反式脂肪酸对人体健康的影响

近年来反式脂肪酸(TFA)在我国引起政府、学术团体、学者以及有关企业的关注。本文就膳食TFA的摄入对人体健康的影响做一综述。膳食中的TFA主要是由部分氢化植物油或鱼油引入。与饱和脂肪酸、顺式单不饱和脂肪酸及多不饱和脂肪酸相比,TFA可降低血浆高密度脂蛋白胆固醇,提高总胆固醇和高密度脂蛋白胆固醇的比例,增加冠心病发作的风险。另外,TFA还可增加致命性的心脏猝死,增加患代谢综合症以及糖尿病的风险。     

Evaluation of the Impact of Ruminant Trans Fatty Acids on Human Health: Important Aspects to Consider

The definition and evaluation of trans fatty acids (TFA) with regard to foodstuffs and health hazard are not consistent. Based on the current situation, the term should be restricted only to TFA with isolated double bonds in trans-configuration. Conjugated linoleic acids (CLA) should be separately assessed. Ideally, the origin of the consumed fat should be declared, i.e., ruminant TFA (R-TFA) and industrial TFA (non-ruminant; I-TFA). In ruminant fat, more than 50% of R-TFA consists of vaccenic acid (C18:1 t11). In addition, natural CLA, i.e., c9,t11 CLA is also present. Both are elevated in products from organic farming. In contrast to elaidic acid (t9) and t10, which occur mainly in partially hydrogenated industrial fat, t11 is partially metabolized into c9,t11 CLA via Δ9-desaturation. This is the major metabolic criterion used to differentiate between t11 and other trans C18:1. t11 indicates health beneficial effects in several studies. Moreover, CLA in milk fat is associated with the prevention of allergy and asthma. An analysis of the few studies relating to R-TFA alone makes clear that no convincing adverse physiological effect can be attributed to R-TFA. Only extremely high R-TFA intakes cause negative change in blood lipids. In conclusion, in most European countries, the intake of R-TFA is assessed as being low to moderate. Restriction of R-TFA would unjustifiably represent a disadvantage for organic farming of milk.     

New Trends in the Microencapsulation of Functional Fatty Acid‐Rich Oils Using Transglutaminase Catalyzed Crosslinking

Preparing stable protein‐based microcapsules containing functional fatty acids and oils for food applications has been a big challenge. However, recent advances with transglutaminase (TGase) enzyme as an effective protein cross‐linker could provide workable solutions for the encapsulation of omega‐3 and omega‐6 fatty acids without compromising their targeted release and their biological and physicochemical characteristics. The recent and available literature related to the microencapsulation techniques, physical and oxidative properties, and core retention and release mechanisms of TGase‐crosslinked microcapsules entrapping edible oils were reviewed. The effects of factors involved in microencapsulation processes, on the efficiency and quality of the produced innovative microcapsules were also discussed and highlighted. A brief focus has been finally addressed to new insights and additional knowledge on micro‐ and nanoencapsulation of lipophilic food‐grade ingredients by TGase‐induced gelation. Two dominant microencapsulation methods for fish, vegetable, and essential oils by TGase‐crosslinking are complex coacervation and emulsion‐based spray drying. The developed spherical particles (<100 μm) with some wrinkles and smooth surfaces showed an excellent encapsulation efficiency and yield. A negligible release rate and a substantial retention level can result for different lipid‐based cores covered by TGase‐crosslinked proteins during the oral digestion and storage. A significant structural, thermal and oxidative stability for edible oils‐loaded microcapsules in the presence of TGase can be also obtained.     

Impact of Trans‐Fats on Heat‐Shock Protein Expression and the Gut Microbiota Profile of Mice

