Amounts Of Lipid Oxidation Products Research Articles

Oxidative stability of linseed oil nano-emulsions filled in calcium alginate hydrogels

The main objective of this study was to fabricate calcium alginate hydrogels filled with linseed oil nanoemulsion (LON). Alginate beads were fabricated at different concentrations of sodium alginate (1% and 2%) and CaCl2 (0.25 and 0.5 M) and filled with whey protein isolate–stabilized LON. The hydrogels mechanical properties were influenced by the concentration of alginate and CaCl2. An increase in the concentration of both constituents decreased the release of LON mainly due to increasing the compactness in the bead microstructure. The first derivative of FT-IR spectra revealed no chemical interaction between LON and alginate matrix. SEM micrographs revealed structural differences among various hydrogels. As determined by Raman spectral mapping, the higher alginate concentration led to more uniform distribution of LON. The amounts of lipid oxidation products developed in LON were decreased after its loading into the alginate beads. The GC-FID analysis of fatty acids profiles revealed that the alginate beads (particularly those prepared from the higher concentrations of alginate and CaCl2) could significantly (p < 0.05) retard the degradation of alpha-linolenic acid. The results of this study showed that the alginate beads are appropriate carriers for delivery of the emulsified form of functional lipids rich in polyunsaturated fatty acids.

Quality of pilsner malt and roasted malt during storage

Malt is usually expected to be stable during 12 months of storage. However, in practice many brewers notice changes in malt aroma during storage. The oxidative stabilities of pilsner malt and roasted malt were evaluated during a 12 month storage at different temperatures (10 and 20 °C) and water activities (0.231 and 0.432). The radical content in malt kernels was measured by electron spin resonance spectroscopy and the volatile profile of the resulting sweet worts was measured by head-space analysis followed by GC-MS analysis. The storage of malt resulted in oxidative reactions and a large change of the volatile profile of the resulting worts. Roasted malt was much more unstable than pilsner malt, as illustrated by a higher initial radical intensity, larger radical decay during storage and a larger change in the volatile profile of the wort with increased amounts of lipid oxidation products. For both roasted malt and pilsner malt, good correlations were found between radical decay and changes in the volatile profile of the wort, where high temperature and high water activity resulted in the largest changes. During the 12 months of storage, the sugar extract of the wort made from the malts remained constant and was not affected by the chemical changes. This study suggests that chemical changes occurring in malts during less than 12 months of storage may potentially affect the aroma of beer, and that water activity and storage temperature should both be kept low in order to maintain a high malt quality. Copyright © 2014 The Institute of Brewing & Distilling

In depth study of acrylamide formation in coffee during roasting: role of sucrose decomposition and lipid oxidation

Coffee, as a source of acrylamide, needs to be investigated in depth to understand the contribution of different precursors. This study aimed to investigate the contributions of sucrose decomposition and lipid oxidation on acrylamide formation in coffee during roasting. Coffee beans and model systems were used to monitor the accumulation of neo-formed carbonyls during heating through sucrose decomposition and lipid oxidation. High resolution mass spectrometry analyses confirmed the formation of 5-hydroxymethylfurfural (HMF) and 3,4-dideoxyosone, which were identified as the major sugar decomposition products in both roasted coffee and model systems. Among others, 2-octenal, 2,4-decadienal, 2,4-heptadienal, 4-hydroxynonenal, and 4,5-epoxy-2-decenal were identified in relatively high quantities in roasted coffee. Formation and elimination of HMF in coffee during roasting had a kinetic pattern similar to those of acrylamide. Its concentration rapidly increased within 10 min followed by an exponential decrease afterward. The amount of lipid oxidation products tended to increase linearly during roasting. It was concluded from the results that roasting formed a pool of neo-formed carbonyls from sucrose decomposition and lipid oxidation, and they play certain role on acrylamide formation in coffee.

