黑穗醋栗果实多糖的制备、结构鉴定及生物活性研究

以黑穗醋栗果实为原料,采用超声波法提取黑穗醋栗果实粗多糖。利用大孔树脂D4006,阴离子交换剂Q-Sepharose FF和葡聚糖凝胶Sephadex G-100对粗多糖进行分离纯化,得到均一黑穗醋栗多糖(black currant polysaccharide,BCP)。高效液相色谱法测定BCP的重均分子质量为16 329 k D。气相色谱法测定BCP单糖组成及物质的量比为:n(半乳糖醛酸)∶n(鼠李糖)∶n(阿拉伯糖)∶n(木糖)∶n(甘露糖)∶n(葡萄糖)∶n(半乳糖)=0.31∶0.66∶1.63∶0.36∶0.23∶0.31∶1.00。傅里叶变换红外光谱分析表明BCP含有多糖的特征吸收峰,紫外光谱和定性实验表明BCP不含花色苷、蛋白质、核酸和淀粉。刚果红实验表明BCP不具有三螺旋结构。生物活性研究结果表明:在0.2~1.2 mg/m L范围内,BCP对1,1-二苯基-2-三硝基苯肼自由基、·OH、超氧阴离子自由基(O2-·)均有较明显的清除作用,随着质量浓度增大,清除率明显升高。BCP对糖基化反应3个阶段产物(Amadori产物、二羰基化合物和糖基化终产物)的形成均表现出良好的抑制作用,抑制率高于阳性对照氨基胍,且随质量浓度的增加,抑制率升高。BCP对α-淀粉酶具有一定的抑制活性,但抑制效果低于阳性对照阿卡波糖。     

Biological activities and physicochemical properties of Maillard reaction products in sugar–bovine casein peptide model systems

The purpose of this study was to evaluate the biological activities and physicochemical properties of Maillard reaction products (MRPs), derived from aqueous reducing sugar (ribose, galactose and lactose) and bovine casein peptide (BCP) model systems. The fluorescence intensity of ribose-BCP MRPs reached the maximum value within 1 h, while it took 3 h for galactose-BCP MRPs. Size exclusion chromatography of all the MRPs indicated molecular rearrangements and production of new smaller molecules, as a function of the heating time. The consumption of ribose and amino groups was the highest in the ribose-BCP MRPs. BCP lost its known angiotensin-I-converting enzyme (ACE) inhibitory activity by the Maillard reaction with reducing sugars. Ribose–BCP MRPs had the lowest ACE inhibitory activity, but they showed the highest 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging activity and ferrous reducing power among all the MRPs. Galactose-BCP MRPs inhibited, slightly the growth of Caco-2 cells, while ribose-BCPand lactose-BCP MRPs had no cytotoxicity.     

QUANTIFICATION OF YEAST FLOCCULATION

A sedimentation method based in the Helm's flocculation test was improved. In this method, all steps were standardised: initial cell concentration, agitation, sampling and determination of settled cells. The results obtained with the sedimentation test do not differ significantly (P = 0.05) from those obtained with the Stratford test; besides, the precision of the two methods do not differ significantly (P = 0.05). The results presented clearly demonstrated that the method improved in this work is rigorous for quantification of yeast flocculation and allows the differentiation of flocculation ability of the strains. The respective micro-flocculation tests were also compared; Stratford micro-flocculation test was selected as producing the most meaningful results.     

Single‐cell gel electrophoresis: a tool for investigation of DNA protection or damage mediated by dietary antioxidants

One method of assessing DNA damage is the comet assay, which was developed in 1988. The comet assay enables the detection of DNA strand breaks in individual cells. This test has also been used to study the in vitro and in vivo genotoxic or genoprotective effects of certain agents such as dietary antioxidants. This paper aims to consolidate the antioxidant and pro‐oxidant effects of a series of dietary agents which have been evaluated by comet assay. Copyright © 2007 Society of Chemical Industry     

Effect of Existence of Exogenous Protein on Physicochemical Properties of Heat- and Transglutaminase-induced Bovine Collagen-peptide Gel

ABSTRACT: The combined influence of preheat treatment, mixing with various proteins, and the addition of microbial transglutaminase (MTGase) on the physicochemical properties of bovine collagen-peptide (BCP) gel was investigated. The preheat treatment and the mixing with various proteins contributed to the enhancement of the gel strength and polymerization of BCP. The gel made with 0.1% MTGase showed the highest breaking strength. The melting point of the preheated BCP gel was higher than that of the unheated one ( P < 0.05). The gel made with a combination of preheated BCP-casein or preheated BCP-soybean protein showed a higher melting point than that made with preheated BCP alone ( P < 0.05). The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern of the mixture of preheated BCP with casein or soybean protein showed that the protein bands with relatively low molecular weights disappeared and the bands with relatively high molecular weights increased. Observation by a scanning electron microscope revealed that the preheated BCP gel prepared with MTGase had a well-defined cross-linked network and showed some clumps of aggregated proteins. These results show that preheating, mixing with other proteins and MTGase treatment, are effective ways to make BCP a fine biopolymer.     

