New polyphenolic compounds in commercial deodistillate and rapeseed oils

Different phenolic compounds were identified in commercial rapeseed oils, as well as in a commercial by-product of oil refining, the deodistillate. Reversed-phase HPLC analysis and the successive fragmentation procedure by ESI-MSⁿ (electrospray ionisation mass spectrometry) showed a significant fragmentation pattern for new compounds, the cis- and trans-diastereomers of 4-vinylsyringol dimer [cis-4,6-dimethoxy-5-hydroxy-1-methyl-3-(3′,5′-dimethoxy-4′-hydroxyphenyl)indane and trans-4,6-dimethoxy-5-hydroxy-1-methyl-3-(3′,5′-dimethoxy-4′-hydroxyphenyl)indane] and the vinylsyringol trimer in trace amounts. The phenylindane were isolated by preparative HPLC and was clearly identified by nuclear magnetic resonance spectroscopy. Besides sinapic acid and its decarboxylated derivative, 4-vinylsyringol, this newly identified 4-vinylsyringol dimer was present in the deodistillate of processed rapeseed oil in significant amounts (sinapic acid, approx. 500 mg/kg, 4-vinylsyringol, approx. 200 mg/kg and 4-vinylsyringol dimer, approx. 3.50 g/kg). Additionally, the phenylindane was also detected in small amounts (6.4–63.0 mg/kg or trace amounts, respectively) in commercial rapeseed oils. The newly identified phenylindane compound had a high antioxidative potential (3.9 trolox-eq.) and might be an important phenolic compound in commercial deodistillate and rapeseed oils.     

中心组合设计优化高温菜籽粕中蛋白的酶解工艺

蛋白肽具有一定的生物活性且容易吸收,广泛应用在食品、医药和化妆品等领域,显示出了诱人的应用前景。研究以超声波法从热榨春油菜菜籽粕中提取的蛋白为原料,利用碱性蛋白酶进行酶解制备菜籽蛋白肽。通过单因素试验及中心组合设计试验研究了底物浓度、酶解温度、酶用量、pH等因素对菜籽蛋白水解度的影响,确定了碱性蛋白酶酶解菜籽蛋白的最佳工艺条件,建立了回归数学模型。结果表明:在底物浓度为3%,酶解温度为46℃,酶用量为12000U/g,pH为9.57的条件下酶解3h,菜籽蛋白的水解度达23.96%。为进一步酶解打下良好的基础,是一条经济可行的工艺路线。     

响应面法优化油菜籽粕中硫苷酶解工艺及其降解产物抑菌作用的初步研究

以油菜籽粕为原料,在单因素实验基础上,选取酶解缓冲液p H、酶解温度和酶解时间为自变量,以酶解产物异硫氰酸酯含量为响应值,利用Box-Behnken中心组合设计原理和响应面分析法,研究各自变量的交互作用对异硫氰酸酯含量的影响,建立异硫氰酸酯含量的二次回归方程,并通过抑菌圈实验,分析了异硫氰酸酯对哈密瓜采后两种常见病原菌的抑制作用。结果表明:酶解缓冲液p H3.70、酶解温度45℃、酶解时间96 min,在此最优条件下异硫氰酸酯含量为3.005%。抑菌实验表明,异硫氰酸酯对镰刀菌和链格孢菌有明显的抑制作用。      

Enzymatic hydrolysis of soybean protein using lactic acid bacteria

The proteolytic activity of 12 lactic acid bacteria (LAB) strains, assayed on soy protein extract at a temperature of 37 °C for 6 h, was evaluated by SDS–PAGE, reverse-phase HPLC and free-amino acid analyses. The results indicated that α- and α′-subunits of β-conglycinin were the preferred substrates for the majority of the LAB. Only a few strains exerted some action against the basic polypeptides of glycinin, this fraction was the least degraded of all soy protein fractions. Whole-cell suspensions of LAB used in this study generated hydrophilic and hydrophobic peptides from mainly soy protein fractions. RP-HPLC analyses indicated differences in the profiles of the hydrolysates, with several peaks decreasing in size and new peaks being formed. Three of the selected strains assayed increased the level of total free amino acids in the soy protein extract (SPE) and hydrolyzed principally essential amino acids and flavour precursor amino acids.     

