Comparative analyses of copigmentation of cyanidin 3-glucoside and cyanidin 3-sophoroside from red raspberry fruits

Cyanidin 3-glucoside (Cy 3-glu) and cyanidin 3-sophoroside (Cy 3-soph) from red raspberry extracts were selected as pigments, and five phenolic acids as copigments. The influences of pH, temperature, structure of anthocyanins and copigments, and molar ratio of anthocyanins to copigments on the copigmentation effect were analyzed with a UV–Visible spectrophotometer. The reaction was thermodynamically defined in terms of ΔH⁰, ΔG⁰ and ΔS⁰ values.     

Effects of electrode materials on the degradation,spectral characteristics,visual colour,and antioxidant capacity of cyanidin-3-glucoside and cyanidin-3-sophoroside during pulsed electric field (PEF) treatment

The effects of three electrode materials – stainless steel (SS), pure titanium (PT), and titanium-based alloy (TA) – on the PEF-induced degradation, spectral characteristics, visual colour, and antioxidant capacity of cyanidin-3-glucoside (Cy-3-glc) and cyanidin-3-sophoroside (Cy-3-soph) were studied. Cy-3-glc and Cy-3-soph were degraded by PEF; SS retained Cy-3-glc and Cy-3-soph the most, while PT and TA led to greater degradation. Cy-3-glc was more susceptible to PEF than Cy-3-soph. The intensity of UV–Vis spectra absorbance at 520 nm decreased, but it increased at 280 and 325 nm after PEF when using the three electrodes. Their lightness (L^∗) exhibited no changes with SS, but showed a significant reduction with PA and TA. Redness (a^∗) significantly decreased with all three electrodes; the yellowness (b^∗) of Cy-3-glc with PA and TA, and of Cy-3-soph with SS, were also significantly reduced. The antioxidant capacity of Cy-3-glc and Cy-3-soph with SS, in contrast to PT and TA, was enhanced after PEF.     

Kinetic analysis of the degradation and its color change of cyanidin-3-glucoside exposed to pulsed electric field

The degradation and its corresponding color change of cyaniding-3-glucoside (Cy-3-glu) exposed to pulsed electric field (PEF) was investigated in the study. In an aqueous-methanol solution of H₂O (0.5% TFA) and methanol (MeOH) (7:3, v/v), the degradation of Cy-3-glu, which was exposed to PEF at 1.2, 2.2 and 3.3 kV/cm, was increased as the electric field intensity and the treatment time increased (p<0.05), the degradation kinetics was well fitted to a first order reaction. The degradation kinetic constant k _A increased while the half-lives (t _1/2) and decimal reduction time (D values) decreased with an increment of the electric field intensity. PEF had a greater effect on the visual color, lightness L ^* value and redness a ^* value had a slight increase (changing towards the positive direction) while yellowness b ^* value and hue angle H value presented a significant decrease (changing towards the negative direction) (p<0.05), the total color difference (ΔE) showed an increase with an increase of the treatment time and the electric field intensity, the change in b ^* value and H was well fitted to the first-order reaction. Furthermore, a good positive linear correlation between b ^* value and Cy-3-glu content, their regression coefficients were 0.994, 0.999, and 0.997 at 1.2, 2.2, and 3.0 kV/cm, respectively.     

Stability and colour characteristics of PEF-treated cyanidin-3-glucoside during storage

The stability and colour characteristics of PEF (pulsed electric field)-treated cyanidin-3-glucoside (Cy-3-glu) was investigated during storage at 4, 24 and 37 °C. The degradation of Cy-3-glu was analyzed using a first reaction kinetics while its colour characteristics was evaluated using colour indices such as colour density (CD) and CIE L^∗a^∗b^∗ parameters. PEF had no post-effect on the stability and colour characteristics of Cy-3-glu during storage while the storage temperature had a significant effect (p < 0.05). The degradation of PEF-treated Cy-3-glu during storage conformed to the first-order reaction kinetics with regression coefficients R² greater than 0.9300. Corresponding to 4, 24 and 37 °C, the degradation rate constant k in Cy-3-glu significantly increased in the exponential order level of 10⁻⁴, 10⁻³ and 10⁻², while the t_1/2 (the time that 50% Cy-3-glu degradation would take) and D-value (the time that 90% Cy-3-glu degradation would take) of Cy-3-glu during storage decreased in the exponential order level of 10³, 10² and 10. The reduction of CD was closely related to the Cy-3-glu content in this study, the Cy-3-glu content was perfectly predicted using CD with a higher coefficient R² > 0.9999. A significant decrease in b^∗ and H⁰ value was obtained at all storage temperature (p < 0.05). A positive correlation was found between the Cy-3-glu content and b^∗ value or H⁰ value with a coefficients R² > 0.8400 during storage. ΔE increased significantly, ΔE was less than 2 at 4 °C while it was greater than 2 at 24 and 37 °C.     

