β-transcrystallinity developed from the novel ringed nuclei in the glass fiber/isotactic polypropylene composite

Glass fiber (GF) was immersed in diluted acid solution and corroded for 4 h. The interfacial morphology of isotactic polypropylene (iPP) reinforced by the corroded GF was studied via polarized optical microscope. It was found that the corroded GF exhibits anomalous nucleating ability to induce ringed nuclei, and β-transcrystallinity can be developed unexpectedly from these nuclei during isothermal crystallization. The present work provides a novel approach, via which β-transcrystallinity can arise in static condition from the surface of the acid-corroded GF.     

缺氧诱导因子-1α与Wnt/β-catenin信号通路在缺氧胃癌细胞中的相互作用

目的在缺氧环境下,探讨缺氧诱导因子-1α(Hypoxia-inducible factor-1α,HIF-1α)与Wnt/β-catenin信号通路在胃癌细胞SGC-7901中的相互作用。方法将质粒β-catenin-micRNA转染SGC-7091细胞,筛选稳定转染细胞株SGC-7901-β-catenin-micRNA。将SGC-7901细胞分为对照组、脂质体组和阴性对照组,对照组:常氧培养48 h;脂质体组:常氧培养24 h后,加入10μl脂质体,培养24 h;阴性对照组:常氧培养24 h后,转染阴性对照质粒,培养24 h;设稳定转染细胞株为干扰组,常氧培养48 h。采用倍增时间试验、平板克隆形成试验及流式细胞术检测各组细胞倍增时间、平板克隆集落数及细胞周期的变化。另取SGC-7901细胞,分为对照组、缺氧组、双重缺氧组;对照组:常氧培养48 h;缺氧组:常氧培养32 h,物理缺氧培养16 h;双重缺氧组:常氧培养24 h,化学缺氧培养8 h后,再同时物理缺氧培养16 h。同时取稳定转染细胞株,分为对照干扰组、缺氧干扰组和双重缺氧干扰组。对照干扰组:常氧培养48 h;缺氧干扰组:常氧培养32 h,物理缺氧培养16 h;双重缺氧干扰组:常氧培养24 h,化学缺氧培养8 h后,再同时物理缺氧培养16 h。采用RT-PCR和Western blot法检测各组细胞中HIF-1α、β-catenin的mRNA及蛋白的表达水平。结果与对照组、脂质体组、阴性对照组比较,干扰组倍增时间延长,平板克隆集落数减少,细胞阻滞在G1期比例增加,S期减少,差异均有统计学意义(P<0.05)。缺氧组与对照组、双重缺氧组与缺氧组、缺氧干扰组与对照干扰组及双重缺氧干扰组与缺氧干扰组相比,HIF-1α、β-catenin的mRNA及蛋白表达水平均升高,差异有统计学意义(P均<0.05)。缺氧干扰组与缺氧组及双重缺氧干扰组与双重缺氧组比较,β-catenin、HIF-1α的mRNA及蛋白表达水平均降低,差异有统计学意义(P均<0.05)。结论 HIF-1α激活可调控Wnt/β-catenin通路,但也受控于Wnt/β-catenin通路,二者之间相互影响,相互调节。     

Milling behavior of hulled barley and its thermal and pasting properties

Eight commonly grown Indian hulled barley cultivars were studied for their dehusking, pearling, physico-chemical, β-glucan, pasting and thermal behavior. Milling of the hulled barley at 14% moisture significantly lowered the dehusking and pearling time as compared to milling at 10% moisture content. The extraction rate ranged from 55.05% to 62.35% and significantly (p < 0.05) differed among the cultivars. Particle size distribution of flours was significantly different among the cultivars with flour from RD-2552 and RD-2035 cultivars having the most even particle size distribution. The colour difference (ΔE) was not significantly different among cultivars. The extractable β-glucan content varied from 1.93% to 3.81% among the cultivars and was highest in PL-172. The final pasting viscosity was significantly different among cultivars while the pasting temperature did not vary significantly. The enthalpy (ΔH) of gelatinization of barley flour varied from 4.45 to 7.08 J/g and gelatinization temperature (T_p) varied from 64.23 to 66.26 °C.     

