Lipids of potato tubers. I. Lipid and fatty acid composition of tubers from different varieties of potato

Tubers from 23 varieties of potato were obtained at harvest and analysed for total lipid content, lipid composition and distribution of component fatty acids. The total lipid content was similar for all varieties (approx. 0.1% of the fresh weight) and no significant differences were observed between varieties in the individual lipid components. The polyunsaturated fatty acids, i.e. linoleic and linolenic acids, represented 51 to 60 and 13 to 24%, respectively, of the total fatty acids. An inverse relationship between linoleic acid and linolenic acid was observed resulting in a very similar proportion of the combined polyunsaturated fatty acids for all varieties (70 to 76% of total fatty acids). The results are discussed in relation to the role of lipids in the potato tuber.     

Influence of vacuum filtration of Viura must on the concentration of fatty acids and their utilization in fermentation

Fatty acids such as palmitoleic, oleic, linoleic and linolenic along with sterols constitute growth or survival factors for yeast. The objective of this work was to study the influence of vacuum filtration of Viura must on fatty acid contents and their use during fermentation. The results were compared with unclarified must, the control. Filtration drastically reduced the total fatty acid concentration (81.5%) and especially unsaturated fatty acids (97.1% of linoleic, and 100% of linolenic), as well as the minor saturated acids, arachidic and behenic. In the first half of fermentation, fatty acids were excreted in the filtered must (76.8%) whereas they were consumed in the control (46.8%). In the second half of fermentation, there was greater consumption in the control sample (74.5%) than in the filtered sample (37.4%).     

Total lipid content and fatty acid composition of the seeds of some Vicia L. species

The seed oils of eight Vicia species (Leguminosae) were investigated for their total lipid contents and fatty acid compositions. The seed lipid contents were found to be between 2.30 and 3.91%. The fatty acid compositions of these eight different species were determined by gas chromatography of the methyl esters of their fatty acids. The seed oils of Vicia species contain palmitic and stearic acids as the major component fatty acids, among the saturated acids, with a small amounts of myristic, pentadecanoic, arachidic and behenic acids. The major unsaturated fatty acids found in the seed oils were oleic, linoleic and linolenic acids.     

木薯全粉对木薯-小麦混合粉加工特性及馒头品质的影响

木薯粉的脂肪酸组成和含量对其营养品质和贮藏期都有着重要的影响。实验以食用木薯粉为试材,通过优化脂肪酸甲酯化方法和气相色谱条件,建立了食用木薯粉中脂肪酸的定性定量检测方法,并对不同品种（系）、不同贮藏时间木薯粉中脂肪酸进行分析检测。结果表明：气相色谱法可准确对木薯粉中多种脂肪酸进行定性定量分析,棕榈酸、硬脂酸、油酸、亚油酸和亚麻酸浓度在20.0~1000.0、4.0~400.0、30.0~1500.0、10.0~500.0和2.0~100.0 μg/mL的范围内线性关系良好,决定系数（R²）在0.9992~0.9999之间;样品重复性相对标准偏差（RSD）在0.5%~3.2%之间;样品在室温下放置24 h浓度变化的RSD在0.7%~1.1%之间;5种脂肪酸样品加标平均回收率在88.0%~105.4%之间,平均回收率RSD在3.4%~10.4%之间,证明样品稳定性、方法重复性和准确度较好。不同食用木薯品种制备的木薯粉中主要有棕榈酸、硬脂酸、油酸、亚油酸、亚麻酸5种脂肪酸,其品种间脂肪酸含量差异较大,5种木薯粉脂肪酸比例（SFA/MUFA/PUFA）为1:（0.91~1.35）:（0.12~0.39）。其中,‘华南9号’食用木薯粉中棕榈酸、油酸、亚油酸和亚麻酸含量显著高于其他品种（系）（P<0.05）,含量分别达到了0.7818、1.088、0.2967和0.0398 mg/g;而该品种的硬脂酸含量最低,仅为0.0868 mg/g。常温贮藏实验表明,5种脂肪酸含量与贮藏时间呈负相关,其中油酸、亚油酸和亚麻酸呈极显著负相关（P<0.01）;5种脂肪酸含量在贮藏12周时达到最低,贮藏后期变化趋于平缓。研究结果可为评价不同品种（系）食用木薯粉中脂肪酸的组成和贮藏过程中脂肪酸的变化提供检测依据。

