Thiobarbituric Acid Reactive Substances Test Research Articles

Involvement of Endoplasmic Reticulum Stress in Isoliquiritigenin-Induced SKOV-3 Cell Apoptosis

Isoliquiritigenin (ISL), a licorice chalconoid, is a bioactive agent with chemopreventive potential that has been patented for tumor treatment in China. This study investigated the mechanisms of ISL-induced apoptosis in ovarian carcinoma SKOV-3 cells. Cell viability was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. The apoptotic rate was determined via flow cytometry using an annexin V-FITC apoptosis detection kit. The intracellular reactive oxygen species (ROS) levels were assessed using a 2,7-dichlorofluorescein probe assay. Malondialdehyde (MDA) formation was determined via thiobarbituric acid reactive substance test. The expressions of growth arrest and DNA damage-inducible gene (GADD153/CHOP), 78 kDa glucose-regulated protein (GRP 78), α-subunit of eukaryotic initiation factor 2 (eIF2α) phosphorylation, activating transcription factor 6α (ATF6α), and unspliced form of X-box binding protein1 (XBP1U) were analyzed via Western blot. Caspase-3 and caspase-12 activities were assessed using a fluorometric kit. Findings indicate that ISL significantly inhibits SKOV-3 cell proliferation, increases intracellular ROS levels, and causes SKOV-3 cell apoptosis. Moreover, ISL-exposed SKOV-3 cells trigger endoplasmic reticulum (ER) stress, as indicated by the enhancement of ER stress-related molecules p-eIF2α, GADD153/CHOP, GRP78, XBP1 expression, and cleavage of ATF6α. However, caspase-12 inhibitor (Z-ATAD) effectively and partially prevents ROS and MDA formation and inhibits ISL-induced SKOV-3 cell apoptosis. ISL induces apoptosis via ER stress-triggered signaling pathways in SKOV-3 cells. ER stress-induced cancer cell apoptosis has been discussed in some patents.

Nitric oxide and membrane lipid peroxidation in photosynthetic and non-photosynthetic organisms under several stress conditions

Fil: Galatro, Andrea Veronica. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Bioquimica y Medicina Molecular. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Instituto de Bioquimica y Medicina Molecular; Argentina

Malondialdehyde Measurement in Oxidized Foods: Evaluation of the Spectrophotometric Thiobarbituric Acid Reactive Substances (TBARS) Test in Various Foods

The ability of the spectrophotometric thiobarbituric acid reactive substances (TBARS) test to determine malondialdehyde (MDA) in various food matrices was evaluated. MDA was extracted from the foods; the extract reacted with thiobarbituric acid (TBA); and the formed TBA-MDA adduct was measured spectrophotometricaly at 532 nm. In parallel, the TBA-MDA adduct was analyzed with high-performance liquid chromatography (HPLC) coupled with fluorescence detection. Oils and unprocessed and uncooked meat and fish products did not exhibit any significant difference in the amount of MDA measured by the two methods, indicating that the major substance reacting with TBA and forming an adduct that absorbs at 532 nm was MDA. However, in products such as dry nuts, pork sausages, cooked fish, and gouda cheese, an overestimation of MDA was observed, indicating that TBARS test was unsuitable for accurate determination of MDA. Furthermore, the results in the present work suggest that the overestimation of MDA by the TBARS test as it was applied is related to the interference of other than secondary lipid oxidation products.

Novel spectroscopic sensor for the hydroxyl radical scavenging activity measurement of biological samples

