An official website of the United States government.

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Chemistry of Lipids in Foods and Tissues

Institutions
University of California - Davis
Start date
2007
End date
2013
Objective
  1. Determine the role of crystalline fat in the physical properties of foods.
  2. Determine the role of fat composition,catalysts and inhibitors on the oxidative stability of foods.
  3. Investigate the role of lipids and lipid oxidation products in modifying food safety.
  4. Investigate the role of lipids in the nutritional value of foods.
More information
NON-TECHNICAL SUMMARY: The proposed research is directed toward an understanding of the basic chemical and biochemical properties of food lipids and how these relate to the organoleptic, structural and nutritional value of foods and diets. The lipid components of food provide desirable organoleptic properties to consumers, challenges to agriculture in quality and safety and are implicated in the overall health consequences of foods and diets. To improve the overall quality of foods and diets, it is necessary to build an integrated view on the lipids to understand simultaneously their benefits and liabilities. Milk is a model of how diet can be an controller of overall metabolism (Smilowitz et al. Aust. J. Dairy Tech.). We have developed technologies to measure the consequences of diet (Ninonueva et al., Electrophoresis, German et al., Metabolomics), and been invited to recruit the nutrition community to this approach (Zeisel et al., JN, Gibney et al. AJCN). It is important to know how the food consumer receives and interprets information about foods and diets in terms of their own health and how these sources of information ultimately influence food choices (Moskowitz et al.CRFSN). Altogether the research is illustrating that critical knowledge of dietary fats is still lacking and designing optimal foods and diets will require the means to both understand the metabolic differences between individuals and to understand the metabolic consequences of consuming different dietary fats.

APPROACH: 1. We will continue development of technologies to further refine an understanding of the basis of the role of lipids in food textures. Phase behaviors, crystallization, emulsification and micellization, are vital to food structure, stability and nutritional value. The molecular and colloidal structures of lipids will be defined by optical NMR and light scattering methods to build knowledge to improve the processes of forming foods, and ultimately to design foods that take advantage of the physical properties of lipids to form desired structures spontaneously. 2. The composition and the structure of lipids alters the rate and pathways of oxidation. Research will define food structures that alter oxidation. Food emulsion systems will be assembled from lipid, protein and carbohydrate polymers using dispersion methods including sonic disruption, physical disruption, membrane filtration and centrifugation. The physical properties of the emulsion particles will be analyzed by optical NMR and light scattering methodologies. Oxidation will be initiated by metal catalysts present as various chelates. Oxidation will be analyzed by separating the various oxidized molecules and analyzing them by chromatography, mass spectrometry and chemiluminescence techniques. 3. The effect of varying polyunsaturated fatty acid composition and the consequences of this change on oxidative processes will be studied. The biomarkers of oxidative damage that have been developed in an attempt to quantify the extent and consequences of oxidation in vivo, are inadequate to the task at hand. Metabolic indices of oxidative damage in vivo will be developed and used to gauge biological damage and its prevention by selected dietary antioxidant molecules. In brief, living organisms, yeast, C. elegans, bacteria will be analyzed for a variety of metabolites including fatty acids, phospholipids and membrane components including ubiquinone and tocopherols. The quantitative metabolic profiles will be analyzed by various comparative methods to determine the biochemical pathways affected by oxidation. 4. Bioinformatic and experimental approaches will be used to explore various genomes for the genes responsible for milk and its role in nutrition. Genomic databases will be examined for genes consistent with expression during lactation by 1) literature precedent, 2) known function, 3) promoter activation by known lactation hormone elements, and 4) promoter activation by consensus sequences to known lactation genes. Genes will be clustered according to known and putative functions by comparison with annotated databases (Swissprot expasy). Novel functions will be deduced by comparing sequence motifs with existing functional genes screened through prokaryotic and eukaryotic genomes. Pathways of lactation activity will be prepared and annotated according to putative nutritional functions. Functions will be confirmed in collaboration with physiologists and nutritionists at UCDavis and around the country.

