自溶法生产呈味核苷酸

1960年日本的国中明博士等，分别从鲣鱼和香菇中发现肌苷酸(IMP)和鸟苷酸(GMP)，它们具有比谷氨酸单钠更鲜美的呈味效应，且与谷氨酸单钠盐具有相乘的协同效应，二者混合的鲜味比单独使用味精的鲜度可提高数倍至十余倍。日本早在上世纪的60年代初，冠以“强力味精”的品名，在鲜味剂市场上悄然独占鳌头。     

养殖大黄鱼冻藏期间呈味物质变化规律分析

通过对不同冻藏时间游离氨基酸和呈味核苷酸含量分析,探究养殖大黄鱼滋味组分物质的变化规律。结果显示,养殖大黄鱼冻藏过程中游离氨基酸含量波动较大,ΣUAA和ΣSAA在第180天最高;ΣBAA无明显变化;AMP含量在第90天最高,IMP的TAV值始终大于1,为养殖大黄鱼肉呈现鲜甜滋味贡献最大,属于滋味活性物质;除0 d外,养殖大黄鱼冻藏180 d EUC值最高。表明随着冻藏时间的延长,养殖大黄鱼整体滋味呈波动变化,冻藏0 d和180 d养殖大黄鱼鲜甜味和呈味丰富性较强,风味品值较好。     

食品中的呈味肽及其呈味机理研究进展

呈味肽因其不同链长度和结构序列具有不同的滋味特征,包括甜味、苦味、酸味、咸味和鲜味。目前国内对于呈味肽的研究主要集中在其种类和数量的发掘阶段,关于呈味肽与味觉感受器相互作用而呈味的机理还不是十分清晰;而国外对于呈味肽的降血压、降血糖等生物活性功能以及5类呈味肽的相应呈味机理研究有相关新报道。本文阐述了食品中的呈味肽以及其在食品中的作用,并综述了其呈味机理的研究新进展,以期为食品风味研究及调味品的开发提供参考依据。     

呈味核苷酸生产与应用（续）

称为食品的味,其基本原味有甜、酸、咸,苦4种,后来根据不同国家进行调查总结认为:日本有5种原味:咸味、酸味、苦味、鲜味、甜味;欧美有6种原味;咸味、酸味、苦味、甜味、碱性味、酸性味;中国有7种原味:咸味、酸味、苦味、甜味、鲜味、辣味、香味。印度有8种原味:咸味、酸味、苦味、甜味、涩味、辣味、淡味、馊味。 在我们的日常的食事生活中,只知道能吃得滋味美好的食物,但不知道食物鲜美的实质是什么。 到了本世纪初期日本池田于1908年发现海带产生鲜味的主要成分是谷氨酸(MSG)后来     

华贵栉孔扇贝闭壳肌蛋白的分离提取及性质

以华贵栉孔扇贝为研究对象,对其闭壳肌蛋白组分进行分离,并对其氨基酸组成、分子质量分布和热稳定性进行检测分析。结果表明:新鲜华贵栉孔扇贝闭壳肌中水分、粗蛋白含量分别为78.12%、18.19%;蛋白组分分离得到3种组成蛋白,其中肌原纤维蛋白占总蛋白46.80%,基质蛋白占32.70%,肌浆蛋白占20.50%;氨基酸组成检测表明3种蛋白组分氨基酸种类齐全,肌浆蛋白、肌原纤维蛋白、基质蛋白中必需氨基酸占氨基酸总量的百分比分别达到41.52%、38.96%、35.49%;十二烷基磺酸钠-聚丙烯酰胺凝胶电泳分析显示:肌浆蛋白亚基分子质量在16~105 k D之间分布广泛;肌原纤维蛋白组分分子质量大多介于35~50 k D和105 k D附近;基质蛋白组分在35~50 k D之间有2条明显的条带,在71 k D附近也有一条带;热稳定性分析显示肌浆蛋白、肌原纤维蛋白、基质蛋白的变性温度分别为65.8、50.5、59.6℃。     

