Comparison of Brown Pigments in Foods by Microbial Decolorization

Coriolus versicolor IFO 30340, Paecilomycesz canadensis NC-1, and Streptomyces werraensis TT 14 were cultured at 27°C and 37°C to investigate their decolorization of model pigments and browned foods. The decolorization rates by these microorganisms differed by model brown pigments and foods. P. canadensis NC-1 mainly decolorized phenol-type model brown pigments, coffee, and black tea. C. versicolor IFO 30340 mainly decolorized model melanoidins and amino-carbonyl reaction-type pigments such as cane molasses, soy sauce, and “miso”. S. werraensis TT 14 decolorized xylose-glycine and glucose-lysine model melanoidins, and some caramel-type pigments. The brown pigments in foods could be categorized by comparing the microbial decolorization pattern of the foods and model brown pigments.     

Decolorization of Brown Pigments in Foods by Immobilized Mycelia of Coriolus versicolor IFO 30340 and Paecilomyces canadensis NC-1

Three microorganisms were cultured to investigate their decolorizing activity on mixtures of 2 types of model brown pigment and 2 types of browned food. The mixture of model brown pigments of the Maillard reaction type and phenol type was not decolorized by cultivation with Coriolus versicolor IFO 30340, but it was decolorized by Paecilomyces canadensis NC‐1 and by Streptomyces werraensis TT 14. The immobilized mycelia of C. versicolor IFO 30340 and P. canadensis NC‐1 were incubated simultaneously or successively with each mixture of 2 types of browned food. It was found that the mixed culture of these 2 mycelia showed a higher decolorization rate than their successive culture.     

红曲甜米酒生产过程中红曲色素稳定性研究

通过固态发酵的方法,制备红曲米,并从中提取出天然红曲色素。以色价为指标,研究光照、温度、受热时间及金属离子对红曲色素稳定性的影响。结果表明:光照条件对红曲色素稳定性影响的大小顺序为日光紫外灯避光处,其中,日光对红曲色素稳定性的影响最为明显;另外随着温度的升高,红曲色素的稳定性越来越差,加热时间越长,色价损失越大;金属离子中,Fe~(3+)对红曲色素的影响最大,而Cu~(2+)和Zn~(2+)影响不显著。     

Extraction and antioxidant property of polyhydroxylated naphthoquinone pigments from spines of purple sea urchin Strongylocentrotus nudus

Purple sea urchin (Strongylocentrotus nudus) spines were dissolved in HCl–ethanol-aqueous solution. The polyhydroxylated 1,4-naphthoquinone (PHNQ) pigments were condensed and purified by using macroporous resin in static adsorption mode. PHNQ in the extract were characterised rapidly by using an ultra-performance liquid chromatography (UPLC) coupled to hybrid quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOFMS). Six known compounds including spinochrome E, 2,7-dihydroxynaphthazarin, spinochrome B, spinochrome C, spinochrome A and echinochrome A, and two new compounds with molecular formula of aminopentahydroxynaphthoquinone and acetylaminotrihydroxynaphthoquinone were identified tentatively. The pigment extract was evaluated for antioxidant activity by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging capacity assay, Fe²⁺ chelating assay, reducing power assay, lipid peroxidation inhibition assay and tertiary-butyl hydroperoxide (t-BOOH)-induced macrophages protection assay. In all testing methods, the extract showed excellent activity, indicating the PHNQ from S. nudus spines are potential sources of natural antioxidants.     

Antioxidant constituents in feverfew (Tanacetum parthenium) extract and their chromatographic quantification

Medicinal herb feverfew (Tanacetum parthenium) has been reported to possess prophylactic properties over migraine and arthritis. However, less attention has been given to its antioxidant activities. In our study the antioxidant activities of the feverfew extract and its bioactive components in terms of their free radical-scavenging activities against the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and their Fe²⁺-chelating capacities were determined. In addition, the bioactive constituents in feverfew were determined by GC–MS and HPLC–UV. The results showed that feverfew powder extracted by 80% alcohol contained camphor, parthenolide, luteolin and apigenin in 0.30 ± 0.08%, 0.22% ± 0.03%, 0.84% ± 0.10% and 0.68% ± 0.07%, respectively. Total phenolic content of the feverfew extract was measured in 21.21 ± 2.11 μg gallic acid equivalent per mg dry material. The feverfew alcoholic extract possessed a strong DPPH free radical-scavenging activity of 84.4% and moderate Fe²⁺-chelating capacity of 53.1%. Luteolin also showed strong DPPH scavenging activity of approximately 80% at ? 0.52 mg/mL. Parthenolide exhibited weak DPPH scavenging activity of 15% and moderate Fe²⁺-chelating capacity of nearly 60%. Similar moderate Fe²⁺-chelating activity (approximately 60%) was observed for luteolin and apigenin at 2 mg/mL.     

