Characterization of the Formation of Branched Short-Chain Fatty Acid：CoAs for Bitter Acid Biosynthesis in Hop Glandular Trichomes

Bitter acids, known for their use as beer flavoring and for their diverse biological activities, are predominantly formed in hop （Humulus lupulus） glandular trichomes. Branched short-chain acyI-CoAs （e.g. isobutyryI-CoA, isovaleryl- CoA and 2-methylbutyryI-CoA）, derived from the degradation of branched-chain amino acids （BCAAs）, are essential building blocks for the biosynthesis of bitter acids in hops. However, little is known regarding what components are needed to produce and maintain the pool of branched short-chain acyI-CoAs in hop trichomes. Here, we present several lines of evidence that both CoA ligases and thioesterases are likely involved in bitter acid biosynthesis. Recombinant HICCL2 （carboxyl CoA ligase） protein had high specific activity for isovaleric acid as a substrate （Kcat/Km = 4100 s-~ M-l）, whereas recombinant HICCL4 specifically utilized isobutyric acid （Kcat/Km = 1800 s-1 M-1） and 2-methylbutyric acid （Kcat/ Km = 6900 s-1 M-~） as substrates. Both HICCLs, like hop valerophenone synthase （HIVPS）, were expressed strongly in glandular trichomes and localized to the cytoplasm. Co-expression of HICCL2 and HICCL4 with HIVPS in yeast led to significant production of acylphloroglucinols （the direct precursors for bitter acid biosynthesis）, which further confirmed the biochemical function of these two HICCLs in vivo. Functional identification of a thioesterase that catalyzed the reverse reaction of CCLs in mitochondria, together with the comprehensive analysis of genes involved BCAA catabolism, supported the idea that cytosolic CoA ligases are required for linking BCAA degradation and bitter acid biosynthesis in glandular trichomes. The evolution and other possible physiological roles of branched short-chain fatty acid：CoA ligases in planta are also discussed.

Inhibitory Effect of 5-Adenylic Acid on Bitter Taste of Antipsychotic Drugs

The purpose of the present study was to examine the effect of adenylic acid (adenosine 5-monophosphate;AMP), a known nutritional enhancer, on inhibiting the bitterness of antipsychotic medicines administered to patients with mental illnesses, including children. First, we chose four antipsychotic medicines, amitriptyline hydrochloride (AMT), chlorpromazine hydrochloride (CPZ), haloperidol (HPD) and risperidone (RIS) and evaluated the inhibition of their bitterness by AMP through taste sensor measurements. AMP showed a significant bitterness inhibition effect on all drugs. Second, MarvinSketch analysis revealed the potential formation of electrostatic interactions between ionic forms (IV) of AMP and ionic (cationic) forms of each drug, which resulted in bitterness suppression. Third, chemical shift perturbations in 1H-NMR studies suggested an interaction between the phosphate group of AMP and amino group of AMT, CPZ, HPD and RIS. Last, conventional elution experiments of up to 1 min simulating oral cavity conditions were performed for 1 whole AMT tablet, half AMT tablet, crushed half AMT tablet, and crushed AMT tablet containing AMP powder/solution (1, 3 mM potency). The taste sensor output values of the crushed AMT tablet containing AMP powder/solution (1, 3 mM potency) were significantly lower than those of the crushed tablet.

