云南大叶种茶树夏秋季鲜叶加工γ- 氨基丁酸白茶的工艺优化

以云南大叶种茶树（Camellia sinensis var.assamica）夏秋季鲜叶为原料,加工富含γ-氨基丁酸（γ-aminobutyric acid,GABA）且风味好的白茶,以期促进夏秋茶资源的高值利用。应用爬坡试验与响应面设计优化茶鲜叶厌氧处理的温度与时间,厌氧处理后,烘干制备白茶,采用高效液相色谱法、比色法等测定茶叶GABA 等化学成分含量。结果显示,GABA 白茶的最优加工工艺为茶鲜叶萎凋8 h 后,34 ℃厌氧处理20 h,50 ℃烘干。该条件制作的白茶GABA 含量为1.52 mg/g,具有汤色橙黄、滋味甜醇、甜香带果香的风味特征。与对照比较,经厌氧处理后,白茶中GABA 与水浸出物含量极显著增加（p<0.01）,茶多酚、儿茶素、咖啡碱、游离氨基酸的含量均降低。     

真空厌氧间歇技术富集福鼎大白茶茶鲜叶GABA的参数优化

选择福鼎大白茶鲜叶为材料,以γ-氨基丁酸(GABA)为评价指标,采用连续真空厌氧处理技术、真空厌氧间歇处理技术进行GABA的富集,通过单因素实验法和正交实验法优化GABA富集工艺。结果表明:兼顾GABA含量和茶叶感官品质,采取一次真空厌氧间歇技术富集GABA的效果最佳。即鲜叶等级为一芽二叶,真空度0.09 MPa,富集温度4 ℃,厌氧时间6 h(真空厌氧3 h→有氧2 h→真空厌氧3 h)。但考虑到技术的应用性和经济性,在其他条件不变的情况下,富集温度采用26 ℃条件下进行富集处理,其茶叶GABA含量达192.79 mg/100 g,氨基酸、茶多酚分别可达4.21%、15.80%,感官品质优异。     

真空及外源谷氨酸钠处理对茶叶中γ-氨基丁酸富集作用研究

研究不同时间及不同谷氨酸钠浓度处理对茶鲜叶富集GABA效果的影响.结果表明:经厌氧处理8 h后,茶叶中GABA含量达1.325 mg/g,为未处理茶叶的6.7倍;先经2.5%谷氨酸钠浸泡4 h后,再厌氧处理8 h,茶叶中GABA得到进一步富集,其含量高达2.501 mg/g,是未经处理茶叶的12.6倍.     

脱氧剂厌氧处理对茶鲜叶γ-氨基丁酸富集的影响

采用脱氧剂对茶鲜叶进行厌氧处理,分析脱氧剂处理中气体成分、GABA代谢相关酶活力和氨基酸含量的变化,研究脱氧剂厌氧处理对茶鲜叶GABA富集的影响。试验结果表明,脱氧剂厌氧处理中茶鲜叶维持在低氧、高二氧化碳的气体环境中,GABA含量3 h时达到最高值1.22 mg/g,显著高于真空处理的1.05 mg/g(P0.05);茶鲜叶经过脱氧剂厌氧/好氧处理后,GABA合成酶谷氨酸脱羧酶(GAD)、二胺氧化酶(DAO)和多胺氧化酶(PAO)被激活,分解酶GABA转氨酶(GABA-T)被抑制,其中GAD活力显著高于真空厌氧/好氧处理(P0.05),其它酶与真空厌氧/好氧处理无显著差异(P0.05),GABA含量最高达到1.75 mg/g,高于真空处理的1.51mg/g。可见,脱氧剂厌氧对GABA的富集能力优于真空处理。     

无性系良种与地方群体种晒青茶品质比较

本研究选取了两个比较有代表性的云南大叶种无性系良种和一个云南大叶种地方群体种作为试验对象,对制成的晒青茶进行综合品质的比较,结果表明,云南大叶种无性系良种制成的晒青茶品质优异,也是普洱茶加工的首选原料。     

