6 种市售工厂化栽培金针菇的氨基酸组成及蛋白质营养评价

为分析工厂化栽培金针菇的蛋白质营养,本研究测定6?种来自不同生产企业的市售金针菇样品中粗蛋白含量及氨基酸组成,分析其中呈味氨基酸的含量,并通过计算蛋白质的氨基酸评分、化学评分、氨基酸比值系数分和必需氨基酸指数,以及预测蛋白质校正氨基酸计分等非生物学指标,评价金针菇的蛋白质营养价值。结果表明,6?种金针菇样品均含有18?种水解氨基酸,其中呈味氨基酸含量比例为56.28%～57.37%。必需氨基酸含量接近WHO/FAO模式,其中蛋氨酸、赖氨酸含量丰富,限制氨基酸为缬氨酸和异亮氨酸。6?种市售金针菇的氨基酸比值系数分为72.61～82.07,必需氨基酸指数均高于90,与卵清蛋白接近。上述结果表明工厂化栽培的金针菇中呈味氨基酸含量丰富,含有利于人体吸收的优质蛋白,具有较大的风味食品开发潜力,适合与谷物、肉类等进行膳食搭配以促进人体对氨基酸的平衡摄取。     

Characteristics and Rheological Properties of Polysaccharide Nanoparticles from Edible Mushrooms (Flammulina velutipes)

Nanotechnology has become relevant in the food‐related industries, and edible mushrooms can be a potential raw material for providing satisfied edible nanomaterial. In this study, by following 3 different pretreatments (hot water or cold alkali or hot alkali) insoluble polysaccharide nanoparticles were prepared from Flammulina velutipes by wet milling and high pressure homogenization and their properties were investigated. The resultant nanoparticles were characterized by SEM, GC‐MS (for its main compositions), FTIR, XRD, and TG. The 1 wt% nanoparticle dispersions presented non‐Newtonian, shear‐thinning fluids with the viscosity in an increasing order for the hot water < cold alkali < hot alkali. Moreover, the dynamical rheological results showed differences of storage (G′) and loss (G″) moduli of these particle dispersions. It was concluded that the Flammulina velutipes‐derived polysaccharides nanoparticles have great potential applications in the food industry, for example, as emulsifiers, reinforcement agents, and bioactive carriers.     

Amino Acid,Organic Acid,and Sugar Profiles of 3 Dry Bean (Phaseolus vulgaris L.) Varieties

In this study, we compared the amino acid, organic acid and sugar profiles of 3 different varieties of dry beans (black bean [BB], dark red bean [DRB], and cranberry bean [CB]). The efficiency of the 2 commonly used extraction solvents (water and methanol:chloroform:water [2.5:1:1, v/v/v/]) for cultivar differentiation based on their metabolic profile was also investigated. The results showed that the BB contained the highest concentration of amino acids followed by DRB and CB samples. Phenylalanine, a precursor for the biosynthesis of phenolic secondary metabolites was detected at low concentration in CB samples and correlated with the reduced anthocyanins content in CB extract as documented in the published literature. Comparing the extractability of 2 extraction solvents, methanol:chloroform:water (2.5:1:1, v/v/v/) showed higher recoveries of amino acids from 3 beans, whereas, sugars were extracted in higher concentration with water. Analytically, gas chromatography detected sugars (9), amino acids (11), and organic acids (3) in a single run after derivatization of the extracts. In comparison, ion chromatography detected only sugars in a single run without any derivatization step with the tested procedure. Bean samples are better differentiated by the sugar content extracted with water as compared to the aqueous organic solvent extracts using partial least‐square discriminant analysis.     

Qualitative and Quantitative Prediction of Volatile Compounds from Initial Amino Acid Profiles in Korean Rice Wine (makgeolli) Model

In Korean rice wine (makgeolli) model, we tried to develop a prediction model capable of eliciting a quantitative relationship between initial amino acids in makgeolli mash and major aromatic compounds, such as fusel alcohols, their acetate esters, and ethyl esters of fatty acids, in makgeolli brewed. Mass‐spectrometry‐based electronic nose (MS‐EN) was used to qualitatively discriminate between makgeollis made from makgeolli mashes with different amino acid compositions. Following this measurement, headspace solid‐phase microextraction coupled to gas chromatography‐mass spectrometry (GC‐MS) combined with partial least‐squares regression (PLSR) method was employed to quantitatively correlate amino acid composition of makgeolli mash with major aromatic compounds evolved during makgeolli fermentation. In qualitative prediction with MS‐EN analysis, the makgeollis were well discriminated according to the volatile compounds derived from amino acids of makgeolli mash. Twenty‐seven ion fragments with mass‐to‐charge ratio (m/z) of 55 to 98 amu were responsible for the discrimination. In GC‐MS combined with PLSR method, a quantitative approach between the initial amino acids of makgeolli mash and the fusel compounds of makgeolli demonstrated that coefficient of determination (R²) of most of the fusel compounds ranged from 0.77 to 0.94 in good correlation, except for 2‐phenylethanol (R² = 0.21), whereas R² for ethyl esters of MCFAs including ethyl caproate, ethyl caprylate, and ethyl caprate was 0.17 to 0.40 in poor correlation.     

