利用γ-谷维素与β-谷甾醇制备葵花油凝胶研究

以一级压榨葵花籽油为原料,添加一定浓度的γ–谷维素与β–谷甾醇混合物制备出葵花油凝胶,探究不同制备工艺条件对葵花油凝胶硬度及微观结构的影响。在单因素试验的基础上,通过正交试验确定了6%γ–谷维素与β–谷甾醇混合物添加量葵花油凝胶的最优制备条件。试验表明,影响葵花油凝胶硬度因素的主次顺序为:冷却温度>γ–谷维素:β–谷甾醇添加比例>加热时间>加热温度;6%γ–谷维素与β–谷甾混合物醇添加量葵花油凝胶的最优制备工艺为:加热温度140℃,加热时间50 min,冷却温度5℃,γ–谷维素∶β–谷甾醇添加质量比例60∶40。在最优工艺条件下,6%γ–谷维素与β–谷甾醇添加量葵花油凝胶硬度为479.61±9.18 g。     

葵花籽油甘油二酯的制备及其在发酵乳应用中的特性研究

以葵花籽油为原料,通过酶法甘油解反应制备富含亚油酸的甘油二酯(DAG)。以乳脂DAG作对比,分析了葵花籽油DAG的主要脂肪酸组成,并作为脂肪替代物制备酸奶,测定了富含亚油酸DAG酸奶的流变特性和质构特性。结果表明,葵花籽油DAG最佳制备工艺条件为:甘油与葵花籽油质量比1∶10,脂肪酶添加量7. 13%,反应时间12. 35 h。在最佳条件下,葵花籽油DAG中DAG含量可达49. 21%,亚油酸含量为60. 17%。与乳脂DAG酸奶及乳脂酸奶相比,葵花籽油DAG酸奶体系的表观黏度较高、凝胶体系凝聚性更好,酸奶结构更稳定。     

葵花籽粕乙醇提取物的抗氧化活性的研究

利用超声波提取葵花籽粕中的乙醇提取物,通过单因素分析得到最优的提取工艺条件:提取料液比1:10、时间30min、温度40;用还原力法测定葵花粕乙醇提取物的抗氧化活性高于VC;用734Rancimat食用油氧化稳定性测定仪测定知葵花粕乙醇提取物粗提物浓度为187.5mg/L时的抗氧化性最佳,以同一浓度的VC、VE、BHA为对照,比较抗氧化活性,从而得到葵花籽粕中的乙醇提取物的抗氧化活性与BHA相当,小于VE、大于VC。     

Nondestructive determination of fatty acid composition of husked sunflower (Helianthus annua L.) seeds by near-infrared spectroscopy

Determination of the fatty acid composition of sunflower (Helianthus annua L.) seeds by near-infrared (NIR) spectroscopy was examined. Sunflower seeds were husked (removed from their hulls by a husking machine or manually with a knife). NIR spectra of these seeds were scanned from 1100 to 2500 nm at 2-nm intervals in a whole-grain cell with a wideangle moving drawer for machine-husked seeds or in a single-grain cup for a manually husked single-grain seed. The extracted oils from machine-husked seeds also were scanned by sandwiching them between a pair of slide glasses to create a thin layer and by placing them on a syrup cup. For extracted oil, the absorption band around 1720 nm filled out to the shorter wavelength region in the NIR second-derivative spectra as the percentage of the linoleic acid moiety increased, because linoleic acid absorbs in this region. On the other hand, for husked seeds and for a single-grain seed, as the percentage of linoleic acid increased, the trough at 1724 nm where oleic and saturated acids absorb decreased in the second-derivative NIR spectra. Determination of the fatty acid composition of sunflower seeds could be carried out successfully according to the NIR spectral pattern for both extracted oil (r=−0.989) and kernel seed (r=−0.993). This is important, especially for a manually husked single-grain seed (r=−0.971), because it can still be germinated after such nondestructive analysis.     

High-performance size-exclusion chromatographic studies on a high-oleic acid sunflower oil during potato frying

The behavior of a high-oleic acid sunflower oil used for 75 repeated deep-fat fryings of potatoes, with a fast turnover of fresh oil during frying, was evaluated by measuring the total polar content isolated by column chromatography. The total polar content increased in the oil from 3.6 ± 0.1 (mean ± SD) mg/100 mg unused oil to 7.6 ± 0.4 mg/100 mg oil after being used in 20 repeated fryings, followed by a tendency to reach a near-steady state throughout the successive fryings. Further, the polar fraction was examined by high-performance size-exclusion chromatography. Triacylglyceride dimers increased continuously from 0.18 ± 0.01 mg/100 mg unused oil to 2.42 ± 0.12 mg/100 mg oil at the 40th frying with no further significant changes. The amount of triacylglyceride polymers increased from 0.03 ± 0.00 mg/100 mg unused oil to 0.70 ± 0.01 mg/100 mg oil at the 60th frying, but did not increase further with continued frying. Oxidized triacylglycerides also significantly increased from 1.13 ± 0.06 mg/100 mg oil to 3.58 ± 0.09 mg/100 mg oil at the 50th frying to reach a near-steady state in successive fryings. Diacylglycerides and free fatty acids levels, related to hydrolytic alteration, did not change from the starting oil after continued fryings. Data from this study indicated that repeated fryings of potatoes in high-oleic sunflower oil with a frequent turnover of fresh oil throughout the frying slightly increased the level of polar material in the fryer oil during the first fryings, followed by minor changes and a tendency to reach a near-steady state in successive fryings.     

