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Acid Degradation (acid + degradation)
Kinds of Acid Degradation Selected AbstractsLeptin stimulates uncoupling protein-2 mRNA expression and Krebs cycle activity and inhibits lipid synthesis in isolated rat white adipocytesFEBS JOURNAL, Issue 19 2000Rolando B. Ceddia The treatment of rats and mice with leptin causes dramatic body fat reduction and in some cases even disappearance of fat tissue. Here, we report the effects of leptin (10 and 100 ng·mL,1) on isolated rat adipocytes maintained for 15 h in culture. Leptin decreased the incorporation of acetate into total lipids by 30%. A reduction in this incorporation (42%) was still observed after the leptin-cultivated adipocytes were exposed to a supra-physiological insulin concentration (10 000 µU·mL,1). On the other hand, leptin increased acetate degradation by 69% and the maximal activity of citrate synthase by 50% in isolated adipocytes. It also increased oleate degradation by 35 and 50% at concentrations of 10 and 100 ng·mL,1, respectively. Eventually, leptin upregulated the uncoupling protein-2 (UCP2) mRNA level by 63% and had no effect on uncoupling protein-3 (UCP3) mRNA in isolated adipocytes. The upregulation of UCP2 mRNA might have contributed to the stimulation of acetate and fatty acid degradation by leptin. The peripheral effects of leptin observed in this study are in line with the general energy dissipating role postulated for this hormone and for UCP2. They suggest mechanisms by which adipocytes regulate their fat content by an autocrine pathway without the participation of the central nervous system. [source] Bovicin HC5 inhibits wasteful amino acid degradation by mixed ruminal bacteria in vitroFEMS MICROBIOLOGY LETTERS, Issue 1 2009Janaína R. Lima Abstract Streptococcus bovis HC5 produces a broad spectrum lantibiotic (bovicin HC5) that inhibits pure cultures of hyper ammonia-producing bacteria (HAB). Experiments were preformed to see if: (1) S. bovis HC5 cells could inhibit the deamination of amino acids by mixed ruminal bacteria taken directly from a cow, (2) semi-purified bovicin was as effective as S. bovis HC5 cells, and 3) semi-purified and the feed additive monensin were affecting the same types of ammonia-producing ruminal bacteria. Because purified and semi-purified bovicin HC5 was as effective as S. bovis HC5 cells, it appeared that bovicin HC5 was penetrating the cell membranes of HAB before it could be degraded by peptidases and proteinases. Mixed ruminal bacteria that were successively transferred and enriched nine times with trypticase did not become significantly more resistant to either bovicin HC5 (50 AU mL,1) or monensin (5 ,M), and amplified rDNA restriction analysis indicated that bovicin HC5 and monensin appeared to be selecting against the same types of bacteria. [source] Multiple roles of PPAR, in brown adipose tissue under constitutive and cold conditionsGENES TO CELLS, Issue 2 2010Makiko Komatsu Peroxisome proliferator-activated receptor , (PPAR,) is a member of the nuclear receptor family, regulating fatty acid degradation in many organs. Two-dimensional SDS-PAGE of brown adipose tissue (BAT) from PPAR,-null mice produced a higher-density spot. Proteomic analysis indicated that the protein was pyruvate dehydrogenase , (PDH,). To observe PDH, regulation in BAT, the organ was stimulated by long-term cold exposure, and the activities of associated enzymes were investigated. Histological and biochemical analyses of BAT showed a significant decrease in the triglyceride content in wild-type mice and some degree of decrease in PPAR,-null mice on cold exposure. Analyses of molecules related to glucose metabolism showed that the expression of PDH, is under PPAR,-specific regulation, and that glucose degradation ability may decrease on cold exposure. In contrast, analyses of molecules related to fatty acid metabolism showed that numerous PPAR,/, target molecules are induced on cold exposure, and that fatty acid degradation ability in wild-type mice is markedly enhanced and also increases to same degree in PPAR,-null mice on cold exposure. Thus, this study proposes novel and multiple roles of PPAR, in BAT. [source] Degradative enzymatic activities in fresh-cut blood-orange slices during chilled-storageINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2009Anna Eghle Catalano Summary Blood-orange fruits are suitable to fresh-cut fruit production because of their chemical compositions. Nevertheless, the main limitation of using freshly cut oranges is their susceptibility to juiciness loss and ascorbic acid degradation because of enzymatic alterations. The aim of this work is: to identify some of the enzymes causing the qualitative decay in blood-orange slices during 15 days of chilled storage (at 4 ± 0.5 °C and 85% RH); to investigate the susceptibility to the previous alterations of five blood-orange clones (Moro nucellare, Sanguinello nucellare, Tarocco arcimusa, Tarocco gallo and Tarocco meli) to select the most suitable one for fresh-cut production. The enzymes studied were: pectinmethylesterase (PME) as index of juiciness loss, ascorbate oxidase (AAO) as index of ascorbic acid's degradation and polyphenol oxidase (PPO) as browning index. As far as we know, the changes of AAO activity during chilled storage of blood-orange fresh-cut slices has not previously reported and studied. Different clones showed different enzymatic activities