Browsing by Subject "Lipid oxidation"

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  • Owen, Michael C.; Kulig, Waldemar; Rog, Tomasz; Vattulainen, Ilpo; Strodel, Birgit (2018)
    In an effort to delineate how cholesterol protects membrane structure under oxidative stress conditions, we monitored the changes to the structure of lipid bilayers comprising 30 mol% cholesterol and an increasing concentration of Class B oxidized 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) glycerophospholipids, namely, 1-palmitoyl-2-(9'-oxo-nonanoyl)-sn-glycero-3-phosphocholine (PoxnoPC), and 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC), using atomistic molecular dynamics simulations. Increasing the content of oxidized phospholipids (oxPLs) from 0 to 60 mol% oxPL resulted in a characteristic reduction in bilayer thickness and increase in area per lipid, thereby increasing the exposure of the membrane hydrophobic region to water. However, cholesterol was observed to help reduce water injury by moving into the bilayer core and forming more hydrogen bonds with the oxPLs. Cholesterol also resists altering its tilt angle, helping to maintain membrane integrity. Water that enters the 1-nm-thick core region remains part of the bulk water on either side of the bilayer, with relatively few water molecules able to traverse through the bilayer. In cholesterol-rich membranes, the bilayer does not form pores at concentrations of 60 mol% oxPL as was shown in previous simulations in the absence of cholesterol.
  • Aaen, Ragnhild; Lehtonen, Mari; Mikkonen, Kirsi S.; Syverud, Kristin (2021)
    The use of wood-derived cellulose nanofibrils (CNFs) or galactoglucomannans (GGM) for emulsion stabilization may be a way to obtain new environmentally friendly emulsifiers. Both have previously been shown to act as emulsifiers, offering physical, and in the case of GGM, oxidative stability to the emulsions. Oil-in-water emulsions were prepared using highly charged (1352 ± 5 µmol/g) CNFs prepared by TEMPO-mediated oxidation, or a coarser commercial CNF, less charged (≈ 70 µmol/g) quality (Exilva forte), and the physical emulsion stability was evaluated by use of droplet size distributions, micrographs and visual appearance. The highly charged, finely fibrillated CNFs stabilized the emulsions more effectively than the coarser, lower charged CNFs, probably due to higher electrostatic repulsions between the fibrils, and a higher surface coverage of the oil droplets due to thinner fibrils. At a constant CNF/oil ratio, the lowest CNF and oil concentration of 0.01 wt % CNFs and 5 wt % oil gave the most stable emulsion, with good stability toward coalescence, but not towards creaming. GGM (0.5 or 1.0 wt %) stabilized emulsions (5 wt % oil) showed no creaming behavior, but a clear bimodal distribution with some destabilization over the storage time of 1 month. Combinations of CNFs and GGM for stabilization of emulsions with 5 wt % oil, provided good stability towards creaming and a slower emulsion destabilization than for GGM alone. GGM could also improve the stability towards oxidation by delaying the initiation of lipid oxidation. Use of CNFs and combinations of GGM and CNFs can thus be away to obtain stable emulsions, such as mayonnaise and beverage emulsions.
  • Damerau, Annelie; Kakko, Tanja; Tian, Ye; Tuomasjukka, Saska; Sandell, Mari; Hopia, Anu; Yang, Baoru (2020)
    A promising way of processing Baltic herring, Clupea harengus membras, is turning the fish into boneless mince. However, Baltic herring is prone to lipid oxidation, which possesses a challenge for industrial applications. The aim of this work was to study the efficacy of press cakes from Finnish berries and a supercritical CO2 plant extract to limit lipid oxidation during frozen storage of Baltic herring mince and to determine the impact of these additions on consumer acceptance in a fish product. Peroxide value, formation of volatile oxidation products and loss of polyunsaturated fatty acids showed that the tested natural additives decreased oxidation to a greater or similar extent as conventional antioxidants during 10-month storage. While potential of berry press cakes and plant extracts as "green label antioxidants" was shown, consumer study indicated need for further research to reach both optimal antioxidative efficacy and sensory properties.
  • Liu, Yuxuan; Yang, Yifang; Li, Binbin; Lan, Qinjie; Zhao, Xixian; Wang, Yilun; Pei, Huijie; Huang, Xiaohong; Deng, Lin; Li, Jianlong; Li, Qin; Chen, Shujuan; He, Li; Liu, Aiping; Ao, Xiaolin; Liu, Shuliang; Zou, Likou; Yang, Yong (2022)
    ABS T R A C T We evaluated the effects of different oxidation levels of lipids on protein degradation and biogenic amines (BAs) formation during Sichuan-style sausages processing. Lipids with varying degrees of oxidation were obtained through storage at different temperatures and added as raw materials of Sichuan-style sausages, followed by the analyses of lipid oxidation, protein degradation, biogenic amine content, and other indicators. During the pro-cessing, with increasing degree of lipid oxidation, the contents of peroxide value (POV), thiobarbituric acid reactive substances (TBARs), protein degradation index (PI), amino acid nitrogen (AAN), free amino acids (FAAs), and BAs increased. Based on the protein electrophoresis results, the higher the oxidation degree of pig backfat, the higher degree of sarcoplasmic protein oxidation, and the greater myofibril protein degradation. Pearson correlation revealed that lipid oxidation, protein degradation, and BAs content correlated significantly (P < 0.05).
