瑞士乳杆菌ND01(L.helveticus ND01)发酵乳中ACE抑制活性和γ-氨基丁酸的研究

从81株分离自新疆地区传统酸马奶中的乳杆菌中筛选到瑞士乳杆菌(L. helveticus)ND01.以该菌发酵1l%脱脂乳,测定其不同发酵时间的ACE抑制活性、游离氨基氮、γ-氨基丁酸(GABA)、pH值、OD值和滴定酸度.测定结果表明:37℃发酵24 h,发酵乳的ACE抑制活性最大值为67.18%;发酵至30h,γ-氨基丁酸的最大含量为165.11 mg/L;该菌株在pH 3.50条件下生长特性良好,具有较强的蛋白分解能力,为开发降血压乳制品提供可行性.     

乳酸菌发酵乳血管紧张素转化酶抑制活力的比较研究

以18种共计61株乳酸菌为研究对象,比较了乳酸菌发酵脱脂乳的血管紧张素转化酶抑制活力(ACE抑制活力),并探讨了ACE抑制活力与pH值、滴定酸度、蛋白水解度的关系。结果表明,乳杆菌ACE抑制活力最强,双歧杆菌次之,链球菌、乳球菌、明串珠菌和片球菌ACE抑制活力很低。ACE抑制活力最高的是Lacto- bacillus helveticus 6024,发酵28 h后ACEI%可达到80%以上,其OPA指数可达到0.800以上,而球菌的ACE抑制活力和蛋白水解能力都很低,甚至检测不到。乳酸菌产酸能力做为一个单一因素与ACE抑制率没有明显相关性(Spearman相关系数r_3=0.526),乳酸菌的蛋白水解能力与ACE抑制率具有显著的正相关性(Spearman相关系数r_3=0.938)。通过对2株产ACE抑制活力高的L.helveticus 6024和L.helveticus T16的研究发现,其共同特点是产酸能力和蛋白水解能力都很强。     

酸奶冻干发酵剂制备中保加利亚乳杆菌不同菌株特性的研究

研究了不同来源的7株保加利亚乳杆菌在乳中的生长与发酵特性、后酸化活性以及抗冷冻干燥特性。结果表明,7菌株在乳中42℃发酵,L.b-S1和L.b-DR凝乳时间最短,为3 h,凝乳后的活菌数、pH值、滴定酸度均无显著差别,活菌数均达1×108 mL-1以上,pH值均达4.5～5.0,滴定酸度均达90～100°T;7菌株在发酵后的酸乳中冷藏期间,L.b-S1和L.b-DR的后酸化活性最低,4℃冷藏21 d,酸度上浮不足10°T,pH值下降0.2～0.4,活菌数下降1个log数量级左右;7菌株在以脱脂乳为保护剂的冷冻干燥试验中,L.b-S1抗冻干性最强,其次为L.b-DR,其冻干存活率分别达31.46%和20.39%。     

Lactobacillus delbrueckii QS701在还原脱脂乳中的生长特性与ACE抑制活性的研究

对Lactobacillus delbrueckii QS701在还原脱脂乳中的生长特性、蛋白水解能力和血管紧张素转化酶(ACE)抑制活性进行测定,还探讨其耐酸、耐胆盐和人工胃肠液的耐受性。结果表明,菌株QS701在10%的还原脱脂乳中37℃培养前期的生长较缓慢,12 h以后生长速度加快;48 h时其生物量、游离氨基氮含量和ACE抑制活性均达到最高值,分别为11.2(OD410 nm×10)、512.8μg/mL Tyr和62.7%。该菌株具有一定的耐酸、耐胆盐能力,经模拟胃肠消化后活菌增长率为37.04%。     