PROGRESS: 2007/01 TO 2007/12
Research continues to understand how dietary lipids alter the metabolic fluxes of animals and humans and how the evolutionary process of mammalian milks provides molecular and mechanistic insights into novel strategies to improve human diets (Hilyard and German, Frankel and German). Studies in 2007 focused on the implications of dietary lipids on metabolic diseases (Zivkovic and German, Zivkovic et al., German et al.). Studies have examined the distinctions between trans fatty acids produced by industrial hydrogenation versus those produced in the bovine rumen (Destaillats et al.). We have continued to examine the role of food structure on its nutritional properties and found that milk is a remarkably structuring food material with considerable delaying of intestinal clearance accomplished by self-assembling structures (Lemay Dillard & German). The consequences of undigestible components in milk to alter the intestinal microflora constitutes a new area of active research in the program with studies to date finding remarkably unique structures of undigestible oligosaccharides in human breast milk (Ninonueva et al., Ward et al., Locascio et al., Seipert et al.). The new fields of nutrigenomics and metabolomics are providing considerable opportunities to assess human health and guide diets to specific individuals (German & Watzke, Lange et al.). Nonetheless, the opportunities possible with these new tools cannot be fully achieved without a considerable investment in building the critical databases needed and making these available to the entire scientific community as standardized, public datasets (Lemay et al). Research is continuing to develop these new tools of bioinformatics and provide examples of their appropriate applications to food and nutrition research.

IMPACT: 2007/01 TO 2007/12
Lipids (i.e. fats and oils) in foods either naturally or due to explicit formulations provide many of the distinct and desirable properties of many foods, though ongoing nutrition research has recognized that diets imbalanced in lipids are potentially highly deleterious to the health of individuals. However, it is not yet certain which dietary fats are deleterious nor for whom. Thus dietary guidelines recommend to limit the consumption of dietary fat without considerable information beyond a simple lower fat diet. Improving human health through better diets will require that the tools to assess variations in human health are matched to the disparate health properties of lipids and to understand simultaneously their benefits and liabilities. Milk is a model of how diet can influence many aspects of metabolism and mammalian milks provide models of various lactation strategies to understand which components in the diet would be optimum from a health perspective. Ongoing studies of human milk have continued to reveal biological strategies for nourishing humans that are not apparent in examining simple plant foods. For example the oligosaccharides that are abundant in human milk are unique in their structures and functions. Having assembled a multi-national collaboration of scientists to understand these components, we have begun apply new tools of bioinformatics, analytical chemistry and new models of biological processes to understand how the principles of nourishment contained in milk can be applied to humans of all ages. These molecules provide unique nutritional values, and the immediate goals are to understand which structures are responsible. Once the structures are known, we shall pursue methods to industrialize their production.

PROGRESS: 2006/01/01 TO 2006/12/31
Research continues to understand how dietary lipids alter the metabolic fluxes of animals and humans and how the evolutionary process of mammalian milks provides molecular and mechanistic insights into novel strategies to improve human diets. Studies have focused in 2006 on the consequences of consuming milk lipids. The lipids of milk are not naturally a simple protein stabilized globule of triglycerides as is produced during homogenization. Rather, the globule structure is a remarkable cocktail of complex lipids including a conspicuous abundance of membrane phospholipids (Ward et al). The implications of the structures and compositions of natural fat globules have not been studied in any detail and thus we have begun to explore the implications of the actual structures of native fat globules. The diversity of fatty acids in milk have not been thoroughly considered either (German and Dillard). The increasing attention of scientists, regulatory agencies and the food industry on trans fats has largely ignored the fact that there is a fundamental chemical difference between naturally occurring trans found in ruminants (bovine meat, milk and dairy products) and the trans fats produced by industrial hydrogenation. A large multi-center trial has been started to understand the metabolic and health consequences of these chemical differences (Chardigny et al.). Perhaps most surprisingly, as the tools of nanoscience have gained widespread acceptance as being a powerful new scientific field, the most critically important nanoparticles in human health; serum lipoproteins, have been ignored in the rush to invent and describe completely novel nano-materials. We have addressed the opportunities available to these two scientific communities if they refocused the attention of nanoscience on biological particles that are of larger impact to the foreseeable future of science based technologies (German et al.). In part to understand the metabolic consequences of consuming lipids and also because metabolic disregulation continues to grow as a threat to health the technologies used to measure metabolism in a comprehensive and accurate manner remain a priority (German et al, Ninonuevo et al). Consensus for how to proceed in the new fields of nutrigenomics and metabolomics particularly as they relate to diet and health is being assembled and published as position documents (Dixon et al). The establishment of the International Milk Genomics Consortium represents a breakthrough in building an International team of scientists to address the multi-disciplinary task of understanding the health implications of mammalian milks (German et al.). Ongoing research under this umbrella is establishing new tools of bioinformatics that are necessary to building a knowledge base that is both accessible to a wide audience of scientists and strategically valuable in guiding cross-disciplinary and collaborative research on milk.

