Lipid‐based fat substitutes

Fats and oils account for 38% of the total calories in the diet of Western populations, especially in the U.S. They provide the most concentrated source of energy, 9 kcal/g of a triacylglycerol molecule compared with 4 kcal/g provided by carbohydrate and protein. In response to consumer demands for low‐calorie or calorie‐free fats and their reluctance to give up the taste of fat, current research efforts have been directed toward the development of lipid‐like fat substitutes. These fat substitutes contain the fatty acids found in conventional fats and oils, with all the physical and organoleptic properties of fats, but provide few or no calories in the diet. Some of the fat substitutes are modified triacylglycerols (glycerol backbone) with reduced digestion and absorption; others are digestible and nondigestible carbohydrate fatty acid esters and polyesters, respectively. Sucrose polyester (Olestra^®), a sucrose molecule esterified with six to eight fatty acids, is the most studied of the lipid‐based fat substitutes containing a carbohydrate backbone. If approved by the FDA, sucrose polyester will find application in almost all fat‐containing foods. Specialty fats or fat substitutes targeted to certain individuals with special needs are being developed. Among these are the medium‐chain triacylglycerols and structured lipids (glycerol backbone), or “nutraceuticals” with reduced absorption and medical applications. Enzyme biotechnology is another tool available to lipid chemists to selectively modify, esterify, transform, transesterify, and interesterify fats and oils or synthesize new lipids such as structured lipids of food, nutritional, and medical importance. These designer fats may be the trend in the future to produce medical lipids that do not occur normally in nature. The different types of lipid‐based fat substitutes are reviewed with respect to their synthesis, analysis, metabolism, potential applications/uses, and the future of fat substitutes.     

酯交换技术及其在油脂工业中的应用

酯交换是目前改善油脂物理性质较有效的一种油脂改性技术 ,主要分两种 :化学酯交换和脂肪酶催化酯交换。化学酯交换的催化机制有两种 ,即羰基加合机制和Claisen浓缩机制 ,而脂肪酶催化的酯交换机制类似于化学催化 ,它的催化位点由Asp/Glu His Ser氨基残基组成。还概述了酯交换在油脂工业中的应用 ,包括在猪油、大豆油以及棕榈油、乳脂、可可代用脂、乳幼儿用脂质、DHA以及EPA等中的应用     

Bioactive compounds in lipid fractions of pumpkin (Cucurbita sp) seeds for use in food

Seeds are considered to be agro-industrial residues, which can be used as source of macronutrients and/or raw material for extraction of vegetable oils, since they present great quantities of bioactive compounds. This study aimed to characterize the lipid fractions and the seeds of pumpkin (Cucurbita sp) varieties Nova Caravela, Mini Paulista, Menina Brasileira, and Moranga de Mesa aiming at using them in food. The chemical composition of the seeds was performed according to the official methods of American Oil Chemists' Society and Association of Official Analytical Chemists. Total carotenoids and phenolic compounds were determined by spectrophotometry, while the levels of tocopherols were analyzed by high efficiency liquid chromatography. It was noted that the seeds contain high amounts of macronutrients that are essential for the functioning of the human organism. As to total carotenoids, Mini Paulista and Menina Brasileira pumpkin varieties presented significant amounts, 26.80 and 26.03 μg/g, respectively. Mini Paulista and Nova Caravela pumpkin varieties showed high amounts of total phenolic compounds in the lipid fractions and in the seeds. It was also found that γ-tocopherol is the isomer that stood out in the lipid fractions and in the seeds, mainly in Menina Brasileira. Finally, the consumption of these seeds and use of lipid fractions provide the supply of large quantities of compounds that are beneficial for health and that may be potentially used in food, besides representing an alternative to better use of agro-industrial residues. PRACTICAL APPLICATION: Bioactive compounds, besides presenting basic nutritional functions, provide metabolic and physiological health benefits when consumed as part of the usual diet. Therefore, there is a growing interest in vegetable oils of special composition, such as the ones extracted from fruit seeds. The seeds of Cucurbita sp are shown to be promising sources of oils, and especially the Cucurbita moschata and maxima species have not yet been fully elucidated. For this reason, it becomes important to investigate the chemical composition and lipid fractions of these seeds, aiming to use them in food.     