Controlled release of sorbic acid from bacterial cellulose based mono and multilayer antimicrobial films

Biodegradable bacterial cellulose (BC) based films, incorporating sorbic acid (SA) as antimicrobial agent, have been obtained. Monolayer films, prepared using powdered BC (BCP) and poly(vinyl) alcohol (PVA), were coated with BC membrane to obtain multilayer films. Tests indicated that both SA and BCP concentration influenced sensitivity to water, release rate and antimicrobial ability of mono and multilayer films. Swelling degree, water vapour permeability and water solubility increased with SA content, but decreased with BCP addition. However in case of multilayer films, water solubility was negligible. Colour measurements indicated no degradation of SA during film preparation. The release of SA was faster when BCP concentration was higher but significantly slower, as a consequence of formed crystals dissolution, when antimicrobial concentration was increased. Furthermore, compared to the results for the monolayer films, an important decrease of SA release rate through the multilayer films was determined. The antimicrobial effect was tested against Escherichia coli K12-MG1655. The results obtained indicated that the new biocomposite films could be promising antimicrobial food packaging materials.     

Hot air-assisted radio frequency drying of black carrot pomace: Kinetics and product quality

This research investigated the application of combined hot air and radio frequency drying technology on the drying efficiency and the quality of black carrot pomace (BCP). Electrode gap (8, 9 and 10 cm), thickness (2, 3 and 4 cm), weight (500, 750 and 1000 g) and compaction density (0.44, 0.66 and 0.88 g/cm³) were the parameters studied to determine the drying characteristics of the pomace by hot air-assisted radio frequency (HARF) drying system. Electrode gap of 8 cm and thickness of 2 cm, weight of 500 g and compaction density of 0.44 g/cm³ were identified as the ideal HARF drying conditions. HARF drying shortened the drying time by 39% compared to conventional hot air (HA) drying. Six different mathematical models were used for describing the drying characteristic of BCP. The effective moisture diffusivities were estimated by two approaches: the diffusion equation method and the method of slope for HARF drying and HA drying methods. HARF drying provided the dried products with better color, phenolic content, anthocyanin content and antioxidant capacity.Industrial relevanceBlack carrot pomace is an industrial waste left after the juice extraction from black carrot. The most common utilization way of this valuable by-product is to use it as animal feed. The reason behind this fact is the difficulties in drying of a high moisture bulk material in huge quantities produced in winter season. If it is not dried on time, it gets fermented and become useless for the separation of valuable components such as anthocyanin, pectin and fiber. So, a fast and efficient drying method and its characterization is essential for the utilization of this valuable by-product.     

基于细胞融合开发双基因共敲除技术

基因编码工具(例如CRISPR/Cas9)的出现使敲除哺乳动物细胞基因成为现实.然而,实现细胞的多基因敲除成功率低且所需时间长.细胞融合技术是构建杂合细胞的常用方法,通过融合两种不同表型的细胞,构建出一种具有杂合表型的新型细胞.但是,由于基因的互补作用,通过基因敲除而获得的性状在细胞融合后成为隐性性状,融合细胞不能表现...     

Bacteriophages BCP1-1 and BCP8-2 require divalent cations for efficient control of Bacillus cereus in fermented foods

Bacillus cereus is a foodborne bacterial pathogen that causes diarrhea and vomiting. In this study, the usefulness of bacteriophages to eradicate B. cereus from fermented foods was investigated. A total of 13 phages were isolated from Korean fermented food products, and 2 (BCP1-1 and BCP8-2) were further characterized. Transmission electron microscopy (TEM), restriction enzyme digestion pattern analysis, and SDS-PAGE of the structural proteins suggest that both phages belong to the family Myoviridae, containing approximately 150 kbp-long genomes. The host ranges of both phages were limited to B. cereus group species (12/13), as they were not able to lyse other Gram-positive or negative strains including Bacillus subtilis. Purified phages were used to inhibit B. cereus growth in a model fermented food system, cheonggukjang, a fast-fermented soybean paste product. BCP1-1 and BCP8-2 were able to effectively eradicate B. cereus from the food only if divalent cations (Ca²⁺, Mg²⁺, or Mn²⁺) were added to the medium. Further studies reveal that divalent cations are essential for phage adsorption, while a monovalent cation (Na⁺) is required for the post-adsorption phase of phage infection. Taken together, our findings imply that a phage could be an ideal anti-bacterial agent for use in fermented food products that require the presence of beneficial microflora and, during phage application, optimization of phage reaction conditions is critical for the successful utilization of phage biocontrol.     

