The structural analysis of wheat flour glycerolipids

The compositions of the fatty acids in the 1, 2 and 3 positions of the principal glycerolipids and their various stereoisomers were determined. Fatty acids in the 1 and 3 positions of triglycerides were similar in composition and less unsaturated than those in the 2 position. Fatty acids in the 1,2-, 1,3- and 2,3-diglycerides were distributed in a pattern which indicated isomerization ofsn-1,2-diacylglycerol. Lysophosphatidyl choline (the principal monoacyl lipid) consisted of about 80% 1-acyl and 20% 2-acyl isomers. The fatty acid compositions indicated that most of the 2-lysophosphatidyl choline was formed by isomerization of 1-lysophosphatidyl choline. Most of the digly cerides and lysophosphatidyl choline were synthesized in the ripening wheat grain. However a small proportion of these partial glycerides and all of the other minor partial glycerides (monoglycerides, digalactosyl monoglycerides) appeared to be the result of limited lipolysis of the corresponding diacyl lipids in the wheat or in the freshly-milled flour. Fatty acids in the 2 position of all the fully acylated glycerides were very similar in composition, but there were considerable differences in the 1 position fatty acids.     

Physicochemical characterization of galactosyldiglycerides and their quantitation in wheat flour lipids by high performance liquid chromatography

A high performance liquid chromatographic (HPLC) method was developed for analyzing digalactosyldiglycerides (DGDG) and monogalactosyldiglyceride (MGDG) in polar lipids fractionated from lipid extracts of wheat or flour. Wheat lipid samples were prepared by solvent extraction, then fractionated on a silica gel packed open column. A Spherisorb ODS (octadecyl silane) column with methanol/water elution system was used for separation of glycolipids in the polar lipid fractions. The detection limit of the refractive index detector with interferometric optics was 0.25μg for both DGDG and MGDG. Separating on nonpolar bonded phase columns permitted us to differentiate, based on fatty acid composition and position, among components within the specific glycolipid classes. Semipreparative HPLC on analytical columns was used to subfractionate the polar lipids. The glycolipids were collected for functional group characterization. Approximately 35% of each DGDG subfraction was accounted for as carbohydrate. The absence of phosphorus precluded phospholipids. Fatty acid analysis by gas chromatography showed the first DGDG to be linoleic acid, whereas the second DGDG peak was composed of linoleic, oleic and palmitic acids. Mass spectrometric analysis of the first DGDG peak showed linoleic acid in both the SN-1 and 2 positions. Mass spectrometric analysis revealed that palmitic or oleic acid in the second peak was preferentially located on the SN-1 position; linoleic acid was on the SN-2 position. Contribution no. 80-207J, Department of Grain Science and Industry, Kansas Agricultural Experiment Station, Kansas State University, Manhattan, KS. Part of a dissertation submitted by T.N. Tweeten in partial fulfillment of the PhD degree. Honored Student Award Presentation at AOCS annual meeting, San Francisco, April 1979.     

Surfactants as replacements for natural lipids in bread baked from defatted wheat flour

Petroleum ether (PE) extracted 1.00% total free lipids (0.70% nonpolar and 0.30% polar) and 2-propanol (PrOH) extracted 1.36% total free and bound lipids (0.73% nonpolar and 0.63% polar) from wheat flour; the lipid fractions were characterized by thin layer chromatography. PE- or PrOH-defatted flours were baked after reconstitution with total, nonpolar, or polar wheat flour lipids; or with equivalent amounts of nonionic sucrose monopalmitate (SMP), ethoxylated monoglycerides (EMG) — each with a hydrophile-lipophile balance (HLB) of 14.0 or anionic sodium stearoyl-2-lactylate (SSL) — with an HLB value of 9.0. Defatted flours supplemented with surfactants alone or in combination with wheat flour lipids were used in bread with no-shortening and with 3%-shortening. The importance of the polar flour lipids in breadmaking was verified. The lipids in wheat flour were essential for maximizing the beneficial effects of shortening on breadmaking quality. Nonionic SMP or EMG completely replaced both PE-extractable wheat flour free total lipids ( or their non-polar or polar fractions) and 3% shortening; nonionic surfactants with high HLB were better than the anionic SSL for replacing free flour lipids. No surfactant completely replaced unfractionated PrOH-extracted lipids (free + bound) and shortening or total polar flour lipids (free + bound). All surfactants, especially anionic SSL, added with PrOH-extracted polar lipids improved the overall bread-making properties of the PrOH-defatted flour both in the absence and in the presence of shortening. Presented at the AOCS Meeting, New York, May 1977     

