Issues in fortification and analysis of omega‐3 fatty acids in foods

It is extensively documented that omega‐3 fatty acids play important roles in many bioactive processes. Omega‐3 can also influence the onset, prevention, and control of many illnesses, including prevention of cardiovascular disease. The main sources of omega‐3 fatty acids are currently from vegetable oils and cold water fish. New sources such as from microalgae and krill oils are quickly increasing their share in the supplement market. Challenges for the incorporation of omega‐3 into foods and supplements have been gradually overcome by the introduction of new, more effective, antioxidants and by the use of various types of encapsulation technologies. Also, the smaller, micronutrient level, amounts of omega‐3 fatty acids normally added to fortified foods and supplements present several challenges of sample extraction, preparation and analysis of bioactive omega‐3 ingredients.     

Extraction of omega‐6 fatty acids from speciality seeds

‘Omega‐6 vegetable oils’ are a small but important group of vegetable oils used widely in the food, neutraceutical, cosmetic and pharmaceutical industries for their linoleic acid (18:2 n‐6) and more importantly gamma linolenic acid (18:3 n‐6) content. These omega‐6 fatty acids have numerous health benefits recognized worldwide. With linoleic acid being readily available from many dietary sources, one wonders why there is a need to extract the oil from speciality oilseeds, however those that suffer with many of the conditions that omega‐6 fatty acids are said to be beneficial for are frequently advised to take extra supplements of these fatty acids. Due to their wide use as a nutraceutical, omega‐6 fatty acids are in high demand, causing a niche market for extraction of these oils from speciality seeds.     

Long‐chain omega‐3 oils: Current and future supplies,food and feed applications,and stability

Increasing recognition of the health benefits of omega‐3 long‐chain (⪈C₂₀) polyunsaturated fatty acids (omega‐3 LC‐PUFA or LC omega‐3 oils) continues. But new sources are needed, with recent developments with novel land plants showing promise. The value of existing and future sources LC omega‐3 oils occurs through aquaculture, livestock and other feeding. There is also a need toenhance the stability of oils containing LC omega‐3 oils. Challenges include increasing DHA levels in land plants, increasing oxidative stability in food products and product labeling. Consumers have difficulty recognizing and differentiating long‐chain and shorter‐chain (SC, C₁₈) omega‐3 PUFA, both of which are referred to as “omega‐3” fatty acids.     

Lipids from Wastewater-Activated Sludge Cultivated on Acetic Acid as Potential Alternatives to High-Value Oils and Fats

This study focuses on new interpretations of the published literature by statistically evaluating the potential of microbial lipids from activated sludge (AS) as alternatives to high-value oils and fats. There are two data analysis stages involved in this study after compilation and organization of fatty acid profiles from the literature databases: (1) comparison of fatty acid profiles of the cultivated AS lipids with that of oils and fats found in the literature databases, and (2) hierarchical cluster analysis of the fatty acids of the combined dataset of literature oils and fats, and the AS lipids. Results show that fatty acid profiles of lipids from cultivated AS were similar to the fatty acid profiles of some oils and fats of plant, animal, single-microbial cultures, and algal origins; hence, lipids from AS could be potential alternatives to specialty oils and fats. The cultivation conditions of AS during lipid content enhancement may influence lipid application.     

Formation of short‐chain glycerol‐bound oxidation products and oxidised monomeric triacylglycerols during deep‐frying and occurrence in used frying fats

