Dietary levels of trans-fatty acids: basis for health concerns and industry efforts to limit use

Approaches of lipid oxidation mechanisms in oil matrices using association colloids and analysis methods for the lipid oxidation

Lipid oxidation is one of the key chemical reactions in foods containing fats and oils during production and storage. For several decades, many researchers have tried to understand the mechanisms of lipid oxidation and ways to control the rates of lipid oxidation. Theories of autoxidation or free radical chain reaction have been developed to successfully explain the phenomenon observed in oxidized lipids. Many studies have been conducted to explain the other factors that can affect the lipid oxidation such as food matrix, oxidation time and temperature, transition metal ions, pigments with sensitizing abilities, and surface-active compounds such as phospholipids, free fatty acids, monoacylglycerols, and diacylglycerols. Several strategies were developed to evaluate the degree of oxidation and oxidative stability. This review provides crucial information on the mechanism of lipid oxidation affected amphiphilic compounds and association colloids. This review article will extensively discuss about the methods for determining the oxidative stability.

The effect of periodate oxidation of basil seed gum and its addition on protein binding

This study attempted to determine the best point of basil seed oxidation by applying response surface methodology (RSM) with 3 factors of temperature (35-45 °C), pH (3-7) as well as time (3-7 h), at 3 levels. The produced dialdehyde basil seed gum (DBSG) was collected and its physicochemical properties were determined. Fitting of quadratic, linear polynomial equations was subsequently done by considering the insignificant lack of fit, as well as highly considerable R², in order to probe the probable relationship existing between these considered variables as well as the obtained responses. So the considered optimal related test conditions, which included pH = 3, T = 45 °C as well as Time = 3 h, were specified to produce the highest percentage of aldehyde (DBSG32), optimal (DBSG34) and the (DBSG74) samples with the highest viscosity. The results obtained by FTIR and aldehyde content determination provided the indication that dialdehyde groups were formed in a way that was in equilibrium with the considered the hemiacetal form which was dominant. Furthermore, AFM investigation related to the considered DBSG34 sample displayed over-oxidation as well as depolymerization; this might be due to the enhanced hydrophobic qualities, as well as the decreased viscosity. While the DBSG34 sample had the most dialdehyde factor group with a particular tendency for the combination having the proteins' amino group, DBSG32 and DBSG74 samples could be desirable for industrial uses owing to no overoxidation.

Enhancement of Oxidative Stability of Perilla Seed Oil by Blending It with Other Vegetable Oils

Perilla seed oil is mainly composed of omega-3 fatty acid (α-linolenic acid, ALA). Despite being nutritionally favorable and rich in unsaturated fatty acids, its low oxidative stability limits its application in food. Thus, the present study aimed to formulate a stable oil blend using perilla seed oil with selected vegetable oil of higher stability characteristics and balance the ratio of the fatty acids. Hence, improving the nutritional and functional value of the blended oil. Perilla seed oil was blended with different edible oil (palm olein, coconut oil, and groundnut oil) in ratios of 20:80 and 30:70. All the blended oils were studied for their fatty acid composition, physicochemical properties, oxidative stability, and nutritional quality index. It was found that perilla seed oil blended with saturated oil like palm olein had improved physicochemical properties and oxidative stability (0.5 h to 6.5 h). The fatty acids ratio of perilla and palm olein blends was close to the recommended value given by the World health organization (WHO). The nutritional quality indices (atherogenic index, the thrombogenic index, and hypocholesterolemic: hypercholesterolemic ratio) of blended oil were also improved compared to the individual oils.

Physicochemical characteristics of anhydrous milk fat mixed with fully hydrogenated soybean oil

There is a growing demand for fats that confer structure, control the crystallization behavior, and maintain the polymorphic stability of lipid matrices in foods. In this context, milk fat has the potential to meet this demand due to its unique physicochemical properties. However, its use is limited at temperatures above 34 °C when thermal and mechanical resistance are desired. The addition of vegetable oil hard fats to milk fat can alter its physicochemical properties and increase its technological potential. This study evaluated the chemical composition and the physical properties of lipid bases made with anhydrous milk fat (AMF) and fully hydrogenated soybean oil (FHSBO) at the proportions of 90:10; 80:20; 70:30; 60:40; and 50:50 (% w/w). The increased in FHSBO concentration resulted in blends with higher melting point, which the addition of 10% of FHSBO increase the melting point in 12 °C of the lipid base. Also, FHSBO contributed for a higher thermal resistance conferred by the coexistence of polymorphs β' and β, which remained stable for 90 days. Co-crystallization was observed for all blends due to the total compatibility of milk fat with the fully hydrogenated soybean oil. The results suggest a potential of all blends for various technological applications, makes milk fat more appropriate to confer structure, and improve the polymorph stability in foods. The blends presenting singular characteristics according to the desired thermal stability, melting point, and polymorphic habit.