A novel spectroscopic sensor was developed and validated for hydroxyl radical scavenging (HRS) activity estimation using terephthalate (TP) as probe. This sensor was designed by electrostatic immobilization of the chromogenic oxidizing agent of the CUPric Reducing Antioxidant Capacity (CUPRAC) method, Cu(II)-Neocuproine (Cu(II)-Nc) complex, on a Nafion cation-exchange membrane, and the spectrophotometric assay developed in aqueous–alcoholic solutions was integrated to the CUPRAC sensor. Hydroxyl radicals (•OH) generated from an equivalent mixture of Fe(II)+EDTA with hydrogen peroxide attacked both the probe and the •OH scavengers in 37°C-incubated solutions for 1/2h. The HRS activity was measured using the decrease in CUPRAC absorbance at 450nm – arising from the reduction of Cu(II)-Nc reagent to the Cu(I)-neocuproine chelate – of the hydroxylated probe (TP) undergoing radical attack in the presence of •OH scavengers. The HRS activity was evaluated as the second-order rate constants of biologically active compounds for •OH scavenging and also as the percentage scavenging of a measured compound or sample relative to a reference compound. Using this reaction, a kinetic approach was adopted to assess the HRS activity of amino acids, plasma- and thiol-antioxidants. This assay, applicable to small molecule antioxidants and tissue homogenates, proved to be efficient for serine and albumin for which the widely used TBARS (thiobarbituric acid-reactive substances) test is nonresponsive. Under optimal conditions, about half of the probe (TP) was converted into 2-hydroxyterephthalate (hTP), and this monohydroxylated derivative, being the only product of hydroxylation, was a more specific marker of •OH than the non-specific malondialdehyde end-product of the TBARS test. The sensor gave a linear response to scavenger concentration in the competition kinetic equation.

Effect of electron beam irradiation on quality indicators of peanut butter over a storage period

Electron beam (e-beam) irradiation is an effective non-thermal processing step for the reduction of Salmonella in peanut butter. The objective of this study was to evaluate the effects of e-beam irradiation on quality indicators of peanut butter. Peanut butter samples were exposed to a range of e-beam doses and examined over a 14-day period at 22°C. Colour analysis (L∗, a∗, b∗), spreadability, peroxide values (PV) and thiobarbituric acid reactive substances test (TBARS) for lipid oxidation were monitored, fatty acid and amino acid profiles were verified and protein degradation was determined by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE). Changes in colour, PV, and TBARS were observed as e-beam dose increased. No significant changes in spreadability were observed (P>0.05). When applied to peanut butter, e-beam irradiation will produce significant changes in quality indicators; future studies should include sensory evaluation and consumer acceptance studies.

Effects of different concentrations of artemisinin and artemisinin-iron combination treatment on Madin Darby Canine Kidney (MDCK) cells

Artemisinin is a sesquitrepenelactone with an endoperoxide bridge. It is a naturally occurring substance from Artemisia species plants. Artemisia species have been used in oriental medicine for centuries to treat malaria, gastrointestinal helminthosia, diarrhea, and as an antipyretic and sedative agent. Antileishmanial activity of the plants has been announced a few years ago. Dogs are the most important reservoir of leishmaniasis in some parts of the world. To use it as an antileishmanial drug in dogs, its side effects on different organs, among them the kidney as the organ of elimination have to be elucidated. Artemisinin with different concentrations (0.15, 0.3, 0.6 and 1.2 μg/ml) was added to the culture of MDCK (Madin darby canine kidney) cells with and without iron (86 μg/dl). All the changes were controlled and photographed every 12 hours using an invert microscope. After 60 hours, supernatants and cell extracts were examined for LDH (lactate dehydrogenase) concentration and total protein. Also TBARS (thiobarbituric acid reactive substances) test was performed on cell extracts. Some microscopic slides were prepared from the cells and stained with hematoxylin-eosin for microscopic exams. Biochemical parameters showed cellular reaction and injury in a concentration dependent manner. Cell injury was more severe in the iron-added groups. Microscopic exams showed cell and nuclear swelling, granular degeneration, vacuole and vesicle formation, cellular detachment, piknosis, karyorrhexis, cellular necrosis and inhibition of new mitosis. On using the drug for leishmaniasis treatment in the dog, it should be done with caution and supervision.

Reutilization of Mango Byproducts: Study of the Effect of Extraction Solvent and Temperature on Their Antioxidant Properties