Determination of Milk Fat Adulteration with Vegetable Oils and Animal Fats by Gas Chromatographic Analysis

This study assessed the potential application of gas chromatography (GC) in detecting milk fat (MF) adulteration with vegetable oils and animal fats and of characterizing samples by fat source. One hundred percent pure MF was adulterated with different vegetable oils and animal fats at various concentrations (0%, 10%, 30%, 50%, 70%, and 90%). GC was used to obtain the fatty acid (FA) profiles, triacylglycerol (TG) contents, and cholesterol contents. The pure MF and the adulterated MF samples were discriminated based on the total concentrations of saturated FAs and on the 2 major FAs (oleic acid [C18:1n9c] and linoleic acid [C18:2n6c], TGs [C52 and C54], and cholesterol contents using statistical analysis to compared difference. These bio‐markers enabled the detection of as low as 10% adulteration of non‐MF into 100% pure MF. The study demonstrated the high potential of GC to rapidly detect MF adulteration with vegetable and animal fats, and discriminate among commercial butter and milk products according to the fat source. These data can be potentially useful in detecting foreign fats in these butter products. Furthermore, it is important to consider that several individual samples should be analyzed before coming to a conclusion about MF authenticity.     

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.     

MONITORING LIPID OXIDATION AND ANTIOXIDANT EFFECTS OF PHOSPHOLIPIDS BY HEADSPACE GAS CHROMATOGRAPHIC ANALYSES OF RANCIMAT TRAPPED VOLATILES

Two of the most frequently used techniques to follow oxidation patterns of fats are headspace gas chromatography (HS-GC) and gas chromatography/mass spectrometry (GC/MS). The HS-GC technique offers the advantages of rapidity and multiple sample analyses, whereas GC/MS offers the advantages of GC separation coupled with the ability of MS to identify volatile compounds separated via GC. No previous information exists in the literature on the use of the volatiles trapped in water contained in the measuring vessel of the Rancimat and HS-GC to monitor lipid oxidation, as was the objective of this study. Oxidative secondary breakdown products of fish oil model systems trapped in water contained within the measuring vessel of the Rancimat were subjected to HS-GC analyses for quantitation of individual volatiles. Results from this study showed that oxidation induction time and products of oxidation can be monitored by the combined use of the Rancimat and HS-GC, and that trapped volatiles are representative of typical by-products of lipid oxidation and of oil type being examined. Addition of phospholipids (PL) to salmon and menhaden oils significantly influenced the production of volatile compounds. The molecular weights of the volatiles identified ranged from 30 to 212 daltons. The reproducibility of the method (std. dev. ≈ 2.04) was good but can be greatly improved through the use of a capillary column. PL having antioxidant activity generated lower concentrations of total volatiles than those found to be prooxidants.     

Lipid Changes during Frying of Frozen Prefried Foods

Fat absorption, lipid interchange and preferential adsorption of polar compounds on food surfaces were studied during frying of frozen prefried foods. Four frying oils were used to fry frozen potatoes and battered hake. Major and minor changes in food fats and frying oils were determined. Lipid determination after frying demonstrated significant differences in fat absorption due to the physical structure of foods. From quantitation of major fatty acids, lipid interchange between frying oils and food fats could be determined. Polar compound concentrations and distributions demonstrated no preferential adsorption on food surfaces during frying of these prefried foods.     