菜籽蛋白的酶水解：复合风味蛋白酶水解条件的研究

用响应面分析方法（RSM）对影响菜籽蛋白酶水解的因素进行分析,得到复合风味蛋白酶Flavorzyme的最佳酶水解条件为温度55.5℃,pH6.2。酶与底物浓度比（E/S）74.31LAPU/g,底物浓度12.0%（W/V）,水解时间3h,最佳酶水解条件下的水解度为26.4%。在最佳酶水解条件下对水解度和时间的关系进行了研究,证实了预测值和实测值是一致的。     

固态发酵法脱除菜籽饼粕中总酚及芥子碱的工艺研究

筛选出能高效降解菜粕中总酚及芥子碱的菌株,并进行混合发酵,研究了不同菌株、不同菜粕原料、不同接种量、不同发酵时间、不同营养源及不同金属离子对总酚及芥子碱降解率的影响。结果表明:酿酒酵母、纳豆芽孢杆菌及枯草芽孢杆菌B4以8%的总接种量,等比例接种到添加了5%糖蜜和0.05%的硫酸铜及硫酸亚铁的菜籽饼粕(含水量为50%)中,发酵72h,菜粕中的总酚和芥子碱降解率可达到70.72%及80.06%。     

双酶水解菜籽粕及水解物的抗氧化活性研究

中性蛋白酶分别与alcalase,protamex,flavourzyme,木瓜蛋白酶及胰蛋白酶相结合,用双酶相继水解菜籽粕,得到5组菜籽粕的双酶水解物。双酶水解物抗氧化活性试验结果表明,所有水解物都具有一定清除DPPH自由基活性的能力、还原能力和抑制亚油酸氧化活性的能力,但以中性蛋白酶和胰蛋白酶组合的水解物最强。该水解物的凝胶层析分离结果表明,4组分离物中分子量为6500-1050Da的组分清除DPPH自由基的活性最高,显示菜籽粕双酶水解物的抗氧化活性取决于水解物的分子结构,即不仅与酶的种类有关,还与水解条件和水解度有关。     

微生物固态发酵和酶解工艺处理棉粕的研究

研究了微生物和蛋白酶共同作用下棉粕中毒性因子和营养成分的变化。在枯草芽孢杆菌GJ00141、酿酒酵母GJ00079和中性蛋白酶等参与的固态发酵和酶解体系中,检测棉粕中游离棉酚、粗蛋白质、酸溶蛋白质、粗纤维、氨基酸组成、益生菌活菌数等指标。结果发现,相比原棉粕,60 h的固态发酵与酶解后,棉粕中游离棉酚含量降低40%以上,酸溶蛋白质提高了108.7%,粗纤维降低约12.7%,枯草芽孢杆菌和酿酒酵母活菌数分别为7.75、7.00 lg(CFU/g),粗蛋白质、氨基酸总量基本没有变化。由此可见,经过发酵和酶解后棉粕的营养价值和饲料品质有所提高。     

魔芋多肽酶解法制备工艺研究

采用碱溶酸沉法提取魔芋飞粉中的蛋白质,再用碱性蛋白酶对提取出的魔芋蛋白进行酶解,探究魔芋多肽的最佳制备工艺。该试验以蛋白质提取率为指标,先确定出魔芋蛋白的最佳提取工艺,再以多肽提取率(TCA–SN)和水解度(DH)为双指标,通过单因素试验和正交试验来优化魔芋多肽制备工艺。结果表明:魔芋蛋白的等电点为p H 3.8,最佳提取条件为酶解p H 8.5、酶解温度50℃、酶用量3 500 U/g、酶解时间150 min。在该组合条件下得到的多肽得率和水解度分别为11.98%和9.19%。     

Investigation of the susceptibility of acid-deamidated wheat gluten to in vitro enzymatic hydrolysis using Raman spectra and free amino acid analysis