Bitter Melon (Momordica Charantia) Reduces Serum Sialic Acid in Type2 Diabetics: Evidence to Delay the Process of Atherosclerosis

More than 1000 herbal products have been used by diverse cultures of the world to treat hyperglycemia and among them bitter melon (Momordica charantia) is one of the most popular herbal resource. The beneficial effects of bitter melon is not limited to hypoglycaemia only, but it also ameliorates diet induced obesity, insulin resistance and exhibit cardioprotective effects. The present study attempts to investigate the effect of bitter melon fruit juice on a newly investigated risk factor, sialic acid in type2 diabetics. A total of 40 type2 diabetic patients, divided into group A (n = 20) and group B (n = 20) were investigated during the present study. The patients of group A were following bitter melon fruit juice treatment along with diet control, whereas the patients of group B were on diet control only. Serum sialic acid (SSA) decreased in group A from 66.20 ± 2.30 mg/dl to 63.50 ± 2.10 mg/dl (<0.11) but, increased in group B from 66.50 ± 1.70 mg/dl to 68.20 ± 2.50 mg/dl (<0.12), compared to baseline. Post-treatment between group comparison revealed a significant difference (<0.05). The beneficial effects on fasting plasma glucose (FPG) and glycohemoglobin (HbA1-c) were also greater in group A compared to group B as was the case with blood lipids, weight and blood pressure. The study provides another mechanism for the cardioprotective effect of bitter melon and further strengthens its value in the management of type2 diabetes.

水杨酸对盐胁迫下苦瓜种子萌发及幼苗生长的影响

为探究水杨酸(SA)对苦瓜盐害的缓解作用,以苦瓜品种良苦1号为试材,采用拌种和叶面喷施的方法,研究不同浓度(0.001、0.01、0.1、1.0 mmol·L^(-1))SA处理对150 mmol·L^(-1) NaCl胁迫下苦瓜种子萌发和幼苗生长的影响。结果表明,0.01 mmol·L^(-1) SA处理显著提高了盐胁迫下苦瓜种子的发芽率、发芽势、发芽指数、活力指数及幼苗的株高、叶面积、根长、鲜质量、干质量。0.1 mmol·L^(-1)SA处理显著提高了苦瓜种子的发芽率、发芽势及幼苗的叶面积、鲜质量、干质量,对种子的发芽指数、活力指数及幼苗的株高、根长无显著影响。0.01 mmol·L^(-1) SA处理显著提高了苦瓜幼苗抗氧化酶(SOD、POD、CAT)的活性及脯氨酸、可溶性糖的含量,显著降低了丙二醛的含量。0.1 mmol·L^(-1)SA处理显著提高了苦瓜幼苗POD的活性及脯氨酸、可溶性糖的含量,对SOD、CAT的活性及丙二醛的含量无显著影响。综上,施用一定浓度外源SA对苦瓜盐害具有缓解作用,0.01 mmol·L^(-1)SA处理是缓解苦瓜盐害的最佳方案。

小孢粉孢牛肝菌营养成分及化学成分分析与评价

小孢粉孢牛肝菌(Tylopilus microsporus)属牛肝菌科真菌,来源于云南省曲靖市陆良县。对该菌营养成分的研究结果表明其营养成分含量丰富,主要营养成分(g/100 g)为:粗蛋白29.9,粗多糖3.68,必需氨基酸11.18,总氨基酸23.80;必需氨基酸对非必需氨基酸指数(E/N)为0.89,必需氨基酸对总氨基酸(E/E+N)为46.97%。总必需氨基酸达到FAO/WHO标准模式,营养成分均衡;EAAI值(必需氨基酸指数)为1.05。其矿物质营养成分主要包括Ca、K、Mg、P、Fe、Cu、Mu、Se等,特别是K含量较高。从该菌中鉴定出949个代谢物,其中有798个代谢物包括10个超类匹配到人类代谢数据库中,且具有多个含量较高的活性代谢物。小孢粉孢牛肝菌(Tylopilus microsporus)为高蛋白质、低含糖量的野生牛肝菌,其氨基酸含量高且种类相对齐全,同时苦味氨基酸和钾含量为新型牛肝菌的苦味研究及开发利用提供了重要依据。