Analytical Methods for Quantification of Modified Fatty Acids and Sterols Formed as a Result of Processing

Fats and oils are often submitted to technological treatments before being consumed. Some treatments like refining, hydrogenation, and frying often lead to the formation of modified fatty acids such as cyclic fatty acid monomers (CFAM), geometrical fatty acid isomers, and/or oxidized fatty acids and sterols (cholesterol and phytosterols). Both cholesterol oxidation products (COP) and phytosterol oxidation products (POP), may be present in foods. As some of the newly formed components may present some adverse effects upon consumption, methods have been developed to analyze these compounds in food products and biological samples. Gas liquid chromatography (GC) on long polar columns (100m) is a good choice to quantify trans mono- and poly-unsaturated fatty acids. In some cases a pre-fractionation step using silver nitrate thin layer chromatography (AgNO₃-TLC) may be necessary to avoid GC overlapping of cis and trans isomers. Analysis of CFAM usually involves transformation of the sample in fatty acid methyl esters (FAME) which after addition of an internal standard (IS) are further hydrogenated. An enrichment step using reverse phase high performance liquid chromatography (RP-HPLC) permits to obtain a fraction which consists of a mixture of CFAM and the IS. This fraction is further analyzed by GC on a polar column. The analysis of oxidized triacylglycerol monomers (oxTG) as a group was feasible by a combination of adsorption and size-exclusion chromatography. Quantification in used frying fats and oils around the limit of rejection for human consumption (25% polar compounds) has shown that the amount of oxTG range 5.9–9.4% expressed on fat or oil weight. In foods and biological tissues, the level of oxidized sterols (SOP) is often a very small fraction of their unoxidized forms. Analysis of SOP involved extraction of lipids, saponification or transesterification, enrichment, and subsequent qualitative and quantitative determination by GC and GC-MS, or HPLC and HPLC-MS. In addition, enrichment of SOP requires complete separation from the unoxidized sterols in order to separate these compounds even by high resolution GC capillary columns.     

天然抗氧化剂抑制油脂氧化的研究进展

油脂在长期贮藏中易受多种因素影响发生氧化酸败,不仅影响食物感官,降低营养价值,同时产生一些有毒物质导致人体衰老、癌症以及多种慢性疾病的发生。天然抗氧化剂因具有安全性高、抗氧化能力较强的特点,已被普遍运用于油脂抗氧化中。从酚类、色素类、多肽类、甾醇类物质以及多糖类物质5个方面,综述了近年来从动植物中提取的天然抗氧化物质对油脂抗氧化的作用,旨在为天然抗氧化剂的开发、应用,油脂储存、保质研究提供参考。     

Health Benefits, Enzymatic Production, and Application of Medium- and Long-Chain Triacylglycerol (MLCT) in Food Industries: A Review

Medium- and long-chain triacylglycerol (MLCT) is a modified lipid containing medium- chain (C6-C12) and long-chain fatty acids (C14-C24) in the same triacylglycerol (TAG) molecule. It can be produced either through enzymatic (with 1,3 specific or nonspecific enzyme) or chemical methods. The specialty of this structured lipid is that it is metabolized differently compared to conventional fats and oils, which can lead to a reduction of fat accumulation in the body. Therefore, it can be used for obesity management. It also contains nutritional properties that can be used to treat metabolic problems. This review will discuss on the health benefits of MLCT, its production methods especially via enzymatic processes and its applications in food industries.     

低热量油脂(脂肪代用品)的市场需求及研究开发现状

扼要阐述了低热油脂将随着国民经济的大发展,饮食生活水平的提高会有广阔的消费市场,并对目前国内在低热量油脂方面的研究开发状况进行了简要介绍。同时对酯化和酯交换技术途径生产热量油脂情况也作了一些介绍。     

我国食用植物油市场的挑战及机遇

我国食用油产业发展迅速,但仍然面临各种挑战。通过对我国食用油市场的发展现状、加工过程中危害物质深度分析欠缺、小品种油料资源的全面化市场调研欠深入、植物油营养评价和特殊人群的专用食用调和油研究开发不足等方面进行分析,提出我国食用植物油市场面临机遇与前景展望,推广油脂精准适度加工新模式,系统开发我国油料资源,研究食用油营养学价值,开发特殊人群的专用食用调和油,为推动油脂加工业的高质量发展提供参考建议。     