Antioxidative Activities of Mushroom (Flammulina velutipes) Extract Added to Bigeye Tuna Meat: Dose‐Dependent Efficacy and Comparison with Other Biological Antioxidants

ABSTRACT: The ability of a hydrophilic extract prepared from edible mushroom (Flammulina velutipes) to stabilize fresh color of bigeye tuna (Thunnus obesus) meat was evaluated to compare it with certain other antioxidants. The fresh color shelf life of bigeye tuna meats, to which were added as 1, 3, or 5 mL of mushroom extract to 100 g of minced bigeye tuna meat, prolonged duration of ice storage by more than 2, 4, and 6 d, respectively, in comparison with the control tuna meat without mushroom extract. The addition of 5 mL of mushroom extract to 100 g of minced bigeye tuna meat was more effective than adding ascorbic acid sodium salt (500 ppm) or α‐tocopherol (500 ppm) with regard to oxidation of lipid in the tuna meat. The color changes significantly correlated with lipid oxidation as well as metmyoglobin formation in the tuna meat. These results clearly show that the mushroom extract is a potential antioxidant, which has the ability to stabilize fresh color of tuna meat during ice storage.     

金针菇多糖对微冻大黄鱼及其鱼片品质变化的影响

为研究金针菇多糖（polysaccharide from Flammulina velutipes，FVP）对微冻大黄鱼及鱼片在贮藏期间肌原纤维蛋白性质的变化及水分分布的影响，实验分别选用0.03、0.06、0.09 g/L FVP浸渍处理大黄鱼和鱼片，以无菌水处理为对照组，分析微冻贮藏期间样品的感官指标得分、总挥发性盐基氮含量、总巯基含量、Ca2＋-ATPase活性、蛋白流变学性质以及水分迁移变化规律。结果表明：FVP可有效抑制整鱼总挥发性盐基氮含量上升和感官得分的下降；减缓整鱼及鱼片在微冻过程中总巯基含量、Ca2＋-ATPase活性下降和水分流失；此外FVP还能够延缓大黄鱼因腐败而出现的蛋白凝胶能力减弱。在本实验选取的多糖浓度范围内，0.09 g/L FVP处理组保鲜效果较强。该研究结果可为FVP用于水产品贮运保鲜提供理论参考。     

Identification of the Critical Amino Acid Residues of Immunoglobulin E and Immunoglobulin G Epitopes in α‐Lactalbumin by Alanine Scanning Analysis

α‐Lactalbumin represents one of the major allergens causing cow milk allergy. Few studies have clearly evaluated immunological relationships between immunoglobulin E (IgE) and immunoglobulin G (IgG)‐binding epitopes of α‐lactalbumin. IgE‐ and IgG‐binding epitopes were immunolabeled with individual sera from cow milk‐allergic patients. Alanine scanning of immunodominant epitopes was used to identify the critical amino acid (aa). Our initial data revealed Val⁸, Phe⁹, Arg¹⁰, Tyr¹⁰³, Leu¹⁰⁵, and His¹⁰⁷ were the critical aa for IgE‐binding epitope. The critical aa of IgG‐binding epitopes were Phe⁹, Leu¹⁵, Pro²⁴, Trp²⁶, and His³². This study will provide necessary information to alter the cDNA to encode a protein capable of activating milk‐specific T cells, but with reduced IgE‐ or IgG‐binding capacity.     