苦味抑制剂阿魏酸的构效关系

探索阿魏酸(ferulic acid,FA)羧基取代基团以及丙烯酸碳链长度对苦味抑制作用的影响。本实验使用分子动力学模拟,分析苦味受体与苦味抑制剂FA、4-(2,2,3-三甲基环戊基)丁酸和苦味激活剂安赛蜜相互作用的构象差异,以获得FA对苦味受体的抑制结构F4。基于F4的相互作用模式,构建系列FA衍生物,结合电子舌分析技术,探讨FA苦味抑制构效关系。结果表明在配体与F4相互作用模式相符的前提下,FA羧基取代基团氢键受体的电荷量与苦味抑制强度呈反比;FA丙烯酸碳链长度改性为二碳长度,会导致配体与关键残基相互作用不稳定,导致其苦味抑制强度降低,改性为四碳长度则增强其苦味抑制强度。FA作为新型苦味抑制剂,在改善食品食用品质方面具有开发潜力。

发酵芒果皮乳酸菌的筛选

芒果皮中存在的苦涩味物质限制芒果皮的食品化利用。该文以芒果皮为原料,采用感官评价法对59株乳酸菌发酵48 h的芒果皮清汁进行分析并初筛乳酸菌,并研究初筛得到的5株菌株发酵过程中对芒果皮清汁总酚含量、总黄酮含量、抗氧化活性和风味特征的影响。结果显示,乳酸菌发酵后芒果皮清汁总酸含量显著增加、pH值明显降低、总酚含量明显降低;电子舌分析结果也表明乳酸菌发酵可以减弱芒果皮清汁的苦味和涩味;其中HGP54菌株改善芒果皮滋味效果最好,感官模糊评分最高,提高13.47%,苦味与涩味量化得分均降低。相关性分析表明,苦味与涩味与总酚含量之间存在显著中等正相关关系。该研究结果表明,筛出的乳酸菌菌株能够有效地改善芒果皮清汁品质,可作为芒果皮工业化微生物制剂进一步开发利用。

Preparation and Evaluation of Poly-γ-Glutamic Acid Hydrogel Mixtures with Basic Drugs or Acidic Drugs: Effect on Ease of Swallowing and Taste Masking

The purpose of this study was to prepare a poly-γ-glutamic acid hydrogel (PGA gel), to examine its ease of swallowing using texture profile analysis (TPA) and to evaluate its taste-masking effects on basic or acidic drugs using the artificial taste sensor. Using TPA, 0.5% and 1.0% PGA gels, 0.5% and 1.0% agar and 1.0% ι-carrageenan in the absence of drug was examined the hardness, adhesiveness and cohesiveness, ranked according to permission criteria published by the Japanese Consumers Affairs Agency. 0.5% PGA gel and 1.0% agar were classified into grade II. In the taste sensor measurement, the bitterness suppressions by 0.5% PGA gel were larger than that by 1.0% agar in all drugs and the bitterness suppressions of basic drugs in 0.5% PGA gel were more potent than those of acidic drugs in 0.5% PGA gel. 1H-nuclear magnetic resonance spectroscopic analysis was carried out to examine the difference in mechanism of bitterness suppression between basic drugs and acidic drugs mixed with PGA gel. The signals of the proton nearest to the nitrogen atom of basic drugs shifted clearly upfield, suggesting an interaction between the amino group of basic drugs and the carboxyl group of PGA gel. In conclusion, PGA gel is expected to be a useful excipient in formulations contained various drugs, especially basic drugs;it also has advantage for not only increasing ease of swallowing but also masking the bitterness of drugs even though a small amount of a single drug dose might be preferred.

