亚临界流体萃取油脂及微量成分研究进展

亚临界流体萃取（subcritical fluid extraction, SFE）作为一种高效提取技术，在油脂加工中的应用备受关 注。本文介绍了国内外学者关于SFE用于油脂萃取的研究成果，详细综述了SFE在不同来源油脂及微量成分提取 领域的研究进展，并就目前研究状况对其前景进行了展望。      

Avenanthramide concentrations and hydroxycinnamoyl-CoA:hydroxyanthranilate N-hydroxycinnamoyltransferase activities in developing oats

Avenanthramides are unique components of oats (Avena sativa L.) that are described as phytoalexins and that have potential health promoting properties. The objectives of this study were to examine the avenanthramide contents and the activity of the avenanthramide biosynthetic enzyme hydroxycinnamoyl-CoA:hydroxyanthranilate N-hydroxycinnamoyl transferase (HHT) in spikelets and leaves of developing field-grown oats and to examine the presence of avenanthramides in unelicited seedling leaves of oats raised in a growth chamber. Avenanthramides were evident in spikelets of field-grown plants within 3–5 days after heading, and they generally increased in concentration throughout maturation. HHT activity was not detected until 21–22 days after heading, but the activity increased with age in most cultivars. In leaves, avenanthramides were evident before heading and generally increased in concentration until about 15 days after heading. At maturity, the concentrations of avenanthramides in spikelets were generally higher than in leaves. Seedling leaves from controlled environments that were not exposed to elicitors had low concentrations of avenanthramides at 7 days after planting, which increased in one cultivar, but not in another, over the next 14 days. These results indicate that unelicited seedling leaves contain avenanthramides, i.e. that avenanthramides are constitutively present in both grains and leaves.     

Validation of an extraction method for the quantification of soluble free and insoluble bound phenolic compounds in wheat by HPLC-DAD

Wheat is one of the three most widely grown grain crops and the most consumed in Europe. Wheat contains different phenolic compounds, mainly phenolic acids and flavonoids that are not evenly distributed in the wheat, being most abundant in the bran. These phenolic compounds are antioxidants against free radicals and other reactive oxygen species. Therefore, over the last few decades, there is a great interest to study and quantify these compounds present in wheat.This work proposes a HPLC-DAD method that allows a good separation of different phenolic compounds occurring as soluble free and insoluble bound compounds in wheat brand and flour. The extraction and the chromatographic conditions allowed the characterization of forty-two phenolic compounds, among phenolic acids (HBA, HCA, DFA and TFA), phenolic aldehydes, phenolic alcohols and flavonoids (flavones). This method is simple, sensitive, reproducible and accurate, and only a HPLC-DAD equipment is required. Thirty-four soluble and insoluble phenolic compounds can be quantified in wheat flour and brand. Hydroxytyrosol, a potent antioxidant compound, has been identified and quantified in wheat for the first time.     

Effect of baking on free and bound phenolic acids in wholegrain bakery products

Phenolic compounds, particularly ferulic acid the most abundant phenolic in wheat, are the major contributors to the in vitro antioxidant capacity. They are present in wheat in free and bound forms which affect their bioavailability. Thus the current study aims to investigate changes in free and bound phenolic acids occurred during baking in wholegrain bread, cookie and muffin. The products were also fortified with lutein due to its proved health benefits, and were previously evaluated with regard to lutein stability and bioavailability and antioxidant properties. The control and fortified wholegrain bakery products contained reasonable amounts of free and bound phenolic acids with bread products exhibiting the highest level per serving (0.6 and 11.7 mg, respectively). Ferulic acid was the principal phenolic both in the free or bound extracts of the three products followed by p-coumaric acid in the bound extracts. Baking resulted in an increase in free phenolic acids in the three products, while bound phenolic acids decreased in bread and slightly changed in cookie and muffin products. Though the effect of baking appeared to be dependent on type of baked product, type of phenolic, recipe and baking conditions, the wholegrain products should be considered good sources of phenolic antioxidants.     

