Characterisation of anthocyanins in the black soybean (Glycine max L.) by HPLC-DAD-ESI/MS analysis

The aim of this study was to isolate and identify the anthocyanins in the black seed coated soybean (cv. Cheongja 3, Glycine max (L.) Merr.) using reverse phase C-18 open column chromatography and high-performance liquid chromatography (HPLC) with diode array detection and electro spray ionization/mass spectrometry (DAD-ESI/MS) analysis, respectively. Anthocyanins were extracted from the coat of black soybeans with 1% TFA in methanol, isolated by RP-C-18 column chromatography, and their structures elucidated by 1D and 2D NMR spectroscopy. The isolated anthocyanins were characterised as delphinidin-3-O-glucoside (3), cyanidin-3-O-glucoside (5), petunidin-3-O-glucoside (6), pelargonidin-3-O-glucoside (7) and cyanidin (9). Furthermore, four minor anthocyanins were detected and identified as catechin-cyanidin-3-O-glucoside (1), delphinidin-3-O-galactoside (2), cyanidin-3-O-galactoside (4), and peonidin-3-O-glucoside (8) based on the fragmentation patterns of HPLC-DAD-ESI/MS analysis.     

Volatile components of cooked tubers of the water yam (Dioscorea alata)

Volatile constituents were isolated from yams, during cooking, by concurrent steam distillation-solvent extraction. The essence which resulted was analysed by linked gasliquid chromatography-mass spectrometry (g.l.c.-m.s.) employing capillary columns and by gas-liquid chromatography coupled with sensory evaluation of the column effluent (nasal appraisal). In addition to hydrogen sulphide and a number of high-boiling fatty acids, 29 compounds, comprising seven hydrocarbons, eight alcohols, eight aldehydes, four ketones, a furan and a disulphide, were identified for the first time in yam. A further five components were tentatively identified by g.l.c.-m.s. and by thinlayer chromatography of derivatives. 4-Phenylbutan-2-one was the major constituent of the acid-free essence.     

Anti-inflammatory activity of American yam Dioscorea trifida L.f. in food allergy induced by ovalbumin in mice

Tropical ecosystems are particularly rich in edible plant species with different bioactive substances. Among the plants with promising benefits for health are species from the genus Dioscorea (Dioscoreaceae), especially those named yam. Recent studies have shown the beneficial effects of different species of Dioscorea, and its main constituent, diosgenine, in the treatment of food allergy. In this study we evaluated the potential of D. trifida, the only yam native from South America, in the treatment of ovalbumin (OVA) induced food allergy in Balb/c mice. HPLC/DAD analysis showed the presence of three very distinctive groups of natural products in extracts and fractions: (I) very polar substances, including allantoin, (II) phenolic substances as flavonoids and phenolic acids and (III) diosgenin and derivatives. Sensitive mice received casein feed with supplementation of crude extract (CE) and fractions. The supplementation with all products from D. trifida reduced IGE, intestinal oedema and mucus production, parameters observed in OVA allergic mice. The results showed the potential of this food to prevent or treat this disease and the necessity to be better explored.     

Hard-to-cook defect in trifoliate yam Dioscorea dumetorum tubers after harvest

In an attempt to study the hard-to-cook defect in Dioscorea dumetorum tubers after harvest, yellow cultivars of trifoliate yam tubers were stored under range of temperatures (15, 30, 45 °C ) and relative humidity (59%, 75%, 86% RH), and then soaked and cooked in distilled water or 5% (w/v) aqueous solution of Na₂ EDTA. The hard-to-cook defect was separated into reversible and irreversible components. Results of phytate and lignin analysis led to the conclusion that these components reflect the pectin-phytate mechanism or reversible hardening and the lignification mechanism or irreversible hardening. Modeling of the hardening process indicated that the rate of reversible and irreversible reaction was dependent on storage conditions, however, irreversible hardening rate was generally faster than reversible hardening and then represented the major component of D. dumetorum tubers hardening.     