Effect of Thermally Oxidized Oil and Fasting Status on the Short-Term Digestibility of Ketolinoleic Acids and Total Oxidized Fatty Acids in Rats

Western diets contain substantial amounts of lipid oxidation products. The effects of fasting status and oil oxidation on short-term digestibility of oxidized fatty acids (ox-FA) and ketolinoleic acids (keto-LA) of sunflower oils were evaluated. Twelve rats were fasted overnight for 3 days, whereas another 12 rats had free access to diet. From day 4, and for 4 days, two groups of rats, nonfasted (NFT) and fasted (FT), received 1 g/100 g body weight of sunflower oil reused from 40 deep-frying processes, and two control groups of rats, nonfasted (NFC) and fasted (FC), received the same amount of fresh oil. Ox-FA and keto-LA were determined 5 h after the last administration in the various gastrointestinal compartments together with the intraintestinal MDA. Oil digestibility was highest in NFC and lowest in FT rats. NFT and FT rats had higher (at least P < 0.05) intraintestinal MDA, ox-FA, and keto-LA than NFC and FC; MDA and keto-LA concentrations correlated with each other (P < 0.05). Ox-FA and keto-LA levels found in the gastric lumen suggest that digestion contributes to the formation of these compounds. Total ox-FA and keto-LA were efficiently absorbed during the first 5 h after test oil administration, but poorly absorbed in the case of fresh oils. Oil alteration influenced the digestibility of these compounds more than fasting, although the digestibility of oxidized oil was significantly affected by fasting.

Mechanism Involved in the Formation of Characteristic Taste and Flavor during the Production of Dried Herring (Clupea pallasii) Fillet

The objective of this study was to identify the mechanisms responsible for the characteristic taste and flavor of dried herring fillet(DHF, migaki-nishin in Japanese). Dialyzed water-soluble fractions (DWSF)obtained from herring fillet were dried for 4 days, mixed with fatty acids, and the reaction products were evaluated for their effects on sensory perception.To clarify the mechanisms of in situ chemical changes in DHF lipid, ESI-MS analysis was done using a phosphatidylcholine probe. Sensory evaluation revealed that addition of the reaction products of DWSF with docosahexaenoic acid to Japanese noodle soup significantly (P < 0.05) enhanced soup flavor characteristics, such as thickness, mouthfulness, and continuity, compared to the reaction products of DWSF with linoleic acid or capric acid. ESI-MS analyses showed that lyso-derivatives were the most abundant compounds in the lipid fraction of DHF. A small amount of lipid oxidation products and their reaction products were also observed in DHF. This study demonstrated that during the drying period, partial hydrolysis of lipids released free fatty acids. These free fatty acids, or their oxidation products, might react withamino acid-related compounds to generate the characteristic taste and flavor of DHF.

Hyperoxia and Thyroxine Treatment and the Relationships between Reactive Oxygen Species Generation, Mitochondrial Membrane Potential, and Cardiolipin in Human Lens Epithelial Cell Cultures

Thyroxine-treated human lens epithelial cells, HLE B-3, were grown in either a normoxic or hyperoxic atmosphere as a first step in identifying factors related to their increased viability. Reactive oxygen species, ROS, and the apparent mitochondrial membrane potential, Δ Ψm, were measured using fluorescent probes. ROS were significantly higher in HLE B-3 cells grown in a hyperoxic atmosphere for both thyroxine-treated and untreated samples. However, treatment with thyroxine produced 40% lower ROS levels than untreated cells. A mitochondrial uncoupler concomitantly reduced ROS generation. In cells that were grown in a hyperoxic atmosphere, the Δ Ψm was significantly higher for samples treated with thyroxine compared to those that were untreated. ROS generation correlated inversely with the apparent Δ Ψm and the amount of cardiolipin, and correlated with the amount of lipid oxidation products. These correlations were valid whether cardiolipin and the Δ Ψm were decreased as a result of oxygen or increased as a result of thyroxine treatment. Therapies that protect mitochondria from damage and reduce damaging ROS generation may potentially ameliorate the effects of oxidation that occur in aging tissues and in diseases such as cataract.

Thyroxine Ameliorates Oxidative Stress by Inducing Lipid Compositional Changes in Human Lens Epithelial Cells