IMPACT: 2006/01/01 TO 2006/12/31
The lipids (i.e. fats and oils) are responsible for many of the distinct and desirable organoleptic properties of many foods, yet nutrition research suggests that fats in foods may be deleterious and the dietary guidelines recommend to limit the consumption of dietary fat. To improve the overall quality of foods and diets, it is necessary to reconcile these disparate properties of lipids, to build an integrated view of the lipids in agricultural commodities and foods and to understand simultaneously their benefits and liabilities. Milk is a model of how diet can influence many aspects of metabolism and mammalian milks provide models of various lactation strategies to understand which components in the diet would be optimum from a health perspective. In studying human milk we have been struck by the complexity of the molecules contained therein and the discouraging lack of scientific knowledge of the evolutionary selective advantages that led to them being there. The oligosaccharides are abundant in human milk but it is still not known why. We have established a large multi-national collaboration of scientists to understand these components. We have begun to develop the tools that all scientists can use to address the many questions that the presence of these metabolites in milk pose. If these molecules provide unique nutritional values, then it is critical to know which structures are responsible. Finally we are pursuing the structure/function relationships of these materials to be able to produce them industrially and make them available to the entire food supply.

PROGRESS: 2005/01/01 TO 2005/12/31
Research has sought to understand how lipids alter the mechanistic machinery of animals. Using a strategy of feeding animals diets varying in only the amount of long chain polyunsaturated fatty acids we have been able to define the various consequences on the metabolism of these animals. These studies found that the inclusion of polyunsaturated fatty acids to the diets of these animals had both acute metabolic effects, i.e. altered the membrane composition of cells and tissues, but also influenced the expression of families of genes in these animals (Mutch et al. FASEB J). Some genes were expected, e.g. those responsible for adding double bonds to fatty acids, but the overall metabolic machinery of the animals was altered as well. The gene encoding the enzyme stearoyl CoA desaturase 1 was down-regulated in response to feeding arachidonic acid. This gene has been implicated in the development of obesity and predisposition to diabetes that is a consequence of obesity. These results imply that arachidonic acid in the diet acts to alter the basic energetic machinery in cells and could represent a novel strategy for understanding and ultimately preventing the energy disregulation that can lead to obesity. Studies have also examined the consequences of consuming milk. There are excellent scientific reasons to study milk since this is the only biomaterial that evolved for the express purpose of nourishing mammals. Therefore we have been interested in understanding how milk affects overall metabolism and in particular energy metabolism, a particular challenge to the young neonate. Milk has also proven to be not just a supplier of nutrients but is emerging as a model of how diet can be an important controller of overall metabolism, improving the storage of excess lipids as adipose and avoiding the inappropriate accumulation of energy intermediates in blood (Smilowitz et al. Aust. J. Dairy Tech.). Because metabolic disregulation is emerging as such a problem to human health we have continued to develop the technologies necessary to measuring metabolism in a comprehensive manner and especially with the accuracy and precision necessary to be able to detect the normally subtle consequences of consuming dietary fats and other macronutrients (Ninonueva et al., Electrophoresis, German et al., Metabolomics). We have also been requested to provide conceptual articles as the means to educate and recruit the larger nutrition community in the USA and around the world to the applications of this approach both for scientific research in Nutritional Sciences, but also to its ultimate applications as foods for human health (Zeisel et al., JN, Gibney et al. AJCN). It is also important to understand how the modern food consumer receives information about foods and diets, how the consumer interprets this information in terms of their own health and how these sources of information ultimately influence food choices. We have examined the internet as a very modern and potentially revolutionary information source for consumers about foods and diets, their risks and benefits (Moskowitz et al.CRFSN).

IMPACT: 2005/01/01 TO 2005/12/31
The lipid components of food provide desirable organoleptic properties to consumers, challenges to agriculture in quality and safety and are implicated in the overall health consequences of foods and diets. To improve the overall quality of foods and diets, it is necessary to build an integrated view on the lipids to understand simultaneously their benefits and liabilities. Polyunsaturated fatty acids exhibit metabolic effects but also influence the expression of multiple genes in animals (Mutch et al. FASEB J). Milk is a model of how diet can be an controller of overall metabolism (Smilowitz et al. Aust. J. Dairy Tech.). We have developed technologies to measure the consequences of diet (Ninonueva et al., Electrophoresis, German et al., Metabolomics), and been invited to recruit the nutrition community to this approach (Zeisel et al., JN, Gibney et al. AJCN). It is important to know how the food consumer receives and interprets information about foods and diets in terms of their own health and how these sources of information ultimately influence food choices (Moskowitz et al.CRFSN). Altogether the research is illustrating that critical knowledge of dietary fats is still lacking and designing optimal foods and diets will require the means to both understand the metabolic differences between individuals and to understand the metabolic consequences of consuming different dietary fats. Professional scientists such as dieticians will need to acquire a greater knowledge of how to guide individual consumers to optimal diets (German et al., JADA).