Recent advances refining galactooligosaccharide production from lactose

The production of prebiotic galactooligosaccharides (GOS) by the β-galactosidase catalysed conversion of lactose has become commercially important. Yet it remains a challenge to sufficiently understand the structure and activity of β-galactosidase, to increase the efficiency of transgalactosylation and GOS production and to improve the quality of GOS products in a rational way. This review covers the broad but related aspects of GOS synthesis including: the structure and reaction mechanism of β-galactosidase, factors effecting yield and productivity of GOS synthesis systems, the structure of GOS products, models for the kinetics of GOS synthesis and reactor configurations for GOS synthesis. It aims to couple recent discoveries with established knowledge to enhance understanding of the complex biochemistry of GOS synthesis.     

Physical characteristics of fish oil encapsulated by β-cyclodextrin using an aggregation method or polycaprolactone using an emulsion–diffusion method

Fish oils have many dietary benefits, but have strong odours and are easily oxidised. For these reasons, β-cyclodextrin (β-CD) a water-soluble polymer and polycaprolactone (PCL) a water-insoluble polymer were used to encapsulate fish oil in this study. In addition, the stabilities of freeze-dried fish oil (FO) in encapsulated complexes were investigated to determine fish oil release rates at different relative humidities and storage temperatures. In order to facilitate the practical applications of the water-soluble and insoluble fish oil complexes produced, release studies of fish oil were performed in de-ionised water, NaCl solution and fish sauce. Based on our studies, fish oil loaded β-CD at a mixing ratio of 10:20 (β-CD:FO (w:w)) was the best composition in terms of encapsulation efficiency (84.1%), fish oil loading (62.7%), fish oil leakage after freeze-drying (11.0%), and eicopentaenoic acid (EPA) encapsulation efficiency (6.5%). In addition, fish oil release rates from β-CD particles were slower in de-ionised water and in 15% and 25% NaCl than in fish sauce at all mixing ratios between β-CD and FO. The storage stabilities of freeze-dried β-CD–FO complexes at 10:20 (w:w) mixing ratio at various relative humidities retained 97% of fish oil within the particles during 3 days. However, the release rate of fish oil from β-CD–FO complexes of 10:20 mixing ratio was accelerated in fish sauce. In terms of the emulsion–diffusion method, PCL more efficiently retarded the release of FO in liquid or powder form, although particles were broken by freeze-drying. It is supposed that PCL better protected FO because of its water insolubility.     

Microstructure and rheology of β-lactoglobulin–galactomannan aqueous mixtures

The effect of the addition of a galactomannan (locust bean gum, LBG, or tara gum, TG) on the microstructure and rheological properties of a globular protein (β-lactoglobulin, β-Lg) solution was studied at pH 7.0, when the protein bears a net negative charge. Confocal laser scanning microscopy was used to explore the microstructure. Steady shear and dynamic oscillatory measurements were performed with a controlled stress rheometer AR2000 (TA Instruments) fitted with a cone-and-plate geometry. Mixtures were prepared with 6.5 wt% β-lactoglobulin concentration and 0.31–0.82 wt% LBG or 0.23–0.71 wt% TG concentration. All mixed systems were two-phase. The microstructure was clearly dependent on the concentration of the galactomannan in the mixture: the systems evolved from a continuous matrix of β-lactoglobulin enriched phase containing some small inclusions of the galactomannan, to a matrix of galactomannan-enriched continuous phase containing aggregates of β-lactoglobulin. Modifications of the flow and viscoelastic properties with respect to the individual components were clearly evidenced for the mixed systems. Phase inversion detected by microscopy could also be detected by rheology as a modification in the flow/viscoelastic behaviour.     