微波法制备焦糖色素的研究

以葡萄糖和尿素为原料，利用微波独特的加热机制制备焦糖色素。探讨了工艺条件对焦糖色素色率的影响，结果显示：调节体系含水量15％、pH8．0，在中火条件下辐射14min，制得色率为93132EBC单位的焦糖色素，产品带正电荷；同时，观察了NaCl、KCl、FeCl3、CaCl2等盐的存在对焦糖色素色率的影响，研究表明：这些金属氯化物均能增加焦糖色素的色率，其中FeCl。的影响最显著，其次为NaCl；稳定性试验显示：不加盐和加入NaCl制备得到的焦糖色素耐酸性和耐盐性均良好，而加入FeCl3制备得到的焦糖色素耐酸性和耐盐性差。     

Enhancement of antioxidant activity,total phenolic and flavonoid content of black soybeans by solid state fermentation with Bacillus subtilis BCRC 14715

In the present study, a solid state fermentation of black soybeans with Bacillus subtilis BCRC 14715 was performed. The effect of fermentation on the changes of total phenolic and flavonoid content and antioxidant activities including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging effect, and Fe²⁺-chelating ability exerted by various solvent (water, 80% methanol, 80% ethanol, 80% acetone) extracts of black soybeans was examined. It was found that fermentation enhanced the total phenolic and flavonoid content as well as antioxidant activity of the black soybean extract. Among the various extracts examined, the acetone extract of fermented black soybeans showed the highest total phenolic and flavonoid content. The acetone extract and the methanol extract of fermented black soybeans showed the highest DPPH free radical-scavenging effect and Fe²⁺-chelating ability, respectively. Analysis of extraction yields showed that the active principle associated with the DPPH radical-scavenging effect was most efficiently extracted from black soybeans using water, regardless of fermentation. Water and methanol effectively extract the Fe²⁺-chelating principles from non-fermented and fermented black soybeans, respectively.     

Antioxidant activity of hot water extract from the fruit of the Doum palm, Hyphaene thebaica

A hot water extract from the fruit of Hyphaene thebaica was examined for its (i) hydrogen donating activity, (ii) Fe²⁺-chelating activity, (iii) hydroxyl radical-scavenging activity, (iv) inhibition of substrate site-specific hydroxyl radical formation, (v) superoxide radical-scavenging activity, and (vi) reducing power. The total phenolic content of the fruit extract was also determined in order to quantitate antioxidant activity as gallic acid equivalent (GAE) per ml reaction. The total phenolic content of the Doum fruit is low, but the extract exhibited potent antioxidant activity in terms of GAE. The activities expressed as mmol pure compound equivalent per g GAE content of extract are: (i) 2.85 mmol ascorbic acid equivalent, (ii) 1.78 mmol ethylenediamine tetraacetic acid equivalent, (iii) 192 mmol gallic acid equivalent, (iv) 3.36 mmol gallic acid equivalent, (v) 1.78 mmol gallic acid equivalent and (vi) 3.93 mmol ascorbic acid equivalent. These values were of the same magnitude as antioxidant activity in black tea except for Fe²⁺-chelating activity which was about 14 times more potent. The results show that the fruit of Hyphaene thebaica’s fruit is a source of potent antioxidants.     

Relationship between the chemical composition and the biological activities of food melanoidins

The relationship between the chemical composition and the biological activities of food melanoidin-rich fractions was investigated. Melanoidin-rich fractions were extracted using ultrafiltration (a 10 kDa cut-off) from coffee, barley coffee, dark beer, and traditional balsamic vinegar. All the food melanoidin-rich fractions were formed mainly of carbohydrates, phenolic compounds, and proteins. In dark beer, barley coffee, and traditional balsamic vinegar melanoidins, glucose was the most abundant sugar incorporated into melanoidins. Coffee melanoidins contained the largest amount of phenolic groups, followed by traditional balsamic vinegar melanoidins. The radical scavenging, Fe²⁺-chelating, and heme binding abilities of food melanoidins were investigated under gastric conditions. The melanoidinrich fraction extracted from coffee was the most active, showing the highest radical scavenging, Fe²⁺-chelating, and heme binding activities, compared to barley coffee, dark beer, and traditional balsamic vinegar. The radical scavenging and Fe²⁺-chelating abilities were assigned to the phenolic groups present in food melanoidins.     