Neutral lipids of chickpea flour and protein isolates

The neutral lipids composition of defatted chickpea flour and two types of protein isolates has been studied. The main compounds in neutral lipids are triacylglycerols, free fatty acids, and diacylglycerols. Other compounds present are wax esters, free fatty alcohols, and free sterols. The main fatty acids in neutral lipids are C_18:2 and C_18:1 among the unsaturated, and C_16:0 and C_18:0 among the saturated acids. Free and esterified alcohols range from C_16:0 to C_28:0, the majority being those with an even number of carbon atoms. Sterols observed are β-sito-sterol, campesterol, stigmasterol, and δ-5-avenasterol. Triacyl-glycerols are partially hydrolyzed, and the amounts of unsaturated sterols and unsaturated fatty acids are reduced as a result of the chemical treatment during production of the protein isolates.     

Solvent solubility parameter and flour moisture effects on lipid extractability

Lipids were extracted with a series of solvent systems whose solubility parameter (δ) values ranged from 7.27 to 12.92 (hexane and its aqueous azeotrope, benzene, acetone and its azeotrope and 2-propanol and its azeotrope) from a flour with 1.2%, 7.2% or 13.8% moisture content (MC). The extracted total lipids (TL) were fractionated into nonpolar lipids (NL) and polar lipids (PL) by silicic acid column chromatography. NL and PL were further subfractionated by thin layer chromatography (TLC). PL were separated into glycolipids (GL) and phospholipids (PhL). TL, NL and PL extractabilities were affected by both flour MC and by the nature and composition of extractants: the overall solvent effects were substantially more pronounced than the flour MC effects. Free fatty acid and digalactosyldiglyceride (DGDG) extractabilities increased for all extractants, in general, as flour MC increased. Significant linear relations between the δ values of extractants and the average amounts of TL, PL, GL and PhL from flours with 3 MC were found. The high correlation (r=0.981) between δ and extractability of TL was primarily caused by PL; extractabilities of monoglycerides (among NL) and all classes of GL and PhL were significantly (at the 0.01 level) linearly related to the δ values at all 3 flour MC levels. The present study indicated no selective binding between flour proteins and a specific PL class. Among PL, DGDG showed a clear-cut breaking point in irreversible restoration of breadmaking characteristics. Thus, the present study confirms the significant role of PL to breadmaking, resulting primarily from the contribution of DGDG. Presented in part at the AOCS Meeting, San Francisco, 1979.     

Lecithins and lysolecithins of wheat flour

Lecithin and lysolecithin from the bound lipid of Thatcher wheat endosperm were separated and purified by column and thin-layer silicic acid chromatography. Lecithin was hydrolyzed with phospholipaseA (Crotalus adamanteus) and the products isolated and purified by silicic acid chromatography. The fatty acid composition of the original lecithin and lysolecithin and of the hydrolysis products was determined by gas-liquid chromatography. The fatty acids in the beta position of the lecithin were found to be almost entirely unsaturated, whereas those in the alpha position were saturated and unsaturated in nearly equal amounts. The differences between the fatty acid composition of the original lysolecithin and that of the lysolecithin obtained by hydrolysis of lecithin with phospholipaseA suggested the presence of both alpha and beta acyl species in the naturally occurring lysolecithin. Contribution No. 48, Food Research Institute, Research Branch, Canada Department of Agriculture, Ottawa, Canada.     

