Characterization of Red Radish Anthocyanins

Red radish (Raphanus sativus L.) anthocyanins were extracted from liquid nitrogen powdered epidermal tissue using acetone, partitioned with chloroform and isolated using C-18 resin. The monomeric anthocyanin content, determined by pH-differential, was 154 ± 13 mg/100g epidermal tissue (pelargonidin-glucoside basis). Thermal processing of radishes showed that the pigments were stable to heat. Four major pigments were identified by Mass Spectroscopy, HPLC, and spectral analyses as pelargonidin-3-sophoroside-5-glucoside derivatives. The two major pigments were acylated with malonic acid and either ferulic or p-coumaric acid. The two other pigments were acylated with only ferulic or p-coumaric acid. Acylation increased pigment resistance to acid hydrolysis.     

Production of Red Water-Soluble Monascus Pigments

Water-soluble and thermal, as well as photo-stable, red Monascus pigments, were prepared by reacting the extracted pigment with aminoacetic acid and aminobenzoic acid. These modified pigments were compared to those using glutamic acid and gelatin as the modifying agents, showing that the colors and stabilities of these modified pigments were similar. Red pigments extracted from the mycelia could be dissolved in ethanol, propylene glycol, or in gelatin solution and freeze-dried. These red pigment concentrates or freeze-dried pigments could also be used as food colorants.     

Properties of red pigments prepared from geniposidic acid and amino acids

Red pigments formed from geniposide and amino acids were studied. Geniposide, the principal iridoid glucoside contained in the fruit of Gardenia jasminoides Ellis, was hydrolysed to geniposidic acid as a precursor for the pigment. The pigments prepared anaerobically with arginine or glutamic acid under acidic conditions with a large excess of citric acid, were reddish purple and had properties governed by the electrostatic character of the amino acid. Relative molecular masses of these pigments were determined to be several thousand by gel filtration. The pigments showed good stability to heat and pH, but were gradually bleached by light. The safety of the pigments was evaluated by studing their oral acute and the 5‐month oral toxicity of arginine‐red pigment using mice. The pigments were considered to be of low toxicity. © 1999 Society of Chemical Industry     

Physicochemical and Microbiological Changes Associated with Bakasang Processing—A Traditional Indonesian Fermented Fish Sauce

The production of ‘Bakasang’, an Indonesian fermented fish sauce, was replicated in the laboratory in order to study the physicochemical and microbiological changes associated with the process. Bakasang samples were produced by incubating mixtures of small sardine ( Engraulis japonicus ) at different concentrations of sodium chloride and glucose at 37°C for 40 days. Changes in pH, total soluble nitrogen, total free amino nitrogen, amino acid composition and total plate counts were observed. The isolation and identification of microflora were also performed. In general, the pH decreased throughout the incubation period, irrespective of NaCl and glucose concentrations. Increases in the amounts of total soluble nitrogen and total free amino nitrogen were noticed during the 40 days of fermentation. The amino acids, glutamic acid, alanine, isoleucine, and lysine were prominent at the end of the process. The total plate count increased during the first 10 days and then decreased gradually for both total microbial population and lactic acid bacteria population. Micrococcus , Streptococcus and Pediococcus spp were predominantly present during Bakasang fermentation.     

Amino Acid Profiles of Common Cultivated Mushrooms Including the Identification of N-(N-γ-L-Glutamyl-3-Sulfo-L-Alanyl)Glycine in Flammulina velutipes

Amino acid profiles of nonprotein nitrogen (NPN) and protein nitrogen (PN) fractions of common cultivated mushrooms were determined. Free amino acids in the NPN fractions were generally characterized by the predominant occurrence of alanine and amino acids metabolically related to the glutamic acid family and also by the common presence of unique nonprotein amino acids, such as saccharopine, cystathionine and ethanolamine. A novel glutathione analog, N-(N-γ-L-glutamyl-3-sulfo-L-alanyl)glycine, was found in Flammulina velutipes. The proportion of the NPN to the total nitrogen was relatively high and large amounts of the NPN were made up of free amino acids and related compounds. Protein amino acids in the NPN and PN fractions accounted for about 65% of the total nitrogen, suggesting that a practical nitrogen-protein conversion factor for the mushrooms may be considered to be about 4 on the average.     