Potential of Milk Fat to Structure Semisolid Lipidic Systems: A Review

Food production and consumption patterns have changed dramatically in recent decades. The universe of oils and fats, in particular, has been changed due to the negative impacts of trans fatty acids produced industrially through the partial hydrogenation of vegetable oils. Regulations prohibiting its use have led the industry to produce semisolid lipid systems using chemical methods for modification of oils and fats, with limitations from a technological point of view and a lack of knowledge about the metabolization of the modified fats in the body. Milk fat is obtained from the complex biosynthesis in the mammary gland and can be a technological alternative for the modulation of the crystallization processes of semi-solids lipid systems, once it is naturally plastic at the usual processing, storage, and consumption temperatures. The natural plasticity of milk fat is due to its heterogeneous chemical composition, which contains more than 400 different fatty acids that structure approximately 64 million triacylglycerols, with a preferred polymorphic habit in β', besides other physical properties. Therefore, milk fat differs from any lipid raw material found in nature. This review will address the relationship between the chemical behavior and physical properties of semisolid lipids, demonstrating the potential of milk fat as an alternative to the commonly used modification processes.

Formulation of Zero-Trans Crystalized Fats Produced from Palm Stearin and High Oleic Safflower Oil Blends

High intake of trans fat is associated with several chronic diseases such as cardiovascular disease and cancer. Fat blends, produced by direct blending process of palm stearin (PS) with high oleic safflower oil (HOSO) in different concentrations, were investigated. The effects of the PS addition (50, 70, or 90%) and the rate of agitation (RA) (1000, 2000, or 3000 rpm) on physical properties, fatty acid profile (FAP), trans fatty acids (TFA), crystal structure, and consistency were researched. The blend containing 50% of each sort of oil (50% PS/50% HOSO) showed that melting point and features were similar to the control shortening. The saturated fatty acids (SFA) were higher followed by monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA). Significant differences in the content of palmitic and oleic acids among blends were observed. The 50% PS/50% HOSO blend contained higher oleic acid (42.9%) whereas the 90% PS/10% HOSO was higher in palmitic acid (56.9%). The blending of PS/HOSO promoted the β crystal polymorphic forms. The direct blending process of equal amounts of PS and HOSO was an adequate strategy to formulate a new zero-trans crystallized vegetable fats with characteristics similar to commercial counterparts with well-balanced fats rich in both omega 3 and omega 6 fatty acids.

Crystallization modifiers in lipid systems

Crystallization of fats is a determinant physical event affecting the structure and properties of fat-based products. The stability of these processed foods is regulated by changes in the physical state of fats and alterations in their crystallization behavior. Problems like polymorphic transitions, oil migration, fat bloom development, slow crystallization and formation of crystalline aggregates stand out. The change of the crystallization behavior of lipid systems has been a strategic issue for the processing of foods, aiming at taylor made products, reducing costs, improving quality, and increasing the applicability and stability of different industrial fats. In this connection, advances in understanding the complex mechanisms that govern fat crystallization led to the development of strategies in order to modulate the conventional processes of fat structuration, based on the use of crystallization modifiers. Different components have been evaluated, such as specific triacyglycerols, partial glycerides (monoacylglycerols and diacylglycerols), free fatty acids, phospholipids and emulsifiers. The knowledge and expertise on the influence of these specific additives or minor lipids on the crystallization behavior of fat systems represents a focus of current interest for the industrial processing of oils and fats. This article presents a comprehensive review on the use of crystallization modifiers in lipid systems, especially for palm oil, cocoa butter and general purpose fats, highlighting: i) the removal, addition or fractionation of minor lipids in fat bases; ii) the use of nucleating agents to modify the crystallization process; iii) control of crystallization in lipid bases by using emulsifiers. The addition of these components into lipid systems is discussed in relation to the phenomena of nucleation, crystal growth, morphology, thermal behavior and polymorphism, with the intention of providing the reader with a complete panorama of the associated mechanisms with crystallization of fats and oils.

