Isolation and characterisation of a water-soluble wheat-flour protein

The main component of the water-soluble proteins of wheat flour has been isolated in sufficient quantity for chemical and physical characterisation. This was achieved by a combination of ion-exchange chromatography on carboxymethyl cellulose and gel filtration through Sephadex G75. The protein isolated was judged to be 90% pure by zone electrophoresis. Sedimentation analysis yielded a single symmetrical peak with an S°_20,w value of 2.45. The molecular weight was found to be 19,300 by gel filtration, and the diffusion coefficient estimated by the same method was 10.47 × 10^?7. A molecular weight of 16,000 was calculated from sedimentation equilibrium analysis in a dissociating medium. The ultra-violet spectrum of the isolated albumin exhibited a maximum at 278 nm and from this an E^1% ₂₇₈ value of 13.1 was calculated. No free sulphydryl groups could be detected. Amino acid analysis showed that this protein has a composition similar to those of other soluble wheat-flour preparations. A molecular weight of 16,300 was calculated from the amino acid analysis. End-group analysis of the protein showed that serine is the N-terminal amino acid. The C-terminal amino acid was found to be resistant to release by both carboxypeptidase A and carboxypeptidase B.     

Lipid binding in wheat-flour doughs: The effect of datem emulsifier

Binding of lipids and added fats increased as more work was applied to wheat-flour doughs mixed under nitrogen. Bound-lipid levels were lower in doughs mixed in air than in those mixed in nitrogen and increase in work input had little effect on the level of bound lipid in the former. The presence of DATEM emulsifier (diacetyl tartaric esters of mono- and diglycerides) had little effect on the air-mixed doughs, but brought about a considerable reduction in lipid binding in the doughs mixed under nitrogen. It is known that DATEM emulsifiers have profound effects on dough and bread properties and it is suggested that one effect of these emulsifiers is to maintain a pool of free lipid in the dough.     

The effects of three thiols on the extractability of wheat-flour proteins

A new technique is described for the progressive extraction of wheat-flour proteins using columns. Purified sand is the only diluent used, and even packing is made possible by the use of a vacuum. Good rate of flow, filtration of effluents and reproducibility of results are obtained, and air can be excluded if necessary. Solutions of cysteine, dithiothreitol and amyl thioglycollate in water or 40% isopropanol raise the extractability of protein from wheat flour, under some conditions nearly to a quantitative level. Their action is attributed to the depolymerisation of glutenins by disulphide scission. Heating flour to 114° in a microwave oven causes little change in the extractability of proteins, but treatment with 1-butanol (to remove lipids) markedly lowers the extractability of proteins, even in the presence of thiols.     

The cuticles of citrus species. Composition of the intracuticular lipids of leaves and fruits

The qualitative and quantitative compositions of the intracuticular lipids of the leaves and fruits of four species of Citrus have been examined. The leaf cuticular membranes (280–316 μg/cm²) were well developed and contained high proportions of cutin (77–87%) of which isomers of dihydroxyhexadecanoic acid (79–82%) were the most abundant monomers. The fruit membranes (221–271 μg/cm²) contained smaller proportions of cutin (59–67%) whose major monomeric constituents were dihydroxyhexadecanoic acid (30–62%) and 16-hydroxyoxo-hexadecanoic acid (21–57%). The substantial amounts of cuticular wax (34–68 μg/cm²) located within the membranes consisted largely of fatty acids (68–97%) with hexadecanoic acid (44–78%) and octadecanoic acid (11–39%) present as the main components.     

Composition, structure and absorption of milk lipids: a source of energy, fat-soluble nutrients and bioactive molecules

Milkfat is a remarkable source of energy, fat-soluble nutrients and bioactive lipids for mammals. The composition and content of lipids in milkfat vary widely among mammalian species. Milkfat is not only a source of bioactive lipid components, it also serves as an important delivery medium for nutrients, including the fat-soluble vitamins. Bioactive lipids in milk include triacylglycerides, diacylglycerides, saturated and polyunsaturated fatty acids, and phospholipids. Beneficial activities of milk lipids include anticancer, antimicrobial, anti-inflammatory, and immunosuppression properties. The major mammalian milk that is consumed by humans as a food commodity is that from bovine whose milkfat composition is distinct due to their diet and the presence of a rumen. As a result of these factors bovine milkfat is lower in polyunsaturated fatty acids and higher in saturated fatty acids than human milk, and the consequences of these differences are still being researched. The physical properties of bovine milkfat that result from its composition including its plasticity, make it a highly desirable commodity (butter) and food ingredient. Among the 12 major milk fatty acids, only three (lauric, myristic, and palmitic) have been associated with raising total cholesterol levels in plasma, but their individual effects are variable-both towards raising low-density lipoproteins and raising the level of beneficial high-density lipoproteins. The cholesterol-modifying response of individuals to consuming saturated fats is also variable, and therefore the composition, functions and biological properties of milkfat will need to be re-evaluated as the food marketplace moves increasingly towards more personalized diets.     