具有高效ACE抑制活性乳酸菌的筛选及其益生特性研究

本研究运用紫外分光光度法初筛,再以HPLC法进行复筛,从31株源自云南传统发酵食品的乳酸菌中筛选具有高效ACE抑制活性菌株,同时研究其益生特性及脱脂乳发酵过程中ACE抑制率的动态变化。综合各项研究结果,最终筛选出ACE抑制率较高、抑菌谱广、耐酸耐胆盐性强,且对抗生素敏感的Lactobacillus plantarum YM-4-3作为研究菌株。益生特性研究表明,该菌株对Escherichia coli O 157:H 7和Listeria monocytogenes的抑菌圈直径可分别达41.30 mm和42.00 mm,甚至在高胆盐(0.3%)及强酸(p H 2.5)处理后仍保持较高活菌数(大于105 cfu数量级)。脱脂乳发酵过程中ACE抑制活性的动态监测表明,37℃发酵48 h是Lb.plantarum YM-4-3菌株发酵产生ACE抑制肽的最适培养条件,该发酵条件下获得的发酵乳的ACE抑制率可高达81.23%,菌体生物量、游离氨基酸及多肽含量也均达到最大值。本研究成果将为新型具有高效ACE抑制活性发酵乳制品的研发提供理论依据及菌株保证。     

产ACE抑制肽菌株的筛选及其在模拟消化道环境中的活性分析

为了筛选出对血管紧张素转换酶（angiotensin-converting enzyme,ACE）抑制活性较高并且具有较强的耐酸耐胆盐和耐盐的乳酸菌,对实验室保存的27株乳酸菌进行了产酸能力、蛋白水解活力、ACE抑制活性、模拟胃肠道消化及酸、胆盐和盐耐受性的测定。结果显示,菌株M3的ACE抑制率可达71.94%±1.39%,具有较好的蛋白水解活力和产酸能力,蛋白水解活力为（86.66±3.51）μg/mL亮氨酸,滴定酸度为（71.67±2.86）°T。菌株M3经人工胃肠液分别处理3 h后,ACE抑制率为74.96%±1.73%;在pH3的环境中3 h,耐受性为14.34%±1.21%,活菌数能达到7 lg CFU mL?1以上;在含有0.3%胆盐的培养基中3 h,耐受性为37.50%±2.47%;在含有4% NaCl的培养基中24 h,耐受性为37.32%±1.84%。该菌经16S rDNA鉴定为Lactobacillus (Lb.) paracasei subsp. paracasei M3。因此,菌株Lb. paracasei subsp. paracasei M3可用作发酵牛乳富产ACE抑制肽且能耐受消化道环境具有益生菌潜力的菌株。     

瑞士乳杆菌与干酪乳杆菌在脱脂乳中发酵特性的研究

研究了瑞士乳杆菌(Lh134)和干酪乳杆菌(Lc134)单独与组合在脱脂乳中发酵32 h的pH、发酵乳酸度值、活菌数和氨基酸态氮变化.结果表明,Lh134在脱脂乳中发酵速度比Lc134快,Lh134和Lc134组合在脱脂乳中的发酵能力高过二者单株发酵,发酵结束时pH下降至3.90,发酵乳酸度达到281.30°T,活菌数...     

双歧杆菌酸奶冻干发酵剂不同菌株特性的研究

研究了不同来源的4株双歧杆菌在乳中的生长与发酵特性、冷藏期间的存活力和后酸化活性以及抗冷冻干燥特性。结果表明:4菌株在乳中42℃发酵的凝乳时间均为6.0h,Blm和Bbm凝乳后的活菌数高,均在1×109cfu/mL以上,而其pH值均在5.0左右,滴定酸度70～80°T,且无显著差别;4菌株在发酵后的酸乳中冷藏期间,Blm和Bbm的存活力高,Blm、Bbm和Blr均表现出较低的后酸化活性;4℃冷藏21d,Blm和Bbm活菌数下降至不足1个log数量级,Blm、Bbm和Blr的酸度上浮不足10°T,pH值下降仅0.2～0.3;4菌株在以脱脂乳为保护剂的冷冻干燥试验中,Blm和Bbm抗冻干性强,其冻干存活率均在30%以上。     