黑龙江省哈尔滨地区传统面制食品中铝含量调查分析

对2012年哈尔滨市城区各露天摊点和快餐店的面制食品进行随机采样,并采用微波消解技术-电感耦合等离子体质谱(ICP-MS)方法检测城区早餐面制食品(馒头、花卷、蒸包、油条、油饼、油炸麻团)中的铝含量。检测样品194份,合格147份,合格率为75.8%;其中油条的合格率最低为35%。哈尔滨市城区早餐市场上铝污染问题突出,望尽早推广膨松剂无铝配方的新技术。     

Optimized separation of nonpolar and polar lipid classes from wheat flour by solid-phase extraction

A method combining solid-phase extraction on prepacked silica and aminopropyl bonded-phase (Bond-Elut) columns has been developed for the separation of neutral lipids, glycolipids and phospholipids from wheat flour into individual classes in high yield and homogeneity. Chromatography on a single silica column (500 mg) with solvent combinations of increasing polarity resulted in complete separation of steryl esters, triglycerides, free fatty acids, 1,2-diglycerides, 1,3-diglycerides, monoglycerides, monogalactosylglycerides, digalactosylglycerides, phosphatidylcholine and lysophosphatidylcholine. Chromatography on an aminopropyl bonded-phase column (500 mg) with ternary mixtures of chloroform/methanol/ammonium hydroxide led to the proper separation of N-acyl-phosphatidylethanolamine and N-acyl-lysophosphatidylethanolamine, previously coeluted on the prepacked silica column. Cross contamination among phospholipid classes tested by normal-phase high-performance liquid chromatography was always less than 14%.     

Fatty Acid Composition of Non-Starch and Starch Neutral Lipid Extracts of Portuguese Sourdough Bread

Fatty acids in each neutral lipid (NL) class from non-starch (NSL) and starch lipids (SL) were quantified in maize and rye flours, and sourdough—to ascertain the effect of mixing, and between sourdough and broa (a traditional Portuguese sourdough bread)—to assess the effect of fermentation. Maize and rye flour lipid extracts showed distinct fatty acid profiles. Maize flour exhibited a higher amount of most fatty acid species and of total NL—where triacylglycerols (TAG) and free fatty acids (FA) represented the dominant NL. The fatty acid profiles varied throughout breadmaking (i.e. from the mixture of flours with water, through fermentation until baking): in NSL, the highest concentrations were found in the flour mixture (i.e. 59?% of maize and 41?% of rye flour) or sourdough, whereas in SL they were found in broa; additionally, SL levels increased, and NSL levels decreased during dough preparation and baking. Palmitic (C16:0), oleic (C18:1) and linoleic (C18:2) acids were the major fatty acids in all food items. Cumulative percentages of C16:0, C18:1 and C18:2 in NSL and SL were over 81 and 75?%, respectively, in the flour mixture, 86 and 66?% in sourdough, and 83 and 82?% in broa. In particular, C18:2 accounted for 52?% of the total fatty acids. The content of sterol esters remained essentially constant throughout fermentation and baking; those of TAG decreased from flours to fermentation, while diacylglycerol and monoacylglycerol increased; the NL fractions were essentially unaffected by baking, yet their FA contents increased.     

Effect of excessive fatty acid ingestion upon composition of neutral lipids and phospholipids of snailHelix pomatia L.

The effect of an excessive intake of oleic acid on the lipids of the Roman snail (Helix pomatia L.) was studied. The total lipid content increased by 30% which was fully attributable to a marked elevation in the neutral esters and free fatty acids, as phospholipid and free sterol contents remained unaffected. The fatty acid composition of the phospholipids, characterized by high amounts of stearic, linoleic, homolinoleic, and, particularly, arachidonic acids, appeared to be nearly insensitive to this excessive oleic acid ingestion. By contrast, the effect of oleic acid upon the depot lipids was striking: active intestinal resorption of the acid from the dietary supply was shown by the fourfold level of lleic acid in the free fatty acid fraction, whereas a fivefold level of this acid in the glyceride and sterol ester fraction was proof of a substantial esterification. These data support the view that the composition of the structural lipids is specifically species oriented, whereas both the content and the composition of the depot lipids are highly governed by dietary fat intake.     

