Amino acid profiles and quality from lotus seed proteins

BACKGROUND: Protein composition, amino acid profile and nutritional value of the lotus seed and its Osborne fractions were investigated. The seed was rich in protein with 19.85%, and showed well balanced amino acid composition compared with FAO/WHO pattern, Its nutritive properties were similar to those observed in the reference soybean protein. Phenylalanine, tyrosine, leucine and lysine were the limiting amino acids in the seed proteins. The albumin and globulin were the main protein fraction, the amino acid profile and nutritional value were close to the seed protein. RESULTS: Changes in transition temperature and thermal stability were observed through different solvent extractions. Albumin possessed the predominant thermal stability (81.4 °C) followed by globulin (74.49 °C), prolamin (69 °C) and glutelin (65.6 °C). So, solvent compositions influence the profile of AAs and their nutritive value, and aqueous solvent with 0.1 mol L^?1 NaCl was an efficient protein solubiliser. CONCLUSION: The results indicated that the extraction processes influenced the lotus seed protein quality and thermal stability. Overall, the study revealed that the lotus seed protein was nutritionally well‐balanced protein and might be of significant importance in the formulation of diets for humans. © 2012 Society of Chemical Industry     

Amino acid profiles of lactic acid bacteria, isolated from kefir grains and kefir starter made from them

The characteristics of cell growth, lactic acid production, amino acid release and consumption by single-strain cultures of lactic acid bacteria (isolated from kefir grains), and by a multiple-strain kefir starter prepared from them, were studied. The change in the levels of free amino acids was followed throughout the kefir process: single-strain kefir bacteria and the kefir starter (Lactococcus lactis C15-1%+Lactobacillus helveticus MP12-3%+(Streptococcus thermophilus T15+Lactobacillus bulgaricus HP1 = 1:1)-3%) were cultivated in pasteurized (92 degrees C for 20 min) cow's milk (3% fat content) at 28 degrees C for 5 h (the kefir starter reached pH 4.7) and subsequently grown at 20 degrees C for 16 h; storage was at 4 degrees C for 168 h. The strain L. helveticus MP12 was unrivaled with respect to free amino acid production (53.38 mg (100 g)(-1)) and cell growth (17.8 x 10(8) CFU ml(-1)); however, it manifested the lowest acidification activity. L. bulgaricus HP1 released approximately 3.7 times less amino acids, nearly 5 times lower cell growth, and produced about 1.2 times more lactic acid. S. thermophilus T15 demonstrated dramatically complex amino acid necessities for growth and metabolism. With L. lactis C15, the highest levels of growth and lactic acid synthesis were recorded (18.3 x 10(8) CFU ml(-1) and 7.8 g l(-1) lactic acid at the 21st hour), and as for free amino acid production, it approximated L. bulgaricus HP1 (17.03 mg (100 g)(-1) maximum concentration). In the L. lactis C15 culture, the amino acids were used more actively throughout the first exponential growth phase (by the 10th hour) than during the second growth phase. The unique properties of the L. helveticus MP12 strain to produce amino acids were employed to create a symbiotic bioconsortium kefir culture, which, under conditions of kefir formation, enhanced lactic acid production and shortened the time required to reach pH 4.7; intensified cell growth activity, resulting in a respective 90- and 60-fold increase in the concentration of lactobacilli and cocci in the mixed culture compared to individual cultures; and accumulated free amino acids in the final kefir with higher total concentrations (56.88 mg (100 g)(-1)) and an individual concentration of essential amino acids (1.5 times) greater than that of yogurt.     

Amino acid profiles of chemical and anatomical fractions of oat grains

Anatomical fractions of oat grains obtained by manual dissection and chemical fractions corresponding to the four major classes of protein present in seeds have been analysed for amino acids by automated column chromatography. Estimates of lysine indicate that this amino acid is concentrated in the embryo and in the albumin and globulin fractions. The salt-soluble proteins can be identified on gels of polyacrylamide following electrophoresis. It is suggested that selection of varieties with high levels of salt-soluble protein offers a means of improving the amino acid balance of oat proteins in relation to the feeding of non-ruminant animals.     