阿魏酸苯环取代衍生物改良支链氨基酸苦味味觉的研究

目的:探索阿魏酸苯环3位上的基团变化对支链氨基酸苦味的抑制效果及呈味特性。方法:通过化学合成阿魏酸及其苯环取代衍生物,经傅里叶红外光谱、核磁共振氢谱和质谱结构鉴定,使用电子舌测试阿魏酸及其衍生物对支链氨基酸的苦味改良效果,包括:苦味抑制率、自身风味以及对其他味道的影响。结果:阿魏酸及其苯环取代衍生物分子对支链氨基酸均表现出一定的苦味抑制效果,除A_(4)(—F)衍生物分子对缬氨酸的苦味抑制效果与阿魏酸(—OCH_(3))接近,在不同的添加量下阿魏酸的苦味抑制效果均优于其他衍生物。结论:分子基团的大小和电负性强弱可能是影响苦味抑制效果的关键因素,阿魏酸苯环上3号位的—OCH_(3)对苦味抑制效果最优。

呈苦味三羟基十八烯酸UPLC-HRMS测定方法优化及其在白酒检测中的应用

为分析白酒中呈苦味三羟基十八烯酸成分的含量,优化超高效液相色谱-高分辨率质谱测定方法。样品经直接稀释过膜后上机分析,结果显示,选择乙腈为有机相,0.1%甲酸溶液为水相,流速0.3 mL/min,进样量2μL,在Hypersic Gold色谱柱(100 mm×2.1 mm,1.9μm)经梯度洗脱程序下可有效分离待测物,同时对比二级子离子与Mass Frontier 8.0软件理论模拟待测物分子离子碎裂子离子结构图可实现定性分析,有效避免样品假阳性结果的出现,故该方法具有前处理简单、分析速度快、检出限低(0.2 ng/mL)、准确度高等优点,可实现白酒样品的检测需求;利用该方法研究酱香型白酒生产过程中呈苦味三羟基十八烯酸的含量变化,结果发现随着发酵时间的延长,酿酒原料中大量的亚油酸可能被氧化分解为三羟基十八烯酸,进而随蒸馏迁移入基酒;不同贮存时间基酒中呈苦味三羟基十八烯酸含量并无明显的变化规律,表明贮存时间对其含量影响不大;酱香型白酒3个典型体以酱香典型体基酒中呈苦味三羟基十八烯酸含量较低,可用于后续包装产品的主体基酒之一。

7种苦味竹笋蛋白质营养品质差异分析

为了探究撑篙竹Bambusa pervariabilis笋、牛角竹Bambusa cornigera笋、大叶慈Dendrocalamus farinosus笋、硬头黄竹Bambusa rigida笋、料慈竹Bambusa distegia笋、慈竹Neosinocalamus affinis笋和佯黄竹Bambusa changningensis笋7种苦味竹笋之间蛋白质营养品质的差异,对其蛋白质含量和16种游离氨基酸含量进行了测定,并对反映其蛋白质营养价值的氨基酸评分(AAS)、氨基酸化学评分(CS)、比值系数(RC)和比值系数分(SRC)进行了比较。结果表明,7种苦味竹笋的蛋白质含量在1.56~2.46 g·100 g^(-1),其中慈竹笋的蛋白质含量最高,为2.46 g·100 g^(-1);7种苦味竹笋的氨基酸总量在1 164.33~1 722.67 mg·100 g^(-1),亮氨酸是7种苦味竹笋中含量最高的必需氨基酸,天冬氨酸是7种苦味竹笋中含量最高的非必需氨基酸;在蛋白质营养价值方面,参考AAS和CS,慈竹笋的营养价值相对其他几种竹笋要好,具有很高的开发价值,但是结合RC、SRC和EAA/TAA值分析,硬头黄竹笋的必需氨基酸组成较其他几个品种更加合理,可以对其充分利用。以上研究结果为苦味竹笋在食品工业中的科学开发和应用提供了理论基础。