Elucidation of chemical structures of pink-red pigments responsible for ‘pinking’ in macerated onion (Allium cepa L.) using HPLC-DAD and tandem mass spectrometry

The chemical structures of pink-red pigments responsible for ‘pinking’ in macerated onion were tentatively elucidated using HPLC with a diode array detector and tandem mass spectrometry. All pigments were produced in conditions that approximated the natural process as closely as possible, using mixtures of onion thiosulphinates, the enzyme alliinase, and free amino acids. The isotopic distribution of protonated molecules of pink-red pigments produced from individual amino acids indicated the absence of sulphur, with the exception of pigment produced from cystine. The pigments had a basic polymethine framework containing two pyrrole rings (3,4-dimethyl-1H-pyrrole and 3,4-dimethyl-2,5-dihydro-1H-pyrrole) bridged by methines. The side chains attached to the nitrogen of the pyrrole rings were derived from the reacting amino acid. The simplest pink-red pigment, produced from glycine, was identified as 2-(2-(3-(1-(carboxymethyl)-3,4-dimethyl-1H-pyrrol-2(5H)-ylidene)prop-1-en-1-yl)-3,4-dimethyl-1H-pyrrol-1-yl)acetic acid. The pigment from alanine was identified as 2-(2-(3-(1-(carboxymethyl)-3,4-dimethyl-1H-pyrrol-2-yl)allylidene)-3,4-dimethyl-2,5-dihydro-1H-pyrrol-1-yl)propanoic acid. The chemical structures of pink-red pigments from leucine, asparagine, glutamine, tyrosine, and cystine also were determined.     

A kind of potential food additive produced by Streptomyces coelicolor: Characteristics of blue pigment and identification of a novel compound, λ-actinorhodin

The blue pigment produced by Streptomyces coelicolor 100 with a yield as high as 3 g/l is a mixture of 10 components. The structure of one of the components was identified and it is a new actinorhodin analogue, named as λ-actinorhodin. The natural pigment can be dissolved in alkaline water solution and a number of organic solvents in common use. The color of a water solution of the pigment changes with pH value. The pigment is stable to light, heat and food additives in common use, and resistant to oxidants and reducers under acidic conditions and to reducers under alkaline conditions. Most inspected metal ions hardly affected pigment stability except for Fe²⁺ at high concentration and Pb²⁺. The pigment is nontoxic with LD₅₀ > 15,000 mg/kg in an acute toxicity trial. The good characteristics of the pigment make it potential useful in the food processing industry as an additive.     

Purification and some properties of α-amylase from post-harvest Pachyrhizus erosus L. tuber

α-Amylase, a starch splitting enzyme, was purified to homogeneity from post-harvest Pachyrhizus erosus L. tuber by successive chromatography on DEAE- and CM-cellulose columns. Purification achieved was 110 fold from the crude extract with a yield of 22.8%. SDS-PAGE showed a molecular weight of 40 kDa for the enzyme. The enzyme is of α-type as it lost total activity in the presence of EDTA, a chelating agent. It is a glycoprotein that contains 2.6% sugar as estimated by the phenol-sulfuric acid method. The enzyme displayed optimum activity at pH 7.3 and 37 °C with an apparent K_m value of 0.29% for starch as substrate. The enzyme was strongly inhibited by Cu²⁺, Fe²⁺ and Zn²⁺, moderately by Li²⁺, Hg⁺ and Cd²⁺ and slightly by Ag⁺, Mg²⁺ and K⁺. Calcium ion almost doubled the activity whereas Fe³⁺, Mn²⁺ and Na⁺ enhanced it appreciably.     

Identification of Candidate Amino Acids Involved in the Formation of Blue Pigments in Crushed Garlic Cloves (Allium sativum L.)

ABSTRACT:  The color-forming ability of amino acids with thiosulfinate in crushed garlic was investigated. We developed reaction systems for generating pure blue pigments using extracted thiosulfinate from crushed garlic and onion and all 22 amino acids. Each amino acid was reacted with thiosulfinate solution and was then incubated at 60 °C for 3 h to generate pigments. Unknown blue pigments, responsible for discoloration in crushed garlic cloves ( Allium sativum L.), were separated and tentatively characterized using high-performance liquid chromatography (HPLC) and a diode array detector ranging between 200 and 700 nm. Blue pigment solutions exhibited 2 maximal absorbance peaks at 440 nm and 580 nm, corresponding to yellow and blue, respectively, with different retention times. Our findings indicated that green discoloration is created by the combination of yellow and blue pigments. Eight naturally occurring blue pigments were separated from discolored garlic extracts using HPLC at 580 nm. This suggests that garlic discoloration is not caused by only 1 blue pigment, as reported earlier, but by as many as 8 pigments. Overall, free amino acids that formed blue pigment when reacted with thiosulfinate were glycine, arginine, lysine, serine, alanine, aspartic acid, asparagine, glutamic acid, and tyrosine. Arginine, asparagine, and glutamine had spectra that were more similar to naturally greened garlic extract.     