菌核净残留免疫分析半抗原的制备和鉴定

菌核净属于半抗原生物小分子,具有免疫反应性,但不具有免疫原性。为了建立菌核净农药残留的免疫分析方法,以苹果酸氯醛交酯和3,5-二氯苯胺为原料,合成N-(3,5-二氯苯基)-2-羟基琥珀酰亚胺,然后与琥珀酸酐反应,合成了菌核净半抗原N-(3,5-二氯苯基)琥珀酰亚胺-2-琥珀酸半酯,产物经红外、核磁和液质连用等方法确认,为研究菌核净的免疫分析奠定基础。     

繁缕叶蛋白中氨基酸组成研究

对繁缕叶蛋白的浓缩及蛋白质氨基酸组成进行研究与分析,结果表明:繁缕蛋白质含量较高.达到15.39%,在浓缩叶蛋白中的含量达到52.03%.对繁缕叶蛋白氨基酸组成分析表明,各种繁缕叶蛋白的氨基酸的平衡性较好.其必需氨基酸含量、必需氨基酸与非必需氨基酸比值、必需氨基酸评价分数均在FAO/WHO推荐值范围内.     

微波固相合成技术及其在多肽(氨基酸)金属螯合物合成中的应用

多肽(氨基酸)金属螯合物是一种新型金属营养补充剂,具有吸收利用率高,代谢过程能耗低,转运速度快和不易被饱和等优点,而且多肽可作为金属元素配体通过小肽转运系统进入肠黏膜细胞,稳定性高,并可减少金属间拮抗作用,具有很好的应用前景。微波固相合成技术作为一种新型多肽(氨基酸)金属螯合技术,相比传统液相合成法,具有反应速度快、反应效率高、能耗低、工艺操作简单、污染少和无废液产生等优点,广泛应用于多肽(氨基酸)金属配位螯合物的合成中。本文从微波固相合成的机理、影响因素、金属螯合物鉴别及其在多肽(氨基酸)金属螯合物合成中的应用等方面进行了系统综述,并对微波固相合成技术的应用提出了一些建议,以期为微波固相合成技术在多肽(氨基酸)金属螯合物合成中的应用起到良好的推动作用。     

不同添加量的氨基酸辅助干热处理对玉米淀粉理化和消化性质的影响（网络首发、推荐阅读）

以玉米淀粉为原料,通过氨基酸（天冬氨酸和赖氨酸）辅助干热处理对其改性,采用快速黏度仪、差式扫描量热仪、X射线衍射仪,对不同氨基酸添加量（0.5%、2%、4%和10%,w/w）的干热玉米淀粉的糊化特性、热特性、结构特性和消化性质进行了研究。结果表明,氨基酸添加量对干热处理玉米淀粉-氨基酸混合物的理化性质和消化性质有显著影响。随着两种氨基酸添加量的增多,淀粉的峰值黏度、回生值和糊化焓值降低,而相对结晶度和抗性淀粉含量升高;干热玉米淀粉-天冬氨酸混合物的糊化温度呈先升高而后降低的趋势,干热玉米淀粉-赖氨酸混合物的糊化温度呈升高趋势。提高氨基酸添加量能促进淀粉颗粒内部的晶体排列更紧密、有序,能更好地抑制淀粉的短期老化,降低淀粉的消化性能;可作为玉米淀粉改性的一种新方法,为生产改性淀粉提供参考。     

Factors Influencing the Free Amino Acid Content of Potato (Solanum tuberosumL) Tubers during Prolonged Storage

Tubers of the potato cultivars Pentland Dell and Record were stored for a period of up to 40 weeks at 5°C and 10°C over four consecutive storage seasons (1989–1990 to 1992–1993). Reconditioning treatments at 20°C were also performed at early, mid and late stages in storage. To assess the turnover of proteins during storage, tubers were analysed for free amino acid and soluble protein content. The net direction of nitrogen flow was dependent on the state of dormancy of the tuber and hence storage duration. An increase in free amino acid content commonly occurred during the latter part of storage, caused by an upturn of proteinase activity on the break of dormancy. This increased enzyme activity was probably due to de novo synthesis of proteinases, in particular of a 47 kDa aspartic proteinase which was purified to homogeneity and shown to have a marked substrate-specificity for endogenous tuber proteins such as patatin. The rate of protein turnover increased with storage temperature, although the net direction of nitrogen flow was temperature independent. However, when nitrogen flow exhibited a distinct direction, such as the protein breakdown in Pentland Dell during late storage, this was enhanced by higher temperatures. The accumulation of free amino acids in Pentland Dell at 10°C corresponded with a deterioration of processing quality that could not be accounted for by an upturn in reducing sugar content. Despite an excess of free amino acids with respect to reducing sugars, amino acids had a probable syn-ergistic influence on fry colour over the later stages of storage resulting in a darker colour per unit reducing sugar than in early storage. Reconditioning treatments were ineffective as a means of lowering the free amino acid pool size, these treatments operating solely through the decrease in reducing sugar content.     