  • Yang, Zhen; Piironen, Vieno; Lampi, Anna-Maija (2019)
    The aim of the study was to investigate the occurrence and formation of peroxygenase catalysed non-volatile oxidised fatty acids (NVOFAs), especially epoxy and hydroxy fatty acids, which potentially provide off-flavours in oat. A method based on extraction of NVOFAs using accelerated solvent extraction and analysis by UHPLC-ELSD/MS was developed. Hydroxy and epoxy fatty acids from oleic and linoleic acids were present as major NVOFAs in non-heat treated (NHT) oat products, and the contents increased markedly during storage. In a controlled storage experiment, NVOFA contents in NHT oat flours increased to 1700-2000 mu g/g, whereas in heat-treated samples, only to 200-400 mu g/g. Epoxy fatty acids seemed to be the first products that occurred, followed by hydroxy fatty acids and minor NVOFAs. The formation of NVOFAs was related to lipase catalysed lipid hydrolysis and the formation of volatile lipid oxidation products. Inactivation of lipid degrading enzymes is crucial to producing stable oat products.
  • Gurbuz, Goker; Kauntola, Vilja; Diaz, Jose Martin Ramos; Jouppila, Kirsi; Heinonen, Marina (2018)
    Interactions of food proteins and lipids under oxidative conditions may lead to alterations in food texture as well as loss of nutritional and sensory quality. Oxidative and physical stability of oil-in-water emulsions stabilized with water-soluble proteins extracted from quinoa (Chenopodium quinoa) and amaranth (Amaranthus caudatus) was monitored in an oxidation study at 30 A degrees C for 7 days. Alkaline extraction of proteins from the flours followed by acid precipitation and freeze-drying was conducted and purified rapeseed oil was used to prepare emulsions via high-pressure microfluidizer. Protein-stabilized emulsions showed lower physical and oxidative stability compared to Tween(A (R)) 20-stabilized emulsions. Lipid oxidation volatile profiles of protein-stabilized emulsions indicated advanced oxidation. Comparison with the physically more stable emulsions stored at 6 A degrees C pointed to the role of co-oxidation between proteins and lipids in coalescence of oil droplets and increase in droplet size. Emulsions stabilized with amaranth proteins showed higher resistance to oxidation compared to quinoa protein containing emulsions.
  • Lehtonen, Mari; Merinen, Maria; Kilpeläinen, Petri O.; Xu, Chunlin; Willför, Stefan M.; Mikkonen, Kirsi S. (2018)
    Hypothesis: Amphiphilic character of surfactants drives them at the interface of dispersed systems, such as emulsions. Hemicellulose-rich wood extracts contain assemblies (lignin-carbohydrate complexes, LCC) with natural amphiphilicity, which is expected to depend on their chemical composition resulting from the isolation method. Lignin-derived phenolic residues associated with hemicelluloses are hypothesized to contribute to emulsions' interfacial properties and stability. Experiments: We investigated the role of phenolic residues in spruce hemicellulose extracts in the stabilization of oil-in-water emulsions by physical and chemical approach. Distribution and changes occurring in the phenolic residues at the droplet interface and in the continuous phase were studied during an accelerated storage test. Meanwhile, the physical stability and lipid oxidation in emulsions were monitored. Findings: Naturally associated lignin residues in GGM act as vehicles for anchoring these hemicelluloses into the oil droplet interface and further enable superior stabilization of emulsions. By adjusting the isolation method of GGM regarding their phenolic profile, their functionalities, especially interfacial behavior, can be altered. Retaining the native interactions of GGM and phenolic residues is suggested for efficient physical stabilization and extended protection against lipid oxidation. The results can be widely applied as guidelines in tailoring natural or synthetic amphiphilic compounds for interfacial stabilization. (C) 2017 Elsevier Inc. All rights reserved.
  • Moilanen, Henna (Helsingin yliopisto, 2020)
    Lipid oxidation presents one of the most important challenges for the processing and storage of edible oils by lowering the shelf life, nutritional value, and organoleptic properties of oils. Microencapsulation is a process where oil droplets are coated within a wall material matrix, and it offers a suitable solution to protect edible oils against oxidative deterioration. This study aimed at exploring the effects of wall material composition and relative humidity (RH) on the potential of microencapsulation to protect camelina and blackcurrant seed oils against lipid oxidation. Camelina and blackcurrant seed oils were emulsified using whey protein isolate (WPI) and maltodextrin (MD) as wall materials in 1:1, 1:3, and 1:9 ratio, and the total solids content and wall-to-oil ratio were kept constant. Microencapsulation was conducted by spray drying, and various parameters were analyzed, including emulsion viscosity, water sorption properties, and the surface oil content of microencapsulated powders. The powders were conditioned at 11% and 44% RHs at 21 °C, after which the sample vials were closed to maintain constant water content. The oxidative stability of the conditioned microencapsulated powders was analyzed over 10 weeks of accelerated storage conditions at 40 °C by measuring the volatile secondary lipid oxidation products every two weeks by headspace-solid phase-microextraction-gas chromatography-mass spectrometry method. The results showed that the best oxidative stability during the storage period was obtained by WPI-MD 1:1 ratio in both of the microencapsulated oils, even though this wall material composition resulted in the highest surface oil content and the lowest encapsulation efficiency. In blackcurrant seed oil powders, the water content obtained at 44% RH seemed to provide better protection against lipid oxidation than that of 11% RH. Regarding camelina oil powders, water content obtained in different RHs did not seem to affect the oxidative stability of the powders. However, based on the peak areas of volatile compounds detected at week 10, the water content obtained at 44% RH might provide better storage stability for camelina oil containing powders in long-term storage than that of 11% RH.