Helvellisin,a novel alkaline protease from the wild ascomycete mushroom Helvella lacunosa

A 33.5-kDa serine protease designated as helvellisin was isolated from dried fruiting bodies of the wild ascomycete mushroom Helvella lacunosa. It was purified by using a procedure which entailed ion exchange chromatography on DEAE-cellulose, CM-Sepharose, Q-Sepharose, and FPLC-gel filtration on Superdex 75. The protease was characterized by unique N-terminal amino acid sequence, thermostability and pH stability. The protease exhibited a pH optimum of 11.0 and a temperature optimum of 65 °C, with about 40% activity remaining at 87 °C and pH 5 and 13. Helvellisin demonstrated a protease activity of 14 600 U/mg toward casein. The K_m of the purified protease for casein was 3.81 mg/ml at pH 11.0 and 37 °C. The V_max was 5.35 × 10^− 2 mg ml^− 1 min^− 1. It was adversely affected by phenylmethylsulfonyl fluoride, suggesting that it is serine protease. The activity of the protease was enhanced by Mg²⁺, Fe²⁺ and Mn²⁺, but was curtailed by Cu²⁺, Hg²⁺ and Fe³⁺. It was devoid of antifungal and ribonuclease activities.     

Characterization of a new yellow pigment from model reaction system related to garlic greening

Three yellow pigments have been identified from three reaction systems containing pyruvic acid and 2-(1H-pyrrolyl) acetic acid, 1-(2′-methyl-1′-carboxy-propyl) pyrrole, and 1-(2′-methyl-1′-carboxy-butyl) pyrrole (a kind of precursor of garlic green pigment) related to garlic greening in previous paper, respectively. In the present study, another kind of yellow pigment from the same system containing pyruvic acid and 2-(1H-pyrrolyl) acetic acid was identified by liquid chromatography–electrospray ionization mass spectrometry (LC-ESI MS/MS) and high-resolution electrospray ionization mass spectrometry. This kind of pigment made predominant contribution to the production of yellow pigment in this model reaction pathway, which was involved in garlic discoloration. It was observed that there were two more methyl groups located on two conjugated double bonds that bridged two moles of 2-(1H-pyrrolyl) acetic acid compared to the structures of pigments, which was identified in our previous paper. Molecular weight of the pigment is 329.1495 [M+H]⁺, and its molecular formula is C₁₈H₂₀N₂O₄ which has a maximal absorbance at 436.9 nm, due to its conjugated structure.     

Effects of metal ions on growth, β-oxidation system,and thioesterase activity of Lactococcus lactis

The effects of divalent metal ions (Ca²⁺, Mg²⁺, Fe²⁺, and Cu²⁺) on the growth, β-oxidation system, and thioesterase activity of Lactococcus lactis were investigated. Different metal ions significantly influenced the growth of L. lactis: Ca²⁺ and Fe²⁺ accelerated growth, whereas Cu²⁺ inhibited growth. Furthermore, Mg²⁺ inhibited growth of L. lactis at a low concentration but stimulated growth of L. lactis at a high concentration. The divalent metal ions had significant effects on activity of the 4 key enzymes of the β-oxidation system (acyl-CoA dehydrogenase, enoyl-CoA hydratase, L-3-hydroxyacyl-CoA dehydrogenase, and thiolase) and thioesterase of L. lactis. The activity of acyl-CoA dehydrogenases increased markedly in the presence of Ca²⁺ and Mg²⁺, whereas it decreased with 1 mmol/L Fe²⁺ or 12 mmol/L Mg²⁺. All the metal ions could induce activity of enoyl-CoA hydratase. In addition, 12 mmol/L Mg²⁺ significantly stimulated activity of L-3-hydroxyacyl-CoA dehydrogenase, and all metal ions could induce activity of thiolase, although thiolase activity decreased significantly when 0.05 mmol/L Cu²⁺ was added into M17 broth. Inhibition of thioesterase activity by all 4 metal ions could be reversed by 2 mmol/L Ca²⁺. These results help us understand the effect of metal ions on the β-oxidation system and thioesterase activity of Lactococcus lactis.     