Influence of nitrogen on the biological aging of sherry wine

Nitrogen compounds are essential to the growth and metabolism of yeasts. The uptake and metabolism of nitrogen compounds by Saccharomyces cerevisiae depend not only on the strain and its physiological condition, but also on the chemical and physical properties of its environment. The effect of the addition of different amino acids (L ‐proline, L ‐threonine, L ‐arginine, L ‐glutamic acid, L ‐leucine and L ‐valine) to nitrogen‐depleted natural or nitrogen‐free synthetic wine on the cell growth, flor velum formation and sherry wine compound production was investigated under controlled biological aging by S. cerevisiae var. capensis strain G1 a typical flor yeast. The formation of flor velum was dependent on particular amino acid, oxygen availability and the composition of wine. Consumption of glycerol was related with the cell growth; in contrast, acetaldehyde tended to be released. Amino acid supplementation resulted in the release to wine of amino acids, esters and higher alcohols. The amino acid which was released in nearly all cases was L ‐leucine. Addition of L ‐glutamic acid resulted in the release mainly of ethyl acetate, in the case of L ‐leucine isoamyl alcohols were released, and for L ‐valine isobutanol. In the three cases, 1,1‐diethoxyethane was released in large quantities. The findings might indicate that the regulation of metabolism succeeds in the most efficient balancing of the redox potential. Copyright © 2006 Society of Chemical Industry     

DECOMPOSITION OF TURMERIC CURCUMINOIDS AS AFFECTED BY LIGHT,SOLVENT AND OXYGEN1

Turmeric curcuminoids are important natural pigments but their instability limits their use in many foods. This study was conducted to examine light-induced degradation of turmeric curcumin as affected by solvent system and oxygen. The rate constants and half-lives were determined for purified curcumin, demethoxycurcumin and bis-demethoxycurcumin exposed to 1450 lux using reversed-phase HPLC. Rates of degradation of each pigment followed first-order kinetics. Differences in rate constants and half-lives between the individual pigments were minor in an acetic acid-NaCl solution; however, in methanol, large differences in stability to light of the individual pigment were observed. Stability of all the pigments to light was several fold greater in methanol than in acid brine. In methanol sparged with air, stability to photooxidation was curcumin > demethoxycurcumin > bis-demethoxycurcumin. In methanol, curcumin was more stable than the other curcuminoids when sparged with air than when sparged with nitrogen. In methanol sparged with nitrogen, demethoxycurcumin was the most stable pigment. All of the pigments were stable in the dark.     

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.     

Ripening time estimation of Kariesh cheese

Kariesh cheese is a popular cheese in Egypt produced by acid coagulation of milk. It can be consumed fresh or after ripening. Proteolysis in cheese was measured by determining soluble nitrogen (SN), amino acid nitrogen (AAN), total amino acids (TAA) and free amino acids (FAA). SN, AAN and FAA increased during ripening. Free amino acids profile revealed in total 16 amino acids and the same distribution of free amino acids. Cheese ripening was influenced by the type of milk and the method of production. The mildly acid sweet flavour was attributed to the concentration of glutamic acid, aspartic acid, proline and valine. Linear regression analysis was carried out to estimate the ripening time of this cheese. A positive correlation between the accumulation of amino acid and ripening time was established. The highest coefficient of determination near one resulted from glutamic acid (R² = 0.99) followed by lysine (R² = 0.97–0.99), then aspartic acid (0.90–0.98). From the linear regression equation for glutamic acid, lysine, aspartic acid or proline, the ripening time of Kariesh cheese in weeks was determined as follows: Time of ripening [weeks] = mg amino acid 100 g cheese-a/b where b = slope and a = intercept of regression straight line at 0 time.     

Fatty Acid Content,Flavor Compounds,and Sensory Quality of Pork Loin as Affected by Dietary Supplementation with l‐arginine and Glutamic Acid

To investigate the effect of functional amino acid on meat flavor and eating quality, 60 growing‐finishing pigs (Duroc × Large White × Landrace) were dietarily supplemented with or without 1.0% l ‐arginine, glutamic acid, or l ‐arginine plus glutamic acid for 2 months. After animals were slaughtered, the muscle fatty acid profile, flavor compounds, and meat sensory quality were comparatively investigated. The results showed that dietary supplementation with arginine, glutamic acid, or arginine plus glutamic acid had little effect on free amino acids, no effect on 5′‐nucleotides and meat sensory taste traits, but supplementation with arginine plus glutamic acid significantly increased (P < 0.05) fat accumulation and fatty acid content in muscle, increased (P < 0.05) the formation of multiple fatty acid oxidation‐derived volatile compounds, and improved the tenderness, juiciness, and overall eating quality of meat. This study revealed that dietary supplementation with 1.0% l ‐arginine and glutamic acid could be used to improve meat eating quality in pork production.     