PROGRESS: 2004/01/01 TO 2004/12/31
Research in the past year has developed further our understanding of the physical, chemical and biological properties of dietary lipids and their specific roles in foods and health. The nutritional value of the wide range of lipids from milk has continued to be a source of controversy as the potential beneficial and detrimental properties are explored. Research illustrates that different fatty acids are likely to have disparate effects on different individuals based on their genetic and metabolic status. Therefore strategies to distinguish metabolic differences between individuals were an important outcome of the project this year. Methods were developed to quantify the broad metabolic effects of various dietary ingredients including but not limited to dietary fats. Since individual metabolism responds to non-essential nutrients International consensus was developed to pursue the means to coordinate research in personalized assessment and dietary intervention. The continuing goals of this research are to provide the analytical tools to enable individuals to routinely monitor their metabolic health and with this information guide their food choices.

IMPACT: 2004/01/01 TO 2004/12/31
Understanding the role of dietary lipids in health and metabolism will provide the knowledge for the food industry to produce food products for improved health. A scientific consensus to establish the metabolic differences between individuals and their different responses to diet will guide the development of technologies to measure those differences and inform both the consumers and their food providers.

PROGRESS: 2003/01/01 TO 2003/12/31
Research in the past year has developed further our understanding of the physical, chemical and biological properties of dietary lipids and their specific roles in foods. The biological and nutritional value of membrane lipids from milk represent an attractive food ingredient, and methods were developed to characterize the effects of processing on their composition and properties. Milk fat globules can be fractionated by directing mammary biosynthesis, and post-harvest by various methods that take advantage of the physical and biological properties of different sizes of globules. The nutritional consequences of consuming specific fatty acids were studied for their influence on mammalian immunological responses. Conjugated linoleic acid was found to not stimulate the immune system of immune-depleted mice. Oils containing 5,11,14 eicosatrienoic acid inhibited the inflammatory cascade and nephrotoxicity in a transplant model. Methods were developed to quantify the broad metabolic effects of various dietary ingredients including but not limited to dietary fats. Finally, individual metabolism is particularly susceptible to non-essential nutrients, and as the world's population is in the midst of a major epidemic of metabolic diseases (atherosclerosis, obesity, type2 diabetes, osteoporosis) it is critical to understand how non-essential components of foods affect health. Perhaps even more importantly, the tools to measure metabolic health comprehensively do not yet exist. The goals of this research are to provide the analytical tools to enable individuals to routinely monitor their metabolic health and with this information guide their food choices.

IMPACT: 2003/01/01 TO 2003/12/31
Understanding the role of dietary lipids in human metabolism will allow the food industry to reformulate food products for improved health. Understanding the differences between individuals in their responses to diet will only be actionable when technologies are in place to measure those differences and inform both the consumers and their food providers.

PROGRESS: 2002/01/01 TO 2002/12/31
The composition and structures of lipids are important factors determining their nutritional, biological and biomaterial functions in foods and diets. In the past period, research has demonstrated new techniques to examine the physical properties and stability of complex biological colloidal structures and foods. We have continued to develop the scientific support for the importance of understanding the mechanisms behind variation in human responses to different diets. The research has illustrated the need for and begun to assemble analytical platforms to quantify individual metabolism in order for agriculture to establish truly optimal diets for the consumers of the future.

IMPACT: 2002/01/01 TO 2002/12/31
Lipids contribute important physical and organoleptic properties to foods and influence preference for their selection. This research has provided new tools to investigate these properties and the nutritional rationale to investigate the individual responses of consumers to dietary fats.