Effects of infrared heating on phenolic compounds and Maillard reaction products in maize flour

Maize grains were heated by infrared radiation for 50–100 s, than flaked and milled. The output was set to 110, 115, 120 and 140 °C to determine the effect of temperature on the formation of acrylamide, 5-hydroxymethylfurfural (HMF) and furosine, as well as the level of phenolic compounds in maize flour and its total antioxidant capacity (TAC). Acrylamide and HMF levels were increased as the load of the heat treatment was increased in grains, while furosine concentration was rapidly increased to an apparent maximum (34.96 μg/g) followed by decrease during heating. Acrylamide, as well as HMF variables correlated very well with TAC of heat-treated flour (r² = 0.98 and 0.86). The process of infrared heating had a great influence on the reduction of phenolic compound contents. However, new antioxidants that were formed as a result of the Maillard reaction increased the total antioxidant capacity of heat-treated maize flour.     

Phenolic compounds in raw and cooked rice (Oryza sativa L.) and their inhibitory effect on the activity of angiotensin I-converting enzyme

Whole rice has been widely studied due to the abundance of bioactive compounds in its pericarp. Some of the beneficial effects of these compounds on human health have been attributed to their antioxidant and other biological activities, such as enzyme inhibition. In this work, we evaluated the contents of total, soluble and insoluble phenolic compounds of 6 red and 10 non-pigmented genotypes of whole rice as well as their inhibitory effect on the activity of angiotensin I-converting enzyme (ACE). The effects of cooking on phenolics and their inhibitory activities were also investigated. Red genotypes showed high content of phenolics, mainly soluble compounds, at an average of 409.7 mg ferulic acid eq./100 g, whereas overall lower average levels (99.4 mg ferulic acid eq./100 g) at an approximate soluble/insoluble compound ratio of 1:1 were observed in non-pigmented rice. Pigmented rice displayed a greater inhibitory effect on ACE than non-pigmented rice. In fact, a significant correlation between the content of soluble phenolics and ACE inhibition was observed (r = 0.8985, p < 0.05). In addition to significantly reducing the levels of total phenolics and ACE inhibition, cooking altered the soluble/insoluble compound ratio, especially among red rice genotypes.     

Sulfated polysaccharides in marine sponges: extraction methods and anti-HIV activity

The extraction, fractionation and HIV-1 inhibition potential of polysaccharides extracted from three species of marine sponges, Erylus discophorus, Cliona celata and Stelletta sp., collected in the Northeastern Atlantic, is presented in this work. The anti-HIV activity of 23 polysaccharide pellets and three crude extracts was tested. Crude extracts prepared from Erylus discophorus specimens were all highly active against HIV-1 (90 to 95% inhibition). Cliona celata pellets showed low polysaccharide content (bellow 38.5%) and almost no anti-HIV activity (<10% inhibition). Stelletta sp. pellets, although quite rich in polysaccharide (up to 97.3%), showed only modest bioactivity (<36% HIV-1 inhibition). Erylus discophorus pellets were among the richest in terms of polysaccharide content (up to 98%) and the most active against HIV-1 (up to 95% inhibition). Chromatographic fractionation of the polysaccharide pellet obtained from a specimen of Erylus discophorus (B161) yielded only modestly active fractions. However, we could infer that the active molecule is most probably a high molecular weight sulfated polysaccharide (>2000 kDa), whose mechanism is possibly preventing viral attachment and entry (fusion inhibitor).     