Isolation and characterization of melanin from Osmanthus fragrans’ seeds

Melanin derived from Osmanthus fragrans’ seeds was isolated from O. fragrans’ seeds by alkaline extraction, acid hydrolysis, and repeated precipitation with a yield of 0.34 g/100 g (wet weight basis). Physical and chemical properties of the melanin revealed that the melanin derived directly from O. fragrans’ seeds were similar to typical melanin. The melanin was stable under ultraviolet light or room-light, stable in the range of 25-100 °C, relatively stable in alkaline solution, reducer and salt, but was bleached by strong oxidants (KMnO₄, K₂Cr₂O₇ and NaOCl). The metal-ion of Ca²⁺, Cu²⁺, Fe³⁺ and Zn²⁺ had the function of color increase or color preservation to the melanin. Although Mg²⁺, Al³⁺ and Na⁺ reduce pigment color, it was not obvious. Amino acid and organic acid did not affect the melanin, while sugar, starch, and glucose affected it slightly.     

Betacyanins in dragon fruit peels: the kinetic models of their degradation under different treatment conditions

In this study, after purification, the content of betacyanins in dragon fruit peels was 9.22 mg g⁻¹ dry sample. The stability of betacyanins under the effect of different concentration of metal cation (K⁺, Na⁺, Cu²⁺, Fe²⁺, Fe³⁺, Mg²⁺, Al³⁺) solutions and sugars (glucose, sucrose, fructose, maltose and lactose) solutions was observed. The results showed that 10% lactose and 0.08 mol L⁻¹ potassium chloride solution increased the stability of betacyanins and could be used as stabiliser agents. The degradation reaction under different temperatures (20, 30, 40, 50, 60, 70, 80 °C), pH (2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0) and light conditions (light and dark) of mixed solution (betacyanins and stabiliser), including aqueous pigments solution (APS), lactose pigments solution (LPS) and potassium chloride pigments solution (PCPS), accorded with the first-order reaction kinetics. The t_1/2 values (the hours needed for 50.0% degradation of betacyanins) of LPS even up to 330.0 h at 20 °C and dark condition.     

Antioxidant and antiradical properties of maillard reaction products in both aqueous and ethanolic fructose-glycine oligomer solutions

The purpose of this study was to evaluate the antioxidant and antiradical properties of Maillard reaction products (MRP) in both aqueous and ethanolic fructoseglycine oligomer solutions. Antioxidant and radical scavenging activities of MRPs were investigated using different in vitro assays: the ferric ion (Fe³⁺) reducing ability, cupric ion (Cu²⁺), ferrous ion (Fe²⁺) chelating effects, DPPH and ABTS radical scavenging activities, and Fe³⁺-TPTZ reducing ability. MRPs derived from fructose-diglycine (GG) were found to be effective antioxidants in different in vitro assays. The antioxidant activity was higher in ethanolic solutions than in aqueous MRP solutions.     

Analysis of tryptophan oxidation by fluorescence spectroscopy: Effect of metal-catalyzed oxidation and selected phenolic compounds

The suitability of using fluorescence spectroscopy to assess tryptophan (TRYP) depletion by quantifying the loss of natural TRYP fluorescence during metal-catalyzed oxidation (MCO) was assessed. To analyze the effect of the oxidation conditions, N-acetyl-l-tryptophanamide (NATA) solutions were oxidized in the presence of Cu²⁺ and Fe²⁺ (40 and 80 μM), with and without 0.8 mM H₂O₂. Also, the effect of selected phenolic compounds (PhC), namely, catechin, genistein, quercetin, rutin, gallic acid and chlorogenic acid (0.08, 0.8 and 8.0 μM), on TRYP MCO was studied. Oxidation systems catalyzed by Fe²⁺ had a major oxidative potential as a result of a higher amount of free radicals formed through the Fenton reaction. PhC could exert both antioxidant and pro-oxidant effects depending on their concentration, chemical structure of the PhC and the oxidation system. In general, all PhC acted as pro-oxidant agents at the highest dose. The major pro-oxidant effect was displayed by gallic and chlorogenic acid in the presence of Fe²⁺, Cu²⁺ or Cu²⁺/H₂O₂. Quercetin, rutin and gallic acid showed antioxidant effect against TRYP oxidation at low concentrations in Fe²⁺/H₂O₂ systems. Plausible mechanisms for the antioxidant and pro-oxidant effects of PhC on TRYP oxidation are discussed in the present article. The antioxidant efficiency of PhC or PhC-rich extracts must be studied before being used as functional food ingredients.