BACKGROUND: The number and surface nature of amino acids (AAs) in substrate proteins available to hydrolytic enzymes are critical. Among them, the micro‐environmental properties of specific AAs in substrates before hydrolysis would probably dominate the susceptibility of substrates to enzymatic hydrolysis. Fundamental knowledge concerning this regard is lacking. The objective of this work was to investigate the relationship between the exposure level of AAs in acid‐deamidated wheat gluten and their susceptibilities to in vitro enzymatic hydrolysis by pancreatin through both high‐performance liquid chromatography and Raman spectra. Wheat gluten deamidated with HCl (HDWG), citric acid (CDWG), succinic acid (SDWG) and acetic acid (ADWG) at the same degree of deamidation under the same heat treatment were chosen as the substrates. Substrate characterisations including degree of hydrolysis, surface hydrophobicity and structural characteristics before hydrolysis, together with analysis of free AAs of the corresponding hydrolysates during hydrolysis, were investigated. RESULTS: Hydrolysates from SDWG had the highest value for the degree of hydrolysis. The susceptibility of CDWG to pancreatin hydrolysis was the lowest, lower than native wheat gluten (CK) after the initial 36 h. Compared with free AAs, the mole increase profiles of CK, Arg production levelled off in HDWG after 12 h whereas it was inhibited in ADWG. For SDWG, Arg release was dramatically inhibited after 12 h and was replaced by Trp. Investigations using Raman spectra of the micro‐environment of Cys, Trp, Tyr and His and the mole increase trend of them indicated that the exposure level of these amino acids in substrates was positively related to their susceptibilities to pancreatin hydrolysis especially after 24 h of hydrolysis. CONCLUSION: Deamidation by four acids has a distinct influence on the structural characteristics of wheat gluten substrates. Although the substrates were selected at the same level of deamidation by the same heat treatment, their resultant conformational differences significantly influenced the exposure level of amino acids for binding to enzymes and the susceptibility of substrates to in vitro enzymatic hydrolysis. Therefore, it had an influence on changing enzyme cutting sites of pancreatin. This information will provide a better understanding of specific behaviour of AAs in wheat gluten during enzymatic hydrolysis from a new perspective. Copyright © 2012 Society of Chemical Industry     

Effect of cross-linking on the resistance to enzymatic hydrolysis of waxy maize starch and low-methoxy pectin

Gelatinised waxy maize starch and low-methoxy pectin mixtures were solubilised/dispersed in water and cross-linked with sodium trimetaphosphate (STMP). The polysaccharides were subjected to α-amylase, β-amylase or amyloglucosidase (AMG) hydrolysis for different times, and at two starch to pectin combination ratios (3:2 and 2:3). The extent of hydrolysis by porcine pancreatic α-amylase of the cross-linked (gelatinised) starch was 54.8–58.9% in comparison with gelatinised starch (for different incubation times), corresponding to 52.3–58.9% and 51.3–55.3% of the starch in the uncross-linked (UL) 3:2 and 2:3 starch to pectin ratios (for the same hydrolysis times). Blends of individually cross-linked starch to pectin ratios (3:2 and 2:3) were hydrolysed to 66.2–67.0% and 65.4–71.8%, respectively, compared with the corresponding UL counterparts. When the gelatinised starch was incubated for 0.5–36 h with β-amylase, hydrolysis ranged from 9.2% to 26.2%, and from 5.4% to 12.2% when the starch was cross-linked (corresponding to 40.0–58.7% of the gelatinised starch). For starch to pectin ratios of 3:2 or 2:3 blended after cross-linking, or by simultaneous cross-linking, hydrolysis represented 2.3–3.4% and 0.3–0.6% for the 3:2 ratio but only 1.2–2.0% and 0–0.3% for the 2:3 ratio. Hydrolysis with AMG using a 0.1 mg ml⁻¹ enzyme concentration caused 51.8% hydrolysis of gelatinised starch, which was lowered to 35.2% (i.e. by 68%) after cross-linking. At a higher enzyme concentration (1 mg ml⁻¹), the comparable figures were 91.7% and 71.9% (a reduction of 78.4%). For the UL 3:2 starch to pectin ratio and 0.1 and 1 mg ml⁻¹ enzyme concentrations, there was 27.8% and 56.5% hydrolysis of the polysaccharide which translated to 24.3% (87.4%) and 45.8% (81.1%), respectively, after cross-linking. Comparable figures for the 2:3 ratio (for the 0.1 and 1 mg ml⁻¹ enzyme concentrations) were 20.2% and 36.5% hydrolysis of the UL samples and 18.2% (90.1%) and 32.5% (89.0%) hydrolysis, respectively, after cross-linking.     