Effect of heating oils and fats in containers of different materials on their trans fatty acid content

BACKGROUND

The nature of the container material and temperature employed for deep-frying can have an influence on the development of trans fatty acids (TFAs) in the fat used. The present study was undertaken to determine the effect of heating vegetable oils and partially hydrogenated vegetable fats with different initial TFA content in stainless steel, Hindalium (an aluminium alloy), cast iron and glass containers. Ground nut oil (oil 1), refined, bleached and deodorised (RBD) palmolein (oil 2) and two partially hydrogenated vegetable oils with low (fat 1) and high (fat 2) TFA content were uniformly heated at 175-185 °C over a period of 12 h.

RESULTS

An increase in TFA content to 20 g kg⁻¹ was observed in oil 2 in the cast iron container, while a decrease in TFA content of 20-30 g kg⁻¹ was observed in fat 2 in all containers. The heating process of fats and oils also led to an increase in Butyro refractometer reading and colour values.

CONCLUSION

This study showed that the TFA 18:1t content of oil 1, oil 2 and fat 1 increased with repeated or prolonged heating. The cast iron container showed the highest increase in TFA 18:1t for RBD palmolein (oil 2). The amount of linoleic acid trans isomers formed in the heating process was negligible. Fat 2 with high initial TFA content showed a decrease in TFA 18:1 and 18:2 on heating in all containers. Oils heated in glass and stainless steel containers showed less TFA 18:1t formation.

Docosahexaenoic acid (DHA): an ancient nutrient for the modern human brain

Modern humans have evolved with a staple source of preformed docosahexaenoic acid (DHA) in the diet. An important turning point in human evolution was the discovery of high-quality, easily digested nutrients from coastal seafood and inland freshwater sources. Multi-generational exploitation of seafood by shore-based dwellers coincided with the rapid expansion of grey matter in the cerebral cortex, which characterizes the modern human brain. The DHA molecule has unique structural properties that appear to provide optimal conditions for a wide range of cell membrane functions. This has particular implications for grey matter, which is membrane-rich tissue. An important metabolic role for DHA has recently been identified as the precursor for resolvins and protectins. The rudimentary source of DHA is marine algae; therefore it is found concentrated in fish and marine oils. Unlike the photosynthetic cells in algae and higher plants, mammalian cells lack the specific enzymes required for the de novo synthesis of alpha-linolenic acid (ALA), the precursor for all omega-3 fatty acid syntheses. Endogenous synthesis of DHA from ALA in humans is much lower and more limited than previously assumed. The excessive consumption of omega-6 fatty acids in the modern Western diet further displaces DHA from membrane phospholipids. An emerging body of research is exploring a unique role for DHA in neurodevelopment and the prevention of neuropsychiatric and neurodegenerative disorders. DHA is increasingly being added back into the food supply as fish oil or algal oil supplementation.

Venous thrombosis risk: effects of palm oil and hydrogenated fat diet in rats

OBJECTIVE

We tested whether diets containing partially hydrogenated fat (PHVO, rich in trans fatty acids) or palm oil (PO, rich in saturated fat-C16 palmitic fatty acid) had different effects on the propensity for venous thrombosis, a marker of haemostatic cardiovascular risk.

METHODS

Female Wistar rats were fed normolipidic diets containing PHVO or PO during lactation, and their young male pups were fed the same diets from weaning until the 180th day of life. We evaluated platelet fatty acid composition, serum lipids, platelet aggregation, clotting time, and venous thrombus formation.

RESULTS

A significant and cumulative incorporation of trans fatty acid was observed only in the platelet lipids from the PHVO group, associated with an increased sensitivity to adenosine diphosphate (ADP) and venous thrombus formation in vivo. Platelets from rats raised on the PO diet also exhibited platelet aggregation induced by ADP and an increase in venous thrombus weight, with a concomitant increase in serum triglycerides.

CONCLUSION

The prolonged replacement of dietary hydrogenated fat by PO impaired platelet aggregability and venous thrombosis, suggesting an increased risk of thromboembolic diseases.