Edible lipids modification processes: A review

Lipid is the general name given to fats and oils, which are the basic components of cooking oils, shortening, ghee, margarine, and other edible fats. The chosen term depends on the physical state at ambient temperature; fats are solids and oils are liquids. The chemical properties of the lipids, including degree of saturation, fatty acid chain length, and acylglycerol molecule composition are the basic determinants of physical characteristics such as melting point, cloud point, solid fat content, and thermal behavior. This review will discuss the major lipid modification strategies, hydrogenation, and chemical and enzymatic interesterification, describing the catalysts used mechanisms, kinetics, and impacts on the health-related properties of the final products. Enzymatic interesterification will be emphasized as method that produces a final product with good taste, zero trans fatty acids, and a low number of calories, requires less contact with chemicals, and is cost efficient.     

Analysis of mesocarp and kernel oils from the American oil palm and F1 hybrids with the West African oil palm

The mesocarp oil of the American oil palm is more unsaturated than that of the West African oil palm. Mesocarp oils obtained from F₁ hybrids of these two oil palms exhibit an intermediate degree of unsaturation. Hybrid kernel oils are similar in composition to that of their West African oil palm parent, whereas kernel oils from the American oil palm are considerably more unsaturated and exhibit a unique fatty acid composition among seed fats of the Palmae family.     

Saturated Sterols (Stanols) in Unhydrogenated and Hydrogenated Edible Vegetable Oils and in Cereal Lipids*

The content of saturated sterols (stanols) was investigated in a small number of samples of hydrogenated fats and oils, and in the ‘free’ and ‘bound’ lipids of various samples of cereals. The sterols, after saponification of the total lipids, were analysed as trimethylsilyl derivatives by GC and identified by GC–MS. Among the hydrogenated fats and oils, coconut oil contained the largest amounts of sitostanol followed by soybean oil (c 80 and 20 g kg⁻¹ of total unsaponifiables, respectively). No sitostanol could be detected in hydrogenated palm oil under the present analytical conditions. Both ‘free’ and ‘bound’ lipids in various samples of wheat, except for wheat germ, contained c 70–120 g kg⁻¹ campestanol and 100–150 g kg⁻¹ sitostanol in total unsaponifiables. In lipids of oats and barley, no campestanol or sitostanol could be detected. Rye total lipids contained 60–90 g kg⁻¹ of campestanol and 100–150 g kg⁻¹ of sitostanol of total unsaponifiables in ‘free’ and ‘bound’ lipids, respectively.     

国际标准化组织动植物油脂国际标准制定（网络首发、推荐阅读）

Increasing volumes of oils and fats are produced annually with a large section that are traded internationally. The International Organization for Standardization(ISO) body develops international standards covering almost all aspects of technology and manufacturing with 23,882 standards currently published. Standards in the animal and vegetable fats and oils sector is developed by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal and vegetable fats and oils. Standards are developed through consensus by national members that represent ISO in their country. Each Standard is developed within a determined timeframe and goes through various pre-determined stages such as project proposal, development, national voting and commenting on the draft Standard to final publication. ISO TC34/SC11 Standards range from sampling of oils and fats, sample preparation to analysis of its composition, the minor components, and quality and identity parameters as well as contaminants. The analysis results are used by industry for product development, labelling, research and to provide peace of mind for consumers on its safety. An important future trend is the focus on the safety concerns from either environmental contamination(e.g. mineral oils) or processing contaminants such as esters of 3-MCPDs(3-monochloropropane-1,2-diol or 3-chloropropane-1,2-diol).     