不同品质类型小麦籽粒游离氨基酸、蛋白质及其组分的动态变化

为了解小麦氮素营养代谢的动态变化规律,给优质专用小麦品种选育与应用提供科学依据,选用不同品质类型的四个小麦品种(系)济南17、PH82-2-2、PH97-4、PH97-5,在两种施氮水平和两种追肥时期下研究了籽粒游离氨基酸、蛋白质及其组分的动态变化.结果表明,籽粒发育初期游离氨基酸含量高,随籽粒发育其含量逐渐下降;蛋白质含量积累呈现"高-低-高"的变化趋势,品种之间差异显著,成熟期蛋白质含量高的品种一般有较高的游离氨基酸和蛋白质积累水平.不同品质类型小麦籽粒蛋白质组分含量变化动态基本一致,灌浆初期清蛋白含量较高,随籽粒发育逐渐下降,灌浆中后期下降趋缓;球蛋白总体含量水平较低,随籽粒发育缓慢下降,灌浆末期略有上升.醇溶蛋白在籽粒发育前期积累较少,花后14 d快速积累;谷蛋白在花后7 d已有一定的积累,随后其含量逐渐上升,强筋高蛋白品种有较高的醇溶蛋白和谷蛋白积累水平,在成熟籽粒蛋白质中谷蛋白和醇溶蛋白所占比例也高,弱筋低蛋白品种有相对较低的醇溶蛋白和谷蛋白积累,醇溶蛋白和谷蛋白所占比例也低.     

土壤肥力对小麦开花后各器官游离氨基酸和籽粒蛋白质含量变化的影响

能过随机区组试验和相关的方法，研究了两种土壤肥力条件下小麦开花后植株体内游离氨基酸含量的变化动态及其与籽粒蛋白质含量的关系。结果表明，开花后小麦植株各器官游离氨基酸含量均与籽粒蛋白质含量呈显著或极显著正相关，土壤肥力高能够显著提高各器官中的游离基酸含量，并延长维持高水平的时间，进而促进籽粒蛋白质合成，提高籽闰蛋白质含量和改善品质。     

稻麦套种对小麦花后地上部游离氨基酸含量及籽粒品质的影响

采用稻麦套种与传统条播两种栽培方式系统比较的方法,研究了稻麦套种对优质中筋小麦扬麦10号和弱筋小麦宁麦9号花后叶、茎鞘、颖壳、穗轴、籽粒游离氨基酸和蛋白质含量以及籽粒品质的影响。结果表明,稻麦套种对不同类型小麦花后地上部各器官游离氨基酸含量和籽粒蛋白质含量及其他品质指标有显著影响。与条播栽培方式相比,稻麦套种小麦花后地上部器官的游离氨基酸含量和籽粒蛋白质、湿面筋含量等主要品质指标均较低,二者差异显著。在同一栽培方式下,弱筋小麦宁麦9号各器官游离氨基酸含量显著低于中筋小麦扬麦10号。套种方式有利于弱筋小麦品质的形成,此栽培方式下宁麦9号各项品质指标均达到国家标准,但中筋小麦扬麦10号的部分品质指标下降。     

Effects of genotype and environment on avenanthramides and antioxidant activity of oats grown in northwestern China

To investigate the effects of genotype and growing environment on avenanthramides and antioxidant activity of oats, the total phenolic content (TPC), avenanthramide compositions, and antioxidant activity were determined for whole oat from 39 cultivars grown in four locations in northwestern China (Inner Mongolia, Qinghai, Shanxi and Gansu). The results demonstrated that environment (E), genotype (G) and the interaction of these factors (E × G) significantly affected TPC, concentration of avenanthramide 2c (2c, ranged from 6.24 to 136.20 mg kg⁻¹), avenanthramide 2p (2p, 6.07–112.25 mg kg⁻¹), avenanthramide 2f (2f, 7.26–222.77 mg kg⁻¹) and antioxidant activity of oats. The effect of E was considerably greater than that of G or E × G. Based on G plus G × E interaction biplots (GGE biplots) analysis, the four locations in northwestern China can be divided into either two or three regions. Qinghai was determined to be distinct from the other locations. Cultivar Bayou 9 and oats grown in Gansu exhibited the highest TPCs, concentrations of 2c, 2p, 2f and antioxidant activity. The results suggest that oats containing more avenanthramides and exhibiting high levels of antioxidant activity could be obtained by selecting an appropriate genotype and growth location.     

