指纹图谱

建立进口西拉葡萄酒的高效液相色谱-二极管-离子阱质谱指纹图谱分析方法。样品采用乙酸乙酯萃取,旋转蒸发仪浓缩,甲醇溶解,高效液相色谱-离子阱质谱分析测定。色谱柱采用MG Ⅱ C18柱（150 mm×2.0 mm,5 μm）,以pH 3.0水-乙腈为流动相,梯度洗脱,流速0.25 mL/min,多波长检测,离子阱质谱采用负离子模式,扫描范围m/z 50～1 200,可对没食子酸等11 个组分进行定性和定量。维拉西拉葡萄酒的15 个共有峰在60 min内得到良好分离,通过与标准品比较,对其中6 个峰进行了确证,10 批次维拉西拉葡萄酒的相似度均大于0.9。方法简便、灵敏、稳定、精确,生成的葡萄酒指纹图谱能够用于进口西拉葡萄酒的质量评价。