Anti-oxidative analysis,and identification and quantification of anthocyanin pigments in different coloured rice

Anthocyanin pigments in coloured rice cultivars were isolated and identified using high-performance liquid chromatography techniques. Two black rice cultivars (Asamurasaki, Okunomurasaki) contained three major anthocyanins: cyanidin-3-glucoside, peonidin-3-glucoside and malvidin. Chinakuromai (black) rice additionally contained a fourth anthocyanin, petunidin-3-glucoside. Four red rice cultivars contained only malvidin. The total anthocyanin content varied greatly among black rice cultivars (79.5–473.7 mg/100 g), but was lower in red rice (7.9–34.4 mg/100 g). Total phenolic content was similar between red (460.32–725.69 mg/100 g) and black (417.11–687.24 mg/100 g) rice. The oxygen radical absorbing capacity was ranked as follows: red (69.91–130.32 μmol Trolox/g) > black (55.49–64.85 μmol Trolox/g) > green (35.32 μmol Trolox/g) > white (21.81 μmol Trolox/g) rice. The antioxidant capacity resulted mainly from the seed capsule, not the endosperm. The anthocyanin pigments contributed little to the total antioxidant capacity of red (0.03–0.1%) and black (0.5–2.5%) rice cultivars. Hence, the antioxidant capacity is derived mainly from other phenolic compounds.     

Effects of pectolytic enzyme treatments on anthocyanins in raspberry juice

Raspberry juices treated with two commercial pectinase preparations lost almost 20% of their total anthocyanin pigments; losses were related to both concentration of enzyme and time of treatment. Analysis of individual anthocyanins showed differences between the enzymes. Ultrazyme reduced all components in similar proportions, whereas Pectinex apparently also converted cyanidin-3-sophoroside and cyanidin-3-glucosylrutinoside into cyanidin-3-glucoside and cyanidin-3-rutinoside respectively, presumably by hydrolysis of β1–2 glucosidic bonds by glucosidase present in the Pectinex.     

Thermal characterization of the anthocyanins from black soybean (Glycine max L.) exposed to thermogravimetry

One anthocyanin compound, cyanin-3-glucoside, was isolated and identified by high performance liquid chromatography tandem mass spectrometry (HPLC_MS/MS) from seed coat of black soybean variety, Heizi to assess its thermal characterization in vitro. The thermal characterization of anthocyanin was studied by thermogravimetry (TG) analysis. The results from the TG curves showed the decomposition of anthocyanin occurred in three stages. Glucose cleaved from the cyanin-3-glucoside occurred in the first stage. Degradation of cyanin and small amounts of cyanin-3-glucoside appeared mainly in the second stage. The sugar in the anthocyanin was decomposed in the third stage. Thermodynamic analysis was applied by free dynamic model. TG-isothermal experiments for the anthocyanins from black soybean seed coats confirmed the correct of the thermodynamic analysis.     

Copigmentation between malvidin-3-glucoside and some wine constituents and its importance to colour expression in red wine

Thermodynamic parameters for intermolecular copigmentation interactions involving malvidin-3-glucoside were determined by UV/visible spectroscopy at wine pH (pH 3.6). These included association constants, enthalpy and entropy changes, which were measured for chlorogenic acid, caffeic acid, quercetin, quercetin-3-glucoside, (−)-epicatechin, (+)-catechin, procyanidin dimer and seed tannin. Quercetin produced the strongest copigment (K_CP = 2900 ± 1300), whilst the addition of glucose at position 3 (quercetin-3-glucoside) reduced its effect by almost 10-fold. Malvidin-3-glucoside self-association (K_D = 3300 ± 300 mol⁻¹ l) was thermodynamically favoured over intermolecular interaction with any of the copigments tested. No colour enhancement due to self-association was observed for malvidin-3-glucoside-derived pigments that cannot enter hydration reactions. In addition, malvidin-3-(6-O-p-coumaryl)glucoside did not show colour enhancement suggesting that the p-coumaryl group prevents self-association. The malvidin-3-glucoside circular dichroism (CD) spectrum was not affected by indicated changes in malvidin-3-glucoside concentration. These observations demonstrate that self-association of malvidin-3-glucoside is more important than copigmentation in young red wine.     