Skin lipids

Concepts regarding the structure and function of the stratum corneum (SC) have changed from that of a tough film of loosely adherent cells to that of a two-compartment system of protein-enriched cells embedded in intercellular lipids. The two-compartment arrangement enlarged the role of epidermal lipids from that of the plasticizing component of the SC to that of the epidermal barrier governing water-holding properties as well as take-up of water, the differences in permeability of topically applied lipophilic and hydrophilic agents as well as cohesion and desquamation of the SC. Barrier properties of SC are dependent largely on the intactness of the lipid lamellae that surround the corneocytes. The pliability of the SC depends on a correct balance of lipids, hygroscopic water-soluble substances and water.
Mammalian differentiation involves characteristic changes in lipid composition consistent with the requirements for waterproofing. There is a progressive depletion of phospholipids and glycosphingolipids with enrichment in ceramides, cholesterol, free fatty acids, and small amounts of other polar (e.g. cholesterol sulphate) and non-polar species (e.g. hydrocarbons, cholesterol esters, triglycerides). The sphingolipids account for the most lipid by weight and are presumed to be of major importance for the water-retaining properties of the epidermal barrier. Decrease of sphingolipid content occurs in aged skin. Deficiency of essential fatty acids leads to enhanced transdermal water transport in addition to dryness and scaliness of the skin. A mixture of both saturated and unsaturated fatty acids produces the optimal barrier to water loss from the SC. The balance between solid crystal and liquid crystalline phases in epidermal lipids is determined by the degree of fatty acid unsaturation and the amount of water.     

Legume lipids

The storage lipids of legume seeds are a major source of dietary fat. As a result of their importance in the food industry, much is known about lipid composition, chemistry, flavor, off‐flavor development, and their technological implications in foods of dry, oil‐rich seeds such as soybeans and peanuts. Lipids from green pea have also been investigated to some extent. Other food legume lipids have not been studied in any great detail because of their low lipid content and limited or negligible use for oil purposes. Literature on the biochemical, nutritional, and toxicological aspects of lipids from these other legumes is scanty, compared to published reports of seed lipids from soybean and peanuts. Lipids of soybean, peanut, and green pea are reported in this article. Their chemistry, interactions with other constituents, role in flavor development, as well as alterations due to processing and removal of off‐flavors are reviewed. The nutritional and toxicological implications of legume lipids from soybean, peanuts, and other food legumes are also discussed.     

Epidermal lipids

From the time an epidermal cell leaves the basal layer to the time it is desquamated, the cell lipids change dramatically, both qualitatively and quantitatively. The most abundant lipid class in basal cells is phospholipid with the remaining lipid being accounted for by roughly equal proportions of cholesterol, non-esterified fatty acid, triacylglycerol and glycolipid: minor components include cholesteryl esters and ceramide. In contrast, approximately half of the lipid in a desquamated cell consists of ceramide, with the remainder consisting largely of cholesterol and non-esterified fatty acid. Immediately before desquamation, small concentrations of cholesteryl sulphate and glycolipid have been found and there is evidence that these polar lipids are important components of the water barrier and also contribute towards the physical integrity of the lower part of the stratum corneum. The change in lipid content as cornification proceeds is no less dramatic than the change in lipid composition. A basal cell contains about 10 pg lipid, whereas a desquamated stratum corneum cell contains approximately six times this amount. The change in lipid composition of a cell undergoing cornification results, therefore, largely from de novo synthesis of lipid, especially cholesterol, non-esterified fatty acid and ceramide.
Les lipides de l'épiderme     

脂质代谢、营养学特点及结构脂质的应用

结构脂质是基于油脂代谢、营养学研究基础上设计的一类新型油脂,极具开发潜力。论述了不同脂肪酸在人体内代谢特点,不同人群的油脂需求以及结构脂质在食品、医药与营养领域的研究、应用现状。     

Composition of the lipids of lupin seed (Lupinus angustifolius L. var. “uniwhite”)

The total lipids (8.6%) extracted from whole lupin seeds (Lupinus angustifolius L. var. “Uniwhite”) were found to be comprised of triglycerides (71.1%), phospho-lipids (14.9%), free sterols (5.2%), glycolipids (3.5%), sterol and wax esters (0.5%), free alcohols (0.4%), hydrocarbons (0.4%) and unidentified waxy material (4.0%). The main fatty acids in the total lipid extract were linoleic (48.3%), oleic (31.2%), palmitic (7.6%) and linolenic (5.4%). Erucic acid was not present, nor were cyclopropenoid acids. Seed coatings constituted 23.9% of the weight of the whole seeds and contained 1.5% lipids, the main classes of which were triglycerides (38.4%), free sterols (28.0%), phospholipids (9.7%), glycolipids (9.1%) and free alcohols (3.7%). The seed coatings and kernels contained the same fatty acid constituents, but the proportions of oleic, linoleic and linolenic acids were markedly different. β-Carotene was present, although at low concentration. When evaluated on its lipid composition, “Uniwhite” lupin seed appears suitable as a supplement for pig, poultry and stock feeding.     