喷施5-氨基乙酰丙酸与调环酸钙对‘秦脆’苹果苦痘病的预防效果

【目的】‘秦脆’是‘蜜脆’的杂交后代,生产上经常观察到苦痘病发生,给生产带来影响,病害严重时会使果品的商品率下降,进而造成较大的经济损失,为此开展该试验探究预防苦痘病适宜的植物生长调节剂。【方法】对‘秦脆’苹果喷施不同浓度的5-氨基乙酰丙酸(5-ALA)与250 mg/L调环酸钙进行试验,研究分析对秦脆苹果苦痘病的预防效果。【结果】试验结果发现5-ALA与调环酸钙配合喷施对秦脆苹果苦痘病发生有一定的预防控制效果。喷施4次100 mg/L的5-ALA与7月下旬喷施1次250 mg/L调环酸钙相结合处理后发病率为5.5%,与对照相比,发病率降低了56%。且喷施100 mg/L的5-ALA能够提高果树光合作用与蒸腾作用。【结论】综合分析表明,5-氨基乙酰丙酸与调环酸钙配合喷施对‘秦脆’苹果苦痘病有一定的预防效果,建议在生产上示范。

一株适用于苦荞米发酵的红曲霉菌株分离与筛选

目的筛选一株适用于苦荞米发酵的红曲霉菌株。方法从豆腐乳、红曲米分离筛选鉴定红曲霉菌株22株,优选长势较快的5株菌株,编号为MZ1、MZ7、MZ18、MZ20和MZ23。综合考察发酵后样品中红曲色价、总黄酮、洛伐他汀、γ-氨基丁酸以及桔青霉素的含量,根据发酵后样品中较高含量的红曲色价、总黄酮、洛伐他汀、γ-氨基丁酸以及较低含量的桔青霉素,筛选适用于苦荞米发酵的最佳红曲霉菌株。结果实验数据表明红曲霉菌株MZ20发酵后样品的红曲色价、总黄酮和洛伐他汀含量均最高;其中总黄酮含量为29.03±4.39mg/g,是发酵前的4.47倍;洛伐他汀含量为0.52±0.04μg/g;γ-氨基丁酸含量为135.89±7.22μg/g;桔青霉素含量均不高于40μg/kg。结论成功分离并筛选红曲霉菌株MZ20作为苦荞米的发酵菌株。

啤酒花抗性机制的研究进展

酒花苦味酸是构成啤酒风味的重要组分,也是啤酒生产过程中的天然抑菌剂,酒花苦味酸通过降低pH梯度而抑制啤酒花敏感菌生长。研究发现,啤酒花抗性菌是通过膜上转运蛋白将酒花苦味酸泵出细胞外,以降低膜上的质子流速,维持了细胞内的pH梯度。结合近年来酒花抗性相关研究结果,讨论了细胞膜上酒花抗性相关组分与酒花抗性间的关系,提出了酒花抗性机制的模型。

感官评定方法确定麻竹笋苦涩味物质成分及与口感的关系

通过分析测定麻竹笋苦涩味物质含量与感官评定方法确定竹笋苦涩味物质成分及与口感的关系。麻竹鲜笋在100℃纯净水中分别进行0、30、90、150 s和420 s 5个时间梯度水煮处理,并测定煮后笋汤、笋渣的可溶性单宁、草酸和游离苦味氨基酸(Phe、Val、Arg、Met和Leu)含量,感官评定小组对其涩味、苦味强度评定,并通过对食品级草酸、单宁标准样品配制的不同质量浓度溶液进行苦涩味感官评定,建立单宁、草酸、单宁和草酸混合液的质量浓度与滋味强度的特征曲线函数。结果表明,影响麻竹笋苦涩味的主要物质是可溶性单宁,竹笋苦味和涩味均与单宁含量呈极显著关系,相关系数分别达0.896和0.867;竹笋涩味与草酸含量呈显著关系,相关系数为0.448,而竹笋苦味与草酸含量无显著关系;竹笋苦涩味与游离苦味氨基酸含量均无显著关系。利用单宁特征曲线函数对竹笋苦涩味偏重的成因进行了分析,对9个笋渣、笋汤的分析结果表明,单宁特征曲线函数对竹笋涩味的解释程度达60.6%~136.4%,对竹笋苦味的解释程度达63.4%~132.0%,较高的可溶性单宁含量是引起麻竹笋苦涩味偏重的主要原因。