Heating fats and oils at high temperature in the presence of air, a common procedure in culinary practices such as frying, results in a complex mixture of oxidation products. These compounds may impair the nutritional value of the food. Among them, there is a growing interest in the group of oxidised triacylglycerol monomers because of their high absorbability. The main structures in this group include triacylglycerols (TG) containing short‐chain acyl groups formed by homolytic β‐scission of the alkoxy radicals coming from allylic hydroperoxides. In addition there are TG containing oxidised fatty acyl groups of molecular weight similar to that of their parent TG, i.e., epoxy, keto and hydroxy fatty acyl groups. In this review, the main routes of formation of oxidised TG monomers are detailed. Also, the most relevant advances in the analysis of intact TG molecules by high‐performance liquid chromatography coupled with mass spectrometry are discussed. Special attention is paid to the present analytical possibilities for accurate quantification of the most important oxidised compounds formed at high temperature. Both the need to convert fats and oils into simpler derivatives, thus concentrating the compounds bearing the oxidised structure, and the methylation procedure selected to avoid artefact formation are justified. Typical concentrations of short‐chain fatty acids, short‐chain aldehydic acids, short‐chain diacids, and monoepoxy fatty acids, ketoacids and hydroxyacids in frying oils from restaurants and fried‐food outlets, with polar lipids levels at the limit of rejection for human consumption, are given.     

Low linolenic soybeans and beyond

Low linolenic soybean oil is the first in a series of modified oilseed products to be introduced to meet food company and consumer needs. Consumer packaged goods and foodservice companies are currently using this oil to successfully replace partially hydrogenated soybean oil, resulting in the reduction of trans fatty acids from the food supply. In addition to meeting consumer demand for healthier foods, many food processors have chosen low linolenic soybean oil based on taste, performance and cost benefits. Seed companies continue to utilize traditional breeding, marker assisted breeding and biotechnology approaches to modify oilseeds that produce oils with health and nutrition benefits. Additional modified oilseeds are at various stages of development. Soybeans with increased levels of stearic acid are being developed as an alternative to partially hydrogenated fats and high saturate fats required to provide solids and structure to food. High stability fry oils with increased levels of oleic acid, reduced levels of linolenic acid as well as a version with lower saturated fat are being developed. Soybeans are also being modified to offer more sustainable sources of omega‐3s including stearidonic acid and eicosapentaenoic acid/docosahexaenoic acid which will result in more efficacious sources of omega‐3s compared to alpha‐linolenic acid‐containing vegetable oil and improved functionality/stability compared to fish and algal oils.     

More than biofuels – Potential uses of microalgae as sources of high‐value lipids

Cultivation of microalgae has potential in producing a feedstock for biofuels and, in addition, high‐value lipid bioproducts such as long‐chain (⪈C₂₀, LC) omega‐3 oils, carotenoid pigments and squalene, as well as other non‐lipid materials including exopolysaccharide. The high‐value LC omega‐3 oils have been conventionally sourced from fish. This paper provides a perspective on our recent study of the heterotrophic growth of thraustochytrids for their wider biotechnological potential, including as a source of a range of higher value lipids in addition to biofuels.     

Short‐chain fatty acids as marker for the degradation of frying fats and oils

The determination of fatty acid composition by gas chromatography as a routine task is established in most laboratories dealing with oils and fats. The scope of this method can be enlarged for a preliminary quality control of used frying fats and oils, which is commonly characterized by the determination of polar compounds and polymerized triacylglycerols. However, for screening purposes the determination of the short‐chain fatty acids C7:0 and C8:0 can give an early indication about the quality of used frying fats and oils.     

Oxidation in EPA‐ and DHA‐rich oils: an overview

Oxidation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) rich omega‐3 oils (hereafter referred to as either EPA and DHA or omega‐3) is a complicated topic, but an important one to understand. A significant number of consumers cite fishy burp and/or taste, thought to be the result of oxidation, as one of the main reasons they do not consume EPA and DHA rich oils. In addition, consumers note that some articles have raised concerns about the potential for adverse effects associated with consumption of oxidized oils. Measuring oxidation in omega‐3 oils is complicated due to the differences in chemical and physical characteristics of many commercially available products, which means not all methods to determine quality are appropriate for all types of oils. A number of consumer advocacy groups, product quality seal programs and academic groups have published data on levels of oxidation in omega‐3 oils. Overall, this data shows that commercially available omega‐3 supplements are low in oxidation. If consumers have a poor sensory experience with their omega‐3 product, they should try another product as an alternative.     

