硫代亚磺酸酯参与大蒜绿变作用机理初探

对新蒜采取三种不同贮藏温度处理，对大蒜中硫代亚磺酸酯含量和蒜泥滤液吸光值进行了多点监测，研究硫代亚磺酸酯与大蒜绿变能力之间的关系。结果表明，大蒜绿变能力同硫代亚磺酸酯含量呈正相关关系，由此推测硫代亚磺酸酯是参与大蒜绿变反应重要物质，其含量决定了大蒜的绿变能力。同时研究乙酸浸泡期间大蒜硫代亚磺酸酯含量的变化，分析硫代亚磺酸酯与大蒜绿变程度之间的关系。试验得出，硫代亚磺酸酯含量与大蒜绿变程度的呈线性负相关关系，推测在大蒜中前体物质——蒜氨酸含量一定的条件下，绿色素形成的越多，作为反应中间体的硫代亚磺酸酯参与转化越多，最终表现在它的含量随大蒜绿变程度增加而降低。这就进一步说明硫代亚磺酸酯参与了大蒜绿变反应。大蒜在低温贮藏过程中，第15d之后蒜素含量有很好的升高趋势，这为提高大蒜中蒜素含量的研究建立了理论依据，为其提取加工提供了生产建议。     

大蒜干燥工艺的研究

分别采用热风干燥、真空干燥、冷冻干燥、微波真空干燥与真空干燥联合干燥法对大蒜进行干燥 ,研究了各种干燥方法对大蒜中硫代亚磺酸酯保留率和品质的影响 ,采用响应面分析得到微波真空干燥和真空干燥联合干燥法干燥大蒜最佳工艺 :3 76 1W、 3min ,3 3 4 3W、3min ,2 1 7 3W、9min ,1 3 9 1W、3min ,硫代亚磺酸酯保留率 90 2 %。     

大蒜中硫代亚磺酸酯的提取工艺

硫代亚磺酸酯是大蒜中的活性成分,由大蒜中非蛋白质氨基酸———蒜氨酸(alliin)经内源酶蒜氨酸酶(alliinase,蒜氨酸裂合酶,EC4.4.1.4)的酶解作用而生成.作者采用溶剂法以温和的条件提取大蒜中硫代亚磺酸酯,研究了乙醇提取前的酶解过程以及乙醇提取中各因素对硫代亚磺酸酯提取率的影响,采用响应面分析得到醇提硫代亚磺酸酯的最佳工艺条件.     

大蒜绿变机理的研究进展

本文结合近几十年来的研究进展，论述了导致大蒜绿变的基本机理、绿变的影响因素以及有关大蒜绿色素的研究。     

分光光度法测定大蒜提取物中硫代亚磺酸酯

提供了一种利用L-半胱氨酸和DTNB检测新鲜大蒜及大蒜提取物中硫代亚磺酸酯的分光光度法，通过对Lawson法的进一步改良，不仅提高了测定的准确性和重现性，而且可应用于大蒜乙醇提取物中硫代亚磺酸酯的定量测定，也同样适用于其它大蒜提取物中总硫代亚磺酸酯的定量测定。     

不同干燥方法对干燥大蒜品质的影响

比较了冷冻干燥和微波真空与真空联合干燥2种干燥方法对干燥大蒜中硫代亚磺酸酯保留率和品质的影响,并采用固相微萃取法(SPME)富集,分析新鲜大蒜、冷冻干燥大蒜、微波真空与真空联合干燥大蒜的风味物质,经气-质联用法(GC-MS)检测,对2种不同干燥方法所得干燥大蒜的风味进行了比较。结果表明,采用微波真空与真空联合干燥得到的大蒜产品可以达到和冷冻干燥相似的品质。     

分光光度法测定大蒜提取物中硫代亚磺酸酯含量

硫代亚磺酸酯是大蒜中的活性成分 ,由大蒜中非蛋白质氨基酸———蒜氨酸 (alliin)经内源酶蒜氨酸酶 (alliinase ,蒜氨酸裂合酶 ,EC4·4·1·4 )的酶解作用而生成的。介绍了一种利用L -半光氨酸和DTNB检测新鲜大蒜及大蒜提取物中硫代亚磺酸酯的分光光度法。此方法具有简便 ,快速和灵敏度高的特点。     

