PURIFICATION AND CHARACTERIZATION OF TRYPSIN FROM PYLORIC CAECA OF BIGEYE SNAPPER (PRICANTHUS MACRACANTHUS)

Trypsin from the pyloric caeca of bigeye snapper was purified and characterized. Trypsin had an apparent molecular weight of 23.8 kDa when analyzed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) and substrate‐gel electrophoresis. The trypsin fraction consisted of three isoforms as evidenced by the appearance of three different bands on native‐PAGE. Optimal activity was observed at 55C and pH range of 8–11. The activity of trypsin fraction was completely inhibited by soybean trypsin inhibitor and was partially inhibited by E‐64 and ethylenediaminetetraacetic acid. CaCl₂ partially protected the trypsin fraction from activity loss at 40C, while NaCl (0–20%) decreased the activity in a concentration‐dependent manner. The apparent Michaelis–Menten constant (K_m) and catalytic constant (k_cat) were 0.312 mM and 1.06 s, respectively when Nα‐Benzoyl‐dl ‐arginine ρ‐nitroanilide was used as a substrate. Trypsin from the pyloric caeca of bigeye snapper generally showed similar characteristics to other fish trypsins.     

碱法分离大米蛋白和淀粉工艺的优化及其产品功能性质研究

本文以籼米为原料，研究了碱法提取分离大米蛋白和淀粉的工艺，并对大米分离蛋白和大米淀粉的功能性质进行了研究。确定了碱法分离大米蛋白和淀粉的最佳工艺条件：氢氧化钠溶液浓度为0．075mol／L；提取时间6h：料液比1：7g／mL；温度40℃。该优化条件下可以得到纯度高于80％大米分离蛋白，蛋白提取率为86．23％，淀粉回收率为92．12％。所得大米分离蛋白溶解性、起泡性好，乳化性能欠佳。     

硫酸酯化香豆胶的制备、表征及其性质

通过单因素和正交试验获得硫酸酯化香豆胶的优化工艺参数:香豆胶添加量为7 g,反应温度为0℃,浓硫酸添加量为3mL,正丁醇添加量为6mL.红外光谱分析表明,该条件下硫酸基已经与半乳甘露聚糖结合成酯.酯化后的香豆胶分子粒径减小,黏度降低,且随取代度的增大而下降,表现出较好的溶解性、透明度.冷水溶和热水溶硫酸酯化香豆胶溶液的表观黏度都随浓度的升高而呈指数规律的上升;酯化香豆胶溶液为非牛顿流体,随着温度的升高,表观黏度下降,具有耐热性;酯化香豆胶溶液在碱性条件下较为稳定;冻融处理可使酯化香豆胶溶液的表现黏度下降.     

CHEMICAL AND SENSORY CHARACTERIZATION OF COMMERCIAL SAUERKRAUT1

Canned sauerkraut from eight U.S. companies was analyzed for salt, titra-table acidity (TA), fermentation substrates and end products, volatile sulfur compounds and sensory characteristics. The TA ranged from 0.9–1.5%, while salt content ranged from 1.4–2.0%, which was lower than in previous surveys. High performance liquid chromatography (HPLC) was used to monitor lactic, acetic, malic, succinic, propionic and butyric acids; mannitol, ethanol, propanol, glycerol, glucose, fructose and sucrose. Low concentrations of propionic acid, propanol and glycerol were found. These three compounds are not characteristic of lactic acid fermentations. No butyric acid was detected. GC analysis revealed seven main sulfur compounds (hydrogen sulfide, methanethiol, dimethyl sulfide, carbon disulfide, dimethyl disulfide, allyl isothiocyanate (AITC) and dimethyl trisulfide) and six other organic compounds (methanol, ethanol, n-propanol, 2propanol, acetaldehyde and ethyl acetate) in the headspace of sauerkraut juice. A profile panel characterized aroma, flavor and after-taste of sauerkraut with ten distinct notes. The sour, sulfur and salt notes had the greatest impact on sauerkraut flavor.     

CHEMICAL CHARACTERIZATION OF DIFFERENCES BETWEEN ALES AND LAGERS

The chemical identification of the substances responsible for differences between ales and lagers has been investigated, using new as well as established techniques. The two types of beer are broadly similar in composition, but lagers are characterized particularly by higher levels of certain sulphur compounds, and ales by higher levels of certain heterocyclic compounds. Several compounds have been identified for the first time as beer components.     