苦杏仁化学成分的研究

对陕西永寿县苦杏仁中苦杏仁甙、脂肪、纤维素、蛋白质、糖类、油脂的含量及理化性质,脂肪酸和氨基酸组成,多种微量元素和维生素含量进行了较为系统的分析测定,并与甘肃镇原、内蒙古赤峰、山西晋南和太原等地的苦杏仁成分进行了对比。结果表明,苦杏仁中含有丰富的脂肪、蛋白质、多种微量元素和维生素,其中不饱和脂肪酸的含量很高,氨基酸种类齐全,搭配合理,钾、钙、铁、镁、锌和维生素E的含量高,不同产地苦杏仁的化学成分具有明显的差异。

苦味肽和苦味受体研究进展

苦味肽是通常在发酵、老化及水解食品中产生的寡聚肽。人类通过一种包含25种苦味受体的T2Rs苦味受体组感受苦味肽的苦味。文章综述了酶法水解获得的苦味肽的氨基酸序列结构特征。通过对苦味受体的胞外结构域的结构特征及T2Rs基因的单核苷酸多态性的研究有助于理解苦味感知的机制,为开发具有生理活性功能的苦味肽提供依据,同时介绍了苦味抑制研究的进展。

苦杏仁主要营养成分研究

对陕西永寿县苦杏仁中脂肪和蛋白质的含量、氨基酸和脂肪酸的组成进行了分析测定,并与扁桃仁、山桃仁、胡桃仁进行了对比。结果表明,苦杏仁含有49.6％的脂肪和27.0％的蛋白质,不饱和脂肪酸的含量占脂肪酸总量的94.85％,17种氨基酸含量为26.725％,必需氨基酸含量为7.575％高于扁桃仁和胡桃仁,氨基酸种类齐全,搭配合理,具有很高的营养价值和保健作用。

不同酶解条件对鳀鱼蛋白水解物苦味及氨基酸组成的影响

研究了不同酶解的鱼可溶性产物苦味及呈味氨基酸组成的差异 ,以及其水解时间、水解率对苦味的影响。结果表明 ,随着酶解时间延长和水解率的提高 ,几种水解液的苦味值都有不同程度增强。胃蛋白酶和胰蛋白酶的复合水解液表现出随水解时间的延长 ,水解率提高明显 ,苦味强度上升平缓。当水解率从4 2 %提高到 78%时 ,苦味值只提高了 2 ,水解液总的苦味分值为 3.5 ;枯草杆菌蛋白酶水解 2h后苦味分值急剧提高 ,水解 4h后苦味分值达到 6,水解液味道很苦 ,水解率从 32 %提高到 62 %时 ,苦味分值提高到了 7,水解液总的苦味值为 8.5。两种方法水解获得的可溶性产物氨基酸及必需氨基酸组成含量接近 ,但胃蛋白酶、胰蛋白酶复合水解的可溶性产物具有更高的氨基酸分值 ,主要鲜味氨基酸含量略高于枯草杆菌蛋白酶水解产物 ,苦味氨基酸则相反。

罗非鱼下脚料酶解液脱腥去苦的研究

采用微生物发酵和活性碳吸附两种处理方式对罗非鱼下脚料酶解液进行脱腥去苦的研究。通过不同的考察指标,选取最佳微生物发酵条件、最佳活性碳吸附条件,并通过游离氨基酸含量分析,比较处理前后营养物质的变化,确定罗非鱼下脚料酶解液最佳脱腥去苦方式为干酪乳杆菌Lc、植物乳杆菌Lp菌发酵,发酵条件:发酵比例为1∶1(Lc∶Lp),接种量2%,发酵时间16h,最适温度37℃,该条件下对罗非鱼下角料酶解液脱腥去苦效果最佳。