保存时间及温度对藠头不同部位中硫代亚磺酸酯含量的影响

用分光光度法检测藠头各部位硫代亚磺酸酯的含量,并研究保存时间及温度对藠头各部位中硫代亚磺酸酯保留的影响。结果表明,藠头各部位均含有较高的硫代亚磺酸酯,但在粉碎之后含量随时间增长迅速降低,并未见明显的储存温度对硫代亚磺酸酯保留量的影响。     

保存时间及温度对藠头不同部位中硫代亚磺酸酯含量的影响

用分光光度法检测藠头各部位硫代亚磺酸酯的含量,并研究保存时间及温度对藠头各部位中硫代亚磺酸酯保留的影响。结果表明,藠头各部位均含有较高的硫代亚磺酸酯,但在粉碎之后含量随时间增长迅速降低,并未见明显的储存温度对硫代亚磺酸酯保留量的影响。      

提高冻干香葱品质的工艺研究

为保持真空冷冻干燥香葱的鲜绿、天然的葱香味及品质,采用漂烫和护色剂对香葱进行浸泡护色处理,固相微萃取气质联用(SPME-GC-MS)测定香葱的挥发性成分,并确定真空冷冻干燥香葱气味最浓郁时的干燥时间、温度和真空度。实验表明:SPME-GC-MS分析确定以硫代亚磺酸酯的含量来衡量干燥后香葱气味的浓郁程度。干燥香葱颜色最鲜亮时的条件为:100℃水中烫漂30s,0.3%碳酸钠碱液中浸泡10min,0.03%氯化锌和0.2%氯化钙护绿液中护色30min。满足香葱香味最浓郁及水分要求的条件为:0℃下升华干燥6h,25℃下解析干燥2h,真空度60Pa。     

吡咯基氨基酸化合物在大蒜绿变中的作用研究

研究了乙酸体系中吡咯基缬氨酸以及吡咯基亮氨酸对\     

腊八蒜中黄色素的理化性质研究

在前期研究的基础上分离制备了腊八蒜色素中的黄色素组分,对黄色素的溶解性及稳定性进行了研究。黄色素可以溶于水,甲醇,乙醇,正丁醇等极性溶剂中,不溶于乙醚,乙酸乙酯,丙酮等非极性溶剂。黄色素在酸性条件下稳定,在碱性条件下褪色;在自然光下30d后损失率不到10%,60℃以下加热损失率低于6%,Cu2+,Zn2+,Al3+,Mn2+,Fe2+等离子的存在对黄色素无影响;Fe3+对色素的呈色有较大影响,Na2SO3和H2O2对色素均有破坏作用,Na2SO3的影响较显著。     

Characterization of a new yellow pigment from model reaction system related to garlic greening

Three yellow pigments have been identified from three reaction systems containing pyruvic acid and 2-(1H-pyrrolyl) acetic acid, 1-(2′-methyl-1′-carboxy-propyl) pyrrole, and 1-(2′-methyl-1′-carboxy-butyl) pyrrole (a kind of precursor of garlic green pigment) related to garlic greening in previous paper, respectively. In the present study, another kind of yellow pigment from the same system containing pyruvic acid and 2-(1H-pyrrolyl) acetic acid was identified by liquid chromatography–electrospray ionization mass spectrometry (LC-ESI MS/MS) and high-resolution electrospray ionization mass spectrometry. This kind of pigment made predominant contribution to the production of yellow pigment in this model reaction pathway, which was involved in garlic discoloration. It was observed that there were two more methyl groups located on two conjugated double bonds that bridged two moles of 2-(1H-pyrrolyl) acetic acid compared to the structures of pigments, which was identified in our previous paper. Molecular weight of the pigment is 329.1495 [M+H]⁺, and its molecular formula is C₁₈H₂₀N₂O₄ which has a maximal absorbance at 436.9 nm, due to its conjugated structure.     