叶面肥喷施对茶叶中GABA含量的影响

采用谷氨酸钠、CaCl2和V B6三种叶面肥喷施茶树,调查三种叶面肥喷施对茶鲜叶和产品红茶中GABA含量的影响。结果表明,三种叶面肥均可显著提高茶鲜叶中GABA含量,在浓度分别为5、5、0.3 g/L时,茶鲜叶中GABA含量最高分别为0.77、0.51、0.48 mg/g,制成的产品红茶中GABA含量显著降低至0.45、0.1、0.08 mg/g。说明三种叶面肥喷施均可促进茶叶中GABA的富集,而红茶加工工序可造成GABA大量损失。     

厌氧胁迫对发芽糙米中γ-氨基丁酸含量变化的影响

以籼稻"扬两优6号"为材料,利用CO2和N2在糙米萌发不同阶段制造厌氧环境,研究不同气体种类的厌氧胁迫及处理时间对发芽糙米中GABA积累的影响,探讨促进发芽糙米中GABA积累的适宜工艺。结果表明,CO2和N2厌氧处理时段以及持续时间均对发芽糙米中的GABA含量有显著影响(P0.05)。在发芽前期进行厌氧处理一般会抑制GABA的积累,在发芽中后期,尤其是在发芽60~72 h时段则起显著促进作用(P0.05),且CO2的促进效果明显优于N2(P0.05)。发芽0~12 h期间进行厌氧处理会抑制GAD活力(P0.05),在发芽24~72 h期间则可以显著提高GAD活力(P0.05)。糙米在发芽66~72 h期间进行CO2厌氧环境处理,在72 h时发芽糙米中GABA含量为(965.44±29.35)mg/100 g(干基),显著高于其他时段处理后的含量,且比未经过厌氧处理的发芽糙米高出460.13 mg/100 g(干基)。     

富含γ-氨基丁酸(GABA)玉米胚芽的应用及其GABA提取的研究

分析经富集处理的玉米胚芽的氨基酸组成和含量,摸索了正己烷脱油的适宜条件,并采用超声波法对其中的γ-氨基丁酸(GABA)的提取条件进行了研究,还利用玉米胚芽进行了面包制作应用试验.分析结果显示:玉米胚芽中含有18种以上氨基酸,GABA的干基含量为286.8 mg/100 g,约占被测氨基酸总量的4.9%.结果表明:脱油的适宜条件为试料:正己烷=1:4;最佳提取条件为温度50℃,时间2h,料液比1:6,平均提取量为163.5mg/100 g,约占玉米胚芽GABA总含量(271.1 mg/100g)的60.3%.经富集处理的玉米胚芽适于制作面包、蛋糕等焙烤制品,其中所含的GABA对热加工较为稳定.     

云南双江4个山头晒青茶品质比较分析

目的 探究云南双江4个山头(冰岛、小户赛、坝糯、荒山)春、夏、秋季晒青茶品质特征差异。方法 利用高效液相色谱法(high performance liquid chromatography, HPLC)测定儿茶素含量、茚三酮比色法测定氨基酸含量, 紫外分光光度法测定咖啡碱含量等, 并结合感官评价对4个山头茶叶品质差异进行比较分析。结果 4个山头同一季节、同一山头不同季节茶叶品质差异显著。冰岛三季的总儿茶素含量整体较高, 其中春茶儿茶素总量最高, 为21.39 mg/g。荒山秋茶儿茶素含量最低, 为16.00 mg/g。冰岛三季水浸出物、茶多酚、氨基酸和咖啡碱整体都处于高水平, 均值分别为44.97%、29.45%、3.56%和3.88%。内含成分差异使得不同的山头茶感官品质明显不同, 冰岛的晒青茶甜醇回甘; 小户赛的晒青茶浓强回甘; 坝糯的晒青茶浓厚强烈, 微涩; 荒山的晒青茶醇厚, 微涩。结论 冰岛是制作晒青茶的优质产区。除冰岛整体表现优异外, 其余3个山头的样品表现也较为优异, 说明双江县生产的晒青茶是加工普洱茶的优质原料。     

不同来源辣木叶中γ-氨基丁酸含量的比较

该研究旨在比较不同来源辣木叶中γ-氨基丁酸的含量,为辣木深加工产品开发及其保健功效机理研究提供理论参考。利用高效液相色谱法(HPLC)对12个辣木叶样品中的γ-氨基丁酸(GABA)的含量进行测定。结果表明,不同来源辣木叶中GABA含量差异很大,含量最高的是源于印度的辣木叶,GABA含量达371.92 mg/100 g,最低的为源于临沧的辣木叶,含量为126.16 mg/100 g;辣木叶中GABA含量一般为200～300 mg/100 g。     