引进美国白肋烟品种比较试验

白肋烟是生产混合型卷烟不可缺少的原料,其在叶组配方中所占的比例为30%~40%[1]。为了填补贵州无白肋烟的空白,2000~2001年开展了引自美国的白肋烟品种比较试验,寻找适宜品种,为贵州白肋烟生产提供依据。1材料及方法试验于2001年1月至10月在松桃苗族自治县大兴镇进行。该地海拔800 m,年均气温17.9℃,年降雨量1373.7mm。试验地前茬作物为水稻,红黄壤土,土壤全氮1.89g/kg;全磷0.63g/kg;全钾13.50 g/kg;有机质15.70 g/kg,土壤p H 6.4。      

白肋烟烘焙工艺温度参数拟合优化及验证

目的：提升白肋烟烘焙后的香味物质含量。方法：建立烘焙后还原糖含量与3个干燥区温度之间的模型,并以烘焙后白肋烟香味物质总量为标准对3个干燥区温度进行优化。结果：所建模型R²达0.947,拟合效果较好。干燥二区和干燥三区的温度对白肋烟烘焙增香的效果大于干燥一区,且此类型白肋烟烟叶的最佳烘焙条件为一区110 ℃（3 min）,二区145 ℃（3 min）,三区135 ℃（3 min）。结论：最佳烘焙温度下,白肋烟中还原糖含量较低且香味物质总量最高,白肋烟烘焙增香效果较好。     

棒络新妇卵袋丝氨基酸组成及其力学行为

采用氨基酸自动分析仪与电子单纤强力仪对棒络新妇（Nephila clavata）卵袋框丝与内层丝2种不同功能蜘蛛丝的氨基酸组成与力学性能进行测试研究,拟探明蛛丝组成、力学行为、性能与生物学功能之间的关系。结果表明,与卵袋框丝相比,卵袋内层丝的甘氨酸和脯氨酸含量较低,丝氨酸和极性氨基酸含量均较高,大侧链氨基酸（LC）与小侧链氨基酸（SC）的比值较高,初始模量较小,其拉伸曲线弹性区增加,屈服区很小,加强区平缓,延展性很好,拉伸行为重复性较好。     

Amino acid profiles in unripe Arabica coffee fruits processed using wet and dry methods

The quality of natural coffee produced in Brazil is quite variable. Fruits at different stages of maturation can be found on the same plant, and unripe fruits are naturally present during the harvest. The pulping of ripe fruits can be effectively used to improve the quality of the coffee, as the ripe fruits will be separated from the unripe fruits; however, the presence of a portion of unripe fruit (with lower quality) in the processing is unavoidable. The wet processing of immature coffee fruit appears to be a potential way of improving its quality. According to the coffee processing used post-harvest, changes were observed in the levels of free amino acids in immature coffee beans. Among the amino acids present, asparagine is the primary amino acid found in unripe coffee beans. Asparagine produces acrylamide, a potentially harmful substance generated during the course of the Maillard reaction. In this study, amino acids in immature coffee beans were analysed using reversed-phase chromatography and ultraviolet detection after the derivatisation with phenylisothiocyanate. The amino acid profiles of the immature coffee beans demonstrated that asparagine is present at more significant levels when immature coffee fruits were processed via dry processing, as compared to wet processing.     

氮素形态对白肋烟特有亚硝胺的积累、烟叶品质、产质量等影响的研究

试验表明,施N量中以50% NO₃--N的处理,白肋烟特有亚硝胺(TSNA)含量最低,烟叶品质最好;施75% NO₃--N次之;施0%、25%、100% NO₃--N时,TSNA含量远远高于50%和75% NO₃--N的处理,且以0% NO₃--N时烟叶品质最差。不同N形态对干物质积累影响较大,且作用顺序为60~80 d > 80~96 d > 40 d前;单产随NO₃--N比例的增加呈下降趋势,而产值、均价、上中等烟则随NO₃--N比例的增加呈上升趋势,当NO₃--N比例增至100%时,各指标都低于其它处理,而且后期易脱肥,晾制后叶薄色淡,品质下降;施100% NH₄+-N,中上部叶片成熟推迟,晾制后叶厚色深,产量增加而品质低劣。在当地施肥管理水平下,以施50%~75%的NO₃--N为宜。      

砍收期与白肋烟游离氨基酸含量变化及品质的关系

用日立835-50 型氨基酸自动分析仪,探索白肋烟砍收期游离氨基酸变化及对烟叶品质的影响。结果表明,检测的 16 种氨基酸中,谷氨酸、天冬氨酸、脯氨酸含量较高,三者合计占总量的63.6%～74.33%,其它13 种较低合计占25.67%～ 36.40%。不同砍收期各部位叶总游离氨基酸含量差异较大,下部叶以3 周时最高,5 周时最低,中部叶、上部叶分别是4 周、 5 周最高,均以6 周时最低,三部位平均以4 周最高,5 周最低。砍收期对各部位氨基酸含量的影响为下部叶>上部叶>中部 叶,对丝氨酸、组氨酸、异亮氨酸的影响较大,而对苯丙氨酸、谷氨酸、总游离氨基酸的影响较小。以打顶后下部3 周、中 部4 周（或全整株收晾）、上部5 周收晾,更有利于各部位烟叶品质的提高。