Evaluation of Fatty Acid Profile of Wagyu Beef by ATR-FTIR Spectroscopy

Japanese black Wagyu beef has its characteristics of fatty well-marbled texture, flavor, and tenderness which are affected by fatty acid composition. The aim of this study was to develop an analytical method for evaluating the fatty acid profile of Wagyu beef by Fourier transform infrared (FTIR) spectroscopy. In the current study, attenuated total reflection–FTIR (ATR-FTIR) spectroscopy and gas chromatography (GC) were applied to the fat tissues, and the solvent-extracted fats which were sampled from subcutaneous, inter- and intramuscular fat tissues. Results of GC analysis showed that monounsaturated fatty acids (MUFA) content became larger in the order of intramuscular, intermuscular, and subcutaneous fats, and saturated fatty acids (SFA) became smaller in the same order. Subcutaneous fat could be discriminated from inter- and intramuscular fats on the basis of fatty acid composition by principal component analysis. The ATR-FTIR analysis revealed that the shift of the peak positions of alkene C–H stretching vibration at around 3,006 cm⁻¹ occurred depending on the unsaturation degree of fatty acids in beef fat. Partial least squares (PLS) regression analysis with leave-one-out cross-validation was applied to the combined regions of 2,800–3,050 and 1,000–1,500 cm⁻¹ for the fat tissues and the extracted fats. The correlation coefficients of the PLS validation models predicting the content of the MUFA and SFA for solvent-extracted fats were higher than those for fat tissues, and the coefficients (R ²) of determination more than 0.873 were obtained for solvent-extracted fats and 0.522 for fat tissues.     

CHARACTERIZING QUALITY OF RENDERED DUCK FAT COMPARED TO OTHER FATS AND OILS

The characteristics of rendered duck fat (RDF) were compared to commercial sources of soybean oil, lard, tallow, butter and olive oil. RDF was highly susceptible to lipid oxidation during storage compared to the other fats and oils. However, 0.005% tert‐butyl hydroquinone delayed the onset of lipid oxidation to an extent that was comparable to the lag phase observed in the commercial fats and oils. Positive attributes of RDF included a relatively high oleic acid content and low saturated fat content. Undesirable attributes of RDF included a lack of conjugated linoleic acid (CLA) and intermediate levels of trans fatty acids (TFA) compared to the other lipid sources. Decreasing the time and temperature of rendering decreased the TFA content in RDF. Around one‐half of the TFA content in RDF was vaccenic acid which is converted to CLA after ingestion.     

Profiles of volatile compounds from some monovarietal Tunisian virgin olive oils. Comparison with French PDO

The volatile profiles of seven Tunisian and four French virgin olive oils were established by solid phase micro-extraction (SPME) and gas chromatography (GC), using flame ionisation and mass spectrometer detectors. Eighty-six compounds were identified and characterized, representing 97.4–99.9% of the total GC area. (E)-2-hexenal, the main compound extracted by SPME, characterized the olive oil headspace for approximately 90% of the oils examined. Significant differences in the proportions of volatile constituents from oils of different varieties were detected. The results demonstrated that the accumulation of the different metabolites in the oils obtained from the various cultivars was strictly connected with the varietal parameters on the basis of the enzyme differences genetically determined. This feature made possible the differentiation of the examined cultivars on the basis of the percent of each metabolite.     

油脂的风味及感知

油脂是一种重要的营养物质。随着我国经济水平的发展,居民越来越多地关注油脂的风味品质。油脂原料本身的差异以及加工制备过程中的脂肪氧化降解、热分解、美拉德反应等是影响油脂形成不同风味品质的主要因素。口腔加工中油脂及其制品经过味觉、嗅觉、三叉神经感觉等方面相互作用,在大脑特定区域形成风味的认知。目前有研究证明脂肪酸转位酶（CD36）、G蛋白偶联受体（GPCR）等受体参与到一个专门用于感知脂质的感官系统。因此,有人提出脂肪可能是第6种味道。复杂的多感官交互依赖于人类所有感官的反应,未来关于脂肪感知以及脂肪参与多感官交互方面还需要进一步研究。