扇贝裙边酶解过程中呈味组分的变化规律研究

本研究以扇贝裙边为原料,利用复合蛋白酶对扇贝裙边进行酶解,在确定扇贝裙边最佳酶解温度的基础上,探索了扇贝裙边酶解液在不同酶解时间下的呈味特点,并探讨了不同酶解液中呈味分子的变化规律,探明不同酶解时间下扇贝裙边酶解液的呈味规律。结果表明不同酶解时间制备酶解液的滋味存在显著性差异,其中8 h的扇贝裙边酶解液鲜味强度最高(9.32分),而12 h酶解液的苦味(7.33分)和饱满度(8.33分)最强。主要是因为酶解时间对酶解液鲜味氨基酸和苦味氨基酸的含量及比例存在较大影响,当酶解8 h时,扇贝裙边酶解液中鲜味氨基酸比例最高(46.80%),而苦味氨基酸比例最低(51.67%);此外,肽分子分布结果显示8h酶解液中5000 u的肽段(对呈味贡献小)和180 u的肽段(苦涩味明显)比例较低,可能是8 h扇贝裙边酶解液取较好的鲜味和饱满度,较低苦味的主要原因。本研究通过研究扇贝呈味组分在酶解过程中的变化规律,为工业上利用扇贝裙边制备高品质呈味基料提供理论基础和指导。     

核桃内种皮游离氨基酸呈味特征及其营养评价

为探究不同品种核桃内种皮游离氨基酸组成、呈味特征和营养价值,本研究对6个核桃品种内种皮中游离氨基酸含量进行检测,并进行滋味活性值（Taste Activity Value,TAV）分析、主成分分析和综合评价。结果表明,不同品种核桃内种皮共检出17种游离氨基酸,总含量为2673.86～3490.12 mg/kg,9种药用氨基酸占氨基酸总量57.67%～68.23%,且Leu为内种皮第一限制性氨基酸。内种皮游离氨基酸主要成分为：Glu、Asp、Thr、Cys和Arg,其中Glu含量最高。6个品种中Glu的TAV值为2.34～3.81,对内种皮鲜味贡献最大。‘京861’、‘薄壳香’和‘金薄香8号’中Arg的TAV值为1.03～1.26,对内种皮苦味有贡献。鲜味氨基酸为含量最高的呈味氨基酸,芳香族氨基酸含量最低,‘农核1号’、‘京861’、‘薄壳香’和‘金薄香8号’内种皮苦味氨基酸与甜味氨基酸含量的比值>1,‘汾核2号’和‘汾核4号’内种皮苦味氨基酸与甜味氨基酸含量的比值<1,且氨基酸综合质量较高。核桃内种皮氨基酸营养价值和药用价值较高,滋味苦涩,作为补充Thr、Ile和含硫氨基酸...     

不同产地禾花鱼营养成分分析评价

以广西全州县、兴安县、湖南郴州市、靖州苗族侗族自治县的禾花鱼为研究对象,对其营养成分进行分析。研究结果表明,4个不同产地的禾花鱼均呈高蛋白低脂肪的特点。禾花鱼含肉率为37.07%～39.28%,蒸煮损失率为21.20%～24.32%,17种游离氨基酸种类齐全、含量丰富,广西全州县禾花鱼、兴安县禾花鱼游离氨基酸含量分别为276.867 mg/100 g和265.731 mg/100 g。4种禾花鱼主要滋味呈味成分为肌苷酸（inosine monophosphate,IMP）。磷酸腺苷（adenosine monophosphate,AMP）、鸟苷酸（guanosine monophosphate,GMP）,主要对禾花鱼风味起协调增效作用。兴安县禾花鱼IMP（223.102 mg/100 g）含量最高。4种禾花鱼IMP对应滋味强度值（taste activity value,TAV）均大于1,其对禾花鱼肉整体滋味起主要贡献作用。     