水酶法芝麻油与其他工艺芝麻油品质差异研究

通过对芝麻油外观品质、理化特性、抗氧化成分及脂肪酸组成进行对比,研究了水酶法芝麻油与其他工艺芝麻油(热榨法芝麻油、冷榨法芝麻油、水代法芝麻油)的品质差异。结果表明:水酶法芝麻油的外观品质好,色泽浅,符合一级成品芝麻油标准;水酶法芝麻油的水分及挥发物的含量介于冷榨法芝麻油和水代法芝麻油之间,酸价、过氧化值、不皂化物含量最低;水酶法芝麻油的抗氧化成分(生育酚、芝麻素和芝麻林素)含量最高,但未检出芝麻酚;与热榨法芝麻油、冷榨法芝麻油、水代法芝麻油相比,水酶法芝麻油的饱和脂肪酸含量最高,不饱和脂肪酸含量最低。     

A comparative study on the phenolic acids identified and quantified in dry beans using HPLC as affected by different extraction and hydrolysis methods

A high performance liquid chromatography procedure was used to assess the phenolic acid content in three different varieties of dry beans (Phaseolus vulgaris L.) grown in Canada. The majority of phenolic acids were extracted from the base hydrolysed fraction of the sequential hydrolysis regime. There was a protective effect of ascorbic acid (AA) and ethylenediaminetetraacetic acid (EDTA) when added to the 10 N NaOH hydrolysis step. The mild direct base hydrolysis (2 N NaOH) with and without AA and EDTA protection resulted in a measured total phenolic acid content that was lower than the total phenolic acid content measured for the more aggressive base hydrolysis (10 N NaOH) with protection, yet were comparable to the values obtained for the aggressive base hydrolysis without AA and EDTA protection. Sequential acid hydrolysis did yield a significant amount of compounds that exhibited the same retention times as gallic and protocatechuic acid, however, the UV spectra and masses of the molecular ions present in the peaks of these compounds did not correspond with masses of authentic standards. Thus, the majority of phenolic acids were detected in the base hydrolysed fraction when AA and EDTA were added to prevent degradation of phenolic acids. Acid hydrolysis did release compounds present in beans that were not obtained from base hydrolysis. This work shows that extraction and hydrolysis procedure has a substantial effect on the detection of phenolic acids present in beans.     

响应面分析法优化菜籽多糖酸法提取工艺的研究

利用响应面分析法对菜籽多糖的酸法提取工艺进行了优化。在单因素试验的基础上,选取酸浓度、料液比、提取时间、提取温度进行了4因素3水平的Box-Behnken中心组合研究,并运用Design Expert 7.0软件对试验数据进行分析。建立了以上4个主要因素对酸提菜籽多糖得率影响的数学模型,并通过响应面分析法对提取条件进行了优化,确定了酸法提取菜籽多糖的最佳工艺。试验结果表明,各提取因素对酸提菜籽多糖得率的影响顺序为:提取温度>酸浓度>提取时间>料液比。所得最佳提取条件为:酸浓度0.28 mol/L、料液比43.05 mL/g、提取时间5 h和提取温度71.9℃,在此条件下预期的多糖得率是4.07%,实际得率为4.01%。     