Sequential hydration with anaerobic and heat treatment increases GABA (γ-aminobutyric acid) content in wheat

γ-Aminobutyric acid (GABA), which displays anti-hypertensive and diuretic effects, is known to be produced in germinated wheat. The effect of sequential hydration combined with anaerobic and heat treatment on the GABA content in wheat was investigated. The GABA content in soft white winter (SWW) and dark northern spring (DNS) wheat was 0.80 and 1.18 mg/100 g, respectively. Both the anaerobic and the heat treatment contributed to the increase of GABA in SWW and DNS wheat. The GABA contents in SWW and DNS wheat was increased by germination for 48 h after sequential hydration with anaerobic and heat treatment at a target moisture content of 35% to 45.65 and 47.40 mg/100 g, respectively. Our results suggest that combined anaerobic and heat treatment after sequential hydration may be used for the preparation of wheat with high GABA content, which can then be used as a natural resource of functional foods.     

厌氧处理对黄茶生物活性的影响及γ-氨基丁酸富集的代谢组学分析

以黄茶为研究对象，探究厌氧处理对茶叶中γ-氨基丁酸（γ-aminobutyric acid,GABA）以及其他活性成分的含量和功能的影响，并利用代谢组学分析厌氧过程促进黄茶富集GABA的机理和代谢途径变化。结果表明，厌氧处理后黄茶中的GABA含量升至3.3 mg/g，且其上下游氨基酸的含量发生了相应变化。同时，厌氧处理后黄茶中的总酚和总黄酮含量均有显著提升。体外抗氧化、抗糖基化和降糖活性分析发现，厌氧处理提高了黄茶的自由基清除能力、总抗氧化能力和抑制糖基化产物形成的能力，但对其抑制淀粉消化酶活性的能力影响较小。经代谢组学分析共筛选出218种差异代谢物，包括氨基酸类、有机酸、类黄酮、类核苷酸和糖类等。经通路富集分析，发现受显著调控的通路包括氨基酸的生物合成代谢、色氨酸代谢、类黄酮生物代谢和丁酸代谢等。厌氧处理通过影响L-谷氨酸和琥珀酸半醛途径调控GABA含量。本研究可为GABA富集茶的研究和开发提供参考。     

Effects of steeping and anaerobic treatment on GABA (γ-aminobutyric acid) content in germinated waxy hull-less barley

Effects of steeping conditions (time, temperature and soaking solution) and anaerobic storage on the gamma-aminobutyric acid (GABA) content in waxy hull-less barley grains during germination was examined. The barley kernel was steeped for 16 h at different temperatures (5, 15 or 35 °C) either in water or in a buffer solution (pH 6.0, 50 mmol/L sodium acetate) and then germinated at 15 °C for 72 h. To reach the optimum water content (36–44 g/100 g) for germination, a longer steeping period was required when steeping temperature was lower (16 h at 5 °C vs. 8 h at 15 °C). At 35 °C for steeping, however, the water content in the grains increased excessively, and thus germination percentage became much less than those at 5 and 15 °C. The GABA content increased with increasing germination time and was higher in the buffer solution than water. These findings indicate that the glutamate decarboxylase (GAD), which is the rate-limiting enzyme for GABA synthesis, is more activated by extending germination at controlled pH (6.0). An anaerobic storage with nitrogen in the dark for the germinated barley grains substantially raised the GABA content: 14.3 mg/100 g after the treatment for 12 h, which was four times higher than that of control sample (3.7 mg/100 g). Overall results suggest that the steeping prior to germination greatly affects the GABA production during the germination of barley, and the anoxia storage with nitrogen after the germination increases the GABA content.     