反复卤煮对老汤品质的影响研究

传统酱卤肉制品因老汤的使用而深受消费者喜爱,卤汤在连续的使用过程中不断积累较多的可溶性滋味物质,使其本身具有鲜醇浓厚独特的美味,进而赋予卤煮制品特有的滋味。本研究以白羽肉鸡鸡腿为原料,对传统卤煮工艺不同卤制次数卤汤中的营养物质如蛋白质、游离氨基酸、呈味核苷酸、味精当量等和有害物质中的杂环胺的变化进行研究。结果表明:与对照组第0锅卤汤相比,当卤制次数达到第9锅时,卤汤中蛋白质含量由0.09%增加至3.86%,总游离氨基酸含量由68.57 mg/100g上升至601.92 mg/100 g,呈味核苷酸含量由0.78 mg/100 g达到了22.97 mg/100 g,味精当量(EUC)值由0.0068 g MSG/100 g升高至1.32 g MSG/100 g,但有害物质中杂环胺含量由12.29 ng/g上升至28.64 ng/g。因此,传统卤煮工艺中随着卤制次数的增加,卤汤中营养物质的含量呈不断上升的趋势,同时有害物质中杂环胺的含量也不断富集。     

我国沿海主要海域雌性三疣梭子蟹呈味成分含量的比较

以我国渤海、黄海、东海和南海4个海域中雌性三疣梭子蟹的肝胰腺、性腺和体肉为研究对象,采用电子舌、氨基酸自动分析法以及高效液相色谱法研究不同海域的生长环境对雌性三疣梭子蟹3个可食部位游离氨基酸含量和呈味核苷酸化合物的变化,并采用滋味强度值和味精当量对呈味成分的强度进行评价。结果表明:电子舌可对4个海域中雌性三疣梭子蟹的肝胰腺、性腺和体肉进行有效区分;在肝胰腺部分,游离氨基酸总量是3个可食部位最高的,3种呈味核苷酸中肌苷酸和腺苷酸的含量较高;在不同海域中,渤海肝胰腺组游离氨基酸总量最高,为3 315.05 mg/100 g,且其味精当量值最高,为15.87 g MSG/100 g;南海肝胰腺组游离氨基酸总量最低,但甜味氨基酸含量所占比例最高,为63.10%,并且呈味核苷酸含量最高,肌苷酸和腺苷酸的滋味强度值大于1。蟹的性腺部分,呈味核苷酸含量与味精当量值是3个可食部位中最高的,其中南海性腺的味精当量值为36.46 g MSG/100 g,是4个海域中最高。蟹的体肉部分中肌苷酸含量较高,黄海体肉肌苷酸组中含量较低,其滋味强度值小于1,对体肉的滋味无直接贡献,但黄海体肉组游离氨基酸总量最高,为2 564.44 mg/100 g;东海体肉组的味精当量值最高,为7.19 g MSG/100 g。     

Validation of biokinetic model of metals in the scallop Chlamys nobilis in complex field environments

A transplantation experiment, using the scallop Chlamys nobilis as the model organism, was carried out to investigate variations in their bioaccumulation of Cd and Zn in different environmental conditions. The diffusive gradients in the thin films technique was employed to monitor in situ dissolved labile metal concentrations. The impact of food quality on assimilation efficiency and ingestion rate also was investigated in the laboratory. The results were combined in a biokinetic model explaining the metal concentrations accumulated in the scallops. The results confirm that scallops accumulate metals differently in different marine environments with comparable ambient metal concentrations. Food quality not only influences their assimilation of metals but also their clearance rates. The ingestion rate together with the growth rate was shown to have an effect on the bioaccumulation of metals. Bioaccumulation is dependent on both the ingestion rate (when food is the dominant metal uptake pathway) and the proportion of metal taken up from the water. Environmental conditions such as food availability and hydrology must be simultaneously considered in any attempt to study metal bioaccumulation in marine bivalves.     