Inter-laboratory comparison study for pyrrolizidine alkaloids in animal feed using spiked and incurred material

Pyrrolizidine alkaloids (PAs) are hepatotoxic metabolites produced by plants. PAs in animal feed can cause acute or chronic intoxications in animals and can be transferred to milk. An inter-laboratory comparison study among 12 laboratories, using their own methods of analysis, was conducted for the detection and quantification of PAs in animal feed. The participants were asked to quantify PAs in a blank test sample, a blank test sample to be spiked with a provided spiking mixture of seven PA standards, and a test sample contaminated with common groundsel (Senecio vulgaris). Ten of the participating laboratories used an LC-MS/MS method, one used an LC-ToF-MS method, and one used a GC-MS method. None of the laboratories reported false-negative samples, while two laboratories reported false-positive results in the blank sample. z-scores were calculated for each laboratory for seven PAs in test samples B and C. z-scores varied considerably between laboratories for the concentrations of the free bases and less for the N-oxides, probably due to the lower levels of the free bases as compared with the N-oxides in the contaminated feed. Questionable or unsatisfactory results for the z-scores were obtained for 8% of the cases for the spiked sample and for 12% of the incurred sample. Three laboratories scored consequently positive or negative results. No preferred method for quantification of PAs in feed could be identified within the methods used for this study due to the relatively small number of participants. It was concluded that this inter-laboratory study shows that the methods used for PA detection need further development for accurate estimation of PAs in contaminated feed.     

Validation of the integrated upward–horizontal–downward wicking test for providing intensive properties of textile fabrics

Traditional wicking tests provide information that is specific to the test fluid, apparatus, and conditions. As a result, this information cannot be used to make predictions about wicking rates beyond the respective test parameters. In contrast, a new upward–horizontal–downward (UHD) wicking test has been presented that provides intensive properties of fabrics in the form of permeability (k) and effective capillary radius (R _c) as functions of saturation (S). The UHD test was developed using water as the test fluid. If the k–S–R _c relationships are truly intrinsic to a given fabric, then they should not depend on the test fluid. Here, we conducted the UHD test on a knit fabric using three different test fluids characterized by different surface tensions, densities, and viscosities: dodecane, tetradecane, and hexadecane. All fluids fall on the same k vs. S and k vs. R _c curves, proving that these curves are intrinsic characteristics of the fabric. We then used the k–S–R _c properties to successfully predict the in-plane horizontal and downward wicking rates of two different fluids, octanol and water, in the fabric. These results validate the UHD wicking test as a method for providing intensive properties of textile fabrics which can then be used for predicting wicking rates.     

山西老陈醋中优势产酸菌的分离纯化及功能分析

该研究从山西老陈醋发酵过程中分离纯化得到3株优良产酸菌,分别为巴氏醋杆菌(Acetobactor pasteurianus)BCP0454、短乳杆菌(Lactobacillus brevis)BCP0738、枯草芽孢杆菌(Bacillus subtilis)BCP0449。从形态学鉴定、分子生物学鉴定等方面对菌株进行鉴定;采用高效液相色谱与气相色谱质谱法对菌株发酵液中所产有机酸和风味物质进行探究。结果表明:BCP0454具有较好产有机酸的能力,并且所产乙酸含量相对较高,达到4885.25 mg/100 mL,产风味物质17种,并且羧酸类和醛类物质含量较高;BCP0738能同时产生乳酸和乙酸,总量为1225.79 mg/100 mL,并且能够产生风味物质23种,其中酯类物质含量最高达到51.70%,并且能产生吡嗪类物质1种;BCP0449能够产2种有机酸,总量达到了2108.24 mg/100 mL,产乙偶姻的含量达到33.55 μg/100 mL,同时能够产生3种吡嗪类物质。     

Differential fluorescent staining of Listeria monocytogenes and a whey food soil for quantitative analysis of surface hygiene

The accurate monitoring of surface cleanliness in terms of bacterial contamination is usually carried out using methods such as plate counts or replica plating. However these methods take at least eighteen hours to obtain results and do not determine the presence or amount of residual organic material on a surface, which may interfere with cleaning and disinfection. This work describes the application of fluorescent stains to cells (Listeria monocytogenes) and food soil (solubilized whey) to optimize a dual staining method that can be used in the quantitative analysis of surface cleanability. Seven different stains were tested at a range of concentrations (0.3%–0.001 mg/ml) and application methods. The best stain combination for differential staining of L. monocytogenes and whey food soil was 0.1 mg/ml rhodamine B with 0.1 g/ml DAPI. Differential staining of the cells and soil occurred regardless of the application method. This method has been successfully used to demonstrate the hygienic status of surfaces in an industrial situation. This novel work enables quantitative assessment of soils and cells on surfaces.     