PROGRESS: 2001/01/01 TO 2001/12/31
This project is helping to build the scientific knowledge necessary to optimize the composition of fats to produce more valuable and healthy foods. During the past year we have demonstrated the importance of lipids to the absorption of essential nutrients, and recommended that fat soluble vitamins be restored to fat-reduced foods. We have demonstrated the potential of complex lipids to modify the growth of cancer cells and argued for the expansion of this research field as a means to influence the incidence of gastrointestinal cancers in humans and animals. Finally, we have demonstrated the importance of lipid metabolism as a reflection of overall health and argued for the use of metabolomic techniques to accurately reflect the overall status of health of individual humans rather than to rely on simple biomarkers of disease risk. We have moved the laboratory research objectives to include genomic knowledge as an important resource of the future and published on its importance to nutrition in general.

IMPACT: 2001/01/01 TO 2001/12/31
Lipids of foods provide positive aspects of food from structure to promoting growth and immunity, yet lipids produce negative aspects from food deterioration to promoting heart disease. Thus, the value of foods depends in part on optimizing the lipids. This research has provided means to stabilize lipids, to improve their nutritional impact and to demonstrate their nutritional value in diets.

PROGRESS: 2000/01/01 TO 2000/12/31
The lipid or fatty component is responsible for much of the beneficial sensory attributes of foods yet the over consumption of specific classes of fats is implicated in the etiology of many of the chronic diseases afflicting humans. Several health organizations have suggested that modulating the fatty acid composition of human diets would significantly improve the susceptibility to diseases such as heart disease, cancer and auto-immune diseases. Unfortunately an understanding of the mechanisms by which these beneficial effects might be acting and even the physical means to implement these changes on the typical western diet are largely unknown. This research project is developing the information that will allow more precise estimates of benefits (and risks) of modulating the lipid composition of foods. During the past year we have demonstrated that flavonoids from apples protect human LDL from oxidation ex vivo, and that flavonoids from olives protect polyunsaturated fatty acids of fish in foods. We have further demonstrated that the major flavonoid of red wine, catechin circulates primarily as conjugated metabolites in the plasma of humans. We have finally shown the growing conditions that influence lipid composition of photoheterotrophic algae.

IMPACT: 2000/01/01 TO 2000/12/31
Since plant flavonoids protect unsaturated lipids in foods and in blood, processes to increase specific flavonoids in foods would improve the risk of chronic diseases. True risk prediction will be possible by applying analytical chemistry to nutritional assessment by directly measuring individual human metabolic profiles rather than population estimates or individual food intake questionnaires.

PROGRESS: 1999/01/01 TO 1999/12/31
The lipid or fatty component is responsible for much of the beneficial sensory attributes of foods yet the over consumption of specific classes of fats is implicated in the etiology of many of the chronic diseases afflicting humans. Several health organizations have suggested that modulating the fatty acid composition of human diets would significantly improve the susceptibility to diseases such as heart disease, cancer and auto-immune diseases. Unfortunately an understanding of the mechanisms by which these beneficial effects might be acting and even the physical means to implement these changes on the typical western diet are largely unknown. This research project is developing the information that will allow more precise estimates of benefits (and risks) of modulating the lipid composition of foods. During the past period we have demonstrated that the short chain fatty acid up-regulates the enzymes that produce Prostaglandin E2 and increases immunologic tolerance, and also induces cell death in cancerous cells by the process known as apoptosis. We have demonstrated that the polyunsaturated fatty acid docosahexaenoic acid when, accumulated in the inner mitochondrial lipid cardiolipin, stimulates oxidant production. Finally we have shown that flavonoids from plants alter the oxidation rate of lipids, and are well absorbed, taken up by cells and metabolized into conjugates that circulate in human blood.

IMPACT: 1999/01/01 TO 1999/12/31
Butyric acid is produced by fermentation of fiber in the colon and is present in bovine milk fat. Results support that butyrate is of benefit for cancer prevention and for specific immunologic situations in which immune tolerance is desired. Plant flavonoids are desirable components and agricultural processes that increase net dietary flavonoid intake are recommended by this research.