热加工处理对华贵栉孔扇贝柱特征风味形成的影响

采用高效液相色谱和顶空固相微萃取结合气相色谱-质谱联用法,在鉴定特征风味化合物组成的基础上,以新鲜和真空冷冻干燥处理的华贵栉孔扇贝柱为对照,探究热加工处理对华贵栉孔扇贝柱特征风味成分的影响。结果表明:扇贝柱粗蛋白和粗脂肪受不同处理方式的影响较小;与新鲜华贵栉孔扇贝柱相比,热加工处理使滋味组分5’-一磷酸腺苷、甜菜碱和Cl-含量显著增加(P0.05),Na+含量也明显增加;游离氨基酸和K+含量明显降低,且5’-三磷酸腺苷及其关联化合物(除5?-一磷酸腺苷)、琥珀酸和PO43-含量显著降低(P0.05)。热加工处理的变化比真空冷冻干燥处理的变化更明显。热加工处理扇贝柱与对照组(新鲜贝柱、真空冷冻干燥贝柱)的挥发性成分组成和种类各不相同,分别得到63、34种及64种挥发性风味物质。新鲜贝柱、真空冷冻干燥处理和热加工处理干贝挥发性风味分别以醇类、酸类和烃类、醛类物质为主,总量分别占26.20%、30.84%和29.38%、16.78%。研究表明,热加工处理干贝的特征香气主要呈现鱼腥味、蜂蜜样香气、水果香和油脂味,主要特征风味物质有三甲胺、1-辛烯-3-醇、顺-2-戊烯-1-醇、1-戊烯-3-醇、1-戊醇、壬醛、十一醛、己醛、庚醛、苯甲醛、羊脂醛、癸醛、3-辛酮。     

A GC-MS-based metabolomics investigation on scallop (Chlamys farreri) during semi-anhydrous living-preservation

We investigated the physiological changes in scallops (Chlamys farreri) during semi-anhydrous living-preservation using metabolomics method to obtain a guiding theory in optimizing the preservation conditions. Glycogen, lactic acid, and crude protein levels were measured in 1-day intervals for 6 days, the median lethal time.The metabolite profiling of scallops after the preservation duration of 10% lethal time (3 days) was achieved based on methyl chloroformate derivation before GC-MS analysis. Carboxyl acids related to respiration (malic, fumaric, and succinic acids), fatty acids (C18:0, C16:0, and C22:6), and amino acids (phenylalanine, glutamic acid, aspartic acid, isoleucine, glycine, pyroglutamic acid, proline, leucine, and 2-aminoadipic acid) were identified as biomarkers. Our results demonstrated that scallops performed an elevated anaerobiosis and depressed aerobiosis, which were not caused by oxygen insufficiency. The switching of energy metabolism patterns and disorder of the osmotic regulation system were also observed, suggesting that oxygen supply is less important for optimizing semi-anhydrous living-preservation.Industrial relevanceIn China, live aquatic products are far more appreciated by consumers than frozen ones. For example, live scallops are more than ten times as expensive as frozen ones in non-local restaurants. However, there is little profit in providing live scallops instead of frozen scallops, due to the high cost of preservation and transportation. Besides the mortality loss, the high costs of running and building the life-preserving condition are the main costs. Thus, optimizing the preservation conditions can reduce the cost. In our case, we introduced metabolomics instead of non-targeted parameter selecting such as the orthogonal test. Based on the elucidated metabolic pathway, we found that oxygen supplementation is not critical. The high cost of building and running oxygen-supplying module in semi-anhydrous living-preservation can be eliminated.     