Some biochemical changes associated with post-harvest storage of white yam (Dioscorea rotundata) tubers

Healthy Dioscorea rotundata tubers were kept for 8 months under local storage conditions and periodically analysed for the activity of some enzymes of carbohydrate metabolism as well as for the concentrations of key tuber metabolites. Except for polyphenol oxidase, all the other enzymes monitored showed low and maximum activities before and at onset of sprouting, respectively. The activities of these enzymes after sprouting remained higher than those in the pre-sprouting period. Hexokinase, alcohol dehydrogenase and phosphorylase showed an approximately 2-fold increase in activity at sprouting while glucose-6-phosphate dehydrogenase showed a more than 3-fold increase in activity. Polyphenol oxidase (PPO) activity and starch content decreased steadily with storage with PPO activity decreasing to one-half by the end of storage. L-ascorbate, total polyphenols, carotenoids and lipids increased with storage and peaked at sprouting.     

Isolation and identification of two major acylated anthocyanins from purple sweet potato (Ipomoea batatas L. cultivar Eshu No. 8) by UPLC‐QTOF‐MS/MS and NMR

In recent years, researches on the isolation and preparation of monomeric anthocyanins have intensified because of the requirements of quantitative and structure–bioactivity relationship analyses. However, simple and effective methods about the scale of monomeric anthocyanins from the natural purple sweet potato powder are rarely reported. In this study, high molecular weight acylated monomeric anthocyanins were isolated from purple sweet potato (Ipomoea batatas L. cultivar Eshu No. 8) via the combination of column chromatography and semi‐preparative HPLC technology and identified mainly by ultra‐high‐performance liquid chromatography quadrupole time‐of‐flight tandem mass spectrometry/mass spectrometry (UPLC‐QTOF‐MS/MS) and ¹H and ¹³C nuclear magnetic resonance (NMR). Two major acylated anthocyanins were unambiguously determined as peonidin 3‐O‐(6‐O‐(E)‐caffeoyl‐(2‐O‐(6‐O‐p‐hydroxybenzoyl)‐β‐D‐glucopyranosyl)‐β‐D‐glucopyranoside)‐5‐O‐(β‐D‐glucopyranoside) and peonidin 3‐O‐(6‐O‐(E)‐caffeoyl‐(2‐O‐(6‐O‐(E)‐feruloyl)‐β‐D‐ glucopyranosyl)‐β‐D‐glucopyranoside)‐5‐O‐(β‐D‐glucopyranoside). The results of this study may help promote the purification of high molecular weight acylated anthocyanins from purple sweet potato as well as from other plant materials in nature.     

Acid phosphatase in the tubers of Dioscorea species and its purification from the white yam (D. rotundata poir)

Acid phosphatase activity was determined in 15 cultivars from four species of yam. A 12-fold purification of the enzyme from Dioscorea rotundata (cv. chikakwondo) gave a homogeneous preparation as demonstrated by polyacrylamide gel electrophoresis. This enzyme preparation has an apparent molecular weight of 115 000 ±2000 and an optimum activity at a pH of 5·20 and a temperature of 50°C. The K_m of the enzyme is 3·81 mM with disodium p-nitrophenylphosphate (p-NNP) as a substrate. The energy of activation, heat of activation, energy of inactivation and heat of inactivation are 7·0, 6·4, 4·41 and 4·34 kcal M^?1, respectively. Although it has very little activity with most organic phosphoric acid esters, it is significantly inhibited by Ca²⁺, Hg²⁺ and EDTA and activated by Mg²⁺. The enzyme has a half-life of 50,17 or 13 days, respectively, when stored at 6-8°C, 0°C or room temperature (29±2°C).     

Study of the hard-to-cook property of stored yam tubers (Dioscorea dumetorum) and some determining biochemical factors

In an attempt to investigate the hard-to-cook phenomenon in Dioscorea dumetorum tubers during storage, selected physical and chemical characteristics were monitored. A 3 × 5 factorial experiment with storage conditions (15 °C, 59% RH; 30 °C, 75% RH; 45 °C, 86% RH) and storage period (0, 2, 4, 7 and 14 days) as variables was carried out. Changes in cooked hardness, water absorption, water-holding capacity and solid loss of steeped tubers as well as phytate, total phenols and lignin contents were monitored. Water uptake and solid loss of steeped tubers decreased significantly (P ⩽ 0.05) with storage period, suggesting that storage affects cell wall membrane permeability of the tubers. Cooked hardness analyses indicated significant difference (P ⩽ 0.05) between fresh and stored tubers and its rate varied with storage time and storage conditions. Cooked hardness values correlated negatively (r = −0.922–0.857, P ⩽ 0.05, d.f. = 146) with phytate and total phenols. A multiple mechanism for D. dumetorum tubers hardening is presented which includes phytate loss as a minimal contributor to cooked hardness during the first days of storage and total phenol loss via a lignification-like mechanism as a major contributor.     