Characterizing the pigmented traditional rice cultivars grown in temperate regions of Kashmir (India) for free and bound phenolics compounds and in vitro antioxidant properties

The purpose of the research was to identify the phenolic and flavonoid compounds of seven different traditional pigmented whole rice cultivars grown in the temperate regions of Kashmir so as to study their relationship with in vitro antioxidant capacities. The completely pigmented rice cultivars were found to have higher phenolic, flavonoid, anthocyanin contents and exhibited higher antioxidant capacities than the light colored and sparely colored rice cultivars. A total of 40 compounds had been identified in the analyzed rice cultivars that were found to be distributed in 6 major categories with 6-phenolics, 6-flavonoids, 11-hydroxycinnamic acid derivatives, 7-hydroxybenzoic acid derivatives, 3-anthocyanins and 7-flavonoid glucosides of different flavonoid compounds. Among the free and bound fractions for each cultivars the light and sparsely colored depicted higher content of phenolics and in vitro antioxidant properties in bound faction, while the completely pigmented cultivars showed higher antioxidant properties in free fractions. The anthocyanins quercetin-3-O-galactoside, cyanidin-3-O-rutinoside and pelargonidin-3-O-diglucoside had been identified by LC-MS existing in the free fractions of the analyzed rice cultivars whereas, the free fraction of acetone + H₂O possessed higher percentage of phenolic compounds as compared to methanolic extracts and bound fractions. The black colored cultivars possessed higher DPPH scavenging activity and lipid peroxidation inhibition.     

Alpha-amylase treatment increases extractable phenolics and antioxidant capacity of oat (Avena nuda L.) flour

In this work, α-amylase was used to treat oat flour with the intent to release phenolic compounds with known antioxidant properties. After methanol extraction, the amounts of nine beneficial phenolic compounds were measured using HPLC. The antioxidant activities of the extracts were assessed using 2,2′-azinobis (3- ethylbenzothiazoline-6-sulfonic acid) (ABTS)，2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and protein oxidative damage protection assays. Compared with heating-only treated oat flour, that treated with α-amylase showed significant increase of extractable total phenolic content (0.46–1.35 μmol gallic acid equivalents per gram oat), total antioxidant capacity, and an increased ability on the protection of protein from oxidative damage. Heating-only increased caffeic acid and vanillin content by 17 (0.03 vs 0.54 μg/g oat) and 1.8 (0.62 vs 1.11 μg/g oat) folds, but slightly increased the content of other phenols. Excluding heating effect, α-amylase treatment increased gallic acid content by 2.6 folds (0.38 vs 1.38 μg/g oat), caffeic acid content by 2.4 (0.54 vs 1.82 μg/g oat) folds, and other phenols by 1.0–1.8 folds. In conclusion, α-amylase treatment can yield oat products containing more extractable phenolic compounds with increased antioxidant capacity.     

Whole wheat bread: Effect of bran fractions on dough and end-product quality

Consumption of whole-wheat based products is encouraged due to their important nutritional elements that benefit human health. However, the use of whole-wheat flour is limited because of the poor processing and end-product quality. Bran was postulated as the major problem in whole wheat breadmaking. In this study, four major bran components including lipids, extractable phenolics (EP), hydrolysable phenolics (HP), and fiber were evaluated for their specific functionality in flour, dough and bread baking. The experiment was done by reconstitution approach using the 2⁴ factorial experimental layout. Fiber was identified as a main component to have highly significant (P < 0.05) and negative influence on most breadmaking characteristics. Although HP had positive effect on farinograph stability, it was identified as another main factor that negatively impacted the oven spring and bread loaf volume. Bran oil and EP seemed to be detrimental to most breadmaking characteristics. Overall, statistical analysis indicates that influence of the four bran components are highly complex. The bran components demonstrate multi-way interactions in regards to their influence on dough and bread-making characteristics. Particularly, Fiber appeared to have a high degree of interaction with other bran components and notably influenced the functionality of those components in whole wheat bread-making.