Partially hydrogenated oils are known to cause metabolic stress and dyslipidemia. This paper explores a new dimension about the interaction between dietary trans‐fats and the defense heat‐shock protein (HSP) system, inflammation, and the gut microbiota of mice consuming a hyperlipidic diet containing partially hydrogenated vegetable oil free of animal fat. Five diet groups were installed: control diet, 2 hyperlipidic‐partially hydrogenated‐oil diets, each containing either casein or whey‐protein hydrolysate (WPH) as protein source, and 2 consuming hyperlipidic‐unhydrogenated‐oil diets containing either WPH or casein as a protein source. The partially hydrogenated oil inhibited c‐Jun NH₂‐terminal kinase phosphorylation in the casein diets, but without altering κ‐B kinase. Neither the lipid nor the protein had an influence on the proinflammatory toll‐like receptor 4 (TLR4) pathway, but the combination of the high‐lipid content and WPH impaired glucose tolerance without altering insulin or glucose transporter‐4 translocation. It was remarkable to observe that, contrary to the case of a common high‐fat diet, the lard‐free hyperlipidic diets were hardly able to invert the Bacteroidetes:Firmicutes phylum ratio. Our results suggest that, in the absence of lard, the intake of trans‐fatty acids is less harmful than expected because it does not trigger TLR4‐inflammation or pose great threat to the normal gut microbiota. WPH had the effect of promoting the expression of HSP90, HSP60, and HSP25, but did not prevent dysbiosis, when the diet contained the unhydrogenated oil. The partially hydrogenated oil also seemed to antagonize the ability of WPH to induce the expression of protective HSPs.     

Nutrient‐Rich Foods: Applying Nutrient Navigation Systems to Improve Public Health

ABSTRACT: The American diet is high in calories, but low in nutrients. To help consumers obtain more nutrition from the calories they consume, research is underway to develop a nutrient profiling approach that can be used to evaluate individual foods and help people build healthful diets. A nutrient profiling system that rates individual foods based on their nutrient content needs to be both science‐driven and user‐friendly, allowing consumers to make more healthful food choices within and across all the food groups. A recent survey, commissioned by the Nutrient Rich Food Coalition, reveals that the majority of consumers and nutrition professionals believe that better information about a food's total combined nutrient content would be effective and useful in helping them make more nutrient‐rich food choices.     

Effect of CMC Molecular Weight on Acid‐Induced Gelation of Heated WPI‐CMC Soluble Complex

Acid‐induced gelation properties of heated whey protein isolate (WPI) and carboxymethylcellulose (CMC) soluble complex were investigated as a function of CMC molecular weight (270, 680, and 750 kDa) and concentrations (0% to 0.125%). Heated WPI‐CMC soluble complex with 6% protein was made by heating biopolymers together at pH 7.0 and 85 °C for 30 min and diluted to 5% protein before acid‐induced gelation. Acid‐induced gel formed from heated WPI‐CMC complexes exhibited increased hardness and decreased water holding capacity with increasing CMC concentrations but gel strength decreased at higher CMC content. The highest gel strength was observed with CMC 750 k at 0.05%. Gels with low CMC concentration showed homogenous microstructure which was independent of CMC molecular weight, while increasing CMC concentration led to microphase separation with higher CMC molecular weight showing more extensive phase separation. When heated WPI‐CMC complexes were prepared at 9% protein the acid gels showed improved gel hardness and water holding capacity, which was supported by the more interconnected protein network with less porosity when compared to complexes heated at 6% protein. It is concluded that protein concentration and biopolymer ratio during complex formation are the major factors affecting gel properties while the effect of CMC molecular weight was less significant.     

Effect of Dietary Partial Hydrolysate of Phospholipids,Rich in Docosahexaenoic Acid‐Bound Lysophospholipids,on Lipid and Fatty Acid Composition in Rat Serum and Liver

Lysophospholipids have been recognized as potent biologically active lipid mediators. However, attention has not been paid to the health benefits of dietary partial hydrolysate of phospholipids (PH‐PL), which is rich in docosahexaenoic acid (DHA)‐bound lysophospholipids. In this study, the effects of PH‐PL on serum and liver lipid profiles of rats upon administration of PH‐PL are demonstrated in comparison to those of fish oil (FO), which comprises eicosapentaenoic acid (EPA) and DHA‐bound triglyceride (TG). PH‐PL containing EPA and DHA was prepared via enzymatic modification of squid (Todarodes pacificus) meal that is rich in phospholipids. Male Wistar rats were fed a basal diet containing soybean oil alone (7%), FO, and PH‐PL. The FO and PH‐PL diets had similar EPA and DHA contents. After the rats had been fed their respective diets for 28 d, their serum and liver lipid contents, fecal lipid excretion, and hepatic gene expression level were measured. The results demonstrated that compared with the soybean oil diet alone, the PH‐PL diet decreased serum and liver TG contents partially because of the enhancement of liver acyl‐CoA oxidase activity and suppression of liver fatty acid synthase activity. In addition, compared with the soybean oil diet, the PH‐PL group exhibited lower serum cholesterol content at least in part because of the reduction of hepatic 3‐hydroxy‐3‐methylglutaryl‐CoA reductase mRNA expression level. We found that dietary administration of EPA and DHA containing PH‐PL has a hypolipidemic effect that may help prevent the development lifestyle‐related diseases.     

