蛋白质水解度测定方法综述

对目前国内外常用的蛋白质水解度测定方法进行了综述，其中pH—state方法是通过滴定水解过程中释放的质子测定DH；OPA、TNBS及国内常用的水合茚三酮和甲醛等测定方法是利用游离氨基的反应测定DH。     

SEROLOGIC IDENTIFICATION OF SPECIES OF ORIGIN OF SAUSAGE MEATS

SUMMARY: A partially purified immunoglobulin G (lgG) solution prepared from the serum of species to be tested was heated to the specifications for sausages. The resulting supernatant fluid was decanted and the precipitate washed with saline and used to immunize rabbits. The supernatant fluid was used to sensitize tanned sheep red blood cells. The immune serum was rendered monospecific by absorptions with heterologous, heated lgG precipitates. A sample of monospecific immune serum was absorbed with a washed homogenate of sausage. Aliquots of the monospecific immune serum, both untreated and sausage absorbed, were tested with cells sensitized with the homologous heated lgG supematant fluid. A significant reduction of titer by sausage absorption indicated that the sausages contained the meat homologous to the immune serum.     

聚多元羧酸盐的合成及应用

研究了聚多元羧酸盐的合成方法及反应机理,将其应用于洗涤剂和PVC制品中分别代替三聚磷酸钠和邻苯二甲酸二丁酯,证明有良好效果。     

STABILITY OF AQUEOUS EMULSIONS OF THE ESSENTIAL OIL OF HOPS

Hop oil emulsions prepared from different varieties of hops have been found to exhibit enhanced physical stability on the addition of blends of the emulsifiers Span 20/Tween 80 or Span 60/Tween 60. Examination of the particle size and volume distributions of an emulsion by use of a Coulter Counter was found to be an excellent method of monitoring its stability. An indication as to the relative efficiency of emulsifiers can be obtained from Coulter Counter measurements on hop oil emulsions after storage for 4 days. The use of an ultracentrifuge provies a rapid means of testing emulsion stability and hence the effectiveness of emulsion stabilizers.     

BASIS OF STABILITY OF AMINE SALTS OF LINOLEIC ACID

SUMMARY— The mechanism and generality of the known stabilization against autoxidation conferred on linoleic acid by certain basic amino acids, such as lysine and arginine, was investigated. Basic amino acids were the only class of compounds found to confer the effect. However, the smallest basic amino acid, 2,3-diaminopropionic acid, was not effective, nor was αβω-diaminc acid, 3,6-diaminohexanoic acid, although a simple isomer of lysine. The stabilization was observed only in the solid phase. Inclusion of sodium chloride in the solid matrix was deleterious to the effect. A large number of physical and chemical observations were made and correlated but it has not been possible to draw detailed conclusions about the mechanism of stabilization, nor can a detailed structure of the stabilized complex be suggested. The cause of the phenomenon appears to be closely associated with the physical arrangement of the ions in the crystal lattice.     

ANALYTICAL CHARACTERIZATION OF THE PRODUCTS OF NONENZYMATIC GLYCOSYLATION OF LYSOZYME

The quantitative analysis of the reaction products of the water activity dependent nonenzymatic glycosylation of lysozyme was not straightforward. Difficulties arose in the determination of the number of bound glucose molecules because glycosylation leads to glucose mediated protein aggregation, and the likely presence of a mixture of relatively labile Schiff-base intermediates, and the more stable ketoamine products generated by Amadori rearrangement. Polyacrylamide gel electrophoresis was used to monitor protein aggregation; periodate oxidation, nuclear magnetic resonance (NMR), and oxalic acid hydrolysis combined with HPLC, emerged as the most promising methods to quantitate the degree of glycosylation. Possible interpretations are advanced to explain the apparent discrepancies in degree of glycosylation suggested by the different analytical methods evaluated.     

DETERMINATION OF THE FILTERABILITY OF BEER

A method for the determination of the filterability of beer has been evaluated by members of the European Brewery Convention Analysis Committee. The method is based on the filtration of a beer sample, with a standard amount of diatomaceous earth (DE), under standardised conditions. Repeatability of the test was quite good, however the predictive value of the test is still questionable since no direct correlation could be established between the different filtercake values and industrial filtration problems. No collaborative test was performed as the filterability has to be determined on unfiltered beer; the test is easy to run, and as for the other filterability tests, day to day practice in a brewery will reveal its usefulness.     

影响大豆分离蛋白乳化稳定性测定的几种因素研究

采用离心法对影响大豆分离蛋白乳化稳定性的测定结果的几种因素进行了研究。通过研究得出如下结论：对乳化稳定性影响最大的是油相体积分数，然后依次是蛋白质溶液浓度、pH、离子强度、离心速度。在测定的范围内，均质速度、均质时间、水浴加热时间、加热温度和离心时间对测定结果的影响都很小。     

STABILITY OF ESSENTIAL OIL OF HOPS

The stability of hop essential oil in beers, in hops and in aqueous emulsions has been investigated. Hop character of beers treated with hop oil emulsion has stability on pasteurization and storage similar to that of dry hopped beers. When bottled with high levels of headspace air, beers lose hop character. Beers dry-hopped with stored hops or with hops damaged during pelleting tend to develop sulphury flavours. However, hop oil emulsions prepared from such hops give rise to a sound hop character in beer. Hop oil emulsion produced by the new process shows good stability physically, chemically and biologically, particularly when mechanically homogenized and stored under an inert atmosphere. The extent of any chemical alteration due to contact with air may be estimated spectrophotometrically.     