Enzymatic Determination of Trimethylamine and Its Relationship to Fish Quality

An enzymatic procedure was developed to determine trimethylamine (TMA) in fish muscle extracts. The method utilized TMA dehydrogenase extracted and purified from Hyphomicrobium X and gave excellent correlations with the pick acid and HPLC methods. The minimum detectable TMA level was 0.05 μmoles. The entire enzymatic procedure required 15–20 min to complete. The method may be used in the laboratory as a spectrophotometric analysis or may be used semi-quantitatively as a visual color comparison test outside the laboratory. The method greatly simplifies the procedures for TMA determination and enables the estimation of microbiological quality of fish with very little laboratory equipment.     

RAPA: a novel in vitro method to evaluate anti‐bacterial skin cleansing products

Development of efficacious anti‐bacterial skin cleansing products has been limited by the availability of a pre‐clinical (in vitro) method to predict clinical efficacy adequately. We report a simple and rapid method, designated as rapid agar plate assay (RAPA), that uses the bacteriological agar surface as a surrogate substrate for skin and combines elements of two widely used in vivo (clinical) methods (Agar Patch and Cup Scrub). To simulate the washing of the human hand or forearm skin with the test product, trypticase soy agar plates were directly washed with the test product and rinsed under running tap water. After air‐drying the washed plates, test bacteria (Staphylococcus aureus or Escherichia coli) were applied and the plates were incubated at 37°C for 18–24 h. Using S. aureus as the test organism, anti‐bacterial bar soap containing triclocarbanilide showed a strong linear relationship (R² = 0.97) between bacterial dose and their per cent reduction. A similar dose‐response relationship (R² = 0.96) was observed for anti‐bacterial liquid hand soap against E. coli. RAPA was able to distinguish between anti‐bacterial products based on the nature and level of actives in them. In limited comparative tests, results obtained by RAPA were comparable with the results obtained by clinical agar patch and clinical cup scrub methods. In conclusion, RAPA provides a simple, rugged and reproducible in vitro method for testing the relative efficacy of anti‐bacterial skin cleansing products with a likelihood of comparable clinical efficacy. Further testing is warranted to improve the clinical predictability of this method.     

乌鸡精、乌鸡肽和乌鸡汤蛋白质含量及相对分子质量分布的比较

文中对乌鸡精、乌鸡肽和乌鸡汤蛋白质含量及蛋白质相对分子质量分布区间进行了比较。结果表明:乌鸡肽总蛋白质含量为84.18%,酸溶蛋白质含量为83.10%,明显高于乌鸡精和乌鸡汤;乌鸡肽的小分子蛋白质含量更高,相对分子质量140-1 000的占92.59%,更利于人体的吸收。     

Evaluation of dermal toxicity of antibacterial cotton textile coated by sol-gel technology

This paper reports about cotton textile modification by sol-gel technology with the purpose of obtaining antibacterial properties, evaluation of antibacterial properties and dermal toxicity tests of cotton textile with Zn and Si coating. Antibacterial properties evaluation against pathogenic microorganisms Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli made using the Parallel streak method in accordance with ATCC147 standard. For more specific evaluation of the coated textile, in vitro cytotoxicity test with epidermal HaCat cells was done. It is concluded that the coatings containing Zn and Si obtained by the sol-gel technology can impart antibacterial properties against pathogenic bacteria to the textile by preventing the bacteria from growing; strong inhibition of growth was detected for all test microorganisms. Based on the dermal toxicity test results, it is not expected that the prolonged contact of the skin with coated textiles will have a negative impact on the skin tissue – epidermis.     