PROGRESS: 1998/01/01 TO 1998/12/31
PHYSICAL AND CHEMICAL PROPERTIES OF FOOD AND BACTERIAL LIPIDS: The composition of proteins and lipids making up a liposomal suspension has an important effect on the stability of the suspension to oxidation and antioxidants need to be selected that match to the interfacial properties of particular suspensions. Listeria monocytogenes, the food borne pathogen, respond rapidly to cold shock modifying the fatty acid and phospholipid compositions of cellular lipids. ROLE OF DIETARY FATS: The polyunsaturated fatty acid docosahexaenoic acid, when incorporated into the mitochondrial lipid cardiolipin, causes a substantial alteration in the oxidant production by the mitochondria within living cells. The short chain fatty acid butyric acid produces an increase in prostaglandin E2 production in hepatic Kupffer cells when delivered as liposomal suspensions, verifying a therapeutic strategy for improving success for immune function and transplanted organ tolerance. OXIDATION AND ANTIOXIDANT ACTIONS: Fruit-derived flavonoids have differential effects on the lipid membrane signaling of isolated cells depending on the extent of polyphenolic polymerization. Enhancing polymerization during fruit processing would have the net effect of reducing the effectiveness of these compounds in modifying the cellular activities after ingestion. P

PROGRESS: 1997/01/01 TO 1997/12/01
PHYSICAL PROPERTIES OF FOOD LIPIDS: Permeability and polymerization mechanization mechanical properties and interfacial interactions of whey protein isolate (WPI) as edible films and stabilized emulsions were studied. Cationic lipids were successfully used to transfect avian hepatoma LMH-2A cells. ROLE OF DIETARY FATS: The modulation of Kupfer cell arachidonic acid metabolism by portal venous transfusion is proposed as a mechanism of enhancing immunosuppression in organ transplantation. Clinical effects of nutritional modifications to T-cell function in immunity was reviewed. Neutral and polar lipids in LISTERIA MONOCYTOGENES were isolated and identified. OXIDATION AND ANTIOXIDANT MECHANISMS: Several reviews of the role of plant and wine phenolics on health and disease were published. Phytochemicals as antioxidants in oxidizing lipid systems were studied, including: antioxidant partitioning in oil-water systems; inhibition of endothelial cell-mediated LDL oxidation by plant phenols; and stimulation of endothelial cell PGI2 release by wine.

PROGRESS: 1996/01 TO 1996/12
PHYSICAL PROPERTIES OF FOOD LIPIDS: Saturated & monounsaturated monoacylglycerols altered the lipid composition & molecular mobility of lipoprotein surfaces in distinct ways. Effects of pH & temperature on protein unfolding & thiol/disulfide interchange reactions during heat-induced gelation of WPI were described, as was disulfide-mediated polymerization reactions & the physical properties of heated WPI-stabilized emulsions. ROLE OF DIETARY FATS: The first symposium on myriad biological effects of dietary arachidonic acid (AA) was assembled. 5,11,14-Eicosatrienoic acid, a fatty acid that replaces AA in tissues, decreased pentobarbital-related mortality in an animal inflammation model. AA & docosahexaenoate were higher in liver but lower in adipose of growth hormone transgenic mice. The diverse nature of polar lipids in LISTERIA MONOCYTOGENES was shown. OXIDATION AND ANTIOXIDANT MECHANISMS: Phytochemicals as antioxidants in different oxidizing lipid systems were studied. The antioxidant activity of carnosol & carnosic acid from rosemary indicated their conversion to compounds with high activity. Comparison of alpha-tocopherol & Trolox activities in bulk oils vs oil-in-water emulsions showed that linoleic acid may not be a valid substrate for evaluating food antioxidants. A new method to determine lipid hydroperoxides was developed, & multiple aldehyde-peroxidation products were measured by GC/stable isotope dilution mass spectrometry.

PROGRESS: 1995/01 TO 1995/12
Progress is reported on phys. chem. of lipids in foods, the role of diet. fats on tissue funct. & mechanisms of oxidation & antioxidants. Butterfat & tripalmitin blends can be used as moisture barriers in edible films. Continuing studies demo'd that such barrier properties depend more on morp. than polymorphic form. In vitro studies showed enhancement of oxidative stability in bulk oils by mixtures of tocopherols is determined by inhib. of hydroperoxide formation rather than of hydroperoxide decomposition. Evidence for mol. & genetic effects of diet. butyric acid, which constitutes up to 10 percent of milk fatty acids, was reviewed. In the form of tributyrin, butyric acid was shown to enhance the expression of a reporter gene in cell lines. Based upon our res. on oxidation of LDL particles, we dev'd math. models suggesting a linking mech. for the lipid & oxidation theories of atherosclerotic card. disease. Overwhelming evidence for influence of diet. micronut. antioxidant compounds on cancer & anticarcinogenesis was presented (intl. nutr./cancer symp). Continuing in vivo studies on diet. oleic anilide showed decreased 12-hydroxyeicosatetraenoic acid prod. in mouse lungs. This finding is relevant to immunoregulation & autoimmune syndromes in Toxic Oil Syndrome patients. Electrospray mass spec was used to characterize protein adducts formed by exposure of model proteins to 4-hydroxy-2-nonenal. Clearly, >99 percent of the adducts were formed by Michael addn, not as Schiff bases.