Alternatives to tropical fats based on high‐stearic sunflower oils

New high‐oleic high‐stearic sunflower lines produce oils that could be a source of disaturated triacylglycerol alternatives to tropical fats. These oils can be fractionated to produce stearins enriched in stearic acid with physical properties similar to cocoa butter and other confectionary fats without hydrogenation or transesterification. These fats can be produced in temperate countries from a well‐established crop like sunflower, and represent a healthy source of saturated fatty acids.     

Triacylglycerol profiling by using chromatographic techniques

Triacylglycerols (TGs) make up the major part of naturally occurring fats and oils. The composition and fine structure of TGs determine to a large extent the functionality of fats and oils as food ingredients and the physiological effects of fats and oils as component of the human diet. Analysis of intact TGs is usually performed by chromatographic methods. In this article the application of gas‐liquid chromatography, high‐performance chromatography in normal and reversed phase mode, thin‐layer chromatography and supercritical fluid chromatography for the qualitative and quantitative determination of TGs is reviewed. Emphasis is put on those factors that are decisive for obtaining reliable quantitative data. Furthermore, techniques for the stereospecific analysis of the fatty acid distribution along the glycerol backbone of TGs are presented briefly.     

Shelf‐life prediction of edible fats and oils using Rancimat

Determining the shelf‐life of edible fats and oils under normal storage conditions is a tedious and time‐consuming task. Accelerated tests are therefore frequently used to determine the stability of the products at ambient conditions. However, the mechanisms of lipid oxidation at accelerated conditions may be different from those under normal storage conditions, leading to errors in the shelf‐life predictions. This article describes an automated accelerated method, namely Rancimat, for shelf‐life prediction of edible fats and oils under normal storage conditions, and the effect of its operational parameters on these predictions.     

Relative nutritional value of various dietary fats and oils

The dietary and nutritional role of fats and oils is quite complex, as evident in the new biological findings about some of their components that are essential to man. Fats and oils must be considered for both their quantitative and qualitative aspects, their fatty acid compositions and relationships with average diets in different countries should be emphasized. Because of some adverse physiological effects ascribed to saturated fatty acids, a tendency to increase the intake of polyunsaturated vegetable oils has occurred to provide a good source of essential fatty acids, mainly linoleic acid. However, saturated fats still are an important part of the diet in developed countries, especially “invisible” fats. Research must continue that is related to modifications fats and oils undergo during industrial processes which affect their nutritional value. Compositions of many fats and oils are provided.     

Seed roasting improves the oxidative stability of canola (B. napus) and mustard (B. juncea) seed oils

Animal fats and partially hydrogenated vegetable oils (PHVO) have preferentially been used for deep‐frying of food because of their relatively high oxidative stability compared to natural vegetable oils. However, animal fats and PHVO are abundant sources of saturated fatty acids and trans fatty acids, respectively, both of which are detrimental to human health. Canola (Brassica napus) is the primary oilseed crop currently grown in Australia. Canola quality Indian mustard (Brassica juncea) is also being developed for cultivation in hot and low‐rainfall areas of the country where canola does not perform well. A major impediment to using these oils for deep‐frying is their relatively high susceptibility to oxidation, and so any processing interventions that would improve the oxidative stability would increase their prospects of use in commercial deep‐frying. The oxidative stability of both B. napus and B. juncea crude oils can be improved dramatically by roasting the seeds (165 °C, 5 min) prior to oil extraction. Roasting did not alter the fatty acid composition or the tocopherol content of the oils. The enhanced oxidative stability of the oil, solvent‐extracted from roasted seeds, is probably due to 2,6‐dimethoxy‐4‐vinylphenol produced by thermal decarboxylation of the sinapic acid naturally occurring in the canola seed.     

