高效液相色谱法测定亚油酸甲酯含量

建立一种高效液相色谱测定亚油酸甲酯含量的方法。采用IntertsilO D S-SP柱,紫外检测器,检测波长为243 nm ,流动相为甲醇－水（体积比为95∶5）混合液,流速为0.8 m L/m in,进样体积为20μL,柱温为30℃。结果可知,亚油酸甲酯质量浓度和峰面积的线性回归方程是y=（2E＋06）x-43628,R 2=0.9999,线性范围是0～4.16 g/L,平均加样回收率为99.92%。     

Suppressive effect of defatted rice bran on the oxidation of methyl linoleate

The bran collected at each of the five steps of milling yields (98–100%, 96–98%, 94–96%, 92–94% and 90–92%) was defatted. Defatted rice bran (DRB) was added to methyl linoleate (ML) under various conditions, and its suppressive effect on lipid oxidation was kinetically evaluated to investigate the effective use of surplus rice bran. The rate constant, k, empirically evaluated by the Weibull equation for the oxidation of ML with DRB, was lower than that without DRB and decreased with increasing the maximum milling yield of added DRB. The oxidation of ML strongly depended on the added amount of DRB, but the k value was almost constant for a specific amount of DBR added to ML. The dependency of the k value on relative humidity was weak, regardless of the addition of DRB. The difference between the k values for oxidation processes of ML, with and without DRB, increased with increasing temperature.     

尿素柱层析分离共轭亚油酸甲酯异构体的研究

利用负载型尿素层析柱对共轭亚油酸甲酯异构体进行分离。考察了固定相中甲醇残留量、尿素硅胶质量比、固定相结晶温度、层析温度及洗脱剂种类对分离效果的影响。结果表明:当固定相中甲醇残留量为3%~5%,尿素硅胶质量比为1∶1,固定相结晶温度0~8℃,层析温度0℃,洗脱剂为石油醚时,经过层析分离反10,顺12共轭亚油酸甲酯的含量从样品中的33.94%提高到57.69%。     

Autoxidation of methyl linolenate and methyl linoleate: The effect of α-tocopherol

α-Tocopherol substantially affects the distribution of peroxidic compounds formed during the autoxidation of methyl linolenate and methyl linoleate. In the autoxidation of both these unsaturated fatty acid esters the proportion of monohydroperoxides with conjugated double bonds in the trans, trans configuration is reduced until at high concentrations of α-tocopherol (5%) only cis, trans isomers are formed. In the autoxidation of methyl linolenate the proportion of hydroperoxy-epidioxides is reduced and only monohydroperoxides are formed when 5% α-tocopherol is present. The results are discussed in terms of recent findings concerning the mechanism of the autoxidation of unsaturated lipids.     

Impact of surfactant type, pH and antioxidants on the oxidation of methyl linoleate in micellar solutions

The oxidation of methyl linoleate micelles has been studied, aiming at elucidating the effect of various variables, including surfactant type, pH and antioxidants. The progress of the methyl linoleate oxidation was evaluated by measurement of conjugated dienes hydroperoxides (CDHP) and malondialdehyde (MDA). It was shown that the oxidative stability of methyl linoleate micelles was influenced by surfactant type, with oxidative rate being greater in SDS micelles than in Tween 20 micelles. Besides, the methyl linoleate micelles at pH 6.8 had greater rates of lipid oxidation than their pH 3.0 counterparts. Moreover, the incorporation of VE and VC in the methyl linoleate micelles successfully slowed the formation of hydroperoxides and their subsequent decomposition product MDA. However, the antioxidant activities of VE and VC were related to their concentrations.     