LC-MS/MS分析测定紫薯花色苷方法研究

目的:通过对紫薯花色苷(anthocyanins from purplesweet potato,APSP)组分的分离、鉴定和相对含量的分析,为紫薯花色苷在食品工业中的应用提供方法借鉴和理论依据。方法:取实验室自制的APSP粉末25mg,置于5m L容量瓶中,用甲醇水混合液(甲醇∶水=2∶1)定容,所得溶液过0.45μm滤膜,利用LC-MS/MS对滤液中的成分进行分离、鉴定,并进行相对含量的计算。结果:根据LC-MS/MS结果可知,分离得到8种组分,并依据相关文献的报道,鉴定其中6种分别为矢车菊素3-咖啡酰槐糖苷-5-葡糖苷(Cyanidin 3-caffeoylsophoroside-5-glucoside)、芍药素3-咖啡酰槐糖苷-5-葡糖苷(Peonidin3-caffeoylsophoroside-5-glucoside)、矢车菊素3-(6"-咖啡酰-6"’-阿魏酰槐糖苷)-5-葡糖苷(Cyanidin3-(6"-caffeoyl-6"’-feruloylsophoroside-5-glucoside))、芍药素-双咖啡酰槐糖苷-5-葡糖苷(Peonidindicaffeoylsophoroside-5-glucoside)、芍药素3-咖啡酰-对-羟基苯甲酰槐糖苷-5-葡糖苷(Peonidin 3-caffeoylp-hydroxybenzoyl-sophoroside-5-glucoside)、芍药素3-咖啡酰-阿魏酰槐糖苷-5-葡糖苷(Peonidin-caffeoylferuloylsophoroside-5-glucoside),另外2种组分未知,同时对各组分的相对含量进行了比较。结论:利用所建立的LC-MS/MS方法可对APSP进行分离、鉴定和相对含量的分析。     

紫皮豇豆(Vigna unguiculata L.)花色苷的研究

首次应用高效液相色谱-二极管阵列检测器-质谱联用技术(HPLC-DAD-MS)鉴定出紫皮豇豆主要含有三种花色苷,分别为飞燕草色素、矢车菊色素、天竺葵色素的葡萄糖苷,其中矢车菊葡萄糖苷相对百分含量达到93.4%;应用pH示差法测定出其单体花色苷的含量为57.15mg/100g鲜重;应用DPPH法测定结果显示,花色苷粗提液有较强的抗氧化能力。     

Effect of short-term storage on phenolic content,o-diphenolase and peroxidase activities of cut yam tubers (Dioscorea sp)

The effect of short-term storage on the protein, phosphorus and phenolic content as well as peroxidase and o-diphenolase activities of cut, harvested Jamaican yam (Dioscorea sp) tubers (D rotundata. D alata and D cayenensis) was studied. There was an initial increase in the total phenolic content up to the third week of storage followed by a gradual decrease to the sixth week. Phenolic content was found to be highest in D cayenensis followed by D rotundata and D alata. The activities of peroxidase (EC 1. 11. 1. 7) and o-diphenolase (EC 1. 10.3.1) increased steadily up to the third week of storage and thereafter decreased to the fifth week. The intensity and rapidity of browning in tubers when cut, correlated very closely with the tuber o-diphenolase and phenolic content levels while the onset of rotting correlated with the peroxidase activity levels in the species studied.     

Anti-Fenton reaction activity of three taxa of water yam (Dioscorea alata L.)

In the present study, we compared the anti‐Fenton reaction activity of three taxa of water yam (Dioscorea alata L.): DS2, TN2 and PSY [D. alata L. var. purpurea (Roxb.) M. Pouch]. Anti‐Fenton reaction activity was evaluated by measuring the damage inflicted on calf thymus DNA by copper ions combined with hydrogen peroxide with the use of an ethidium bromide binding assay and agarose gel electrophoresis. We found that extracts of tuber pulp from all three taxa of yam had significant anti‐Fenton reaction activity. The protection pattern of the three tuber pulp extracts was similar to that of EDTA, a typical divalent metal ion chelator, which displayed a significant protection lag‐phase. With the use of thin‐layer chromatography, we found that a common, major ansialdehyde‐sulphuric acid stained spot (possibly a polysaccharide mucilage) with an R_f of 0.09 may be the most likely contributor to the anti‐Fenton reaction activities of the yam tuber extracts investigated. The present study identifies the mechanism of the health benefit of the Dioscorea family. The copper‐chelating and absorbing capability of yam tuber pulp extracts may be useful in functional screening.     