Fatty acid concentration, proximate composition, and mineral composition in fishbone flour of Nile Tilapia

Nile tilapia (Oreochormis niloticus) fishbone is a fish part with unknown composition. After elaboration of flour fishbone of tilapia it was analysede. The results in 100 g of flour were: moisture (14.2%), protein (40.8%), total lipids (25.3%), and ash (18.3%), and mineral (in 100 g) was 2715.9 mg (calcium), 1.3 mg (iron), and 1132.7 mg (phosphorus). A total of 22 fatty acids were detected in fishbone flour total lipids (TL), being the major ones in (g) of total lipids: 16:0 (208.5 mg); 18:1n-9 (344.3 mg); and 18:2n-6 (109.6 mg). The concentration of linolenic acid--LNA (18:3n-3); eicopentaenoic acid--EPA (20:5n-3), and docosahexaenoic acid--DHA (22:6n-3) were (29.9 mg), (3.3 mg), and (12.9 mg), respectively. The content to saturated (SFA) were (296.2 mg), monounsaturated (MUFA) 415.0 mg, and polyunsaturated (PUFA) 175.6 mg. The ratio PUFA:MUFA:SFA was 1:2.4:1.7, and the ratio omega-6/omega-3 fatty acids were 2.8. The last is within the recommended values. The results show low concentrations of omega-3 fatty acids in flour. The value caloric and calcium, iron, phosphorus, and protein content the fishbone flour of tilapia may results a valuable alternative food in the human diet.     

Chemical composition and biological quality of defatted hazelnut flour

The results of the chemical composition and biological quality of deffated hazel nut flour are shown. The samples analyzed contained significant amounts of proteins (19%) comparable to legume flour, higher than cereals and lower than deffated oleaginous flours. The oil extracted from the seed was analyzed and the average results obtained were the following: Refraction index, 1.47; saponification No. 184.8; iodine No. 85.0. The average composition of the fatty acids obtained by gas liquid chromatography was: Palmitic acid 2.3% Palmitoleic acid 37.0% Stearic acid 0.5% Oleic acid 39.5% Linoleic acid 6.9% Linolenic acid 1.1% Eicosanoic acid 2.3% Eicosaenoic acid 4.6% Docosenoic acid 3.4% Tetraeicosanoic acid 0.3% These results indicate a good-quality oil due to the low content of linolenic acid. The nutritive value of the deffated meal measured in the rats gave a net protein ratio (NPR) of 3.58, lower than the corresponding casein value (4.10). The true protein digestibility measured in the rat gave a value of 7.3%, compared to 95% for casein. The amounts of iron and phosphorous are comparatively lower than those reported for rape-seed meal and sunflower meal.     

Effect of barley flour and freeze-thaw cycles on textural nutritional and functional properties of cookies