and quality changes during chilled-storage. In particular a low juiciness loss in orange slices was correlated with a lower PME activity, as described in T. meli clone, while a high degradation of ascorbic acid was correlated with an higher AAO activity, as described in T. gallo clone; PPO activity seemed to have no significant action in quality degradation. Tarocco meli was the most suitable clone to the fresh-cut blood-orange production because it has the lowest enzymatic activity (PME, PPO and AAO) and the highest sensorial quality. [source] EFFECT OF ANTICAKING AGENT ADDITION AND HEADSPACE REDUCTION IN THE POWDERED-DRINK MIX SENSORY STABILITYJOURNAL OF FOOD QUALITY, Issue 3 2006INAR A. CASTRO ABSTRACT The objective of the present study was to assess the effect of the addition of 0.2% anticaking agent "silicon dioxide" (S) and of 70.0% reduction of the headspace in the package (H) both individually and combined (SH), on the sensory and physicochemical characteristics of a powdered-drink mix over a shelf-life period of 120 days. The "difference from control" test was applied to 10 trained panelists in order to assess the four treatments at 30-day intervals throughout the experimental period, according to visual aspect of the powdered mix and drink flavor. The results demonstrated that a reduction of 70% of the headspace was the most effective treatment for product sensory stability. Water activity (Aw) was a more sensitive parameter than moisture content and ascorbic acid degradation. Although Aw has shown a significant difference over time, the sensory properties still seemed to be a better shelf-life indicator for powdered mixes. Based on the sensory alterations of the aspect of the powder, a reduction of headspace and the limiting of shelf life to between 60 and 90 days could be recommended for powdered-drink mixes packaged in polypropylene containers. [source] Aroma Components of American Country HamJOURNAL OF FOOD SCIENCE, Issue 1 2008H. Song ABSTRACT:, The aroma-active compounds of American country ham were investigated by using direct solvent extraction-solvent assisted flavor evaporation (DSE-SAFE), dynamic headspace dilution analysis (DHDA), gas chromatography-olfactometry (GCO), aroma extract dilution analysis (AEDA), and gas chromatography-mass spectrometry (GC-MS). The results indicated the involvement of numerous volatile constituents in the aroma of country ham. For DHDA, 38 compounds were identified as major odorants, among them, 1-octen-3-one, 2-acetyl-1-pyrroline, 1-nonen-3-one, decanal, and (E)-2-nonenal were the most predominant, having FD-factors , 125 in all 3 hams examined, followed by 3-methylbutanal, 1-hexen-3-one, octanal, acetic acid, phenylacetaldehyde, and FuraneolÔ. For the DSE-SAFE method, the neutral/basic fraction was dominated by 1-octen-3-one, methional, guaiacol, (E)-4,5-epoxy-(E)-decenal, p-cresol as well as 3-methylbutanal, hexanal, 2-acetyl-1-pyrroline, phenylacetaldehyde, and ,-nonalactone. The acidic fraction contained mainly short-chain volatile acids (3-methylbutanoic acid, butanoic acid, hexanoic acid, and acetic acid) and Maillard reaction products (for example, 4-hydroxy-2,5-dimethyl-3(2H)-furanone). The above compounds identified were derived from lipid oxidation, amino acid degradation, and Maillard/Strecker and associated reactions. Both methods revealed the same nature of the aroma components of American country ham. [source] CONTRASTING EFFECTS OF METHIONINE SULFOXIMINE ON UPTAKE AND ASSIMILATION OF AMMONIUM IN ULVA INTESTINALIS (CHLOROPHYCEAE),JOURNAL OF PHYCOLOGY, Issue 4 2004Neill G. Barr Ammonium is assimilated in algae by the glutamine synthetase (GS),glutamine:2-oxoglutarate aminotransferase pathway. In addition to the assimilation of external ammonium taken up across the cell membrane, an alga may have to reassimilate ammonium derived from endogenous sources (i.e. nitrate reduction, photorespiration, and amino acid degradation). Methionine sulfoximine (MSX), an irreversible inhibitor of GS, completely inhibited GS activity in Ulva intestinalis L. after 12 h. However, assimilation of externally derived ammonium was completely inhibited after only 1,2 h in the presence of MSX and was followed by production of endogenous ammonium. However, endogenous ammonium production in U. intestinalis represented only a mean of 4% of total assimilation attributable to GS. The internally controlled rate of ammonium uptake (Vi) was almost completely inhibited in the presence of MSX, suggesting that Vi is a measure of the maximum rate of ammonium assimilation. After complete inhibition of ammonium assimilation in the presence of MSX, the initial or surge (Vs) rate of ammonium uptake in the presence of 400 ,M ammonium chloride decreased by only 17%. However, the amount that the rate of ammonium uptake decreased by was very similar to the uninhibited rate of ammonium assimilation. In addition, the decrease in the rate of ammonium uptake in darkness (in the absence of MSX) in the presence of 400 ,M ammonium chloride matched the decrease in the rate of ammonium assimilation. However, in the presence of 10 ,M ammonium chloride, MSX completely inhibited ammonium assimilation but had no effect on the rate of uptake. [source] A study on degradation kinetics of ascorbic acid in drumstick (Moringa olifera) leaves during cookingJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2005Nisha P Bineesh Abstract The kinetics of ascorbic