磷酸酯渗透剂R的制备与性能

采用辛醇与Ｐ２Ｏ５合成磷酸酯,再与多种表面活性剂复配成的渗透剂Ｒ浊点〉１００℃,耐碱１００ｇ／Ｌ,低泡,渗透力≤５ｓ;经常州第一绒线厂染色试验,经纱着色增深１０％～２０％,染槽液无泡沫,成本低,综合性能优于ＪＦＣ。     

PREPARATION AND CHARACTERIZATION OF SEVERAL FISH BONE COLLAGENS

As a part of the study regarding an effective use of underutilized resources, type I collagen was prepared from several fish bones and partially characterized. The yield of collagen was fairfy high with values ranging from about 41 to 54% on the basis of lyophilized dry weight. The pattern of lysyl endopeptidase peptide fragments from fish bone collagen obtained from different fish specie were very similar. However, the submit structures were quite different and were as follows: Japanese sea bass; (α1)₂α2, horse mackerel; (α1)₃ and ayu; α1 α2 α3. These results suggest a wide distribution of molecular forms in fish bone collagen.     

酸性染料可染改性聚酯的制备及表征

以层状硅酸盐作为改性剂,采用插层聚合法制备层状硅酸盐改性聚酯复合材料,采用DSC,热失重、红外、WXRD、熔融指数仪等考察了改性聚酯的结晶性能、热稳定性、红外光谱特性以及流变性能等。研究结果表明:改性聚酯与纯PET的红外谱图基本没有变化;改性聚酯的DSC升温曲线没有出现冷结晶峰,可能是生成了PET/层状硅酸盐聚合物,形成了多元混合体系,从而使得体系不容易结晶;与纯PET相比,改性聚酯的熔点、热稳定性较纯PET有所提高。由广角X射线衍射计算得到的改性聚酯的微晶尺寸在各个晶面上都有所增大。改性聚酯对酸性染料的上染率有一定的提高,但与PA6的上染率相比仍有差距。     

PREPARATION AND CHARACTERIZATION OF PEPSIN-SOLUBILIZED TYPE I COLLAGEN FROM THE SCALES OF SNAKEHEAD (OPHIOCEPHALUS ARGUS)

Pepsin-solubilized collagen prepared from the scales of snakehead ( Ophiocephalus argus ) was separated into two fractions, major and minor, by NaCl precipitation. The results of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), amino acid composition, and secondary structure showed that the major collagen was typical type I collagen; in contrast, the minor collagen might be classified as type V collagen from the SDS-PAGE patterns and precipitation properties by NaCl. A sharp decrease in solubility of type I collagen was observed at the NaCl concentration of 40 g/L. The maximum and the minimum solubilities of collagen were observed at pH 3 and 8, respectively. Peptide maps of type I collagen digested by trypsin and V8 protease were different from those of calfskin and fish skin collagens. The imino acid content of type I collagen was lower than those of mammalian collagens and so did its denaturation temperature that was 30.3C obtained by viscosity measurement.

PRACTICAL APPLICATIONS

Collagen has been widely utilized as a material for foods, cosmetics, and pharmaceuticals. However, the use of collagen-derived products from land animals (e.g., bovine and pig) has been called into question because of foot-and-mouth disease crisis etc. Aquatic animal offals, which are readily available and inexpensive, seem to be safe sources for extraction of collagen. This work reports on preparation and characterization of collagen from snakehead scales, which will have potential in supplementing the skins and bones of land animals as an important collagen resource for use in functional food, biomedical, and cosmetic industries.     

CHARACTERISTICS OF MUSCLE FROM TWO SPECIES OF BIGEYE SNAPPER, PRIACANTHUS TAYENUS AND PRIACANTHUS MACRACANTHUS

Composition and some properties of muscle from two species of bigeye snapper, P. tayenus and P. macracanthus, were investigated. Both species had a similar composition with the same myofibrillar protein content. However, muscle proteins from P. tayenus had higher thermal stability than those from P. macracanthus, as indicated by the higher enthalpy for transitions as well as the lower inactivation rate constant (K_D). Upon 15 days of iced storage, natural actomyosin Ca^2*‐ATP ase and Mg²⁺‐Ca²⁺‐ATPase activities decreased, whereas Mg²⁺‐EGTA‐ATPase activity increased, suggesting the denaturation of myosin, actomyosin and troponin/tropomyosin complexes, respectively. Increased surface hydrophobicity and decreased sulfhydryl groups indicated the denaturation possibly occurred via hydrophobic interaction and disulfide formation. Heading and eviscerating offish retarded the denaturation and physicochemical changes of proteins during iced storage. The results indicated that a rapid and proper post harvest handling was of importance to maintain the muscle quality of bigeye snapper.     