Mango biowastes, obtained after processing, contain large amounts of compounds with antioxidant activity that can be reused to reduce their environmental impact. The present study evaluates the effect of solvent (methanol, ethanol, acetone, water, methanol:water [1:1], ethanol:water [1:1], and acetone:water [1:1]), and temperature (25, 50, and 75 °C) on the efficiency of the extraction of antioxidants from mango peel and seed. Among the factors optimized, extraction solvent was the most important. The solvents that best obtained extracts with high antioxidant capacity were methanol, methanol:water, ethanol:water, and acetone:water (β-carotene test, antioxidant activity coefficient 173 to 926; thiobarbituric acid reactive substances test, inhibition ratio 15% to 89%; 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid ABTS(·+); and 2,2-diphenyl-1-picrylhydrazyl DPPH· scavenging, 7 to 22 and 8 to 28 g trolox equivalent antioxidant capacity [TE] per 100 g mango biowaste on a dry matter basis [DW]). Similarly, the flavonoid (0.21 to 1.4 g (+)-catechin equivalents per 100 g DW), tannin (3.8 to 14 g tannic acid equivalents per 100 g DW), and proanthocyanidin (0.23 to 7.8 g leucoanthocyanidin equivalents per 100 g DW) content was highest in the peel extracts obtained with methanol, ethanol:water, or acetone:water and in the seed extracts obtained with methanol or acetone:water. From the perspective of food security, it is advisable to choose ethanol (which also has a notable antioxidant content), ethanol:water, or acetone:water, as they are all solvents that can be used in compliance with good manufacturing practice. In general, increasing temperature improves the capacity of the extracts obtained from mango peel and seed to inhibit lipid peroxidation; however, its effect on the extraction of phytochemical compounds or on the capacity of the extracts to scavenge free radicals was negligible in comparison to that of the solvent. There are many antioxidant compounds in mango peel and seed, and they could be used as a natural and very inexpensive alternative to synthetic food additives. However, the conditions in which the antioxidants are extracted must be optimized. This work proves that conditions such as extraction solvent or temperature have a crucial impact on obtaining extracts rich in antioxidants from mango biowastes.

Investigation of the in vitro and ex vivo acetylcholinesterase and antioxidant activities of traditionally used Lycopodium species from South America on alkaloid extracts

Ethnopharmacological relevanceThe study was aimed at evaluating medicinal and therapeutic potentials of two Lycopodiaceae species, Lycopodium clavatum (L.) and Lycopodium thyoides (Humb. & Bonpl. ex Willd), both used in South American folk medicine for central nervous system conditions. Alkaloid extracts were evaluated for chemical characterization, acetylcholinesterase and antioxidant activities. Materials and methodsThe alkaloid extracts obtained by alkaline extraction were determined for each species by GC/MS examination. The evaluation of the anticholinesterase and the antioxidant activities of the extracts were tested by determining in vitro and ex vivo models. Effects on acetylcholinesterase (AChE) were tested in vitro using rat brain homogenates and ex vivo after a single administration (25, 10 and 1mg/kg i.p.) of the alkaloid extracts in mice. The in vitro antioxidant effects were tested for the 2-deoxyribose degradation, nitric oxide (NO) interaction, 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activity and total reactive antioxidant potential (TRAP). After an acute administration (25 and 10mg/kg i.p.) of the extracts in middle-aged (12 months) mice, the antioxidant effects were estimated through the thiobarbituric acid reactive substances test (TBARS), and the antioxidant enzymes activities for catalase (CAT) and superoxide dismutase (SOD) were measured. ResultsAChE activity was inhibited in vitro by the alkaloid-enriched extracts of both Lycopodium species in a dose and time-dependent manner in rat cortex, striatum and hippocampus. A significant inhibition was also observed in areas of the brain after acute administration of extracts, as well as decreased lipid peroxidation and increased CAT activity in the cortex, hippocampus and cerebellum. A moderate antioxidant activity was observed in vitro for the extracts. Chemically, the main alkaloids found for the two species were lycopodine and acetyldihidrolycopodine. ConclusionThis study showed that the biological properties of the folk medicinal plants Lycopodium clavatum and Lycopodium thyoides include AChE inhibitory activity and antioxidant effects, two possible mechanisms of action in Alzheimer's related processes.

The Effect of a Flaxseed Oil‐Enhanced Diet on the Product Quality of Farmed Brook Trout (Salvelinus fontinalis) Fillets

The effects of dietary modification with flaxseed oil-enhanced (Flax) feed on the product quality of brook trout fillets were examined. Trout were fed a commercial feed supplemented with fish oil (CD) or flaxseed oil (Flax) for 165 d before harvesting. Proximate composition and fatty acid profile were determined on fillets. Quality parameters of the raw fillets were examined over the storage period by measuring color (L*, a*, b*), muscle pH, and thiobarbituric acid reactive substances test. Evaluations on the cooked fillets included sensory evaluation with triangle tests and a paired preference test. There were no differences in proximate composition between the groups; however, the total omega-3 fatty acids were greater in Flax fillets (P<0.05). Diet and day were shown to interact in their effect on whiteness, pH, and lipid oxidation (P<0.05); however, linear regression did not determine that malondialdehyde concentration was associated with time in either diet type implying that lipid oxidation in the vacuum-packed fish was controlled at storage temperatures (4°C). Sensory panelists were able to choose the odd sample in a replicated triangle test analyzed using the β-binomial model, and there was preference for Flax fillets (P<0.05). Results indicate that a Flax-enhanced diet would have favorable effects on product quality of farmed brook trout.