Membrane‐Filtered Olive Mill Wastewater: Quality Assessment of the Dried Phenolic‐Rich Fraction

A current trend in olive mill wastewater (OMWW) management is to not only decrease environmental pollution but also to extract and utilize valuable by‐products. Therefore, the objectives of this study were to explore different techniques for drying a phenolic‐rich membrane filtration fraction of OMWW and compare the techniques in terms of the dried product quality and feasibility of the process. The OMWW from 2 (3‐phase and 2‐phase) California mills was subjected to a 2‐step membrane filtration process using a novel vibratory system. The reverse osmosis retentate (RO‐R) is a phenolic‐rich coproduct stream, and the reverse osmosis permeate is a near‐pure water stream that could be recycled into the milling process. Spray‐, freeze‐, and infrared‐drying were applied to obtain solid material from the RO‐R. Drying of the RO‐R was made possible only with addition of 10% maltodextrin as a carrier. The total soluble phenolics in dried RO‐R were in the range 0.15 to 0.58 mg gallic acid equivalents/g of dry weight for 2‐phase RO‐R, and 1.38 to 2.17 mg gallic acid equivalents/g of dry weight for the 3‐phase RO‐R. Spray‐dried RO‐R from 3‐phase OMWW showed remarkable antioxidant activity. Protocatechuic acid, tyrosol, vanillic acid, and p‐coumaric acid were quantified in all dried RO‐R, whereas 3‐hydroxytyrosol was found in 3‐phase dried RO‐R. This combination of separation and drying technologies helps to add value and shelf‐stability to an olive oil by‐product and increase environmental sustainability of its production.     

Low‐calorie Sweeteners and Other Sugar Substitutes: A Review of the Safety Issues

Sugar‐free or reduced‐sugar foods and beverages are very popular in the United States and other countries, and the sweeteners that make them possible are among the most conspicuous ingredients in the food supply. Extensive scientific research has demonstrated the safety of the 5 low‐calorie sweeteners currently approved for use in foods in the United States–acesulfame K, aspartame, neotame, saccharin, and sucralose. A controversial animal cancer study of aspartame conducted using unusual methodology is currently being reviewed by regulatory authorities in several countries. No other issues about the safety of these 5 sweeteners remain unresolved at the present time. Three other low‐calorie sweeteners currently used in some other countries–alitame, cyclamate, and steviol glycosides–are not approved as food ingredients in the United States. Steviol glycosides may be sold as a dietary supplement, but marketing this product as a food ingredient in the United States is illegal. A variety of polyols (sugar alcohols) and other bulk sweeteners are also accepted for use in the United States. The only significant health issue pertaining to polyols, most of which are incompletely digested, is the potential for gastrointestinal discomfort with excessive use. The availability of a variety of safe sweeteners is of benefit to consumers because it enables food manufacturers to formulate a variety of good‐tasting sweet foods and beverages that are safe for the teeth and lower in calorie content than sugar‐sweetened foods.     

Potassium Chloride‐Based Salt Substitutes: A Critical Review with a Focus on the Patent Literature

High dietary sodium intake (DSI) represents a major health‐related public issue in most countries all over the world. Such a diet can lead to increased risk of hypertension and related cardiovascular diseases. This situation has resulted in important public policies for various salt reduction strategies. One of these is based on the use of salt substitutes or salts with reduced sodium content. Among several options, potassium chloride (KCl) has proved to be a key nutritional ingredient for this purpose. It provides similar properties like common salt (NaCl), but with several unwanted side effects, of which the most important have relatively offensive side tastes: bitter, acrid, and metallic. To successfully formulate KCl‐based salt substitutes, numerous taste‐improving agents and formulation concepts have been used. The field of salt substitutes is mainly described in the patent literature. Since patents are both scientific and legal documents, careful and critical consideration is required when using them as a source of scientific information. This review brings a deep insight into the area of KCl‐based salt substitutes with a focus on the patent literature through the eyes of food science and technology. The most important classes of taste‐improving agents that have been employed in numerous formulation concepts of KCl‐based salt substitutes are nutritionally acceptable mineral salts; food acids, amino acids, and their nutritionally acceptable salts; simple carbohydrates and sugar substitutes; food polymers; umami ingredients; spices, vegetables, and flavors; miscellaneous taste improvers; as well as a plethora of their specific combinations. A critical review of the respective patent literature is given.     