Within-day variation of taurine and other nitrogen substances in human milk

Milk samples were collected from seven mothers during their 8th wk of lactation. On the day of collection one breast was completely emptied at 600, 1000, 1400, 1800, and 2200 h. Concentrations of total nitrogen, protein nitrogen, urea nitrogen, and free amino acids (taurine and glutamine plus glutamic acid) were determined. Concentrations of these nitrogen substances in the milk differed significantly among women but were relatively constant during the day. The mean concentrations of these substances per 100 ml of milk were total nitrogen, .189 g; protein nitrogen, .145 g; urea nitrogen, .020 g; taurine 34.9 mumol; glutamine plus glutamic acid, 200.0 mumol.     

谷氨酸清洁发酵工艺研究

为了解决谷氨酸发酵培养基中色素、杂质多所引起的发酵过程稳定性差、产酸低等问题,该研究采用生物氮素对发酵培养基中的主要氮源（玉米浆和豆粕水解液）进行替代,并通过单因素试验和正交试验对清洁发酵培养基中的关键因素生物氮素、生物素、VB1和甲硫氨酸的添加量进行优化,进而获得谷氨酸清洁发酵培养基,进行谷氨酸的清洁发酵工艺研究。结果表明,清洁发酵培养基中关键成分的最佳添加量为生物氮素2.0 g/L、生物素7 μg/L、VB1 10 mg/L、甲硫氨酸0.6 g/L。在最优工艺条件下,清洁发酵菌液OD600 nm值为84.2,谷氨酸产量为171 g/L,糖酸转化率为68.5%,分别较对照提高16.14%、12.50%、4.74%,发酵上清液透光率由0.9%提高至31%,说明清洁发酵培养基能够较好地提升谷氨酸发酵性能。     

Monitoring of free glutamic acid in Malaysian processed foods,dishes and condiments

A study to quantify the free glutamic acid content of six processed foods, 44 dishes and 26 condiments available in Malaysia was performed using high-performance liquid chromatography with a fluorescence detector (HPLC-FRD). Recovery tests were carried out with spiked samples at levels from 6 to 31 mg g^?1. High recovery in different matrices was achieved ranging from 88% ± 13% to 102% ± 5.12%, with an average of 97% ± 8.92%. Results from the study revealed that the average free glutamic acid content ranged from 0.34 ± 0.20 to 4.63 ± 0.41 mg g^?1 in processed foods, while in prepared dishes it was as low as 0.24 ± 0.15 mg g^?1 in roti canai (puffed bread served with curry or dhal) to 8.16 ± 1.99 mg g^?1 in dim sum (a small casing of dough, usually filled with minced meat, seafood, and vegetables, either steamed or fried). Relatively, the content of free glutamic acid was found to be higher in condiments at 0.28 ± 0 mg g^?1 in mayonnaise to 170.90 ± 6.40 mg g^?1 in chicken stock powder.     

福建烟叶游离氨基酸等主要含氮化合物与感官质量的关系

【目的】为明确烟叶游离氨基酸等主要含氮化合物与感官质量的关系。【方法】以烤烟品种云烟87为试验材料,测定不同施氮量和留叶数对初烤烟叶各叶位的烟碱、总氮、蛋白质、20种游离氨基酸含量的影响,通过感官质量评价分析主要含氮化合物与感官质量的关系。【结果】1）不同部位烟叶游离氨基酸总量差异显著,依次为下部叶>上部叶>中部叶;2）简单相关分析表明,总氮、蛋白质、游离氨基酸总量以及非烟碱氮占总氮含量的比例,与感官质量呈极显著的负相关关系;脯氨酸占游离氨基酸总量的比例,与感官质量呈极显著的正相关关系;3）逐步回归分析表明,在烟碱、蛋白质和20种游离氨基酸中,谷氨酸、谷氨酰胺、丙氨酸对感官质量的负面效应大于烟碱、蛋白质以及其它游离氨基酸。4）在8个处理中,施氮量127.5kg/hm2、留叶数14片/株处理的烟叶,非烟碱氮、谷氨酸、谷氨酰胺、丙氨酸含量以及游离氨基酸总量最低,感官质量较好。【结论】控制烟叶非烟碱氮含量,尤其是降低谷氨酸、谷氨酰胺、丙氨酸以及游离氨基酸总量,有利于提高烟叶品质。     

Amino Acids in the American Groundnut (Apios americana)

The amino acid composition of groundnut (Apios americana Medikus) was analyzed using ion-exchange column chromatography. Aspartic and glutamic acids were the predominant amino acids in both seeds and tubers. Other amino acids present in significant quantities were leucine, histidine and proline. The most abundant free amino acids, other than aspartic and glutamic acids, were arginine and leucine in the seeds and histidine and serine in the tubers.     