Optimal soaking conditions and addition of exogenous substances improve accumulation of γ-aminobutyric acid (GABA) in germinated mung bean (Vigna radiata)

Germinated mung beans have been widely used as fresh vegetable or processed healthy food due to their high amounts of bioactive and nutritional compounds, including γ-aminobutyric acid (GABA). The objectives of this study were to investigate the effects of different soaking conditions (temperature, ratios of seeds to water, soaking time, pH, addition of L-glutamic acid (L-Glu) or gibberellic acid (GA3)) and germination time on accumulation of GABA in the germinated mung bean seeds. The mung bean seeds, soaked at 40°C for 4 h with ratio of seeds to water of 1:4 (g mL⁻¹) and then germinated for 7 h, accumulated higher amount of GABA than other soaking conditions and germination time. The addition of GA3 (0.30 mg L⁻¹) or L-glu (1,000 mg L⁻¹) or acidifying to pH 5.5 of the soaking water had high impact on the GABA accumulation. Among them, the soaking water with pH 5.5 was more effective than adding with the L-Glu or GA3 in the production of GABA (1677 mg/kg powder) and essential amino acids (16.56 g/100g powder) in the germinated mung bean seeds. The findings of this study provide useful information to produce GABA-enriched and healthy foods from mung beans.     

两步酶法生产γ-氨基丁酸的研究

提出两步酶法(包括发芽和均相反应2个阶段)生产γ-氨基丁酸(GABA)的新方法。以大豆为原料,采用两步酶法生产GABA,讨论了Ca2+对大豆发芽和均相反应过程中蛋白酶和谷氨酸脱羧酶活力,以及谷氨酸游离和GABA生成的影响。实验结果表明,不同浓度的Ca2+对这两种酶分别表现出激活和抑制作用。在发芽过程中,蛋白酶和谷氨酸脱羧酶的活力,以及GABA和游离谷氨酸的含量随发芽时间呈先上升后下降的趋势。在浸泡液CaCl2浓度3.0mmol/L、发芽时间60h的条件下,发芽大豆中GABA和游离谷氨酸的含量分别为111.9mg/(100g干物大豆)、224.8mg/(100g干物大豆)。在均相反应过程中,GABA和游离谷氨酸的含量增加。在固体含量20g/100mL、反应时间2h的条件下,游离谷氨酸含量在料液CaCl2浓度为1.0mmol/L时达到最大值369.9mg/(100g干物大豆),GABA含量在CaCl2浓度为3.0mmol/L时达到最大值316.1mg/(100g干物大豆)。采用两步酶法可充分发挥大豆内源酶的活力,生产出游离谷氨酸和GABA含量都较高的食品材料。     

超高压处理对发芽糙米酒中γ-氨基丁酸及挥发性成分的影响

以发芽糙米为原料酿造米酒,对发芽温度、发芽时间、超高压处理压力、超高压处理时间进行单因素实验,考察不同条件下酒中γ-氨基丁酸(γ-aminobutyric acid,GABA)含量,并对米酒成品采用顶空固相微萃取(HS-SPME)结合气相色谱质谱联用(GC/MS)技术检测发芽糙米酒中的挥发性成分。结果显示,发芽条件为温度28℃、时间20 h,获得的发芽糙米GABA含量较高,为346.7 μg/g。发酵后获得的发芽糙米酒GABA含量为24.7 mg/L。在超高压处理压力200 MPa、超高压处理时间30 min,获得的糙米酒成品GABA含量较高,达到27.4 mg/L。在200 MPa处理后的发芽糙米酒中共检测出醇类12种,酯类20种,酮类5种,酸类1种。相较于未经超高压处理的发芽糙米酒,超高压处理后的发芽糙米酒中酯类种类增加,醇类含量减少,酸类含量减少。通过感官评价,发现200和300 MPa处理的样品均优于未处理组,说明加压处理提高了发芽糙米酒的滋味,大大提高了米酒的风味品质。     

Survey of the furosine content in cheeses marketed in Spain

The furosine content in 53 samples of different cheese types (fresh, ripened with molds, artisanal hard-pressed, industrial hard-pressed, and processed) marketed in Spain was analyzed. The lowest furosine values were observed in artisanal hard-pressed cheeses (4.8 to 10.2 mg per 100 g of protein) and ripened with molds cheeses (4.2 to 12.8 mg per 100 g of protein). Industrial hard-pressed cheeses showed furosine values between 3.5 and 43.8 mg per 100 g of protein. Differences between samples may be attributed to the heat-treatment intensity given to cheese milk and to cheesemaking conditions. The highest contents of furosine were observed in processed cheeses (20 to 366.6 mg per 100 g of protein). A wide range of furosine content was found in fresh cheeses (17.9 to 73.6 mg per 100 g of protein), which could be due to the different amounts of dried milk added during the manufacture of cheeses.