PROGRESS: 1994/01 TO 1994/12
Progress is reported concerning the physical chemistry of lipids in foods, and the role of dietary fats on tissue function and on lipid oxidation. Triglycerides from milkfat were isolated and separated. The tendency to promote crystallization and plasticity in milkfat assigned to the fully saturated species, which contain a saturated fatty acid on all three positions on the glycerol. Since the products of lipoprotein hydrolysis would be saturated monoglycerides, which we have also shown alter surface structure and subsequent metabolism, this is an important property of milkfat. We continue to define the specificity of fatty acid incorporation into tissues. We demonstrated that the unusual non-methylene interrupted fatty acids are readily incorporated into certain tissue membranes replacing arachidonic acid. This replacement in an animal model of autoimmunity, the NZB mouse prolonged its survival, suggesting that this fatty acid would have therapeutic value in certain human diseases. In ongoing studies on the composition and oxidative stability of circulating lipoproteins in humans we have demonstrated that phenolics inhibit the oxidation of lipid emulsions, vesicles and lipoproteins, and may thus have significant nutritional value as biological protectants.

PROGRESS: 1993/01 TO 1993/12
Progress is reported for the physical chemistry of lipids in foods, the role of dietary fats on tissue function and on lipid oxidation. The composition of triglycerides affects the rate and extent of fat crystallization in food emulsions. We have found that we can direct the crystallization rate by modifying the properties of the surface using surfactants. We have similarly demonstrated that monoglycerides alter the catalytic rates of surface active enzymes. Thus, the products of lipoprotein hydrolysis are important determinants in regulating lipoprotein and membrane remodeling. Furthermore, since diet modifies the lipid structures, this represents a key factor in dietary modification of lipoprotein clearance. We continue to define the specificity of fatty acid incorporation into tissues. We demonstrated that uptake of fatty acids into brain was much more precise and clearly regulated by different mechanisms than into other tissues. Thus, unusual non-methylene interrupted fatty acids are very poorly incorporated into membranes of brain. In ongoing studies on the composition and oxidative stability of circulating lipoproteins in humans we have found that the cholesterol ester core of these particles oxidizes most rapidly and that the phenolics in wine and other fruits are excellent antioxidants in vitro. We further proposed that this activity could partially explain the paradoxically low incidence of coronary disease in populations consuming red wine.

PROGRESS: 1992/01 TO 1992/12
Progress is reported for our three perspectives in research; the physical chemistry of fats in foods, the role of dietary fatty acids on tissue composition and function and the role of lipoxygenases in lipid oxidation. We have found that monoglycerides modify the crystallization behavior of pure triglycerides and triglyceride mixtures in foods using NMR imaging and verified these results using Differential Scanning Calorimetry. These approaches are continuing to define the targets to modifying fat functions in foods. We have shown that there is considerable specificity in different tissues for the uptake of fatty acids from the diet. In particular, one advance is important for our continued work. We have extended our previous work on the regulation of desaturation and elongation to show that polyunsaturated fatty acids which are products of the desaturation and elongation enzymes accumulate to a greater extent in membranes relative to their precursors. This implies that diets which are rich in these fatty acids will significantly alter membrane composition. We have also identified the unique competitiveness of non-methylene interrupted fatty acids, a distinct class of unsaturated fatty acids, for incorporation into membranes. In ongoing research on the lipoxygenase of fish tissue we have found that substrate liberation by cellular phospholipases determines the net metabolism by the enzymes in fish.