     

Effect of drying lactic fermented uji (an East African sour porridge) on some carboxylic acids

Maize, finger millet, cassava, maize–finger millet and cassava–finger millet flours were fermented and sun‐, cabinet‐, or drum‐dried. Total titratable acidity (TTA), fixed acidity (FA), pH and carboxylic acids were determined. The TTA of the non‐fermented flours ranged from 0.22%(w/w) lactic acid in cassava to 0.36%(w/w) lactic acid in the maize–finger millet composite. After fermentation the TTA ranged from 3.26%(w/w) lactic acid in cassava–finger millet to 4.54% in maize‐finger millet while FA ranged from 2.86% in cassava–finger millet to 4.26% in cassava and maize–finger millet. Fermentation decreased the pH from about 5.5 to 3.7–4.1. Drying did not change the pH but TTA decreased by 20–60%. Acetic acid levels in the fermented slurries varied from 0.80 to 0.95 µg per 5 µg while those of hexanoic acid varied from 0.9 to 1.8 µg per 5 µg. Propionic acid was absent in the fermented slurries. Acetic and formic acids were completely lost when the fermented slurries were dried. On average hexanoic acid losses on drying varied from 33% in maize to 91% in cassava fermented slurries. These losses were not significantly influenced by the drying system. In sensory evaluation panellists could not detect flavour loss as a result of drying. © 2000 Society of Chemical Industry     

Souring and breakdown of cyanogenic glucosides during the processing of cassava into akyeke

The population and composition of the lactic acid bacteria microbiota as well as the content of cyanogenic glucosides occurring at various stages of fermentation and subsequent processing of cassava roots into akyeke, a steamed sour cassava meal, were investigated. The number of lactic acid bacteria and percentage titratable acidity increased during 5 days of fermentation, but decreases were observed in the subsequent operations of 'washing' the dough with water followed by partial drying and steaming. In field and laboratory samples, Lactobacillus plantarum accounted for 59.3% and 52.3%, Lactobacillus brevis 23.3% and 22.8% and Leuconostoc mesenteroides subsp. cremoris 14.5% and 15.8%, respectively, of all lactic acid bacteria isolated at various stages of fermentation and processing. A reduction of about 98% occurred in the total cyanogens (CN) content of cassava roots during processing, from 69.3 to 1.4 and 110.3 to 2.8 mg CN equivalent/kg dry weight for laboratory and field samples of akyeke, respectively.     

Lipid Content and Fatty Acid Composition in Bamboo Shoots

Lipids from bamboo shoots (Phyllostachys pubescens), peeled and divided from top to base, were extracted and fractionated into three classes, and each class separated into constituent components by thin-layer chromatography (TLC). Fatty acid composition and amount of separated lipids were determined. Total lipids (TL) ranged from 800 (top) to 380 mg (base) per 100g fresh weight and the ratio of nonpolar lipids (NPL):glycolipids (GL):phospholipids (PL) was about 17:27:56. The main fatty acids of the three lipid classes were palmitic, linoleic and linolenic acids, but composition was remarkably different among these fractions. The fatty acid composition of triglycerides (TG) was similar to the original NPL. Palmitic acid was almost all located in 1-, 3-position, linoleic acid mainly located in 2-position of TG, while linolenic acid was distributed in each position. Digalactosyl diglyceride (DGDG) and monogalactosyl diglyceride (MGDG) were the main components of GL; the average of the former had about 37% linoleic and 29% linolenic acids, while the latter had about 25% linoleic and 62% linolenic acids. Bamboo shoots contained 9 PL fractions, the major being phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE). PC contained about 48% linoleic, 31% palmitic and 11% linolenic acids, and PE also had the similar tendency as PC.     