Effects of Sorbic Acid‐Chitosan Microcapsules as Antimicrobial Agent on the Properties of Ethylene Vinyl Alcohol Copolymer Film for Food Packaging

This paper discusses the possibility of using sorbic acid‐chitosan microcapsules (S‐MPs) as an antibacterial component of active ethylene vinyl alcohol copolymer (EVOH) film. S‐MPs with a diameter of approximately 1 to 4 μm showed a sorbic acid loading capacity of 46.5%. Addition of S‐MPs (3%, w/w) increased the tensile strength, haze, oxygen, and water vapor barrier properties, as well as reduced the elongations at break and transmittance of S‐MPs‐EVOH (S‐MP‐EVOH) film. Antibacterial tests showed that the inhibitory capacity of S‐MP‐EVOH film against Salmonella Enteritidis and Escherichia coli was higher than that against Listeria monocytogenes. Moreover, the antibacterial effect of sorbic acid‐EVOH (S‐EVOH) film was stronger than that of S‐MP‐EVOH film. However, S‐MP‐EVOH film demonstrated a longer effective time than S‐EVOH film. Using the total viable counts and total volatile base nitrogen as the judgment standard, S‐MP‐EVOH/polyethylene terephthalate (PET) composite film could extend the shelf life of fish fillets by 4 d at 4 °C, compared with EVOH/PET film. For this reason, S‐MP could be a potential antibacterial component of active films.     

Acid‐soluble and pepsin‐soluble collagens from grass carp (Ctenopharyngodon idella) skin: a comparative study on physicochemical properties

In this study, acid‐soluble (ASC) and pepsin‐soluble (PSC) collagens with triple helical structures were successfully extracted from the skin of grass carp (Ctenopharyngodon idella) by two different extraction approaches. SDS‐PAGE pattern revealed that ASC and PSC are type I collagens with typical α1, α2 and β‐chains. In addition, the intensity of χ‐chain (trimer) in ASC was higher than that of PSC, representing the presence of the high proportion of intra‐ and intermolecular cross‐links of extracted collagens with large molecular weight using the acid method. Differential scanning calorimetry (DSC) results demonstrate that T_d (69.04 °C) of ASC was higher than T_d (62.20 °C) of PSC. Both ASC and PSC had the highest solubility at acidic pHs or at a low concentration of NaCl (<2%, w/v). The results of FTIR suggested the ASC and PSC maintained in the helical secondary structure at high degree.     

Effect of Hops Beta Acids on the Survival of Unstressed‐ or Acid‐Stress‐Adapted‐Listeria Monocytogenes and on the Quality and Sensory Attributes of Commercially Cured Ham Slices

This study evaluated the antilisterial activity of hops beta acids (HBA) and their impact on the quality and sensory attributes of ham. Commercially cured ham slices were inoculated with unstressed‐ and acid‐stress‐adapted (ASA)‐L. monocytogenes (2.2 to 2.5 log CFU/cm²), followed by no dipping (control), dipping in deionized (DI) water, or dipping in a 0.11% HBA solution. This was followed by vacuum or aerobic packaging and storage (7.2 °C, 35 or 20 d). Samples were taken periodically during storage to check for pH changes and analyze the microbial populations. Color measurements were obtained by dipping noninoculated ham slices in a 0.11% HBA solution, followed by vacuum packaging and storage (4.0 °C, 42 d). Sensory evaluations were performed on ham slices treated with 0.05% to 0.23% HBA solutions, followed by vacuum packaging and storage (4.0 °C, 30 d). HBA caused immediate reductions of 1.2 to 1.5 log CFU/cm² (P < 0.05) in unstressed‐ and ASA‐L. monocytogenes populations on ham slices. During storage, the unstressed‐L. monocytogenes populations on HBA‐treated samples were 0.5 to 2.0 log CFU/cm² lower (P < 0.05) than control samples and those dipped in DI water. The lag‐phase of the unstressed‐L. monocytogenes population was extended from 3.396 to 7.125 d (control) to 7.194 to 10.920 d in the HBA‐treated samples. However, the ASA‐L. monocytogenes population showed resistance to HBA because they had a higher growth rate than control samples and had similar growth variables to DI water‐treated samples during storage. Dipping in HBA solution did not adversely affect the color or sensory attributes of the ham slices stored in vacuum packages. These results are useful for helping ready‐to‐eat meat processors develop operational procedures for applying HBA on ham slices.