氨基改性羟基硅油乳液的制备与性能

采用氨基硅烷602对乳液聚合的羟基硅油进行改性，经氨基改性的羟基硅油乳液兼具羟基硅油的平滑和氨基硅油的柔软，乳液稳定性好。     

QUANTIFICATION AND SOME CHEMICAL AND BIOCHEMICAL CHARACTERIZATION OF NITROGENOUS SUBSTANCES FROM VARIETIES OF COMMON BEANS (PHASEOLUS VULGARIS, L.).

Crude protein, extracted protein, and nonprotein nitrogenous substances were quantified in 55 varieties of common dry beans. Crude protein (% N x 6.25) on a dry basis varied from 23.01 to 35.22%, with a mean value of 28.51%. Methionine varied from 0.40 to 1.73% of the crude protein with a mean value of 0.80%. The ratio of globulin/albumin ranged from 1.00 to 3.31. Thirty percent of the total nitrogen was of low MW and was lost in the dialysis (MW cut off 8,000 daltons). Electrophoretic patterns (PAGE) revealed from 3 to 11 bands in the globulin fraction and 4 to 11 in the albumin fraction. Trypsin and chymotrypsin inhibitory activity was much higher in the albumin fraction than in the globulin fraction. The globulin fraction from most of the varieties was more inhibitory against trypsin than chymotrypsin. On the other hand, in the albumin fraction of the majority of the varieties the activity was stronger against chymotrypsin. Hemagglutination titer for 57 varieties ranged from 1024 to 32. Eight varieties had titers of 1024 and only four had titers of 32.     

反应性氨基硅油微乳液的制备与性能

讨论了反应性氨基硅油微乳液的制备工艺及其结构与性能之间的关系，通过乳液聚合方法制备了反应性氨基硅油微乳液。结果表明：经其整理的织物手感丰满、柔软滑爽，回弹性优异。     

PURIFICATION AND CHARACTERIZATION OF A PHYTASE FROM SPELT

Four soluble phytases were identified in germinating spelt. Although numerous purification strategies were applied, none of the four phytases could be purified to homogeneity. The purest phytase preparation, called D21, contained a phytase (major component) and an acid phosphatase (APH) (minor component). The phytase behaves like a monomeric protein of a molecular mass of about 68 kDa and shows a broad substrate specificity. Optimal pH for degradation of phytate was 6.0 and the optimal temperature 45C. Kinetic parameters for the hydrolysis of Na-phytate were K_M 400 μmoll^?1 and k_cat 368s^?1 at pH 6.0. The spelt phytase D21 degrades phytate stepwise.     

ISOLATION AND CHARACTERIZATION OF BACTERIOCIN-PRODUCING MICROORGANISMS FROM AGOS-OS

Agos-os, a fermented meat and sweetpotato mixture, was produced and analyzed for its microbial characteristics. pH decreased during fermentation. Mold and anaerobic bacterial counts increased while yeasts and aerobic bacterial counts decreased during the third and seventh day of fermentation. Six isolates with the widest zones of inhibition on the indicator lawn were selected for bacteriocin production. These isolates had exactly the same morphological, physiological and biochemical characteristics. The ribosomal RNA sequence was 99.5% identical with Enterococcus faecalis VRE 1492. The identification was confirmed through DNA homology test by the EMBL Genbank, Canada. This bacterium produced the L-isomer lactic acid. The amount of bacteriocin produced by the bacterium was optimized by growing the bacterium at different growth media, initial pH and fermentation time. Maximum production of bacteriocin was achieved in MRS (De Man Rugosa and Sharpe) medium (with glucose) at pH 7.50. The crude bacteriocin inhibited the growth of gram-positive bacteria such as Lactobacillus sake 15521 and Listeria innocua. The gram-negative bacteria such as Escherichia coli DH 5-alpha (with plasmid, PUC) , Salmonella typhii and Staphylococcus aureus were weakly inhibited. Other microorganisms such as Lactobacillus curvatus D31685 , Lactobacillus confusius M23036 , Lactococcus lactis MG1363 , Leuconostoc paramesenteroides S67831 , Pediococcus pentosaceus M58834 , Saccharomyces cerevisiae SS553 (wild type) and Escherichia coli JM109 (no plasmid) were not inhibited.