Studies were carried out on cookies prepared by incorporating barley flour (10%, 20%, 30%, and 40%) into wheat flour. The cookies were evaluated for their physical, chemical, nutritional, textural and sensory characteristics. All the cookie samples showed high fiber, mineral and protein contents when compared to those from 100% wheat flour. Incorporation of barley flour improved the color of the cookies from pale cream to golden brown. The cookies became crispier as indicated by the reduction in the breaking strength value from 4.94 to 3.29 kg. Considering the color, taste, flavor, surface appearance of the cookies, 30% incorporation of barley flour was found to be optimum giving cookies containing 1.7% β-glucan, 36.6 ppm iron, 31.8 ppm calcium, 22.9 ppm zinc while the texture characteristics showed that 30% barley incorporated cookies had breaking strength of 4.021 kg lower than wheat cookies and also indicating that the product was nutritionally rich as compared to the 100% wheat flour cookies. The incorporation of barley flour increased the antioxidant properties and polyphenolic content and hence increased functional properties of the cookies compared to the control. The prepared product was safe microbiologically as well as chemically upto 6 months of storage in different packaging materials under varying temperature conditions. The cookie dough contained 30% barley flour and 100% wheat flour (control) was allowed to under go frozen storage and freeze-thaw cycles (freeze for 12 h and thaw for 4 h). After each freeze-thaw cycle, cookie dough was evaluated for its texture profile and also dough was baked to prepare cookie and assessed for its physical, textural and sensory characteristics. It was found that cookies prepared after freeze-thawing of dough were crisper than the normal ones.     

Development of bakery products for greater adult consumption based on wheat and rice flour

The present investigation was developed as a contribution to Guatemalan's elderly food and nutrition. Its main objective was to evaluate the chemical, nutritional and sensory quality of bread prepared from the partial substitution of wheat flour with rice flour. Wheat flour substitutions with rice flour in the order of 15, 20, 30, 40, 50 and 60% were evaluated. Differences with the control (100% wheat bread) were found during the process of preparation, as well as texture, volume, height, weight and specific volume. Important effects in dough handling were noted specifically in the 40, 50 and 60% rice bread. Thus, a sandy texture was found in breads of higher rice levels. The bread protein quality increased with the level of substitution; however the protein quality difference between the wheat bread and the bread with 60% rice flour did not achieve statistical significance. Based on a statistical analysis of the physical properties the bread with 30 and 40% rice flour was selected, and through a preference test between these last two, the 30% rice flour bread was selected as the sample best suited to the present study's purposes. This bread was not different to wheat bread in many nutritional parameters, although in others it showed to be superior. Each serving size of bread has a weight of 80 grams (2 slices) that contributes adequate quantity of calories, protein and sodium, although a little less dietary fiber than 100% wheat bread.     

Solvent extraction of oil from soybean flour II— pilot plant and two-solvent extractions

The process of grinding soybeans to a fine flour and extracting the flour with hexane was studied on a pilot plant scale. The crude oil from the pilot plant study had 15 ppm phosphorus and was suitable for physical refining after a light acid pretreatment and bleaching. The refined oil showed a Lovibond color of 1.4 yellow and 0.3 red. The pilot plant study also showed that grinding of the soybeans and the separation of solid from miscella were the most difficult steps in solvent extraction with fine flour. A laboratory study on separation of miscella from meal by aqueous ethanol reduced the hold-up volume, but it did not remove all the miscella. A test with betacarotene showed that only the miscella outside the flour particles was displaced. Aqueous ethanol solutions used as a second solvent extracted additional nontriglyceride materials (primarily phospholipids) from the meal. Also, the free fatty acid content of the oil was increased with aqueous ethanol solution wash. The quality of the extracted crude oil was lowered by using a second solvent, but it had the advantage of needing only one centrifugation to separate miscella from meal.     

The lipids of human pancreas with special reference to the presence of fatty acid methyl esters

Total lipids were extracted from human pancreas with chloroform-methanol, chloroform-methanol following acidification, and benzene. A similar proportional amount of total lipid was obtained by each procedure. Regardless of the method of extraction (i.e., whether or not methanol was present), a small proportion (about 1%) of the total lipid was found to consist of fatty acid methyl esters. Triglycerides constituted the major fraction (about 80%) of the pancreatic lipids; in addition to methyl esters, the remaining lipids comprised free fatty acids, phospholipids, cholesterol esters, and traces of free cholesterol. In general, each class of lipid had a similar over-all fatty acid composition with palmitic and oleic acids as predominant components. The methyl esters had a relatively high content of linolenic acid, and the free fatty acids contained a notably high proportion of palmitic acid, in each case accompanied by a corresponding decrease in the proportion of oleic acid present.     