Crinumin,a chymotrypsin-like but glycosylated serine protease from Crinum asiaticum: Purification and physicochemical characterisation

Plant latex could be a potential source of novel proteases usable in the food and feed industries because of broad substrate specificity with high stability in extreme conditions. Crinumin, a glycosylated serine protease with chymotrypsin-like activity was purified from the latex of Crinumasiaticum using cation-exchange column chromatography. Crinumin shows activity over a wide range of pH (4.5–11.5 and optimum at 8.5), temperature (75 °C and optimum at 70 °C) and is also functional against chaotrophs, organic solvents, and detergents, even after prolonged exposure. The molecular mass (67.7 kDa), extinction coefficient (17.7), isoelectric point (6.9), and numbers of tryptophan (13), tyrosine (24) and cysteine (15 with 7 disulphide bridges) residues were estimated. K_m of the enzyme was 31.7 μM with casein and 5 × 10⁴ μM with N-succinyl-l-phenylalanine-p-nitroanilide. Easy availability of the aqueous latex, simple purification procedure, high yield (33%), stability and activity in adverse conditions makes it applicable for the pharmaceutical and food industries.     

多元线性回归设计玉米须β-谷甾醇的提取

建立了玉米须β-谷甾醇测定方法及热回流提取的多元线性回归模型,实验分别考察了提取温度、时间、液固比及乙醇浓度对β-谷甾醇含量的影响,并通过多元线性回归设计了热回流提取模型。结果表明,β-谷甾醇测定方法准确可靠,可以用于玉米须中的β-谷甾醇的测定。同时乙醇提取玉米须β-谷甾醇多元线性回归模型显著,不失拟。玉米须β-谷甾醇的最佳工艺参数为提取温度45℃、时间80min、液固比25∶1、乙醇浓度75%,其中β-谷甾醇的提取率可达1.52%。     

Screening of microorganisms for bioconversion of (−)β-pinene and R-(+)-limonene to α-terpineol

This work is focused on the bioconversion of (−)β-pinene and R-(+)-limonene to α-terpineol. To carry out the present study, 400 microorganisms were tested for their ability to bioconvert the substrates. From the microorganisms, no one was able to convert R-(+)-limonene and 4 were able to bioconvert (−)-β-pinene to oxygenated monoterpenes. The metabolites recovered were α-terpineol (2856.54 ± 50.23 mg/L) and fenchol (traces) for Aspergillus niger ATCC 16404, α-terpineol (688.13 ± 41.27 mg/L) for A. niger ATCC 9642, α-terpineol (172.07 ± 32.94 mg/L) for A. niger ATCC 1004 and α-terpineol (24.38 ± 2.78 mg/L) and trans-pinocarveol (traces) for Penicillium camembertii ATCC 4845. After screening and optimization experiments, the best experimental condition for bioconversion of (−)β-pinene to α-terpineol was established using A. niger ATCC 16404 at 35 °C without addition of vitamin solution, yielding a conversion in α-terpineol of 15494.34 ± 193.87 mg/L.     

Studies on the usefulness of Cucurbita maxima for the production of ready-to-eat dried vegetable snacks with a high carotenoid content

Recent research indicates a beneficial influence of a diet rich in β-carotene on human health. For that reason, experiments were undertaken to process winter squash with a high carotenoid content into ready-to-eat dried snacks. Sensory quality and dietary value of chips and crispy cubes made from different cultivars were investigated.The suitability of winter squash for drying purposes depended mainly on the dry matter content in the raw material. Although all the investigated cultivars can be used for producing chips, obtaining high quality porous cubes requires at least 15% of dry matter. ‘Justynka F1’ emerged as the most suitable cultivar for processing; both chips and cubes produced from its fruits were characterized by a high sensory quality and contained significant amounts of beta-carotene (225- 253 μg g-1). Also, the cultivar ‘Amazonka’ could be considered for the production of chips as it allowed us to obtain a product with a high beta-carotene content (200 μg g-1) and good sensory properties. The dried ready-to-eat crispy vegetable snacks made from the new cultivars of winter squash could be exploited as a novel attractive product with the attractive taste and colour to serve as a valuable source of carotenoids in human diet.