Antinutritional factors changes occurring in trifoliate yam (Dioscorea dumetorum) tubers after harvest

Studies were conducted on the changes in antinutritional factors occurring during the storage of Dioscorea dumetorum (cv. Yellow) yam tubers. The tubers were harvested and stored under prevailing tropical ambient conditions (19–28 °C, 60–85% RH) for 0, 2, 5, 7, 14, 21, 28, 42 and 56 days. The samples were evaluated for total phenols, tannins, phytic acid, α-amylase inhibitors, trypsin inhibitors and oxalates. Results showed that, during storage, total phenols and tannin contents decreased by approximately 22–28% after 56 days of harvest, due to the hardening phenomenon and sprouting. Phytate and α-amylase inhibitor levels declined, respectively, from 690–416 mg/100 g and 1013–659 AIU/g, while oxalates and trypsin inhibitor contents increased during the first week of storage (days 0–7) and, after this period, they started to decrease progressively. Since sprouting of most tubers was observed after 28 days of storage, the results suggest that post-harvest hardening and sprouting influence antinutritional composition of D. dumetorum tubers.     

Extraction and identification of anthocyanins from Smilax aspera L. berries

Anthocyanins, present in the berries of Smilax aspera L., a creeping shrub typical of the Mediterranean region, were extracted and identified for the first time. The pigments were extracted from the skin of the berries with of 0.1% HCl in methanol solution, purified on a C-18 solid-phase cartridge and characterized by means of HPLC-DAD-MS analysis. From spectral analysis before and after acid and alkaline hydrolysis, it was noted that pelargonidin 3-O-rutinoside represented about 83% of the total anthocyanin content in the skin of Smilax aspera berries. A low quantity of cyanidin 3-O-rutinoside (13%) was also found. The attractive colour and the great abundance of the plant in the south of Italy make Smilax aspera berries a new and very good source of natural pigments.     

Chemical compositions and enzyme activity changes occurring in yam (Dioscorea alata L.) tubers during growth

The purpose of this study was to establish the chemical compositions, enzyme activity and nutritional values of four cultivars of yam tubers at different stages of their maturation, and compare such levels during yam growth. The results have indicated that yam tubers featured a reasonably substantial content of protein when compared with other root and tuber crops, the protein content being of the order of 10.4-13.0 g/100 g (dry basis (db)) at time of harvest (day 260 post-emergence). Starch content of the four yam tubers increased as growth progressed and remained in the range of 70.5-85.3 g/100 g (db) during their growth period. The activity of yam-contained polyphenol oxidase (PPO) decreased remarkably over the early period of harvest (day 155-225 post-emergence), and subsequently decreased only slightly as growth progressed to harvest for all tested species of yam with the exception of CH yam tubers. Contrasting this, however, the activity of α-amylase increased significantly over the growth period for all cultivars, and dioscorin content of yam tuber also increased as growth progressed for all cultivars. All yam cultivars contained remarkably substantial amounts of essential amino acids, all of which were superior to the FAO reference pattern for such amino acids except for sulfur-containing amino acids and lysine contents.     

山药淀粉的特性及应用研究

详细介绍了山药淀粉的制备与组成,并对其物理化学特性和加工特性,包括淀粉的颗粒形态、溶解度和膨胀度、凝胶特性等进行了较全面的综述.     