Enzymatic interesterification of anhydrous milk fat with rapeseed and/or linseed oil: oxidative stability

Blends of anhydrous milk fat (AMF) and linseed oil (70:30) and of AMF, rapeseed oil (RO), and linseed oil (LO) (70:20:10) were submitted to enzymatic interesterification. The oxidative stabilities of the blends, the interesterified (IE) blends, and IE blends with 50 ppm of alpha-tocopherol added as antioxidant were studied. Samples were stored in open flasks at 60, 25, and 4 degrees C and periodically submitted to peroxide, p-anisidine, and TBA value determinations and UV measurement at 232 and 268 nm. The analysis of volatile compounds was carried out by SPME for the samples stored at 60 degrees C. Peroxides appeared to be the only significant oxidation products after 12 weeks of storage at 4 degrees C. As expected, the binary blends (BB) were more sensitive to oxidation than the ternary blends (TB). The BB were associated with increased volatile emission compared to the TB. Interesterification led to variable effects on the oxidation of fat mixtures, depending on composition and temperature (beneficial effect on BB, at both 25 and 60 degrees C, and a rather neutral effect on TB). The IE blends exhibited higher volatile release prior to aging. A pro-oxidant effect of alpha-tocopherol addition was observed at 25 degrees C on both BB and TB. At 60 degrees C, an antioxidant effect was observed on TB.

Development of the Healthy Eating Index-2005

The Healthy Eating Index (HEI) is a measure of diet quality as specified by Federal dietary guidance, and publication of the Dietary Guidelines for Americans 2005 necessitated its revision. An interagency working group based the HEI-2005 on the food patterns found in My-Pyramid. Diets that meet the least restrictive of the food-group recommendations, expressed on a per 1,000 calorie basis, receive maximum scores for the nine adequacy components of the index: total fruit (5 points), whole fruit (5 points), total vegetables (5 points), dark green and orange vegetables and legumes (5 points), total grains (5 points), whole grains (5 points), milk (10 points), meat and beans (10 points), and oils (10 points). Lesser amounts are pro-rated linearly. Population probability densities were examined when setting the standards for minimum and maximum scores for the three moderation components: saturated fat (10 points), sodium (10 points), and calories from solid fats, alcoholic beverages (ie, beer, wine, and distilled spirits), and added sugars (20 points). Calories from solid fats, alcoholic beverages, and added sugars is a proxy for the discretionary calorie allowance. The 2005 Dietary Guideline for saturated fat and the Adequate Intake and Tolerable Upper Intake Level for sodium, expressed per 1,000 calories, were used when setting the standards for those components. Intakes between the maximum and minimum standards are pro-rated. The HEI-2005 is a measure of diet quality as described by the key diet-related recommendations of the 2005 Dietary Guidelines. It has a variety of potential uses, including monitoring the diet quality of the US population and subpopulations, evaluation of interventions, and research.

Synthesis and characterization of canola oil-stearic acid-based trans-free structured lipids for possible margarine application

Incorporation of stearic acid into canola oil to produce trans-free structured lipid (SL) as a healthy alternative to partially hydrogenated fats for margarine formulation was investigated. Response surface methodology was used to study the effects of lipozyme RM IM from Rhizomucor miehei and Candida rugosa lipase isoform 1 (LIP1) and two acyl donors, stearic acid and ethyl stearate, on the incorporation. Lipozyme RM IM and ethyl stearate gave the best result. Gram quantities of SLs were synthesized using lipozyme RM IM, and the products were compared to SL made by chemical catalysis and fat from commercial margarines. After short-path distillation, the products were characterized by GC and RPHPLC-MS to obtain fatty acid and triacylglycerol profiles, 13C NMR spectrometry for regiospecific analysis, X-ray diffraction for crystal forms, and DSC for melting profile. Stearic acid was incorporated into canola oil, mainly at the sn-1,3 positions, for the lipase reaction, and no new trans fatty acids formed. Most SL products did not have adequate solid fat content or beta' crystal forms for tub margarine, although these may be suitable for light margarine formulation.

Trans fatty acid-forming processes in foods: a review

There is a mounting concern about the intake of foods containing trans fatty acids (TFA) due to their deleterious effects on human health, mainly on the cardiovascular system. In this way, it is important to consider the processes that form TFA in foods, and the alternatives to minimize them. Among the processes that result in the formation of TFA, the hydrogenation of vegetable oils stands out for its impact on the diet of people living in industrialized countries. Other processes such as edible oil refining, meat irradiation, food frying, and biohydrogenation also contribute to increase the daily intake of TFA.