Validation of Best Detection Methods for Measuring Oxidative Stress

We assessed the antioxidative effects of quercetin-feeding on ddY strain male mice by measuring luminol-amplified chemiluminescence that was enhanced by a hydrophilic free radical initiator 2,2′-azobis(2-amidinopropane) dihydrochloride. Quercetin suppressed chemiluminescent intensity in a dose-dependent manner in vitro with a half-inhibition concentration (IC50) of 3×10−8 M, which was lower than the value of synthetic antioxidant 2,6-di-tert-butyl-p-cresol (IC50: 7×10−7 M). Lysosomal (12 000×g pellet) and supernatant fractions obtained from the livers of mice fed a diet containing 0.2% quercetin for 7 days showed more inhibition of chemiluminescent intensity than those from non-treated mice. Quercetin feeding also resulted in the inhibition of lipid peroxidation as determined by a thiobarbituric acid reactive substance test which detected suppression of the release of lysosomal enzymes induced by lipophilic free radical initiator 2,2′-azobis(2,4-dimethylvaleronitrile). These results probably reflect radical quenching activity of quercetin, indicating that the measurement of chemiluminescence is a useful tool for the assessment of total antioxidant activity in biological systems.

Hippocampus lipid peroxidation induced by residual oil fly ash intranasal instillation versus habituation to the open field

Epidemiological studies have demonstrated the adverse effects of particulate matter (PM) inhalation on the respiratory and cardiovascular systems. It has been reported that air pollution may affect the central nervous system and decrease cognitive function. In rats, residual oil fly ash (ROFA) instillation causes decreased motor activity and increased lipid peroxidation in the striatum and the cerebellum. Our objective was to determine whether chronic instillation of particles induces changes in learning and memory in rats and whether oxidants in the hippocampus may contribute to these adverse effects. Forty-five-day-old male Wistar rats were exposed to ROFA by intranasal instillation and were treated with N-acetylcysteine (NAC) at 150 mg/kg i.p. for 30 days. Control groups were exposed to ROFA, NAC, or neither. On days 1, 8, and 30 of the protocol, rats were submitted to the open field test to evaluate habituation. After the last open field session, the rats were killed by decapitation. The hippocampus was used to determine lipid peroxidation (LP) by the thiobarbituric acid-reactive substances test. ROFA instillation induced an increase in LP in the hippocampus compared to all treatment groups (p = .012). NAC treatment blocked these changes. All of the treatment groups presented a decrease in the frequency of peripheral walking (p = .001), rearing (p = .001), and exploration (p = .001) over time. Our study demonstrates that exposure to particles for 30 days and/or NAC treatment do not modify habituation to an open field, a simple form of learning and memory in rats, and that oxidative damage induced by ROFA does not modulate these processes.

Vacuum-packed ripened sausages: Evolution of oxidative and hydrolytic degradation of lipid fraction during long-term storage and influence on the sensory properties

An experimental investigation was carried out with the aim to understand the oxidative and hydrolytic phenomena involving the lipid fraction of vacuum-packed sausages during long-term storage (5 months) and to verify their influence on the sensory characteristics. The data obtained pointed out that the oxidation was more pronounced in the initial stages of storage than in the further period, while the hydrolysis of lipid fraction significantly advanced during the whole storage time, supported by the high moisture level of the product. Both these phenomena resulted to be correlated with the sensory decay of the product. In particular, in the first stage of vacuum storage overall acceptability was found to be negatively correlated ( p < 0.05) with rancid taste, acid value, and oxidized triacylglycerols. In the further stage the oxidative processes slowed down and affected in a lesser extent the sensory properties, which were more distinctly characterized by the onset of pungent perception attributed to compounds arising from multiple origins such as carbohydrate fermentation. This investigation confirmed the unreliability of thiobarbituric acid reactive substances test and the usefulness of high performance size exclusion chromatography analysis of the polar compounds of the lipid fraction to correctly determine the levels of the oxidative and hydrolytic degradation of the lipid fraction of vacuum-packed ripened sausages during long-term storage.