4-Oxo-2-nonenal as a pro-oxidant during the autoxidation of methyl linoleate in bulk phase

The effect of aldehydic lipid peroxidation products on the autoxidation of methyl linoleate (MeL) was studied at 60 °C in bulk phase. Addition of 4-oxo-2-nonenal (ONE) to MeL accelerated the formation of MeL hydroperoxides. Other tested aldehydes showed no effect on the rate of MeL autoxidation. The pro-oxidative effect of ONE disappeared when pre-existing peroxides and transition metals were removed from MeL. Further addition of ferric ion to the peroxide- and metal-free MeL recovered its pro-oxidative effect. ONE reduced ferric ion to ferrous ion effectively. Furthermore, it had a chelating ability with ferrous ion. The results suggest that the pro-oxidative effect of ONE is due to its ability to reduce transition metals and to chelate the reduced form of metal ions. Thus, ONE could accelerate the metal-dependent lipid peroxidation.     

Studies on changes in flour tocopherols following ageing and treatment of the flour with chlorine dioxide

The tocopherols in freshly milled flour were measured using two-dimensional chromatography. Total tocopherols were in the range 1500–1600 μg/100 ml, but only 17–18% of this was α-tocopherol. Aerobic storage for 190 days caused a reduction of all tocopherols by 62–67%. Treatment of the flour with chlorine dioxide at the usual commercial level caused a comparable reduction, averaging 58%; ?-tocopherol was rather less affected than α-tocopherol. Studies in human volunteers indicated that a daily supplement greater than 10 mg of tocopherol was needed to bring about a significant change in the level of α-tocopherol in the blood. When bread made from untreated and chlorine dioxide-treated flour was fed to groups of volunteers in a double-blind crossover trial for 50 days on each type of bread, no significant correlation could be found between blood tocopherol levels and the type of bread consumed. To examine whether a longer period of time on the diet was necessary, the blood tocopherol levels of thirteen English students who had habitually consumed bread made from treated flour were compared with those of thirteen French students, matched for age, who had for several years consumed French bread which is made from untreated flour. The analyses were carried out in Birmingham and in Paris by the same investigator. No significant differences in tocopherol levels were found. It is concluded that the consumption of bread made from flour treated with chlorine dioxide will have no significant effect upon the blood level of α-tocopherols under the dietary conditions at present prevailing in Britain.     

Effects of sesamol, sesamin, and sesamolin extracted from roasted sesame oil on the thermal oxidation of methyl linoleate

This study investigated the effects of lignan compounds extracted from roasted sesame oil, which were sesamol, sesamin, and sesamolin, on oxidation of methyl linoleate (ML) during heating. These compounds were added at 500 or 1000 mg/kg to ML, and α-tocopherol was used as a reference antioxidant. The ML added with lignans or α-tocopherol was heated at 180 °C for 60 min. Thermal oxidation of ML was evaluated by conjugated dienoic acid (CDA) contents, p-anisidine value (PAV), and ML retention. Contents changes of lignan compounds or α-tocopherol in ML during heating were monitored by high-performance liquid chromatography. CDA contents and PAV of samples increased and ML decreased with heating time at 180 °C. Samples added with lignan compounds showed lower CDA contents and PAV but higher ML retention than samples without lignan compounds. The antioxidant activity of sesame oil lignan compounds in ML oxidation during heating tended to be higher than that of α-tocopherol. The contents of lignan compounds in samples decreased with heating time due to their degradation, but the degradation rates were lower than that of α-tocopherol. This study suggested that sesame oil lignan compounds be used as antioxidants in oil at high temperatures for deep-fat frying due to their higher effectiveness and stability than α-tocopherol.     

Suppression of the oxidation of methyl linoleate encapsulated with the extract from defatted rice bran by a compressed hot water treatment

Bran extracts prepared by a compressed hot water treatment at 120, 150, and 180 °C for 7.5 min were used in association with maltodextrin for encapsulation of methyl linoleate. Mixtures of the bran extracts at 120 and 150 °C showed a higher emulsion-stabilizing ability than that at 180 °C. The bran extracts prepared at the higher temperature provided a higher oxidative stability as shown by the longer induction period for the oxidation of the encapsulated methyl linoleate. The induction periods of the encapsulated methyl linoleate using the bran extract prepared at 250 °C for 5 min as the aqueous phase were 3–6 times longer than those of the encapsulated methyl linoleate using water.     