Improved Method for Mastitis Detection and Evaluation of Disinfectant Efficiency During Milking Process

In automatic milking systems, rapid methods to detect mastitis and also to prevent mastitis are very important since reduced milk quality and economic losses are the consequences of mastitis. Based on IDF Standard 148 a rapid and reliable method to detect somatic cell count with Coulter Counter technique was developed in this study and the efficiency of peracetic acid (PAA) to prevent bacterial cross-contamination was investigated using Escherichia coli as test microorganism. Besides conventional microbiological methods, flow cytometric analysis using carboxyfluorescein diacetate, thiazole orange, propidium iodide and DiOC₂(3) were applied using E. coli as test organism to study the efficiency of PAA. Acceleration of mastitis detection method was realised using centrifugation for lipid separation of foremilk samples before Coulter Counter measurements. During inflammation, an increase in somatic cell count was detected by Coulter Counter with a peak at particle sizes between 8 and 12 μm. E. coli was reduced by 5.6 log cycles, 7.7 log cycles and 4.9 log cycles after 0.25% PAA treatment for 15 s at 0 °C, 10 °C and 20 °C. However, flow cytometric analysis showed that most of the cells are damaged but still have metabolic activity. The efficiency of PAA against mastitis-related bacteria was shown with plate count methods but flow cytometric analysis indicates that the cells may still have the potential to cause mastitis. The potential of Coulter Counter to detect somatic cell count within a short time was shown in this study. Important data regarding safety monitoring and quality control can be derived with this method.     

Evaluation of the EEC four-plate test and Premi test for screening antibiotic residues in trout (Salmo trutta)

The four‐plate test (FPT) method was used for the determination of sulfadiazine/trimethoprim residues in trout in the European Community (EC). This microbiological inhibition test used three media seeded with Bacillus subtilis at different pH values (6, 7.2 or 8.0) and a fourth medium seeded with Micrococcus luteus. The Premi test was also used for the determination of sulfadiazine/trimethoprim residues in trout. The effects of a trout muscle supernatant on detection limits of antibiotics with microbiological inhibition tests were measured. The supernatant was applied directly on top of the paper disks impregnated with aqueous antibiotic solutions. Inhibition zones were compared with those obtained by the same standard solution of sulfadiazine/trimethoprim without the trout supernatant. The detection limit of penicillin, sulfadimidine, streptomycin groups of antibiotics were determined for checking the test plates. For supernatant from fish fed with pellets containing antibiotics (sulfadiazine/trimethoprim), the inhibition zones increased according to the duration of the feed application. In the control group, no inhibition zones were detected. The concentration of the residues accumulated and reached a plateau after 5 days. The antibiotics were detectable in the same concentration as on day 7, but three days later (on day 10) they were no longer detectable in the fish samples. In contrast to the ‘FPT’, 3 days after discontinuing the medicated diet, there were still residues detectable by ‘Premi test’ on day 10. Data is presented that shows that the FPT and the Premi test methods are very useful for the determination of sulfadiazine/trimethoprim residues in trout.     

ACCELERATED STORAGE TESTING OF FREEZE-DRIED IMMOBILIZED LACTOBACILLUS ACIDOPHILUS-FERMENTED BANANA MEDIA

ABSTRACT

Freeze‐drying was applied as a drying method for the production of dehydrated immobilized Lactobacillus acidophilus‐fermented banana medium containing high levels of probiotics and appropriate prebiotic (mainly fructooligosaccharides) contents in an attempt to develop dried synbiotic products. Ca‐alginate and κ‐carrageenan were used for the immobilization of L. acidophilus, and the immobilized bacteria were employed directly in the banana media fermentation. The fermented products were then freeze‐dried. Results indicated that cell immobilization could provide effective protection to L. acidophilus, and reduce the damage caused by freezing and freeze‐drying. Meanwhile, accelerated storage testing using temperatures of 50, 60 and 70C was applied to the dehydrated products. Gel‐entrapped L. acidophilus appeared to have lower decimal reduction, and Ca‐alginate immobilized cells had a better survival than κ‐carrageenan. Results of accelerated storage test showed that immobilization could effectively increase the thermal resistance of entrapped microorganisms, and Ca‐alginate showed a better effect than κ‐carrageenan, and the beneficial effects increased with the decrease of the storage temperature. The freeze‐dried products exhibited little hygroscopicity because of the consumption of monosaccharides during fermentation. Results revealed that freeze‐drying could be used as a proper method for the development of dried product of immobilized L. acidophilus‐fermented banana media, and accelerated storage test could be used to evaluate the storage stability of the dried products.

PRACTICAL APPLICATIONS

This research demonstrates the feasibility of the application of accelerated storage testing to the prediction of shelf life and storage stability of freeze‐dried probiotic products manufactured by lactic acid bacteria fermentation. The Arrhenius equation was associated in this study. This will provide an efficient approach for the estimation of shelf life of probiotic products.