Fatty acids in lipids of maturing wheat

Two varieties of hard red winter wheat were sampled at various stages of maturity. The lipids in those samples were fractionated into free polar, free nonpolar and bound lipids. Fatty acids of those fractions were determined. Major acids present were palmitic, oleic, linoleic and linolenic. Both wheat samples showed similar qualitative, but not quantitative patterns in distribution of fatty acids during maturation. In the free polar lipid fraction, the palmitic acid content decreased with maturation while the linoleic acid content increased. The free nonpolar fractions showed a slight increase in linoleic acid; the concentration of other acids decreased slightly as the wheat matured. The bound lipid fraction showed a marked increase in linoleic acid, accompanied by decreases in the other major fatty acids, especially linolenic. Cooperative investigations of Kansas Agricultural Experiment Station and Crops Research Div., ARS, USDA.     

Soy flour in European-type bread

Effect of soy flour, soy protein concentrate, and isolate on dough and loaf properties of breads produced from flour, yeast, salt, and water with no shortening or added improvers was investigated. Wheat flour, rye flour, and mixtures of the two were included in the studies. Three wheat flours, varying in baking quality and extraction, ash content 0.65 and 0.80%, were used; 1.5, 3, and 5% soy products, flour basis, were added. Water absorption increased 3.8–4.7% at the 3% soy level and 6.1–7.3% at the 5% level of soy product addition. Dough development time and stability were increased and dough softening reduced. Dough gassing power increased ca. 7–25%. By using a shorter proofing time, more intensive mixing, and the sponge dough process, loaves only slightly smaller in volume than the control were obtained at the 3% soy level. Panel evaluations scored bread highest with 1.5 or 3% soy flour and that with 3 or 5% soy protein concentrate as lowest, but acceptable. Use of 2% lard as shortening, or 2% lard plus emulsifier, produced soy breads of excellent quality and ca. 25% higher loaf volume than controls.     

Evaluation of the partial substitution of precooked corn flour by rice flour in the preparation of arepas

The purpose of this research was to evaluate the effect of the partial substitution of rice by precooked corn flour, fortified or not with soy, on the organoleptic and nutritive characteristics of the arepas and on the expansion of the dough. Blends with 10, 20 and 30% of raw and precooked rice flours, and 8% soy flour were utilized. The results for arepas indicate that the partial substitution had no significant effect on the organoleptic characteristics nor nutritive value. The soy improved significantly the nutritive value. The expansion of the dough of the blends varied in respect to corn flour, without causing appreciable difficulty in the preparation of the arepas. The industrial precooked rice flour imparted great adhesivity, thus difficulty in the kneading, a fact which could lead to rejection by the consumer.     

Studies of lipid class and fatty acid profiles of rat mammary tumors induced by 7,12-dimethylbenz(a) anthracene

The lipid class and fatty acid composition profiles of mammary glands of female rats fed a nutritionally adequate diet are compared to those of tumors induced in the mammary glands by intravenous injection of dimethylbenz(a)anthracene of animals fed the same diet. Ca. 95% of the lipids of the mammary glands of the control group of animals consisted of triglycerides; glycolipids and phospholipids were present in only minor amounts. In contrast, the lipids of the mammary tumors contained much lower amounts of neutral lipids and higher concentrations of phospholipids. The glycolipid fraction was a minor component of both tissues but differed greatly in composition. The composition of the phospholipid and neutral lipid fractions, particularly the latter, of the mammary tumors also differed from that of the mammary glands of the control animals. The neutral lipids of the tumor tissues contained elevated levels of free fatty acids and cholesterol and much lower concentrations of triglyceride compared to the mammary gland lipids. Differences also were observed in the fatty acid composition of tumor and mammary gland lipid. The greatest differences occurred in the concentrations of polyunsaturated fatty acids which were generally much higher in the tumor lipids.