Profiles of Organic Acid and Volatile Compounds in Acid-Type Cheeses Containing Herbs and Spices (Surk Cheese)

A study was conducted to evaluate the basic chemical composition, organic acids, volatile compound profiles, and overall acceptability of Surk cheese (acid cheese). The organic acids were determined by reverse phase high performance liqued chromatography method, and volatile compounds were analyzed by static headspace/gas chromatography/mass spectrometry technique. A total of 134 volatile compounds, including 42 esters, 40 terpenes, 15 alcohos, 11 free fatty acids, 6 ketones, 5 aldehydes, 4 alkenes, 4 phenyl propanoids, 3 phenolics, and 4 other compounds, were identified in the Surk cheeses. The main compounds were found to be carvacrol, γ-terpinene, p-cymene, hexanoic acid, octanoic acid, decanoic acid, butanoic acid, and eugenol. The mean total organic acid content of the Surk cheese was 1.71 g/100 g. The main organic acid in the Surk cheese was lactic acid (1067 mg/100 g), followed by acetic, propionic, oxalic, formic, citric, pyruvic, orotic, hippuric, and uric acids.     

Accumulating mechanism of γ‐aminobutyric acid in soybean (Glycine max L.) during germination

γ‐aminobutyric acid (GABA) has been found accumulating significantly in soybean seeds during germination. However, the mechanism of the accumulating process is not clear. Therefore, gene expression, enzyme activity and metabolites associated with GABA shunt in ZH 13 soybean during germination were analysed in this paper. GABA content in 5‐day germinated soybean was 0.26 ± 0.016 mg g^?1 DW, which was equivalent to six times concentration of original soybean. The GAD activity has a positive effect on the accumulation of GABA, as well as the GABA‐T activity was found to play a significant role in the degradation of GABA. The expression levels of GmGAD and GmGABA‐T may affect the GABA content by regulating the respective enzyme activities. In conclusion, upregulation of GAD and downregulation of GABA‐T may cause the accumulation of GABA.     

Identification of radical scavenging peptides (<3 kDa) from Burgos-type cheese

The aim of the present study was to identify low molecular weight peptides with radical scavenging activity from cheese made using different types of rennet: batch 1, animal rennet (95% chymosin and 5% bovine pepsin), batch 2, rennet of plant origin (Cynara cardunculus) and batch 3, microbial rennet (Mucor miehei). After preparation of the peptide extracts (<3 kDa), antioxidant activity was assayed by their DPPH radical scavenging and metal chelating a6ctivity. All of the batches showed antioxidant activity, which could be dependent on the peptides which are present in extracts: Batch 2 and 3 showed the highest values for DPPH inhibition and chelating effect. Fourteen fractions out of the total peptide fractions collected after RP-HPLC analysis showed radical scavenging activity using the DPPH inhibition method. Free amino acids and peptides were identified from these fractions. One of the peptides, derived from α_s1-casein, was a potential new antioxidant peptide. These antioxidant peptides were present in a lower content in extracts obtained from animal rennet cheese in comparison with the other extracts.     

菜籽蛋白水解物体外和细胞内抗氧化性评价及氨基酸分析研究

以“双低”油菜籽秦优7号为原料,碱溶酸沉法获得菜籽分离蛋白后进一步用Alcalase2.4L酶解得到菜籽蛋白水解物（rapeseed protein hydrolysates,RPHs）;采用聚丙烯酰胺葡聚糖凝胶柱（Sephacryl S-100HR）对RPHs进行分离纯化,得到3 个组分;采用抗氧化能力指数（oxygen radical absortion capacity,ORAC）方法以及细胞抗氧化活性（cellular antioxidant capacity,CAA）的方法分析筛选得到抗氧化性最好的组分3。结果表明组分3的ORAC值为（1610.38±112.51）μmol TE/g;CAA值为（124.66±2.18）μmol QE/g,EC50值为（57.84±3.38）μg/mL;在此基础之上,对组分3进行氨基酸分析以及电泳分析,表明其抗氧化性与分子质量分布及氨基酸组成可能存在一定关系。     

Mechanisms Involved in the Therapeutic Effects of Soybean (Glycine Max)

Soybeans contain nutritional and medicinal properties. It is a rich source of quality proteins, phytosterols, fibers, and other biologically active compounds, notably daidzein and genistein. Soybeans provide health benefits due to their functional ingredients such as proteins, polysaccharides, and isoflavones. These functional ingredients play a vital role in the reduction of different types of cancer, cardiovascular diseases, postmenopausal problems, diabetes, and some neurodegenerative disorders. This review primarily envisages the different mechanisms involved in the therapeutic effects of soybean components as well as their contribution toward the reduction of different diseases.