Browsing by Subject "LIPID OXIDATION"

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  • Liu, Chang; Damodaran, Srinivasan; Heinonen, Irma Marina (2019)
    The potential use of microbial transglutaminase (MTG)-treated faba bean protein isolate (FBPI) as emulsifiers to maintain physical and oxidative stability of oil-in-water (O/W) emulsion was investigated. MTG-treated FBPIs (MTG-FBPIs) were prepared by incubating with MTG for 60, 120 or 240 min. O/W emulsions were stabilized by 3% (w/v) of MTG-FBPIs or control-FBPI (treated with inactive MTG) and stored at 37 degrees C for 7 days. MTG treatments induced cross-linking in FBPI, raised the protein net surface charges by 5%-8%, and increased the emulsion particle size by 19%-135%. MTG treatment for 120 and 240 min but not 60 min induced excessive surface hydrophobicity, resulting in decreased emulsifying activity and physical stability of emulsion. By day 7, all MTG-treated FBPIs showed similar inhibiting effects against lipid oxidation in emulsion, indicated by less conjugated dienes and hexanal production. MTG-FBPIs moderately promoted protein oxidation (120 min > 240 min approximate to 60 min). Thus, prolonged MTG treatment should be avoided to prevent accelerated protein oxidation and droplets coalescence. MTG treatment for 60 min makes FBPI a potential emulsifier to maintain physical stability while improving lipid oxidative stability in emulsion, potentially attributed to thicker interfacial layer, larger droplet size, and protective effect of protein.
  • Bao, Yulong; Ertbjerg, Per (2019)
    Protein oxidation readily occurs in postmortem muscle during storage and processing. Over the past decade new analytical methods have been developed and new aspects of protein oxidation in meat have been studied, such as the reaction mechanism, and impacts on eating quality and nutritional value. It is now evident that amino acid side chains in myofibrillar proteins undergoes modifications due to oxidative stress. In turn this will lead to formation of new protein-protein cross-links in structural proteins, however, also the overall level of fixed-charge groups attached to the peptide backbones is modified. Meat texture and water-holding are important quality attributes and they are affected by the oxidation of structural proteins. Different mechanisms have been suggested to explain the oxidation-induced quality changes, focusing mainly on reduced proteolysis and formation of cross-links. This review explores the current understanding of protein oxidation in fresh meat in relation to texture and water-holding. The consequences of protein oxidation at molecular level in relation to oxidation-induced cross-linking and changes in net charges of myofibrillar proteins, and the impacts on texture and water-holding are discussed.
  • Brick, Tabea; Schober, Yvonne; Boecking, Christian; Pekkanen, Juha; Genuneit, Jon; Loss, Georg; Dalphin, Jean-Charles; Riedler, Josef; Lauener, Roger; Nockher, Wolfgang Andreas; Renz, Harald; Vaarala, Outi; Braun-Fahrlander, Charlotte; von Mutius, Erika; Ege, Markus Johannes; Pfefferle, Petra Ina; PASTURE Study Grp (2016)
    Background: Living on a farm has repeatedly been shown to protect children from asthma and allergies. A major factor involved in this effect is consumption of unprocessed cow's milk obtained directly from a farm. However, this phenomenon has never been shown in a longitudinal design, and the responsible milk components are still unknown. Objectives: We sought to assess the asthma-protective effect of unprocessed cow's milk consumption in a birth cohort and to determine whether the differences in the fatty acid (FA) composition of unprocessed farm milk and industrially processed milk contributed to this effect. Methods: The Protection Against Allergy-Study in Rural Environments (PASTURE) study followed 1133 children living in rural areas in 5 European countries from birth to age 6 years. In 934 children milk consumption was assessed by using yearly questionnaires, and samples of the ``usually'' consumed milk and serum samples of the children were collected at age 4 years. Doctor-diagnosed asthma was parent reported at age 6 years. In a nested case-control study of 35 asthmatic and 49 nonasthmatic children, 42 FAs were quantified in milk samples. Results: The risk of asthma at 6 years of age was reduced by previous consumption of unprocessed farm milk compared with shop milk (adjusted odds ratio for consumption at 4 years, 0.26; 95% CI,0.10-0.67). Part of the effect was explained by the higher fat content of farm milk, particularly the higher levels of omega-3 polyunsaturated FAs (adjusted odds ratio, 0.29; 95% CI,0.11-0.81). Conclusion: Continuous farm milk consumption in childhood protects against asthma at school age partially by means of higher intake of omega-3 polyunsaturated FAs, which are precursors of anti-inflammatory mediators.
  • 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.