超声波对红花籽油甲酯化影响研究

以红花籽油(经GC–MS分析含亚油酸80.17%)为原料,以亚油酸甲酯转化率为考察指标。采用超声波促进红花籽油的甲酯化反应,研究了超声功率、超声时间、碱用量、温度对甲酯化率的影响,经过试验确定最佳工艺条件为:240 W,时间20 min,KOH–甲醇∶油(mL/g)7.5∶1,温度40℃,亚油酸甲酯转化率为92.29%。     

玉米油脱色条件对生育酚含量影响研究

通过对脱色温度、脱色时间、脱色白土用量3个因素进行单因素及正交实验,研究脱色条件对玉米油生育酚含量的影响。结果表明:对生育酚含量影响的因素依次为脱色时间>脱色白土用量>脱色温度,当脱色时间为20 min,脱色白土用量为2.5%,脱色温度为105℃时,生育酚损失最少,损失率为9.3%,此时脱色油的色泽为Y35R3.2,色泽达到二级油标准。     

Role of sugar–amino acid interaction products (MRPs) as antioxidants in a methyl linoleate model system

Effects of early Maillard reaction products (MRPs) as antioxidants in methyl linoleate model system, during refrigerated storage at 5 °C for 6 days, have been evaluated. MRPs were prepared by reacting glucose with five different amino acids – glycine, methionine, tryptophan, aspartic acid and lysine – using two different concentrations and time intervals (30 mM/1 h, 30 mM/2 h, 60 mM/1 h and 60 mM/2 h). The preformed MRPs were incorporated, after studying pH and optical density profile, in a model system comprised of methyl linoleate and microcrystalline cellulose. Antioxidative characteristics were evaluated by estimating the thiobarbituric acid-reactive substance value (TBARS) and peroxide value (PV) and monitoring the gas chromatographic degradation pattern of methyl linoleate immediately after heating, as well as after storage at 5 °C for 2, 4 and 6 days. Analysis of variance revealed highly significant differences among TBARS, PV and the % of methyl linoleate degradation (p < 0.01) values, both initially and during storage in glucose + lysine and glucose + glycine with respect to control. Other treatments, such as glucose + methionine and glucose + tryptophan exhibited moderately significant differences (p < 0.05). But glucose + aspartic acid was not significantly different (p > 0.05) Significant differences were observed between 60 mM/2 h and 30 mM/1 h of MRPs with glucose + lysine and glucose + glycine (p < 0.01). Out of the five combinations tried, glucose + lysine and glucose + glycine exhibited good antioxidative potential at 60 mM/2 h. The % of antioxidant activity was in the order 60 mM/2 h > 60 mM/1 h > 30 mM/2 h > 30 mM/1 h for the treatments glucose + lysine > glucose + glycine > glucose + tryptophan > glucose + methionine > glucose + aspartic acid, respectively.     

Flowering catch crops used as forage plants for dairy cows: influence on fatty acids and tocopherols in milk

The effect of several flowering dicotyledonous catch crop plants (dicots) on milk fat quality in cows was investigated to test the hypothesis that their phenolic compounds may inhibit ruminal biohydrogenation and thus enhance the transfer to milk of intact, plant-derived polyunsaturated fatty acids. Berseem clover (Trifolium alexandrinum), buckwheat (Fagopyrum esculentum), and phacelia (Phacelia tanacetifolia) were sown in mixture with ryegrass (Lolium multiflorum; intended biomass proportion of 0.2) on 1 ha. For comparison, nonflowering chicory (Cichorium intybus, also sown in mixture with ryegrass) and pure ryegrass were cultivated. Realized biomass proportions (wet weight) were 91% for berseem clover, 69% for buckwheat, 54% for phacelia, and 51% for chicory. At the start of flowering (or from d 47 after sowing onward), cultures were harvested daily and fed for 20 d ad libitum to groups of 6 midlactation cows each. Additionally, 1 kg each of energy and protein concentrate and pure ryegrass hay were fed. Individual intake and milk yield of the cows were measured daily. Milk samples were obtained twice daily 5 d before and from 11 to 20 d after the start of treatment feeding. Feed samples were drawn twice a week from the fresh feeds. Apart from standard traits, feeds and milk were analyzed for fatty acids, tocopherols, and phenolic fractions. Only a few substantial treatment effects on intake and performance were observed. All diets based on dicots increased α-linolenic acid (ALA) concentrations in milk fat compared with the ryegrass diet even though the corresponding swards were not generally richer in ALA. The highest ALA concentration in milk fat (1.3 g/100 g of fatty acids) occurred with the berseem clover diet. Transfer rate of ALA from feed to milk was highest with the buckwheat diet (0.09) and lowest with ryegrass (0.05). This was congruent with the differences in total extractable phenols, being high in the buckwheat sward (2.6% of dry matter) and low in the ryegrass sward (1.2% of dry matter). Intermediates of ALA biohydrogenation were lowest in the milk fat of the buckwheat group, indicating an inhibitory effect of this treatment, which provided the highest dietary levels of phenols. The α-tocopherol concentration in milk was higher with the buckwheat diet than with berseem clover and phacelia diets. The study provides evidence that the ALA concentration in milk fat could be enhanced by feeding flowering dicots; however, this was due to different modes of action.     