高效表达冷休克蛋白的乳酸菌发酵体系质构特性分析

以高效表达冷休克蛋白C和D的乳酸菌菌株和对照菌株、发酵脱脂乳,通过检测发酵过程体系的胞外多糖产生量,以及发酵体系酸度和质构的变化趋势,从而确定乳酸菌中冷休克蛋白对发酵乳质构特性的影响。结果表明,超量表达菌株在42℃条件下,4 h内的发酵前期,活菌数略低于对照菌株,进入稳定期之后,3个样品的活菌数趋于一致。超长发酵实验的条件下,表达菌株具有一定的自我修复能力,通过抑制产酸,控制环境pH值的改变量,从而更好的适应环境的变化,保持较高的活菌数和菌体活力。高效表达冷休克蛋白C和D的发酵体系,在发酵初期弹性模量和黏性模量均明显高于对照组。发酵后的样品,在全部的频率范围,表达菌株的弹性模量和粘性模量明显高于对照样品。表达菌株的胞外多糖产量一直明显高于对照组,这一结果可以解释质构分析结果中的差异性。     

甘南藏族传统发酵乳中高产胞外多糖菌株筛选及发酵特性研究

采用苯酚-浓硫酸法检测胞外多糖含量,对从甘南藏族传统发酵乳中分离的20株乳酸菌进行筛选。结果表明,菌株MN-002为高产菌株,在12%脱脂乳中产生的胞外多糖为(502.92±17.46)μg/m L。综合培养形态、显微形态、生理生化指标和16S rRNA基因序列分析,鉴定其为嗜热链球菌(Streptococcus thermophilus)。发酵结果显示,在12%脱脂乳中发酵5 h后pH即降至4.6以下,发酵6 h后活菌数达到7.8×10~8 cfu/g,菌株产酸速度快,为产黏菌株,发酵风味突出,且后酸化弱;稳定性研究结果表明,发酵乳在4℃贮藏21 d后,其中的乳酸菌活菌数仍保持在3.2×10~8 cfu/g,在43℃条件下发酵12%脱脂乳7 d后,pH值降至3.65,酸度为140°T,活菌数保持在4.7×10~7 cfu/g,揭示该菌株在酸性发酵乳中具有较好的稳定性。综上,菌株MN-002为一株性能优良、具有良好稳定性的菌株,可作为乳酸菌发酵剂进行进一步开发。     

软烤贻贝中蜡样芽孢杆菌生长/非生长界面模型建立与评价

建立软烤贻贝中蜡样芽孢杆菌标准菌株(ATCC49064与DSMZ 4312)在不同贮藏温度(T)、pH、水分活度(Aw)下生长/非生长界面模型,对其拟合情况和来自软烤贻贝蜡样芽孢杆菌(YB001)的验证情况进行分析和评价,并与已建立的脑心浸出液肉汤(BHI)中蜡样芽孢杆菌生长/非生长界面模型进行比较。所建模型总方程为Lopit(P)=-208.457-2.167·T+35.304·pH+705.573·Bw+1.117·T·pH-7.072·T·Bw-174.946·pH·Bw,其中R2-Nagelkerke=0.979和χ~2=0.019(df=8,P=1)显示拟合度较高,而且其预测一致率明显高于BHI培养基中建立的模型,表明该模型在预测软烤贻贝中蜡样芽孢杆菌的生长/非生长情况有很高的精确度和很好的适用性。此外,贮藏温度、水分活度、pH及其交互作用显著影响蜡样芽孢杆菌的生长/非生长(P0.05)。因此可以通过所建生长/非生长界面模型量化温度、水分活度、pH值等栅栏因子并结合其交互效应来确保软烤贻贝的高品质与安全性。     

三因子金黄色葡萄球菌生长/非生长模型构建

运用统计分析R软件,建立金黄色葡萄球菌在温度、pH、盐浓度3种环境因子影响下的生长/非生长模型,构建的回归模型参数值a_1、a_2、a_3、a_4、a_5、a_6值均低于0.01,具有高度显著的拟合效果。分析各因子不同取值得到的方程式曲线图得出:在温度为10~25℃,pH值为4.5~5.5,盐浓度为0.5%~14.5%时,单因子对金黄色葡萄球菌生长/非生长影响显著;其他选值范围,3种因子协同影响。     

纳米技术与非织造布产业

最近在巴尔的摩召开的由非织造布工业协会与世界纸浆、造纸和印染加工工业技术协会(INDA—TAPPI)举办的国际非织造布技术会议上，人们发现用于非织造布制造的技术种类越来越多，也越来越复杂。随着非织造布工业的发展，围绕非织造布生产的主要工艺流程和原材料的学术     

1993 Industry growth

According to industry tracker Technomic Inc., 1993 food purchases in noncommercial foodservice will increase only slightly, moving up a little less than 1%. While this is greater than the 1992 growth rate of 0.3%, it's still less than half as strong as that of the commercial market.     