Isolation and identification of pelargonidin 3-glucoside in mangosteen pericarp

In the present study, we have identified pelargonidin 3-glucoside, along with two known anthocyanin; cyanidin 3-sophoroside and cyanidin 3-glucoside, from acidified, methanolic extract of mangosteen pericarp. The compounds were separated by preparative HPLC after purification by partition against ethyl acetate and Amberlite XAD-7. The structures of the compounds were confirmed by high performance liquid chromatography (HPLC), UV–Vis absorption spectra, high-resolution electrospray mass spectrometry and 1D, 2D nuclear magnetic resonance (NMR) spectroscopy. This new pigment family adds to the growing body of data supporting the use of natural colourants in food. Cyanidin 3-sophoroside was the major anthocyanin detected in large amount (76.1%), followed by cyanidin 3-glucoside (13.4%) and pelargonidin 3-glucoside (6.2%).     

Products of Thermal Degradation of the Anthocyanins Cyanidin-3-glucoside,Cyanidin-3-rutinoside and Cyanidin-3-sophoroside

During thermal degradation of anthocyanins, cyanidin-3-glucoside, cyanidin-3-rutinoside, cyanidin-3-sophoroside, at 98 °C in model systems of pH = 1, 2.5 3.5 and 4.5, seven compounds were isolated by means of paper chromatography. Among them quercetin, phloroglucin-aldehyde and protocatechuic acid were identified.     

Isolation and characterization of mutatoxanthin-epimers from red paprika (Capsicum annuum)

 (3S,5R,8R,3′R)- and (3S,5R,8S,3′R)-mutatoxanthin were isolated from red spice paprika (Capsicum annuum) and characterized by their UV-VIS, CD, ¹H-NMR, ¹³C-NMR and mass spectra. Received: 22 November 1999 / Revised version: 11 February 2000     

Stability of DON and DON-3-glucoside during baking as affected by the presence of food additives

The mycotoxin deoxynivalenol (DON) is one of the most common mycotoxins of cereals worldwide, and its occurrence has been widely reported in raw wheat. The free mycotoxin form is not the only route of exposure; modified forms can also be present in cereal products. Deoxynivalenol-3-glucoside (DON-3-glucoside) is a common DON plant conjugate. The mycotoxin concentration could be affected by food processing; here, we studied the stability of DON and DON-3-glucoside during baking of small doughs made from white wheat flour and other ingredients. A range of common food additives and ingredients were added to assess possible interference: ascorbic acid (E300), citric acid (E330), sorbic acid (E200), calcium propionate (E282), lecithin (E322), diacetyltartaric acid esters of fatty acid mono- and diglycerides (E472a), calcium phosphate (E341), disodium diphosphate (E450i), xanthan gum (E415), polydextrose (E1200), sorbitol (E420i), sodium bicarbonate (E500i), wheat gluten and malt flour. The DON content was reduced by 40%, and the DON-3-glucoside concentration increased by >100%, after baking for 20 min at 180°C. This confirmed that DON and DON-3-glucoside concentrations can vary during heating, and DON-3-glucoside could even increase after baking. However, DON and DON-3-glucoside are not affected significantly by the presence of the food additives tested.     

Identification of degradation pathways and products of cyanidin-3-sophoroside exposed to pulsed electric field

Pulsed electric field (PEF) can induce the degradation of anthocyanins. In this study, the degradation products and postulated degradation mechanism and pathways of cyanidin-3-sophoroside (Cy-3-soph) by PEF were investigated using a combination of UV–vis spectra and HPLC-MS. Four isomers of quinonoid benzoyloxyphenylacetic acid esters resulting from the oxidative degradation of Cy-3-soph at pH 1.5 and 3.5 were detected in a model solution after PEF. The prevailing degradation pathway was different from thermal degradation. Cy-3-soph was degraded through a Baeyer–Villiger oxidation by the nucleophilic attack of hydrogen peroxide and then further oxidised by other oxidants, such as the hydroxyl free radical induced by the electrochemical reactions during PEF treatment. The thermal degradation pathways at pH 1.5 and 3.5 were also involved in the degradation of Cy-3-soph during PEF treatment.     