Nucleation of amino acid‐rich crystals on the surface of dried scallop (Chlamys farreri) during storage: formation mechanism and influence of environmental relative humidity

Formation of crystals on the surface of dried scallop (Chlamys farreri) adductor muscle is often observed during storage. The composition of these white crystals was determined, and the effect of relative humidity (RH) during storage on their formation was also studied. The white crystals were determined as the crystal of free amino acids, mainly composed of taurine (Tau) and glycine (Gly). The main polymorphic form of glycine in the crystals was further confirmed as the γ‐form. Besides free amino acids, another major part of the crystal composition was ions, such as Na⁺, NH₄⁺, K⁺, PO₄^3? and Cl^?. The presence of various free amino acids and Na⁺ and K⁺ might contribute to the crystallisation of γ‐glycine. RH particularly at 65% and above significantly increased the amount of crystals. RH of 43% and below was recommended to prevent the formation of amino acid‐rich crystals on dried scallops during storage.     

Rehydration properties of dried onion

Abstract

The effect of pretreatment preceding convective drying and the mode of drying on reconstitution properties of dried onion was investigated. Soaking in water, dipping in starch solution and osmotic dewatering were used as pre‐drying treatments. Convective drying at 60, 70, and 80°C, infrared drying and convective drying assisted with microwaves were applied to remove water from raw onion. Rehydration was done in water at room temperature and in boiling water. In general amount of absorbed water and increase in mass during rehydration, both were higher for pretreated material than those observed with dried raw onion. The mode of drying seemed to affect the course of rehydration of dried onion, and to improve its reconstitution properties. However, this was observed at room temperature rehydration only. Pre‐drying treatment followed by convection drying affected much stronger reconstitution properties of dried onion than the mode of drying.     

Rehydration properties of dried plant tissues

Apples, carrots and potatoes cut in cubes were dried by convection and then subjected to rehydration in water at room temperature. Mass and volume changes were followed during rehydration. A minimal displacement gauge was used to record changes of height of individual cubes during wetting. Porosity of the dried material was calculated and its changes during rehydration were observed. Comparing volume increase with mass gain during rehydration it was found that the mechanism of water imbibing is strongly influenced by porosity and chemical composition of the dried material. Dried apple was very porous, hence its mass gain was much faster than the volume increase. On the other hand, gelatinised starch in dried potato strongly absorbed water and the volume increase outpaced the mass gain. Recording changes of height of the dried cubes upon rehydration evidenced phase changes and injury incurred to the tissue structure by dehydration. In apple a collapse of structure was observed, while potato cubes swelled from the very beginning of the wetting process. In carrot instantaneous changes of height of the cube were observed, which could be due to relaxation of shrinkage stresses and displacements of injured tissue structures.     

扇贝肌原纤维蛋白浊度和黏度特性的研究

以扇贝为原料对其肌原纤维蛋白进行提取,研究不同温度、PH、离子强度、蛋白浓度对扇贝肌原纤维蛋白浊度、黏度特性的影响.试验结果表明:温度升高,扇贝肌原纤维蛋白溶液浊度上升.在40℃时浊度达到最大值,PH在4.0～4.5之间时蛋白的浊度最大,离子强度为0.6 I时蛋白浊度最小,而蛋白浓度与浊度呈正线性相关;蛋白的黏度随着温度升高而下降,60℃后变化不显著,PH值为4.0时黏度最小,离子强度为0.6 Ⅰ时黏度最大,随着蛋白浓度升高黏度显著增大.     

Moisture-dependent physical properties of dried pomegranate arils

Physical properties of dried pomegranate arils and its variation with moisture content play an important role in designing of equipment for storage, conveying and handling. Physical properties of dried pomegranate arils in the moisture content range of 7–28 % (d.b.) were investigated. Size (GMD), sphericity, weight of the thousand dried arils, true density, bulk density, angle of repose and coefficient of friction at different surfaces (wood, galvanized iron and aluminum) increased, whereas porosity, hardness and toughness decreased with increase in the moisture content. All physical properties except porosity and angle of repose were significantly affected by the change in moisture content at probability level p ≤ 0.01.