向日葵茎髓提取物的抑菌活性及机制

以向日葵茎髓为原料,制得3种不同极性向日葵茎髓提取物。采用琼脂扩散法测定3种不同极性向日葵茎髓提取物对4种受试菌的抑菌活性;并以其中的金黄色葡萄球菌和大肠杆菌为研究对象,探讨了乙酸乙酯萃取部位(EE)的抑菌机制。结果显示:不同极性萃取部位对4种受试菌均有一定抑制作用。其中,EE处理金黄色葡萄球菌和大肠杆菌的最低抑菌质量浓度(MIC)均为0.78 g/L,半数抑制质量浓度(IC50)分别为(1.11?0.01)和(1.59?0.03)g/L;抑菌作用与其总酚、总黄酮含量呈显著正相关性(P0.05)。通过SEM分析发现,EE处理引起菌体形态变化,破坏菌体的细胞膜结构;EE可增加金黄色葡萄球菌和大肠杆菌细胞膜结构的通透性,使菌体内的电解质、蛋白质、碱性磷酸酶向胞外泄露;应用4?,6-二脒基-2-苯基吲哚(DAPI)染色和荧光检测发现,EE能干扰细菌遗传物质(DNA)的复制,最终抑制受试菌增殖。     

高速逆流色谱分离纯化氧化葵花油中三亚油酸甘油酯单氢过氧化物

该文为了获得较高纯度的三亚油酸甘油酯单氢过氧化物,用于"脂肪调控氧化-热反应"制备肉味香精机理的研究。葵花油在70℃下通空气0.72 m3/(kg.h)氧化70 h制备含三亚油酸甘油酯单氢过氧化物的氧化产物,采用液-质联机定性及液相色谱-蒸发光散射检测器面积归一化定量,氧化产物中三亚油酸甘油酯单氢过氧化物质量分数为1.95%。高速逆流色谱分离该氧化产物中的三亚油酸甘油酯单氢过氧化物,较佳的两相溶剂系统为V(正己烷)∶V(二氯甲烷)∶V(乙腈)=4∶1∶3。以上相为固定相,下相为流动相,正向洗脱,流速1.5 mL/min,转速850 r/min,上样5 g,分离时间195 min,一次性得三亚油酸甘油酯单氢过氧化物53 mg,液相色谱-蒸发光散射检测器分析纯度为96.3%,回收率52.3%。     

The effects of intercepted solar radiation on sunflower (<Emphasis Type="Italic">Helianthus annuus</Emphasis> L.) seed composition from different head positions

The effect of intercepted solar radiation during fruit filling on seed weight and oil content from seeds of three sectors of the head in two sunflower (Helianthus annuus L.) hybrids of low and high potential oil percentage was investigated. Seed weight in each sector depended on both the level of radiation intercepted (modified by shading and thinning plants) and the genotype grown. A higher level of intercepted solar radiation increased seed weight in each sector. Central seeds of shaded plants showed the lowest weight. The seed and kernel oil content hierarchy among the three sectors was modified only in the hybrid with high potential oil content. For each head sector, variations in seed oil content associated with changes in the level of intercepted radiation could be accounted for by changes in the kernel oil content, not in the kernel/seed ratio. Significant relationships were found between seed oil and kernel oil contents when analyses between treatments (R>0.86) and sectors (R>0.92) were carried out. These relationships together with the growing conditions of plants during seed filling, the genotype, and the seed position on the head are essential factors that should be taken into account when selecting seeds in sunflower breeding programs since they affect the commercial/industrial quality of seeds.     

Short communication: Diurnal profiles of conjugated linoleic acids and trans fatty acids in ruminal fluid from cows fed a high concentrate diet supplemented with fish oil, linseed oil, or sunflower oil

Trans-18:1 and 18:2 isomer composition in ruminal fluid during the daily feeding cycle was examined in 3 cows fed a high concentrate diet (35:65) with 5% (DM basis) sunflower oil (SO), 5% linseed oil (LO), or 2.5% fish oil (FO) in a 3 x 3 Latin square with 3 4-wk periods. Grass hay and concentrate mixtures were fed at 0900, 1300, and 1700 h daily. Ruminal fluid was collected at 0900, 1100, 1300, 1500, 1700, 2000, and 0000 h. Feeding SO resulted in the greatest mean concentrations (% of total fatty acids) of trans10,cis12-18:2 and cis9,trans11-18:2. In particular, trans10,cis12-18:2 with SO was greater at 1500 (0.29%), 2000 (0.34%), and 0000 h (0.25%) relative to 0900 h (0.07%). Cis9,trans11-18:2 concentration increased from 0.47% at 0900 h to a peak of 2.06% at 1100 h; it remained greater than the percentage determined at 0900 h at 1300 (1.4%) through 0000 h (1.1%). Concentration of trans11,cis15-18:2 was greatest with LO, ranging from 3.3% (0900 h) to a peak of 11.4% at 2000 h. Mean trans10-18:1 concentration ranked by diet was SO > FO > LO. Peak trans10-18:1 with SO was observed at 1700 h (14.9%) compared with 0900 h (5.1%). Trans11-18:1 did not differ with diet or time. Stearic acid decreased over time with all diets reaching minimum concentrations at 1700 to 2000 h relative to 0900 h. Feeding FO, however, decreased mean 18:0 concentration 4-fold compared with LO or SO. The moderate effect on concentration of trans-18:1 coupled with accumulation of 18:2 intermediates and the decrease of 18:0 over time suggest that oils reduced the biohydrogenation of 18:2 isomers to trans-18:1.