对引进乳酸菌胶囊菌种的分离、鉴定和某些生长特性的研究

对引进的乳酸菌胶囊中的菌种进行了分离和纯化，经形态和生理生化检测，鉴定为肠球菌族、兰斯斐尔德Ｄ族、粪肠球菌［１］，对该菌的某些生长特性进行了研究，结果表明，其生长的最适培养温度为３７℃，最适ｐＨ值范围为７．０～９．０，耐牛胆汁盐浓度为４０％。     

Interaction between Cyanidin 3-glucoside and Cu(II) ions

The interaction between cyanidin 3-glucoside (Cy 3-glc) and Cu(II) in a binary solvent (methanol–water, 1:1, (v/v)) and in a phosphate buffer was studied. It is demonstrated that Cy 3-glc and Cu(II) ions form a complex that is manifested by appearance of a new absorption band. In the complex, the reduction of Cu(II)–Cu(I) and oxidation of Cy 3-glc takes place. The association constant of the complex formation was calculated using the Rose–Drago method. The complex stoichiometry in the binary solvent was 1:1, and the association constant was K = (28,600 ± 2600) M⁻¹. Interaction of Cy 3-glc and Cu(II) ions has two stages “fast” and “slow”. The kinetics of these processes has been investigated. Thermodynamic data for the “fast” process: enthalpy (ΔH^∗) and entropy (ΔE^∗) of activation, were calculated.     

红树莓色素的纯化及成分初步鉴定

以红树莓果实为原料提取天然色素,采用大孔树脂法对样品进行纯化,纯化后样品采用纸层析法分离,同时运用紫外可见光谱法和纸层析法对各组分进行了初步鉴定。结果表明:HPD-700大孔吸附树脂较适宜用于纯化红树莓色素,粗提液pH为2时吸附效果较好,以60%乙醇为洗脱液、洗脱体积为4BV、流速为0.6mL/min进行洗脱时,洗脱效果较好;通过纸层析分离出四个组分,初步鉴定分别为矢车菊-3-葡萄糖苷、矢车菊-3-芸香糖苷、矢车菊-3-槐糖苷和矢车菊-3-葡萄糖-芸香糖苷。     

花色苷类物质分离鉴定方法

本系统介绍了花色苷类物质的分离鉴定方法。     

两株琼胶酶高产细菌的筛选和鉴定

琼胶酶能降解琼胶多糖,生成琼胶寡糖。这些降解产物在食品等方面有良好的应用价值。本研究从江蓠中分离筛选到两株琼胶酶高产菌,编号分别是2．1-f和1.1-e,它们均为革兰氏阴性菌,呈细杆状。通过API条带分析,它们除了在对柠檬酸盐的利用上存在差别外,其它的生理生化特征完全相同,最终确定它们均为Sphingobacterium multivorum(多食鞘氨醇杆菌),其可信度分别是98．7％和99．5％。     

燃料乙醇用高产酒精酵母的筛选及鉴定

采用含有高浓度酒精选择性培养基从自然界中分离得到115株耐高酒精酵母,经过初筛、复筛,得到1株高产酒精酵母菌株SP—48,在料水比1：2,发酵72h的条件下,静止发酵,成熟醇酒精的体积分数可达16．2。经签定该酵母属(Saocharomyoes)的酿酒酵母(Saccharomyces cervisiae)。     

Effects of baking on cyanidin-3-glucoside content and antioxidant properties of black and yellow soybean crackers

Black soybean is a potential functional food ingredient with high anthocyanin content, but the ability to maintain anthocyanin content under dry heat processing has not been reported. This study investigated the effects of soybean seed coat colour and baking time–temperature combinations on the extractable antioxidant properties of a soy cracker food model. Crackers prepared with black soybeans had significantly higher TPC, total isoflavones, and peroxyl, hydroxyl, and ABTS⁺ radical scavenging abilities than their yellow counterparts, at all time–temperature combinations. Cyanidin-3-glucoside (C3G) was detected only in black soybean crackers, and all baking treatments significantly decreased C3G. The greatest losses occurred at the low temperature × long time and high temperature × short time, the smallest loss with moderate temperature × short/medium time. The high temperature treatment altered phenolic acid and isoflavone profiles; however, total isoflavones were unaffected. Overall results suggest that moderate baking temperature at minimal time may best preserve anthocyanin and other phenolics in baked black soybean crackers.