acid degradation in drumstick (Moringa olifera) leaves as well as in pure ascorbic acid solutions at the initial concentrations present in drumstick leaves over a temperature range of 50,120 °C (isothermal temperature process) has been studied. The degradation kinetics of ascorbic acid was also evaluated in normal open-pan cooking, pressure-cooking and a newly developed and patented fuel-efficient eco cooker (non-isothermal heating process). The ascorbic acid degradation followed first-order reaction kinetics where the rate constant increased with an increase in the temperature. The temperature dependence of degradation was adequately modelled by the Arrhenius equation. A mathematical model was developed using the isothermal kinetic parameters obtained to predict the losses of ascorbic acid from the time,temperature data of the non-isothermal heating/processing method. The results obtained indicate the ascorbic acid degradation is of similar order of magnitude in all the methods of cooking. Copyright © 2005 Society of Chemical Industry [source] Effect of a high-protein diet on food intake and liver metabolism during pregnancy, lactation and after weaning in micePROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 14 2010Björn Kuhla Abstract Major hepatic metabolic pathways are involved in the control of food intake but how dietary proteins affect global metabolism to adjust food intake is incompletely understood, particularly under physiological challenging conditions such as lactation. In order to identify these molecular events, mice were fed a high-protein (HP) diet from pregnancy, during lactation until after weaning and compared with control fed counterparts. Liver specimens were analyzed for regulated proteins using 2-DE and MALDI-TOF-MS and plasma samples for metabolites. Based on the 26 differentially expressed proteins associated with depleted liver glycogen content, elevated urea and citrulline plasma concentrations, we conclude that HP feeding during lactation leads to an activated amino acid, carbohydrate and fatty acid catabolism while it activates gluconeogenesis. From pregnancy to lactation, plasma arginine, tryptophan, serine, glutamine and cysteine decreased, whereas urea concentrations increased in both groups. Concomitantly, hepatic glycogen content decreased while total fat content remained unaltered in both groups. Consideration of 59 proteins differentially expressed between pregnancy and lactation highlights different strategies of HP and control fed mice to meet energy requirements for lactation by adjusting amino acid degradation, carbohydrate and fat metabolism, citrate cycle, but also ATP-turnover, protein folding, secretion of proteins and (de)activation of transcription factors. [source] Comparison of the Stability of Pelargonidin-based Anthocyanins in Strawberry Juice and ConcentrateJOURNAL OF FOOD SCIENCE, Issue 4 2002G.A. Garzón ABSTRACT Strawberries were processed into juice (8° Brix) and concentrate (65° Brix) and different lots were fortified with pelargonidin 3-glucoside, pelargonidin 3-sophoroside, and acylated pelargonidin 3-sophoroside 5-glucoside. Changes in pigment concentration, color (CIE L*a*b*) and ascorbic acid content were monitored during storage at 25 °C. Anthocyanin and ascorbic acid degradations followed 1st order reaction kinetics. Fortification increased the half-life of the pigments from 3.5 to 5 d in concentrate and from 5 to 12 d in juice. The half-life of ascorbic acid was 2 d in juice samples and ranged from 3 to 10 d in concentrate samples. Both systems showed changes in chroma and hue angle, but maintained L* values. [source] Degradative enzymatic activities in fresh-cut blood-orange slices during chilled-storageINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2009Anna Eghle Catalano Summary Blood-orange fruits are suitable to fresh-cut fruit production because of their chemical compositions. Nevertheless, the main limitation of using freshly cut oranges is their susceptibility to juiciness loss and ascorbic acid degradation because of enzymatic alterations. The aim of this work is: to identify some of the enzymes causing the qualitative decay in blood-orange slices during 15 days of chilled storage (at 4 ± 0.5 °C and 85% RH); to investigate the susceptibility to the previous alterations of five blood-orange clones (Moro nucellare, Sanguinello nucellare, Tarocco arcimusa, Tarocco gallo and Tarocco meli) to select the most suitable one for fresh-cut production. The enzymes studied were: pectinmethylesterase (PME) as index of juiciness loss, ascorbate oxidase (AAO) as index of ascorbic acid's degradation and polyphenol oxidase (PPO) as browning index. As far as we know, the changes of AAO activity during chilled storage of blood-orange fresh-cut slices has not previously reported and studied. Different clones showed different enzymatic activities and quality changes during chilled-storage. In particular a low juiciness loss in orange slices was correlated with a lower PME activity, as described in T. meli clone, while a high degradation of ascorbic acid was correlated with an higher AAO activity, as described in T. gallo clone; PPO activity seemed to have no significant action in quality degradation. Tarocco meli was the most suitable clone to the fresh-cut blood-orange production because it has the lowest enzymatic activity (PME, PPO and AAO) and the highest sensorial quality. [source] | |||||||||||||