Effects of l-arginine on growth hormone and insulin-like growth factor 1

Food Science and Biotechnology - l-Arginine has been reported to promote cellular and organismal growth. In this study, the effects of l-arginine on the expression of growth hormone (GH) and...     

Control of growth and differentiation of the mammary gland by growth factors

Mammary gland development is a complex process regulated by various steroid and polypeptide hormones. Although the systemic importance of hormones, such as estrogen, progesterone, prolactin, and growth hormone, in the growth of the mammary gland has been well documented, these hormones are virtually incapable of stimulating mammary cell growth in vitro. Thus, the growth stimuli for mammary cells requires clarification. In recent years, a number of growth factors have been discovered; this has prompted interest in examining possible involvement of these biologically active agents in the process of mammary gland development. Results presented herein indicate that several growth factors including epidermal growth factor, transforming growth factor alpha and beta, basic fibroblast growth factor, insulin-like growth factor-I, and mesenchyme-derived growth factor participate in the regulation of mammary cell growth and differentiation.     

A simplified approach for modelling the bacterial growth/no growth boundary

A simplified growth/no growth (G/NG) model, conceptually derived from the Gamma model and making direct and explicit use of growth limits of bacteria through a normalization constant (η), was proposed. The η value, which quantifies the product of the cardinal optimal distances for growth probability, is a species-independent constant. This is of importance when experimental data is missing or insufficient. The simplified G/NG model was developed including the effect of temperature, pH and water activity, and was expanded incorporating the preservative effects. As a practical application, the model was investigated for its ability to describe published data. The successful validation of the simplified G/NG model is discussed in regard to its potential applicability as a first estimate method for the development of safe food products.     

乳源性表皮生长因子和胰岛素样生长因子Ⅰ研究进展

主要概述了乳源性表皮生长因子(EGF)和胰岛素样生长因子Ⅰ(IGF-Ⅰ)的发现、来源、结构、理化性质、作用机制及对细胞增殖的影响.     

Muscle growth and exercise

This paper first reviews muscle growth and then considers the influence of exercise in growth. Knowledge about how muscle cells grow and some factors that may influence the growth pattern are discussed first since these effects must be considered before the influence of exercise becomes clear. Growth of muscle can occur in three ways: (1) by an increase in muscle cell numbers, (2) by an increase in muscle fiber diameter, and (3) by an increase in fiber length. All three of these mechanisms are involved in muscle growth. However, growth in cell numbers is limited to the prenatal and immediately postnatal period, with the animals and man being born with or soon reaching their full complement of muscle cells. Thus, growth occurs by either hypertrophy of the existing muscle fibers by adding additional myofibrils to increase the muscle mass or by adding new sarcomeres to the ends of the existing muscle fibers to increase their length. Both of these mechanisms occur during the growth process. Growth in the girth of the muscle fibers appears to take place by splitting of the myofibrils. This may be stimulated by development of stress creating an unequal pressure with splitting at the Z-band and development of additional SR and T-tubule systems. This adds to the diameter or girth of myofibers without any hyperplasia. The growth in length occurs at either end of the fibers and results in addition of new sarcomeres. In both cases, new myofibrillar protein must be synthesized and deposited in the muscle cells. It is suggested that adaptation by adding or removing sarcomeres is physiologically determined by the degree of force a muscle can generate that is in turn dependent on the degree of overlap of the thick and thin filaments. Thus, the amount of tension would control the number of in-series sarcomeres in a single muscle fiber. Nutrition is also known to play an important role in muscle and was discussed from the standpoint of the effects of nutritional adequacy and restriction. Although a nutritionally balanced and calorically adequate diet is required to achieve optimum muscle growth, it may be less efficient in terms of protein deposition than a moderately restricted diet. Muscle and bone deposition, however, can be limited on severely restricting the dietary intake. Although fat deposition is the first tissue to suffer on a severely restricted diet, muscle and bone follow next with the nervous system, brain and eyes being the last systems to be affected.(ABSTRACT TRUNCATED AT 400 WORDS)