板栗黄酒渣粉对小麦粉面包品质特性、微观结构、生物活性成分及抗氧化性影响的研究

为了提高板栗资源的利用率,将板栗黄酒渣粉(Chinese chestnut rice wine residue flour,WRF)作为膳食纤维源和生物活性物质源应用于小麦粉面包中,以改善小麦粉面包的营养结构并探讨开发WRF强化面包的可行性。研究了自然干燥板栗黄酒渣粉(Natural-dried Chinese chestnut rice wine residue flour,NDWRF),烘箱干燥板栗黄酒渣粉(Oven-dried Chinese chestnut rice wine residue flour,ODWRF),真空冷冻干燥板栗黄酒渣粉(Vacuum freeze-dried Chinese chestnut rice wine residue flour,VFDWRF)的基本组成成分、理化特性、微观结构以及以WRF作为膳食纤维源和生物活性物质源添加到小麦粉面包中,对其品质特性、微观结构、生物活性成分及抗氧化性的影响。试验表明,3种干燥方式渣粉的基本营养成分、膳食纤维、总多酚、总黄酮和类胡萝卜素含量以及pH、色度L*、a*、b*值、持水力、持油力、溶胀力、DPPH自由基清除率、ABTS自由基清除率、铁还原能力均存在显著性差异,其扫描电镜微观结构差异不显著,傅里叶红外光谱分析其结构基团基本相同,X射线衍射图谱分析其晶体结构存在明显差异。WRF的不同添加水平对小麦粉面包的理化特性、质构特性、微观结构、生物活性物质含量、抗氧化特性以及感官特性均具有显著性影响。2%~4%WRF添加水平对小麦粉面包总体可接受性影响不显著,3种WRF可纳入小麦粉面包的最高水平均达4%。     

Aspects of vegetable structural lipids. I. The lipids of leaf protein concentrate

Leaf protein concentrates contain 10% or more of lipids which have been analysed in detail with a view to establishing both the classes of lipid present and their component fatty acid profiles. Variable factors such as the species of crop, its degree of maturity and the cellular origin of the concentrate fraction have been shown to have a quantitatively important influence on lipid patterns and on yields.     

Oxidative stability of structured lipids

The current popularity on structured lipids (SLs) is well known because they are presented as improved lipids from the technological or nutritional point of view. Regardless of the demonstrated health or therapeutic properties of a novel SL, it is important to consider that whether such lipid shows instability, deteriorates the quality of the food, worse the sensory attributes or reduce its self-life, its production for the food industry field would not be worthwhile. The current review attempts to collect the reported information so far on SLs regarding their quality and oxidative stability as affected by diverse parameters, as well as the impact of SLs on the oxidative stability of food model systems or real food products. In general, most researchers have reported a worse oxidative stability of SLs with respect to original oils, mainly related to the loss of endogenous antioxidants, due to that, both synthetic and natural antioxidants are being tested in SLs. Furthermore, other diverse parameters are involved in the stability of SLs, such as the conditions of production technology, the oil sources, the positional distribution of fatty acids or the unsaturation degree of lipids. Therefore, due to the huge diversity of factors affecting SLs, stating general and definitive conclusions on their oxidative behavior is difficult since complicated and controversial results are reported.     

脂质中的蛋白质与多肽及其对脂质品质的影响

脂质中蛋白质和多肽的存在在一定程度上影响了脂质的品质.本文介绍了植物油和磷脂产品中蛋白质与多肽的分离和分析方法,并对其在脂质氧化稳定性、食品安全性(主要是过敏性)方面的影响进行了详细的论述,以期为脂质产品品质的提高提供参考.     

臭黄荆叶理化组成及挥发油成分分析

为探明臭黄荆叶主要理化组成及挥发油成分,采用水蒸气蒸馏法提取臭黄荆叶挥发油,应用气相色谱-质谱(GC-MS)对挥发油进行分离分析,鉴定出具体化合物的组分和含量。结果表明：臭黄荆鲜叶中水分含量(质量分数,下同)为79.06%;臭黄荆叶粗粉中灰分含量为7.37%,果胶含量为35.57%,蛋白质含量为18.70%,粗脂肪含量为4.27%,粗纤维含量为6.87%,总黄酮含量73.43mg/g,总多酚含量为29.44mg/g;挥发油中鉴定出68种化合物,约占挥发油总量的96.34%,包括醇14种(24.5%)、烯14种(18.85%)、酮8种(8.81%)、酯6种(7.95%)、醛8种(6.41%)、呋喃2种(3.95%)、烷3种(1.93%)、石竹烯氧化物(9.71%)、1,1,5,6-四甲基-茚(3.06%)、长叶松萜烯-(V4)(1.25%)等;臭黄荆叶挥发油中含量较高的成分主要有1-辛烯-3-醇(11.45%)、石竹烯氧化物(9.71%)、α-石竹烯(5.82%)、反式-β-紫罗(兰)酮(3.43%)。臭黄荆叶中含有多种具有食用或药用价值的活性成分。