木薯酒发酵过程中的有机酸变化及对其品质的影响分析

以新鲜甜木薯为原料,跟踪监测木薯酒发酵过程中的理化指标,并采用高效液相色谱法分析木薯酒发酵期间的有机酸组成及动态变化情况,进一步分析酒发酵过程中的酸味强度。结果表明,发酵过程中,木薯酒中的还原糖含量先快速上升至最高点最后趋于平稳（54.67 mg/mL）;酒精度先上升后平稳（7.11%vol）;总酸含量先缓慢减少至2.21 mg/mL,再缓慢增加,后快速增加,与pH值变化趋势相反。酒石酸、乳酸、乙酸、柠檬酸、琥珀酸是木薯酒发酵中重要有机酸,分别占木薯酒总有机酸含量的2.66%～12.31%,41.50%～63.53%,18.21%～23.82%,1.22%～27.77%,3.17%～15.89%,其他有机酸是酒中的辅助酸味特征成分。乳酸和乙酸是木薯酒的主体酸,其味道强度值（TAV）占总TAV值的65.82%～95.84%,发酵84 h的木薯酒有最高的味道强度值,其可达到223.87。     

蛋黄甘油三酸酯的脂肪酸组成分析

采用毛细管气相色谱法分析酶法制备的蛋黄甘油三酸酯的脂肪改组成及相对含量，结果表明：其主要合有棕榈酸、油酸、硬脂酸、亚油酸、棕榈油酸，此外还含有微量的亚麻酸、花生四烯酸和二十二碳六烯酸。不饱和脂肪酸超过60％，是一种极具开发价值的营养保健油脂。     

Total lipid content and fatty acid composition of oilseed from lesser known sweet pomegranate clones

The oil content and fatty acid composition of the oilseed of seven lesser known Spanish sweet pomegranate (Punica granatum L) clones were determined by gas chromatography. The seeds contained oil in the range of about 63–122 g kg⁻¹ dry matter, a notably lower content than that of some oriental pomegranate cultivars. Levels of lipid content probably could be considered insufficient for economic industrial exploitation compared with those of conventional oilseeds. The predominant fatty acid was the polyunsaturate (n − 3) linolenic acid (43.4–88.2%), followed by the diunsaturate linoleic (5.3–16.5%), the monounsaturate oleic (3.7–20.3%) and palmitoleic (traces to 2.9%) acids. To a lesser extent the saturates palmitic (2.6–14.9%) and stearic (1.2–9.0%) acids were also found in all clones. Lauric and arachidic acids were rarely detected. We have not confirmed the presence of behenic (C22:0) and lignoceric (C24:0) acids previously reported in edible and non‐edible pomegranate cultivars. Intervarietal differences in fatty acid composition were shown and they could be useful to establish chemotaxonomic differences. In contrast with previous reports on sweet pomegranate cultivars, a very low (0.04–0.35) saturated/unsaturated fatty acid ratio was found. © 2000 Society of Chemical Industry     

Quality control method based on quartz crystal microbalance and WGA for flour milled from germinated wheat

Plasma membrane is the initial sensor of different stress conditions and its composition is modified with response to environmental changes. In the present study, we have modified the lipid composition of the membrane by growing Saccharomyces cerevisiae in the presence of different fatty acids and ergosterol. All supplemented fatty acids were incorporated into the cell and this incorporation produced significant changes in the lipid composition. The incubation with ergosterol also modified the lipid composition of the cells; however, these cells presented a strong reduction in the content of this sterol. The different cellular lipid composition has been related to viability and fermentation performance at low temperature (13 °C). The cells incubated with palmitoleic acid (C16:1) showed higher viability and significant reduction in the fermentation length. These cells presented higher C16:1 and ergosterol content, shorter chain length of the fatty acids and higher ratio of sterols/phospholipids. Therefore redesigning the composition of cellular membranes during industrial yeast propagation seems to be a promising strategy for improving fermentation performance in the winery.     