Freeze-dried fresh onion powder prevents green discolouration (greening) in macerated garlic

Green discolouration (greening) of macerated garlic products is a major concern in the garlic-processing industry, and is caused by reactions between free amino acids and 2-propenyl 1-propenyl (2-Pe/1-Pe) thiosulphinates in the garlic. Efficacy of freeze-dried fresh onion powder that contains the active onion enzyme lachrymatory factor synthase (LFS) to prevent greening in processed garlic was evaluated. LFS converts 1-propenesulphenic acid to the volatile lachrymatory factor (LF). We hypothesised that this conversion would decrease the production of 2-Pe/1-Pe thiosulphinates, and thus, would reduce the subsequent discolouration of the garlic. Cooked onion powder added to fresh garlic, which was equivalent to adding crude 1-PeCSO, resulted in intensified green discolouration and increased 2-Pe/1-Pe thiosulphinate levels. On the other hand, fresh onion powder added to fresh garlic (0.5 g powder to 100 g fresh garlic) prevented greening and decreased the 2-Pe/1-Pe thiosulphinate levels. Similarly, a crude onion enzyme solution prevented greening in a garlic homogenate. The 2-propenyl 2-propenyl thiosulphinate (allicin) content was inconsistently altered by the addition of onion powder. However, the expected production of LF by the fresh onion powder or enzyme solution was not detected by gas chromatography, possibly due to changes in the sample matrix. This method using fresh onion powder is an effective technique for preventing greening of fresh garlic that does not use artificial food additives or cause safety concerns.     

大蒜绿变物质提取及其分离纯化方法的初步研究

研究了提取及分离纯化大蒜绿变物质的方法。结果表明,浓度为80%的甲醇溶液,按料液比1∶3,室温浸提24h,提取效果最好;利用薄层层析法进行色素的分离纯化,确定展层剂为含77%甲醇,3%乙酸乙酯,0.24%HCl的水溶液,最终能达到初步分离纯化的目的。     

蒜泥变绿变褐的原因及控制方法

本试验对蒜泥加工中变绿、变褐的原因及控制方法进行了研究。大蒜破碎后立即变绿、变褐。通过热处理（８０～８５℃，２～４分钟）能钝化蒜酶，防止氨基酸亚矾水解生成ＰＥＣＳＯ（绿色物质）。此外，热处理和焦亚硫酸钠（＞０３％）处理能有效地抑制大蒜酶褐变     

Effect on garlic greening and thermal stability of 1-(2′-hydroxybenzene-1′-carboxy-ethyl) pyrrole

1-(2′-Hydroxybenzene-1′-carboxy-ethyl) pyrrole (P-Tyr) was synthesized to study its effect on garlic greening. The puree of freshly harvested garlic bulbs turned green after being soaked in solutions of P-Tyr, and with increasing concentration, the green color of the puree became deeper. The thermal stability of P-Tyr was studied by differential scanning calorimetry. Thermodynamic analysis showed that the conversion of P-Tyr followed an Arrhenius relationship, where the delta enthalpy (H) and activation energy (Ea) were 399.102 J/g and 82.137 ± 3.243 kJ/mol, respectively. Furthermore, the relationships between the degree of conversion of P-Tyr and time or temperature were reported. This study demonstrated that the evaluated P-Tyr is stable over a wide range of temperatures and time.     

Isolation and identification of one kind of yellow pigments from model reaction systems related to garlic greening

It was established that green pigment(s) responsible for garlic greening is composed of yellow and blue species, and pyruvic acid (a product from 1-PeCSO or 2-PeCSO under the action of alliinase) reacted with pigment precursor (PP) model compounds, 2-(1H-pyrrolyl) carboxylic acids to produce yellow pigments. However, the structure of the yellow pigments is unknown. In present paper, we identified three yellow pigments (Y1, Y2 and Y3) from three reaction systems containing pyruvic acid and 2-(1H-pyrrolyl) acetic acid (P-Gly) or 1-(2′-methyl-1′-carboxy-propyl) pyrrole (P-Val) or 1-(2′-methyl-1′-carboxy-butyl) pyrrole (P-Ile), respectively, by LC-ESI MS/MS and IT-TOF mass spectrometry. The three pigments have a UV/visible maximum absorbance between 400 and 434 nm and might be formed by dimerisation of the three corresponding PP under participation of pyruvic acid, molecular formula of which are C₁₆H₁₆N₂O₄ (Y1), C₂₂H₂₈N₂O₄ (Y2) and C₂₄H₃₂N₂O₄ (Y3), respectively.