搅拌和均质对牛乳稳定性的影响

采用BECKMAN LS13-320激光粒度分析仪对不同搅拌速率和均质条件的牛乳脂肪球粒径进行检测分析.结果表明,高搅拌速率特别是在2 000 r/min时随搅拌时闻的延长对牛乳脂肪球粒径的影响较显著,转速为1 500 r/min时一直到搅拌12 h才开始出现脂肪球轻微聚集现象,搅拌速率为1 000 r/min时搅拌12 h后仍与原鲜奶的粒径分布图相似.不同的均质条件对牛乳粒径分布图有一定的影响,其中,75℃/25 MPa均质后牛乳的粒径分布图相对而言较圆滑、重叠最少,体系较稳定.经中试试验同样证明75℃/25 MPa的均质条件更适于UHT乳的生产,牛乳体系相对而言最稳定.     

生育酚与生育三烯酚在油脂中稳定性研究

为研究油脂中生育酚(tocopherols,T)与生育三烯酚(tocotrienols,T_3)在高温和加速氧化条件下的稳定性,使用棕榈油、大豆油和小麦胚芽油配制成含有8种生育酚与生育三烯酚的调和油。测试棕榈调和油脂中生育酚与生育三烯酚在100℃、150℃、180℃和200℃的热稳定性,并使用Rancimat仪测试生育酚与生育三烯酚在25℃、100℃、110℃、120℃下的加速氧化稳定性。结果表明:随着温度的升高和时间的增加,生育酚与生育三烯酚的损失率变大,在150℃以上高温氧化时8种生育酚与生育三烯酚损失率排序为δ-Tβ-Tα-Tγ-Tδ-T_3β-T_3α-T_3γ-T_3。100℃高温氧化及100℃、110℃、120℃加速氧化条件下,8种生育酚与生育三烯酚的损失率顺序为δ-Tδ-T_3γ-Tβ-Tγ-T_3β-T_3α-Tα-T_3。在25℃加速氧化6 h,生育酚与生育三烯酚几乎无损失,而在100℃、110℃下加速氧化6 h,生育酚与生育三烯酚的总损失率分别为45.25%、97.32%,说明油脂中生育酚与生育三烯酚在低温下加速氧化时稳定性较好,温度大于100℃后,加速氧化时损失速度明显加快。本研究为减少油脂中生育酚与生育三烯酚的损失提供参考。     

流行音乐影响下的服饰设计风格研究

音乐作为一种表演艺术,可借助声乐来展现生活、表达情绪、塑造形象、传递情感,而音乐也来源于生活,是对人们生活情感的提炼和艺术处理。服饰是人们生活的关键组成部分,与音乐之间存在紧密联系,可以说音乐与服饰之间存在的神韵是相互依存、相互统一的。近年来,朋克、哥特、K-pop等流行音乐的广泛传播,为服饰设计师们提供了诸多灵感。从设计文化角度出发,将流行音乐中的典型时代特征与服饰设计进行巧妙融合,可创造出现代文化的经典盛宴。