发酵条件对发酵性丝孢酵母脂肪酸组成的影响

通过摇瓶发酵，研究了温度、摇瓶转速、碳源种类和浓度对发酵性丝孢酵母（Trichosporom fermentans）脂肪酸组成的影响。气相色谱法分析结果表明，较高发酵温度能提高菌体油脂的脂肪酸饱和程度，此条件下饱和脂肪酸含量占脂肪酸总量的49．1％：摇瓶转速高有利于菌体油脂不饱和脂肪酸的生成；木糖浓度为100g／L时菌体油脂中饱和脂肪酸含量最高，占脂肪酸总量的50．4％；木糖比葡萄糖更容易被转化生成饱和脂肪酸含量较多的油脂。菌体脂肪酸组成包括肉豆蔻酸、棕榈酸、棕榈油酸、硬脂酸、油酸和亚油酸，其中棕榈酸和油酸含量较高。     

长柄扁桃油脂肪酸成分分析

长柄扁桃是一种新型的沙生木本油料植物。采用GC-MS法对长柄扁桃油的脂肪酸成分进行分析。结果表明,长柄扁桃种仁中油含量在55%以上,由棕榈酸、棕榈油酸、油酸、亚油酸、亚麻酸、花生烯酸和芥酸7种脂肪酸组成,其中不饱和脂肪酸高达98.1%,单不饱和脂肪酸与多不饱和脂肪酸的比例与橄榄油比例相似,芥酸含量仅为0.8%。表明长柄扁桃油是一种品质优良的食用油,具有广阔的开发前景。     

Total lipids content and fatty acid composition of seed oils from six pomegranate cultivars

The fatty acid composition of the seed oils of six pomegranate (Punica granatum L) cultivars was qualitatively and quantitatively determined by gas chromatography. The seeds contained oil in the range 51-152 mg kg^?1 dry matter. Intervarietal differences in fatty acid composition were demonstrated (fatty acid esters as % (w/w) total fatty acid esters. Sour varieties had the highest while sour-sweet varieties had the lowest oil content. Eleven fatty acids were identified. In all varieties, the predominant fatty acids were linoleic (25.2-38.6%) and oleic acid (24.8-35.5%) followed by palmitic (18.2-22.6%), stearic (6.9-10.4%) and linolenic acid (0.6-9.9%). To a lesser extent arachidic (1.1-3.4%) and palmitoleic acid (0.2-2.7%) were also found in all varieties. Lauric, myristic, behenic and lignoceric acids were rarely detected. As far as we know linolenic (18:3), arachidic (20:0), behenic (22:0) or lignoceric (24:0) acids have not been previously reported in the seed oils of edible pomegranate varieties. Lignoceric acid has not previously been found in pomegranate seed oil.     

GC-MS法分析橄榄油中的脂肪酸

采用气相色谱．质谱联用技术分析了橄榄油中的脂肪酸组分,共分离鉴定得到15种脂肪酸,其中饱和脂肪酸6种,以棕榈酸含量最多,占14．147％;单不饱和脂肪酸7种,以油酸含量居多,占65．389％;多不饱和脂肪骏2种,为亚油酸和亚麻酸,含量分别为7．326％和0．598％。另外,检测得到两种反式脂肪酸,含量为0．101％。橄榄油的营养保健价值较高,具有很好的开发利用前景。     

Survey of the fatty acid composition of retail milk in the United States including regional and seasonal variations