PROGRESS: 1990/01 TO 1990/12
This summary reports progress in our research to understand the functional role of fats and the effects which specific fatty acids in the diet exert on biological processes as a goal to optimize the health value of the fat component of foods. Using nutritional experiments we determined that omega or n-3 polyunsaturated (PUFA) fatty acids from plants (linseed oil 18:3 n3) and fish (20:5 n3 + 22:6 n3) are metabolized differently. Whereas both sources of n-3 PUFA modify arachidonic acid (20:4 n6) levels in tissues consistent with a desirable shift in eicosanoid precursors, preformed 22:6 n3 is selectively accumulated in the mitochondrial phospholipid cardiolipin but not if ingested as its precursor 18:3 n3. Thus the precise form of dietary n-3 polyunsaturated fatty acid is important. We are pursuing consequences of 22:6 in cardiolipin. The lipoxygenases we found in fish are responsible for volatile products released3ed by fresh fish tissues. Flavor in such foods is hence related to the reactions of endogenous oxidative enzymes which lose their activity during processing and storage. We are continuing to improve our understanding of how to regulate these enzymes.Using our relaxation weighted magnetic resonance imaging techniques to quantify the fat in foods we have followed the crystallization of purified triglycerides. we have shown that crystallization kinetics are dependent on the species of triglyceride, the states of dispersion, the presence of nucleii and the temperature.

PROGRESS: 1989/01 TO 1989/12
Progress is reported in our research in the effects of specific fatty acids in the diet on physiolocal functioning of cells and tissues, the role of endogenous enzymes on lipid deterioration in foods and tissues and the role of fat in the structure and textural properties of multiphase foods such as foams and emulsions. Work is based on the underlying assumption that only by understanding both the functional role of fats in foods and the specific effects which fatty acids in the diet exert on biological processes can we ultimately optimize nutritional quality of this component. Dietary experiments were designed to answer questions about the regulation using fatty acids not normally found in diets. We found convincing evidence that these unique fatty acids are readily retroconverted to essential fatty acids only in certain organs but are then available to all tissues. This opened a means to investigate the regulation of absolute levels of all the essential fatty acids and their physiological function. We showed that similar lipoxygenses in both fish gills and animal lungs are sensitive to oxidative stress either through external prooxidants or through inhibition of glutathione peroxidase by pharmacological agents such as gold. We also found that two separate lipoxygenases in fish tissues act sequentially to produce multiply oxygenated polyunsaturated fatty acids.

PROGRESS: 1988/02 TO 1991/12
Progress is reported for our three perspectives in research; the physical chemistry of fats in foods, the role of dietary fatty acids on tissue composition and function and the role of lipoxygenases in lipid oxidation. We have demonstrated the crystallization behavior of pure triglycerides and triglyceride mixtures in actual food models using NMR Imaging and verified these results using Differential Scanning Calorimetry. These approaches are continuing to define the targets to modifying fats in foods. We have shown that there is considerable specificity in different tissues for the uptake of fatty acids from the diet. In particular one advance is important for our continued work. We were very interested in the difference between short and long chain n-3 fatty acids in delivering long chain fatty acids to tissues. To put it in commercial terms is linseed comparable to fish oil? With respect to many aspects the two were similar but we have demonstrated that the long chain highly oxidizable fatty acid 22:6 accumulates in the mitochondrial phospholipid cardiolipin to a far greater extent if fed intact as compared to fed as its metabolic precursor 18:3 n3. We have extended this with other studies to show that the peroxisome is an important regulator of fatty acid composition. In ongoing research on the lipoxygenases of fish tissue we confirmed that this enzyme class is responsible for much of the 'fresh' flavor associated with fresh fish.

PROGRESS: 1988/01 TO 1988/12
The preliminary results of nutritional studies indicate considerable selectivityin in corporation of dietary fats differing in chain length and unsaturation into some phospholipids but not in others. In the past year we have identified the 12 lipoxygenase enzyme in marine fishes and the stereochemistry as (S) and the hydrogen abstraction site as C n-11 of this reaction on polyunsaturated fatty acids. We have characterized the major products formed from endogenous fatty acids by this enzyme and have found that the gills of fish and the lungs of mammals make essentially the same products on tissue disruption: 12(S) HETE. Modeling studies suggested that high levels of hydroperoxides would inactivate the enzyme in vivo. This prediction was tested in actual experiments using exogenous hydroperoxides and found to be true in both fish gills and mammalian lungs. Mangnetic resonance imaging (MRI) and coupled kinetic modeling of unstable food systems has been developed and we have submitted a publication on the utility of this method in dynamic analyses, In preliminary experiments we have developed model systems in which the fat and aqueous phases are chemically well characterized and have provided data that these two phases can be simultaneously but separately imaged using MRI. We have also shown that ice cream, a classic model of structural stability attributable to its fat component, can be investigated using this new technique.

Funding Source
Nat'l. Inst. of Food and Agriculture
Project source
View this project
Project number
CA-D*-FST-4929-H
Accession number
134682
Categories
Bacterial Pathogens
Natural Toxins
Commodities
Dairy
Produce