Effects of different storage conditions on steroidal saponinsin yam (Dioscorea pseudojaponica Yamamoto) tubers

Effect of storage on steroidal saponins, furostanol and spirostanol glycosides, in yam (D. pseudojaponica Yamamoto) tubers was determined. Unpeeled and vacuum-sealed peeled tubers were stored at −18, 4, 17 and 25 °C from 5 to 80 days separately. Furostanol glycosides in unpeeled tubers could be converted by furostanol glycoside 26-O-β-glucosidase (F26G) to spirostanol glycosides after 4 °C storage for 35 days (chilling injury could be found), or 17 and 25 °C storage for 50 days. The conversion increased with storage times. Peeled tubers stored at 17 and 25 °C for 5 days could experience organoleptic injury, which would enlarge with increasing storage period. After 35 days of storage, large part of vacuum-sealed tubers transformed to juice with stench. In the early 20 days storage, saponins in these tubers were lost rapidly. F26G activity in decreasing order was 25 °C > 17 °C > 4 °C and could be inhibited under vacuum.     

Pectin lyase and polygalacturonase of Aspergillus niger pathogenic for yam tubers (Diascorea rotundata)

Polygalacturonase and pectin lyase of Aspergillus niger partially purified by ethanol, ammonium sulphate precipitation, DEAE-cellulose and Sephadex G-150 column chromatography were characterized. Polygalacturonase gave optimum activity at pH 4–5, and at 35°C. It was stable at pH 3–7 and at 20–50°C. The molecular weight was 38020. For pectin lyase optimum activity occurred at pH 5 and 45°C. The enzyme was stable at pH 3–4 and at 40–50°C. The molecular weight was 30 900. Yam tissue was optimally macerated at pH 4–5 by the enzymes. At pH 4.5, potassium sorbate (0.6 mg/ml), benzoic acid (0.8 mg/ml) and sodium benzoate (1.0 mg/ml) caused complete inhibition of polygalacturonase activity. With pectin lyase, this effect was achieved with potassium sorbate and benzoic acid each at 0.9 mg/ml, but not with sodium benzoate.     

Influence of fermentation on some quality characteristics of trifoliate yam (Dioscorea dumetorum) hardened tubers

Processing of Dioscorea dumetorum tubers into flour could be a means of adding a longer-term value to this tropical plant with a high nutritional potential but which possesses a post-harvest hardening problem, characterised by a hard-to-cook defect. In an attempt to investigate the changes leading to fermentation of hardened tubers, CIE L^∗a^∗b^∗ parameters and some physicochemical properties of the yams were monitored. Four fermentation periods (0, 2, 4, 7 and 14 days) under ambient temperature (23 ± 5 °C) in the presence and absence of oxygen were studied. The results showed that fermentation significantly (p ? 0.05) increased a^∗ and b^∗ parameters, and decreased L^∗ parameter. However, browning affected more tubers fermented in the presence of oxygen. All the anti-nutrients evaluated (total phenols, phytic acid, oxalates, trypsin inhibitors and α-amylase inhibitors) decreased by significant levels (p ? 0.05) within 14 days of fermentation. However, the rates of anti-nutrient losses varied for each constituent and followed first-order reaction kinetics.     

Effect of Dioscorea opposita Thunb. (yam) supplementation on physicochemical and sensory characteristics of yogurt

A study was conducted to examine the physicochemical, microbial, and sensory properties of yogurt made by supplementing powdered yam Dioscorea opposita Thunb. (YPT) at different concentrations (0.2, 0.4, 0.6, and 0.8%, wt/vol) into milk, which was pasteurized and then fermented at 43°C for 6 h and stored for 16 d. The pH values of all samples decreased, whereas viscosity values and mean microbial counts increased during storage. The L* and a* color values (indicators of lightness and redness, respectively) of yogurt samples were not remarkably influenced by adding YPT, whereas the b* values (indicating yellowness) significantly increased with the addition of YPT at all concentrations at 0 d of storage, probably due to the original yellow color of yam powder. In functional component analyses, when the concentration of YPT increased, the amount of allantoin and diosgenin proportionally increased. The content of allantoin was 3.22 and diosgenin 4.69 μg/mL when 0.2% (wt/vol) YPT was supplemented and did not change quantitatively during the storage period (16 d). The sensory test revealed that the overall acceptability scores of YPT-supplemented yogurt samples (0.2 to 0.6%, wt/vol) were quite similar to those of the control throughout the storage period of 16 d. Based on the data obtained from the present study, it was concluded that the concentrations (0.2 to 0.6%, wt/vol) of YPT could be used to produce YPT-supplemented yogurt without significant adverse effects on physicochemical, microbial, and sensory properties, and enhance functional components from the supplementation.