Consumers are increasingly aware that food components have the potential to influence human health maintenance and disease prevention, and dietary fatty acids (FA) have been of special interest. It has been 25 years since the last survey of US milk FA composition, and during this interval substantial changes in dairy rations have occurred, including increased use of total mixed rations and byproduct feeds as well as the routine use of lipid and FA supplements. Furthermore, analytical procedures have improved allowing greater detail in the routine analysis of FA, especially trans FA. Our objective was to survey US milk fat and determine its FA composition. We obtained samples of fluid milk from 56 milk processing plants across the US every 3 mo for one year to capture seasonal and geographical variations. Processing plants were selected based on the criteria that they represented 50% or more of the fluid milk produced in that area. An overall summary of the milk fat analysis indicated that saturated fatty acids comprised 63.7% of total milk FA with palmitic and stearic acids representing the majority (44.1 and 18.3% of total saturated fatty acids, respectively). Unsaturated fatty acids were 33.2% of total milk FA with oleic acid predominating (71.0% of total unsaturated fatty acids). These values are comparable to those of the previous survey in 1984, considering differences in analytical techniques. Trans FA represented 3.2% of total FA, with vaccenic acid being the major trans isomer (46.5% of total trans FA). Cis-9, trans-11 18:2 conjugated linoleic acid represented 0.55% total milk FA, and the major n-3 FA (linolenic acid, 18:3) composed 0.38%. Analyses for seasonal and regional effects indicated statistical differences for some FA, but these were minor from an overall human nutrition perspective as the FA profile for all samples were numerically similar. Overall, the present study provides a valuable database for current FA composition of US fluid milk, and results demonstrate that the milk fatty acid profile is remarkably consistent across geographic regions and seasons from the perspective of human dietary intake of milk fat.     

Identification and quantitative determination of the lipids of Alocasia macrorrhiza tubers

The identity, composition and concentration of each of the major lipids found in Alocasia tubers were investigated using a combination of chromatographic procedures. On a weight to weight basis, the neutral lipids, glycolipids and phospholipids comprised 60.5, 19.0 and 20.5% respectively while the total extractable lipids accounted for 0.6% of the dry weight. In addition to the conventional lipid classes of tubers, the presence of tri- and tetragalactosyl diglycerides was confirmed. The predominant fatty acid in each lipid class was linoleic acid with palmitic, oleic and linolenic acids being the other ones. In general, a high degree of unsaturation (66%), similar for most tuber lipids, was established for the component fatty acids of Alocasia.     

Effects of Lactic Fermentation of Milk on Milk Lipids

Fermentation of whole milk by Lactobacillus acidophilus, Lactobacillus bulguricus and Streptococcus thermophilus resulted in moderate but significant increase in the levels of saturated fatty acids and oleic acid with a concomitant decrease in the levels of linoleic and linolenic acids in the glyceride fraction. Similarly, the increase in the levels of free fatty acids was moderate. There were significant increases in the levels of stearic and oleic acids. Unusual fatty acids of bacterial origin were not detected, and monoglycerides disappeared completely upon fermentation. Changes in cholesterol levels were also not significant. Acid degree value and free fatty acid levels were correlated significantly (r = 0.711). Results indicate that previously reported hypocholestermic effect of fermented milk is not due to changes in the composition of lipid classes investigated.     

冬虫夏草液体发酵富硒大豆对脂类和硒含量的影响

采用冬虫夏草菌丝体发酵富硒大豆,对冬虫夏草菌丝体发酵富硒大豆不同时间发酵液的脂类总量、酸价、碘价、游离脂肪酸、硒含量进行测定。结果表明：发酵48h 的发酵液与对照相比,脂类总量变化不明显,酸价增加2.8 倍,碘价增加1.2 倍,亚麻酸、亚油酸、油酸、花生四烯酸分别增加5.3、2.9、6.8 倍和5.6 倍。48h以后发酵液中脂类成分变化不明显。不同时间发酵液中硒含量基本不变。