Protein Contents,Amino Acid Compositions and Nitrogen-to-Protein Conversion Factors for Cassava Roots

Root protein contents of 15 cassava varieties ( Manihot esculenta Crantz) ranged from 5 to 19 g kg⁻¹ dry matter. Intervarietal differences in amino acid profiles of cassava roots were evident. Differences in the levels of aspartic acid, glutamic acid and arginine were most notable. The nitrogen-to-protein conversion factors ( k _AA ) based on nitrogen recovered from total amino acid analyses including ammonia ranged from 4·75 to 5·87, showing that the traditional conversion factor of 6·25 was not valid for cassava root proteins. Conversion factors ( k _P ) for 15 cassava varieties based on Kjeldahl nitrogen ranged from 2·49 to 3·67. Therefore an average k _P value of 3·24±0·31 may provide a better estimate of the protein content in cassava roots.     

Production and Food Applications of the Red Pigments of Monascus ruber

Following our investigations on food additive production through fermentation, we studied properties of red pigments secreted by Monascus ruber in submerged culture, using ethanol and glutamate as carbon and nitrogen sources. After extraction and purification, these colorants were suspended in water for evaluation. The stability of the extract was tested both in solution and when incorporated into meat products (sausage and pâté). The pigments added to sausage or pate remained stable when stored for 3 mo at 4°C; their stability was between 92 and 98%. Sensory tests revealed that Monascus pigments could replace some traditional food additives such as nitrite salts or cochineal.     

Influence of ripening on proteolysis and lipolysis of Murcia al Vino cheese

The aim of this study was to evaluate the influence of five different manufacturers and two ripening periods on the proteolysis and lipolysis patterns of Murcia al Vino goat cheese. The manufacturers significantly affected the water activity (a_w), pH, dry matter and fat content, several nitrogen fractions: water soluble nitrogen (WSN), trichloroacetic acid (12% w/v) soluble nitrogen (TCASN) and phosphotungstic acid (5% w/v) soluble nitrogen (PTASN); also the free amino acid (FAA) and free fatty acid (FFA) contents, with the exception of C_4:0, C_16:0 and C_18:0. Different ripening periods significantly affected the dry matter content, WSN and PTASN and all FAA, except serine.     

Effect of grass hay substrate on nutritional value of Pleurotus ostreatus var. columbinus

Fruitbodies of P. ostreatus var. columbinus harvested from grass hay and wheat straw substrates were analyzed and compared in order to assess changes of their nutritional status depending upon cultivation substrate. The results showed that grass hay substrate increased significantly the protein content expressed as crude protein, digestible protein, protein precipitated with copper hydroxide or trichloroacetic acid and protein calculated from amino acid nitrogen. Protein content increase was likely, resulting from a significant increase of aspartic acid, arginine, glutamic acid, leucine, lysine and valine contents. Chitin content unfortunately increased significantly in Pleurotus mushroom grown on grass hay substrate. No significant difference was recorded in the case of acid detergent fibre, lipids, minerals and vitamins. In contrast, neutral detergent fibre, acid detergent lignin and sugar contents decreased in Pleurotus grown on grass hay.     

Influence of grapevine leafroll associated viruses (GLRaV-2 and -3) on the fruit composition of Oregon Vitis vinifera L. cv. Pinot noir: Free amino acids,sugars, and organic acids

Individual free amino acids, yeast assimilable amino acid (YAN) content, ammonia, organic acids, and simple sugars of berries from vines infected with GLRaV-2 or -3 were compared with paired vines free of these viruses. Samples were taken from two commercial vineyards during two growing seasons (2005 and 2006), with three different rootstock/scion combinations. Vines infected with GLRaV-2 did not differ significantly from their healthy counterparts in individual free amino acids, ammonia, or YAN content. Vines infected with GLRaV-3 were significantly lower in valine and methionine from Vitis riparia rootstock/‘Pinot noir’ clone 114 (VY2a) samples, and lower in glutamic acid from self-rooted/‘Pinot noir’ clone Pommard (VY2b) samples, compared to samples from their healthy counterparts. Samples from VY2b (self-rooted/‘Pinot noir’ clone Pommard) infected vines had significantly lower levels of malic acid and total organic acids compared to samples from their healthy counterparts. There were no significant differences between healthy and infected vines from all three rootstock/scion pairs in ammonia or free amino acids in samples taken during the weeks before ripening and at commercial harvest. This is the first study to report the influence of GLRaV-2 and -3 on ‘Pinot noir’ berries nitrogen (N) compounds significant to fermentation. Individual free amino acids may be inferior to phenolic compounds as indicators of GLRaV infection status.