  • Valoppi, Fabio; Maina, Ndegwa; Allen, Marja; Miglioli, Roberta; Kilpelainen, Petri O.; Mikkonen, Kirsi S. (2019)
    The food industry has a considerable demand for functional foods, such as emulsions as delivery system for omega-6 and omega-3 fatty acids. Such delivery systems must be stabilized, ideally with a compound that fulfills the criteria for both functionality and sustainability. Spruce galactoglucomannans (GGM) are novel, wood-derived, natural, value-added, versatile, multi-purpose emulsifiers that can physically stabilize oil-in-water emulsions while simultaneously protecting the oil phase against oxidation. In this study, we present for the first time the use of GGM-stabilized emulsions as complex multicomponent delivery systems for omega-6 and omega-3 fatty acids, i.e., (1) cod liver oil in drinkable yogurt and (2) oat oil in a gluten-free vegan beverage. The emulsions and the resulting functionalized beverages were characterized in terms of their physical stabilities. In addition, functionalized, drinkable yogurt was characterized in terms of the oxidative stability of the oil. Results highlighted that oil droplets stabilized with GGM were stable during storage, against thermal treatment, upon addition into the beverages, and GGM protected cod liver oil against oxidation in drinkable yogurt. The results reported here highlight the vast potential for the use of wood lignocellulose-derived, multi-functional hydrocolloids in modern foods.
  • Mikkonen, Kirsi S. (2020)
    Wood biomass is an abundant renewable source of materials, but due to the accelerating depletion of natural resources, it is important to explore new ways to use it in a more sustainable manner. Modern technologies enable the recovery and valorization of the main components of wood—namely, cellulose, lignin, and hemicelluloses—contributing to sustainability. However, the method of isolation and resulting structure and purity of lignocellulosic materials determine their functionality and applicability. This review discusses the properties of all three main wood-based compounds that can stabilize emulsions, a class of industrial dispersions that are widely used in life science applications and chemicals. Due to the multi-billion-dollar annual market for hydrocolloids, the food, pharmaceutical, cosmetic, coating, and paint industries are actively seeking new sustainable emulsion stabilizers that fulfill the demanding requirements regarding safety and functionality. Wood-derived stabilizers facilitate various mechanisms involved in emulsion stabilization: (1) development of amphiphilic structures that decrease interfacial tension, (2) stabilization of interfaces by particles according to the Pickering theory, and (3) increase in the viscosity of emulsions’ continuous phase. This review presents pathways for treating cellulose, lignin, and hemicelluloses to achieve efficient stabilization and provides suggestions for their broad use in emulsions.
  • Raitanen, Jan-Erik; Järvenpää, Eila; Korpinen, Risto; Mäkinen, Sari; Hellström, Jarkko; Kilpeläinen, Petri; Liimatainen, Jaana; Ora, Ari; Tupasela, Tuomo; Jyske, Tuula (2020)
    Bark of Norway spruce and Scots pine trees contain large amounts of condensed tannins. Tannins extracted with hot water could be used in different applications as they possess antioxidative and antimicrobial activities. The use of bark tannins as e.g., food preservatives calls for increases in our knowledge of their antioxidative activities when applied in foodstuffs. To assess the ability of bark tannins to prevent lipid oxidation, hot water extracts were evaluated in a liposome model. Isolated tannins were also applied in dry-cured, salty meat snacks either as liquid extracts or in dry-powder form. Consumer acceptance of the snacks was tested by a sensory evaluation panel where outlook, odor, taste, and structure of the snacks were evaluated and compared to a commercial product without tannin ingredients. Our results show that conifer bark tannin-rich extracts have high capacity to prevent lipid oxidation in the liposome model. The efficacies of pine and spruce bark extracts were ten to hundred folds higher, respectively, than those of phenolic berry extracts. The bark extracts did not significantly influence the odor or taste of the meat snacks. The findings indicate that bark extracts may be used as sustainable food ingredients. However, more research is needed to verify their safety.
  • Liu, Miao; Lampi, Anna-Maija; Ertbjerg, Per (2018)
    Abstract Lard from pork back fat was dry fractionated based on crystallization temperature, resulting in fractions with a ratio of saturated to unsaturated fatty acids of 1.10 and 0.61. Lean minced pork was mixed with the saturated and unsaturated fat fraction and stored in modified atmosphere (80% O2 and 20% CO2) at 5 °C for 2, 5, 7, 9, and 12 days under light to investigate the effect on oxidative stability of lipids and proteins. The saturated fat group developed higher TBARS values and lower levels of free thiol groups during storage, indicating that the unsaturated fat fraction in minced pork promoted increased oxidative stability of both lipids and proteins. A higher content of α-tocopherol in the unsaturated fat fraction suggests that the differences in oxidative stability is causatively linked to the balance between the fatty acid composition and content of antioxidants. The TBARS values and free thiol content were negatively correlated, suggesting a relationship between lipid and protein oxidation.