Antioxidant activity in banana peel extracts: Testing extraction conditions and related bioactive compounds

Abstract Banana (Musa acuminata Colla AAA) peel extracts obtained in this work had a high capacity to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH ) and 2,2′-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS +) free radicals, and they were also good lipid peroxidation inhibitors. Acetone:water extracts were considerably more effective (compared with methanol, ethanol, acetone, water, methanol:water or ethanol:water) at inhibiting the peroxidation of lipids in the β-carotene/linoleic acid system or scavenging free radicals. However, aqueous extracts had a high capacity to protect lipids from oxidation in the thiobarbituric acid reactive substances (TBARS) test, as well as in the β-carotene bleaching assay. In addition, acetone:water most efficiently extracted all extractable components (54 ± 4%), phenolic compounds (3.3 ± 0.8%), and anthocyanin compounds (434 ± 97 μg cyanidin 3-glucoside equivalents/100 g freeze-dried banana peel). Banana peel contained large amounts of dopamine and L-dopa, catecholamines with a significant antioxidant activity. However, ascorbic acid, tocopherols or phytosterols were not detected in the different extracts. The antioxidant activity of banana peel extracts from different cultivars was similar. However, the impact of extraction time or temperature should be studied in greater depth.

Evaluation of processed cheese fortified with fish oil emulsion

Abstract Processed cheese fortified with fish oil is an excellent food for the delivery of omega-3 long-chain polyunsaturated fatty acids (omega-3 LC PUFA). However, oxidation and the “fishy” flavour of fish oil limit the level of fortification. The physical properties, lipid oxidation, and sensory perception of model processed cheese slices fortified with a fish oil emulsion (encapsulated fish oil) were examined and were compared with those of samples fortified with straight fish oil. Peroxide values, the results of thiobarbituric acid reactive substances (TBARS) tests, and propanal values showed that cheese samples fortified with fish oil emulsion had lower levels of oxidation than cheese samples fortified with non-encapsulated fish oil. A sensory panel detected a “fishy” flavour at a higher level of fish oil addition in the samples fortified with fish oil emulsion. This suggests that a fish oil emulsion made with a milk protein complex is a useful carrier for elevating the fortification level of omega-3 LC PUFA in processed cheese products.

230 COMPARISON OF SEMEN SAMPLES FROM NORMAL AND MUSCULAR DYSTROPHY AFFECTED ANIMAL MODELS BY THIOBARBITURIC ACID REACTIVE SUBSTANCES TEST AND FLUORESCENCE-ACTIVATED CELL SORTING ANALYSIS

Duchenne’s muscular dystrophy (DMD) is the most common human muscular affliction with high frequency in male individuals. The condition is characterized by progressive muscle degeneration, weakness, and loss of motion capacity. These individuals exhibit longer lifespans resulting from improvements in technical patient care and now raise new questions ranging from ethical to physiological issues never observed before, such as the possibility of reproduction. Thus, this study used Golden Retriever muscular dystrophy (GRMD)-affected dogs, a natural experimental model of DMD, to evaluate semen quality and oxidative stress by thiobarbituric acid reactive substances (TBARS) test. Thirty-seven ejaculates from 4 non-affected Golden Retriever and 5 GRMD-affected dogs (from 1.5 to 4.5 years old) were collected monthly and evaluated as 5 different replicates. Semen samples were processed, and initial analysis comprised of sperm concentration, percent of straightforward motility and morphology. Samples were then diluted to a final concentration of 106 spermatozoa mL–1 of prior incubation with each fluorescent probe. Acrosome integrity assessment was conducted with PSAFITC (100 g mL–1), and mitochondrial activity was assessed by JC1 (50 g mL–1). Fluorescence-activated cell sorting was performed in 103 spermatozoa, from a pre-selected gate that contained only these cells. Seminal plasma was submitted to TBARS quantification by spectrophotometer under normal and oxidative conditions (stress). Parametric data were compared by Student’s t-test. There were no significant differences in ejaculate volume, sperm concentration, acrosomal integrity, mithocondrial activity, and ejaculate TBARS tests between GRMD and normal dogs. Data are summarized in the table. GRMD does not affect the production and quality of semen of dogs. This animal model suggests that ejaculates from DMD men can be obtained by the proper stimulation and that conventional in vitro fertilization techniques combined with preimplantation genetic diagnosis for single gene disorders may be able to satisfy the desire of paternity of DMD patients with the birth of non-affected children. Table 1.Sperm analysis and TBARS tests of ejaculates from GRMD and normal dogs FAPESP for the financial support (06/50272-3); Surgery Department and Reproduction Department of FMVZ-USP; Canil GRMD Brazil.