重组聚半乳糖醛酸酶PGB的生化特征及其酶解产物活性分析

解析重组聚半乳糖醛酸酶PGB的酶学性质,研究PGB制备的果胶水解物的基本成分和生物学活性。通过摇瓶发酵制备聚半乳糖醛酸酶酶液,研究其基本酶学性质。再在最优作用条件下对果胶进行水解,并考察水解产物的组成、抗菌活性和抗氧化活性。在摇瓶发酵水平,黑曲霉聚半乳糖醛酸酶PGB的酶活达到10790 U/m L;该酶的最适作用温度和p H分别为55℃和5.0;在40℃或p H4.0⁶.0条件下具有较好稳定性。Mg²⁺和Cu²⁺对其活性有促进作用,K⁺、Ca²⁺、Zn²⁺、Mn²⁺、Co²⁺、Fe³⁺和Fe²⁺等对其活性均有不同程度的抑制作用;它对低酯果胶的K_m和V_max分别是0.756 mg/m L和9.225 mg/（m L·min）。高效阴离子交换色谱-脉冲安培检测法（HPAEC-PAD）的分析表明,PGB对果胶的酶解产物是半乳糖醛酸单体和聚合度2⁴为主的寡聚半乳糖醛酸,它对金黄色葡萄球菌的生长有显著抑制作用,其最小抑菌浓度和抗氧化活性分别为0.64 mg/m L和6.125 U/m L。      

Aroma compounds and sensory characteristics as biomarkers of quality of differently processed Tunisian virgin olive oils

The influence of the extraction system (continuous vs. discontinuous) and the degree of freshness of olives on the chemical composition and the quality of Chemlali and Chétoui virgin olive oil has been studied. Analytical data mainly concerning the volatile and sensory profiles revealed statistically significant differences in relation to the extraction system. All quality indices and sensory characteristics showed statistically significant differences associated with the degree of freshness of fruits. These results further confirm the general consensus that volatile compounds can be very useful as biomarkers of the quality of virgin olive oil and show correlations with the sensory characteristics.     

菜籽油脱臭馏出物酶法酯交换制备脂肪酸甲酯

以菜籽油脱臭馏出物为原料,采用化学法进行酯化反应后,再利用酶法进行酯交换反应制备脂肪酸甲酯。在脂肪酶Lipase EC 3.1.1.3用量4%的条件下,通过单因素实验考察了甲醇用量、体系pH、反应温度、反应时间对酯交换转化率的影响,然后通过正交实验对酯交换反应条件进行了优化。结果表明:在脂肪酶Lipase EC 3.1.1.3用量4%、甲醇用量45%(以菜籽油脱臭馏出物质量为基准)、体系pH 7.0、反应温度55℃、反应时间16 h的条件下,酶法酯交换转化率达到85.35%。实验结果表明脂肪酶应用于菜籽油脱臭馏出物酯交换反应是可行的,为实现清洁生产提供了新途径。     

灵芝菌丝体中灵芝酸T、R和S的HPLC测定方法的建立和应用

采用YMC C18柱（250mm×4.6mm,5μm）,以0.5%冰醋酸溶液（A）-甲醇（B）为流动相梯度洗脱（0²0min,85%B→100%B;20³0min,100%B）,检测波长在245nm,流速1mL/min,柱温为30℃的条件下,用HPLC考察灵芝酸T、灵芝酸S、灵芝酸R在不同灵芝菌丝体中的含量差异。结果表明,不同种类的灵芝菌丝体中三种灵芝酸成分的含量存在显著的差异,p=0.0003,而且此方法操作简便,稳定性和重复性良好,适用于同时快速检测灵芝菌丝体中三种灵芝酸含量。      

微波辅助酶解棉籽粕的条件优化及酶解产物功能性质研究

研究了微波辅助碱性蛋白酶和风味蛋白酶双酶酶解棉籽粕的工艺条件.通过单因素实验确定了碱性蛋白酶酶解的最佳工艺条件为:微波温度60℃,微波功率500 W,酶加量5％(以底物质量计),酶解时间15 min;风味蛋白酶酶解的最佳工艺条件为:微波温度60℃,微波功率600W,酶加量5％(以底物质量计),酶解时间15 min.参照单因素优化条件,对棉籽粕进行连续酶解,酶解液多肽含量为13.32 mg/mL.棉籽粕经过微波连续双酶酶解后,吸油性、起泡性、乳化性等功能性质得到改善.