Lipid saturation and sphingolipids make model membranes less susceptible to oxidation. A human lens epithelial cell line, HLE B-3, was treated with thyroxine to determine whether this treatment increases lipid saturation and membrane sphingolipids, as it does in other tissues, and if so, to see whether the treatment ameliorates the affects of lipid oxidation. One group of HLE B-3 cells was treated with thyroxine, and another group was not. Cells were then grown in a normoxic (20% O(2)), or hyperoxic (80% O(2)), atmosphere. Phospholipid composition was determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry and (31)P nuclear magnetic resonance spectroscopy. Cell viability was determined with a trypan blue dye assay. A chromogenic reagent was used to measure the secondary products of lipid oxidation. After 6 days of growth in a hyperoxic atmosphere, the thyroxine-treated cells were 20 times more viable than were the untreated cells. As a result of thyroxine treatment, the phosphatidylcholine (PC)-to-sphingolipid molar ratio decreased significantly (by 52%), and the PCs were eight times more unsaturated than were the sphingomyelins. The decrease in the amount of PCs coupled with a 33% decrease in the average unsaturation of the sphingolipids resulted in a phospholipid membrane with fewer double bonds. Products of lipid oxidation were three times higher in untreated cells after growth in a hyperoxic atmosphere than in untreated cells grown in a normoxic atmosphere. Thyroxine treatment reduced the amount of lipid oxidation products by approximately 60% compared with that in untreated cells. A 100% increase in cardiolipin with thyroxine treatment may contribute to a decrease in reactive oxygen species generated by the mitochondria. The total antioxidant power was not affected by thyroxine. Therefore, thyroxine-induced fluctuations in antioxidant levels are unlikely to influence increased cell viability and a concomitant decrease in the amount of lipid oxidation products in thyroxine-treated cells. The results support the idea that membranes containing more cardiolipin and more sphingolipids and having higher levels of saturation are more resistant to oxidation and protect cells from oxidative stress. Development of a therapy to increase sphingomyelins and lipid saturation in the lens may delay the onset of cataract.

Fluorometric analysis of 2-thiobarbituric acid reactive substances in turkey

Three experiments were conducted to develop a sensitive and reliable fluorometric thiobarbituric acid (TBA) reactive substances (TBARS) method to determine lipid oxidation products in meat. The first study was conducted to find the optimum sample preparation conditions for meat in the fluorometric method. The second study was to compare the original and the modified methods by using meat and blood samples. The modified fluorometric method was compared with a conventional spectrophotometric method in a third study. Four different extraction solutions (2.5 M acetic acid, 0.5 M hydrochloric acid, 0.8 M perchloric acid, and 1.4 M trichloroacetic acid) and two ratios of extraction solution to TBA (20 mM) solutions (2:1 and 1:1) were examined in the first study. Hydrochloric acid was the optimum among the four extraction solutions tested, and the ratio of extraction solution to TBA solution at 1:1 was the best for the fluorometric TBARS method in raw ground turkey. The modified fluorometric method had high recovery rates (91%, average), and the regression coefficient of the standard curve prepared with spikes was also high (r2 = 0.99). The analysis of raw meat and plasma samples indicated that the modified fluorometric method had greater sensitivity than the original method. The pH of the reaction mixture played an important role in extraction TBARS from samples, and low pH conditions were preferable to high pH conditions. The amount of lipid oxidation products in raw turkey breast meat indicated that the fluorometric method had much greater sensitivity than the spectrophotometric method. The results from the three studies showed that the modified fluorometric TBARS method was useful for the samples with low lipid oxidation products, such as fresh raw meat. The sensitivity of the modified fluorometric method also facilitates the determination of oxidation products in small quantities of samples.

Effects of Microwave Cooking and Refrigerated Storage of Main Broiler Parts on Lipid Oxidation in Chicken Muscle and Skin

From a total of 78 chickens, 24 carcasses were used to estimate the percentage for the individual cuts and their composition. Fifty-four carcasses were cut vertically into halves of which two-thirds were quartered, yielding front and hind quarters (Cuts 2 and 3). Half of these quarters were cut into individual pieces, yielding breasts and thighs with back ribs, drumsticks, and wings. The muscles and skin of one-third from each of the seven different cuts described above were analyzed raw for lipid oxidation products; while the remaining two-thirds were microwaved. Half of the microwaved cuts were analyzed 2 hours after cooking; the other half, after 4 days of storage at 4 C.The results indicated that the absolute amount of lipid oxidation products in chicken muscles and skin after microwave cooking and refrigerated storage was affected by the initial level of those products in the raw samples and by the particular cut of meat Cooking the different cuts of chicken carcasses by microwave significantly increased the amount of malonaldehyde (MA) and lipid-oxidation fluorescent products (LOFP) in the aqueous phase of Folch-extracted muscles and skin and in the organic phase of Folch-extracted skin lipids. Microwave cooking for the separate broiler parts (especially the drumsticks and wings, as compared to halves or quarters) produced the lowest amount of lipid oxidation products due to the shorter cooking time. Refrigerated storage of broiler parts cooked by microwave produced substantial amounts of MA and LOFP in the aqueous phase of the Folch extracted skin and in the organic phase of the Folch-extracted lipids from the muscles.