A simple automated procedure for thiol measurement in human serum samples

Thiol groups have been described as the main responsible for antioxidative effects of plasmatic proteins. Also, thiol serum levels have shown a positive correlation with total antioxidant capacity (TAC) in many studies. Measurement of TAC by substract oxidation-based methods have been widely used as a reference to measure antioxidant status; however, in many cases these methods are inexact or imprecise, usually when performed by manual procedures. In this paper we describe a simple automated procedure for the determination of total thiols in serum, which was based on Ellman’s method. It was correlated with several markers of oxidative/antioxidative status, such as TAC and thiobarbituric acid reactive substance test (TBARs). Serum thiol levels were correlated positively with TAC (r = 0.298, p < 0.001) and negatively with TBARs levels (r = -0.330, p < 0.001). The novel automated procedure for thiol groups measurement can be a great tool in estimation of antioxidant status together with TAC assay. This procedure makes the determination of total thiol groups in large scale possible in clinical chemistry or research laboratories where this approach is necessary.

Copper(II) interactions with non-steroidal anti-inflammatory agents. III – 3-Methoxyanthranilic acid as a potential [rad]OH-inactivating ligand: A quantitative investigation of its copper handling role in vivo

Pharmacological activities of copper(II) complexes are a direct function of the nature of their ligands associated with the metal ion in vivo. Some of these, defined as OH-inactivating ligands (G. Berthon, Agents Actions 39 (1993) 210–217), may act as specific “lures” for hydroxyl radicals at inflammatory sites and behave as pseudo-catalase-like agents. This property has been advanced for anthranilic acid (H. Miche, V. Brumas, G. Berthon, J. Inorg. Biochem. 68 (1997) 27–38). With a view to improve the chemical features required to render such inactive substances effective anti-inflammatory drugs through their association with copper(II), an in vitro investigation into copper(II) interactions with the anionic form of an anthranilic acid derivative, namely 3-methoxyanthranilate (Man), has been performed under experimental conditions pertaining in vivo. Copper(II)–Man complex equilibria have been determined using glass electrode potentiometry, then checked by UV–vis and mass spectrometries. Given the prime role of histidine as a copper(II) ligand in blood plasma, copper(II)–histidine–Man ternary equilibria have also been studied. Subsequent computer simulations of the distribution of copper(II) in the extracellular fluid revealed that Man can specifically mobilize Cu(II) ions under inflammatory conditions without affecting their distribution under normal physiological conditions. Thiobarbituric acid reactive substances (TBARS) tests conducted with respect to standardized copper-mediated Fenton-type reactions (P. Maestre, L. Lambs, J.P. Thouvenot, G. Berthon, Free Rad. Res. 20 (1994) 205–218) have shown that, like anthranilic acid, Man can effectively both increase the Fenton-like reactivity of copper and decrease the amount of TBARS detected in solution, i.e., act as a potential OH-inactivating ligand.

Effect of Antioxidant (α-Tocopherol and Ascorbic Acid) Fortification on Light-Induced Flavor of Milk

The effectiveness of added antioxidants against oxidation off-flavor development in light-exposed milk was evaluated using sensory and chemical analysis. Sensory testing for similarity showed no perceivable difference between control milk and milk with added (1) 0.05% α-tocopherol (TOC) and (2) 0.025% α-tocopherol and 0.025% ascorbic acid (TOC/ASC), but did demonstrate a perceivable difference when adding (3) 0.05% ascorbic acid (ASC) alone. Subsequently, sensory testing for difference showed a significant difference in oxidation off-flavor between light-exposed control milk and light-exposed milk with added TOC/ASC, whereas milk fortified with TOC was not different from control. Gas chromatography-olfactometry showed that more aroma-active flavor compounds were observed in light-exposed milk treated with TOC and TOC/ASC than light-exposed milk with no added antioxidants. The thiobarbituric acid reactive substances (TBARS) test verified chemically the extent of oxidation in control and antioxidant-treated milk samples. Milk that was exposed to light for 10h showed a significantly higher TBARS value (0.92±0.09 mg/kg) than milk that was protected from light (0.59±0.184 mg/kg), or milk that was treated with TOC/ASC (0.26±0.092 mg/kg). Direct addition of low levels of antioxidants (TOC/ASC) to milk protected its flavor over 10h of light exposed storage.