Fatty alcohols in capelin,herring and mackerel oils and muscle lipids: II. A comparison of fatty acids from wax esters with those of triglycerides

The fatty acids recovered from the triglycerides and wax esters of common northwest Atlantic copepods are compared with the fatty acids of wax esters recovered intact from certain fish skin and body lipid, and from commercial fish oils. The fish species, herring, capelin and mackerel, all feed on copepods, and many resemblances of the copepod lipid fatty acids to those of a previous analysis of similar copepods suggest that the basic dietary fat input for these fish may be quite constant. The two copepod fatty acid analyses differed quantitatively in triglyceride 20∶1 and 22∶1 and also in 20∶5ω3 and 22∶6ω3, confirming the primary role of the wax esters in copepods. Selectivity factors are discussed in comparing the copepod wax ester fatty acids with the fatty acids of the wax esters recovered intact from the fish lipids and oils. The basic role of copepods in supplying all types of fatty acids to fish depot fats is considered to be strongly supported by these findings.     

Biomarkers of long‐chain PUFA omega‐3 fatty acids and the human nutritional status

The association of dietary fats with disease risk or outcome can be determined from epidemiological studies and/or from food frequency questionnaires; a better assessment of the dietary intake of the long‐chain polyunsaturated fatty acids omega‐3 is obtained by the fatty acid composition of the platelets or of erythrocyte membranes yet these procedures are lengthy. Other investigators have used adipose tissue obtained by percutaneous biopsy, but it must be pointed out that this procedure is not only invasive but time‐consuming as well. Also, it has to be noted that the turnover time for fatty acids has been estimated to be 1–3 years.     

Rapid and direct quantitative analysis of positional fatty acids in triacylglycerols using 13C NMR

There is increasing evidence that the positional fatty acid composition (FAC) of TAG is more important than total FAC with regard to nutrition values of edible oils and fats. A rapid and direct regiospecific analysis of positional fatty acids in TAG using ¹³C NMR was developed to overcome the tedious conventional methods which involve enzymatic hydrolysis, Grignard chemical degradation, and chromatography analysis. A set of NMR data acquisition parameters and processing methods had proven their excellent versatility and applicability on various types of oils and fats, with systematic error of 1.0 mol%. It was found that there are discrepancies between the regiospecific analysis results obtained by the current method and by conventional methods. Probable acyl migration occurring in the hydrolysis process in conventional methods is a noted problem. As the current ¹³C NMR method is a direct measurement and no hydrolysis of the sample is needed, acyl migration during the analysis is eliminated. As a result, the saturation level is always higher at sn‐1, 3 positions and lower at sn‐2 position in TAG structure of oils in the regiospecific data obtained from the current ¹³C NMR than that from conventional methods. In the absence of laborious chemical derivatization, this method is simple, accurate, and user‐friendly for researchers, especially for nutritionists to support their nutritional studies from the perspective of positional FAC of edible oils and fats.     

Die Analyse von Raffinationsfettsäuren zur Charakterisierung von Futterölen für Kleintiere

Analysis of Feeding Oils for Small Animals Fatty acids used as feeding oils in small animal keeping are mainly acids, which are obtained as by-products during the neutralisation step of edible fats refining process. However, up to now often products with sub-optimal or even low quality were offered in the market. Therefore, the characterization of feeding oils by means of suitable analytical data becomes more important. Up to now used quality criteria are critically investigated especially considering modern methods of analysis and possible alternatives. Among others a method for determination of oxidized fatty acids is reported.     

Thraustochytrids as an alternative source of omega‐3 fatty acids,carotenoids and enzymes

Currently the most common microalgae used for commercial production of omega‐3 fatty acids are marine derived, particularly from family members of Thraustochytriaceae and Crypthecodiniaceae. Thraustochytrids are marine heterotrophic fungi like microorganisms known to produce several commercially interesting biotechnological compounds including omega‐3 fatty acids such as docosahexaenoic acid (DHA), docosapentaenoic acid (DPA) and eicosapentaenoic acid (EPA), carotenoids, sterols, exopolysaccharides and enzymes. Therefore, exploring the potential of thraustochytrids has much to offer to the commercial production of bioactive compounds. In response to growing demand for omega‐3 fatty acids, various isolation, fermentation and lipid recovery strategies have been developed in recent years.