ATR-Fourier transform mid-infrared spectroscopy for determination of trans fatty acids in ground cereal products without oil extraction

Fourier transform mid-infrared (FT-IR) spectroscopy was investigated as a method of analysis for trans fatty acid content of cereal products without the need for prior oil extraction. Spectra were obtained, with an FT-IR spectrometer equipped with an attenuated total reflectance (ATR) device, of ground samples pressed onto the diamond ATR surface, and trans fatty acids were measured by a modification of AOAC Method 996.01. Partial least-squares (PLS) models were developed for the prediction of trans fatty acids in ground samples using several wavenumber selections on the basis of bands related to lipids. The models (n = 79) predicted trans fatty acids in ground samples with standard error of cross-validation (SECV) of 1.10-1.25 (range 0-12.4) % and R2 of 0.85-0.88 and in validation samples (n = 26) with standard error of performance (SEP) of 0.96-1.12 (range 0-12.2) % and r2 of 0.89-0.92, indicating sufficient accuracy for screening. Sample trans fatty acid % was predicted as accurately with the fingerprint region (1500-900 cm(-1)) as with the entire range (4000-650 cm(-1)) indicating, in concert with the regression coefficients, the importance of the isolated trans double bonds at 966 cm(-1) in development of the model. Data is also presented on prediction of trans fatty acids using the spectra of residual oil films on the ATR surface after removing the solid portion of the sample.

Butters Varying in trans 18:1 and cis-9,trans-11 Conjugated Linoleic Acid Modify Plasma Lipoproteins in the Hypercholesterolemic Rabbit

The experiment was designed to study the effects of butters differing in conjugated linoleic acid (CLA) and trans 18:1 contents on lipoproteins associated with the risk of atherogenesis. New Zealand White male rabbits (9.6 weeks; 2.1 kg) were assigned for 6 or 12 weeks to three diets (n = 6 per diet) made of conventional pellets with 0.2% cholesterol and with 12% fat provided from a butter poor in trans-10 and trans-11 18:1 and in CLA (standard group), or rich in trans-10 18:1 (trans-10 18:1 group) or rich in trans-11 18:1 and in cis-9,trans-11 CLA (trans-11 18:1/CLA group). Blood samples were collected at the end of dietary treatments. Lipoproteins were separated by gradient-density ultracentrifugation. Lipid classes were determined enzymatically and apolipoproteins A-I and B by radial immunodiffusion. Mainly in the 12-week rabbits, higher plasma triglycerides and apolipoprotein B levels shown in the standard and trans-10 18:1 groups compared with those in the trans-11 18:1/CLA group are associated with higher plasma levels of very low density lipoproteins (VLDL) and low density lipoproteins (LDL) also shown in these two groups. In the 12-week rabbits, a shift towards denser LDL, considered as more atherogenic, was shown only in the trans-10 18:1 group. In these animals, the VLDL + LDL to HDL ratio was 1.7-2.3 times higher in the trans-10 18:1 group than in the other groups (P = 0.076). These results suggest a rather neutral effect of trans-11 18:1/CLA butter towards the risk of atherogenesis, whereas trans-10 18:1 butter would tend to be detrimental.

Dietary trans fatty acids: Review of recent human studies and food industry responses

Dietary trans FA at sufficiently high levels have been found to increase low density lipoprotein (LDL)-cholesterol and decrease high density lipoprotein (HDL)-cholesterol (and thus to increase the ratio of LDL-cholesterol/HDL-cholesterol) compared with diets high in cis monounsaturated FA or PUFA. The dietary levels of trans FA at which these effects are easily measured are around 4% of energy or higher to increase LDL-cholesterol and around 5 to 6% of energy or higher to decrease HDL-cholesterol, compared with essentially trans-free control diets. Very limited data at lower levels of intake (less than 4% of energy) are available. Most health professional organizations and some governments now recommend reduced consumption of foods containing trans FA, and effective January 1, 2006, the U.S. Food and Drug Administration requires the labeling of the amounts of trans FA per serving in packaged foods. In response, the food industry is working on ways to eliminate or greatly reduce trans FA in food products. Current efforts focus on four technological options: (i) modification of the hydrogenation process, (ii) use of interesterification, (iii) use of fractions high in solids from natural oils, and (iv) use of trait-enhanced oils. Challenges to the food industry in replacing trans FA in foods are to develop formulation options that provide equivalent functionality, are economically feasible, and do not greatly increase saturated FA content.