Effect of dietary non-protein energy levels on condition and oxidative status of Senegalese sole ( Solea senegalensis) juveniles

The effects of dietary non-protein energy levels on growth, oxidative status and condition were studied in juveniles of Senegalese sole ( Solea senegalensis). Four isonitrogenous diets with four energy levels were used: A—low (11% lipid, raw carbohydrate); B—intermediate (11% lipid, digestible carbohydrate); C—intermediate (21% lipid, raw carbohydrate); and D—high (21% lipid, digestible carbohydrate). Survival, relative growth rate (RGR) and feed conversion rate were not significantly affected by the dietary treatments. The fatty acid composition of the fish muscle varied little among the treatments, but trans 18:2 n−6, total n−6 and EPA/DHA ratio, tended to be higher in fish fed diets with low lipid level. Cellular energy allocation (CEA) results (indicative of metabolic status and net energy budgets) showed significant differences in liver, but not in muscle samples. Livers of fish fed diet C contained the lowest carbohydrate, protein and CEA values, but the highest cellular energy consumption. Fish fed diet A had the highest CEA for growth, followed by fish fed diets B and D and then diet C. The liver and muscle peroxidation and antioxidant activity were measured by thiobarbituric acid reactive substances (TBARS) test and the enzymatic activities levels of catalase (CAT) and superoxide dismutase (SOD). TBARS values were higher for fish fed diets with high lipid content. However, no clear relation was found between HUFA level and TBARS value. The activity levels of the antioxidant enzymes CAT and SOD were higher in livers of fish fed diets with a high lipid level. Furthermore, CAT and SOD activity and TBARS values were influenced by the type of dietary starch in the diet. Higher oxidation rates were observed in fish fed diets containing raw carbohydrate. These data suggest that lipid and carbohydrate energy sources affect the oxidative status of Senegalese sole. Diets containing low levels of lipid and digestible starch reduce the susceptibility of the fish to oxidation and may enhance growth rate.

The Effect of Open-market Retail Conditions in Nigeria on Oxidative Deterioration of Imported Frozen Upper Arms (Brachium) of Turkeys

The effect of different periods of display and/or storage, as practiced under retail conditions for frozen turkey upper arms in Nigerian open markets, on physical appearance, odour and extent of lipi d peroxidation of the meat was investigated. Five batches of frozen turkey shipments, sampled bi-monthly at 45 upper arms per batch were used. The frozen upper arms from each batch were displayed on the counter for up to 3 days, but re-frozen overnight. Five samples from the same batch were removed at 6 hourly intervals, giving a total of 9 treatments per batch. The samples were assessed for physical quality attributes (appearance and odour) by a 7-member panel using a 9-point Hedonic scale. The turkey upper arms were dissected and the moisture and lipid contents of the muscles measured. Extent of oxidation of muscle was determined by quantifying the malonaldehyde (MDA) concentration using the thiobarbituric acid reactive substances test. Muscle, bone and skin were found to represent 65.05 ± 4.28, 23.51 ± 4.21 and 14.44 ± 2.49% by weight of the intact upper arms. The relationship between the intact upper arms and the skin, bone and muscle, as measured by the correlation coefficient were found to be 0.60, 0.50 and 0.95 respectively (P<0.001). A strong relationship (r = 0.95, P<0.001) was found between physical appearance and odour of the meat. The physical appearance and odour of turkey upper arms were adversely affected (P<0.01) by increasing length of display and/or storage. The meat were disliked at the afternoon (for odour) and evening (for physical appearance) of the second day of display. Moisture and lipid contents of samples were 69.89 ± 0.94 and 4.58 ± 0.75% respectively. MDA concentrations of the turkey upper arms were found to increase with increased length of display and/or storage and were 2.90 ± 0.82 mg MDA/kg muscle for the fresh and 4.87 ± 0.83 mg MDA/kg muscle at the end of third day of display and/or storage.