EFFECTS OF TYPES OF FAT AND OF RATES AND TEMPERATURES OF COMMINUTION ON DISPERSION OF LIPIDS IN FRANKFURTERS

ABSTRACT— The effect of time, temperature and rpm of comminution of emulsions was determined on the dispersion of approximately 25% of beef fat, pork fat or cottonseed oil in frankfurters. The numbers of lipid particles 5 μ or less in diameter increased in frankfurters containing either beef or pork fat as comminution was continued to higher temperatures, with pork fat dispersed more thoroughly. Fat tended to separate from frankfurters containing beef fat in particles 200 μ or more in diameter. In contrast, no specific degree of dispersion of particles 5 μ or less in diameter consistently indicated emulsion stability, or its lack. Increased rpm during comminution produced an increased dispersion of beef or pork fat. Under the same conditions pork fat was dispersed more finely than beef fat. Dispersion of cottonseed oil produced finely dispersed particles beyond the resolution of light microscopy, as was confirmed by electron microscopy which showed a substantial number of particles to be less than 1 μ in diameter.     

灵芝不同部位多糖含量测定

采用苯酚-硫酸法对灵芝菌盖表皮层、木栓层、菌柄、孢子粉、发酵菌丝体等部位中的灵芝多糖进行了测定,结果发现,灵芝发酵菌丝体中的多糖含量明显高于灵芝的其它部位,其含量顺序分别为：发酵菌丝体〉菌盖表皮层〉孢子粉〉菌柄〉木栓层。     

TERMINOLOGY OF THE TEXTURE OF CREAM

An enquiry among experts into the use of terms to describe subjectively assessed properties of double cream (48% fat) showed that ‘body’, ‘texture’ and ‘homogeneity’ were the most important and widely used, though inadequately defined. Only ‘body’ appeared to be analogous to a rheological property; ‘texture’ and ‘homogeneity’ appeared to refer to small scale and large scale structures.     

EFFECT OF COMPOSITION OF GLUTHNIN SUBFRACTIONS ON RHEOLOGICAL PROPERTIES OF WHEAT

Gluten extracted from defatted flours of cv. Aubaine (extra‐strong), Hereward (strong) and Riband (weak) was separated into five different fractions (R2 to R6) by sequential centrifugation and addition of sodium chloride. A seven‐minute mixing time was used to carry out fractionation on the basis of depolymerization of glutenin macropolymers (GMP). Depolymerization of GMP occurred at much higher rates in dough of the weak cultivar compared to the strong and extra‐strong cultivars. Polypeptide compositions of different ghttenin fractions were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis under reduced and non‐reduced conditions, followed by densitometric scanning of stained patterns. The amount of HMW‐glutenin subunits decreased and LMW‐glutenin subunits increased correspondingly in each cultivar with the fractionation from R₂ to R₆. The rheological behavior of the fractions was analyzed by small deformation rheological tests (strain sweep and frequency tests). The high molecular weight fraction (R₂) from extra‐strong wheat had a higher vahte of G' and a lower tan δ value as compared to strong and weak bread‐making wheats. The moduli of HMW glutenin fractions (R2 and R3) were frequency independent and promoted the network properties, whereas moduli of LMW glutenin fractions were frequency dependent and gave rise to a plasticizing effect. Therefore, it was concluded from the present studies that HMW‐glutenin subunits are not the only factors governing good bread‐making quality but their proportions in relation to low molecular weight glutenin subunits is equally important in sinking a balance between viscous and elastic properties essential for bread making performance.     

棉浆粕制备条件对粘胶生产适用性的影响

本文论述了过低的棉短绒成熟度会引致粘胶生产过程压榨困难和过滤障碍。描述了在蒸球内设置中通管、来用重蒸轻漂、稳定漂白聚合度、以及漂后的除杂疏解等先进的工艺制造棉浆粕，有助于反应性能的提高，改善粘胶的过滤性能。但打浆时过分切断使纤维长度过短，会影响碱纤维素的压榨。采用干毯抄浆、浆粕存放（一段时间）均有助于浆粕水份均匀性的提高。     

KINETICS OF THERMAL SOFTENING OF VEGETABLES

The rate of softening in several canned vegetables during the retort process was studied. The rate of softening is consistent with two simultaneous first order kinetic mechanisms; mechanism 1 acting on substrate "a" and mechanism 2 acting on substrate "b". The rate constants for mechanism 1 are 20 times or more greater than the rate constantsfor mechanism 2. Approximately 85% to 97% of the firmness of the raw commodity is contributed by substrate "a" and the remaining firmness is contributed by substrate "b". Mechanism 1 is probably due to pectic changes in the interlamellar layer. The biochemical nature of substrate 2 is a matter of speculation. The apparent Arrhenius activation energies range from 5.1 to 35.0 Kcal/mole. The data indicates that softening kinetics of vegetables is more complex than has been formerly assumed.     

针刺法非织造布针刺密度工艺参数的计算

介绍了针刺法非织造有针刺密度的计算公式及其变换，以及计算尺的使用，以利于生产者方便应用。     

高产EPA和DHA藻株的筛选

为筛选出高产EPA和DHA藻株,针对8种海洋微藻进行培养,测定了它们的最佳吸收波长和生长曲线一藻体在对数期末期收获．经过提取脂肪,进行皂化酯化处理后用气相色谱测定EPA和DHA的含量。结果筛选出EPA高产藻株为新月菱形藻,EPA产量为16mg／L占粗脂肪重的26％,占细胞干重的3．3％;等边金藻为DHA高产藻株,DHA产量为3．2mg／L,占粗脂肪重的9．1％,占细胞干重的5．2％。     

KINETICS OF OSMOTIC DEHYDRATION OF MANGO

The effects of sucrose syrup concentration (40–70 g/100‐g solution) and temperature (40–90C) on water loss and sucrose uptake by mango mesocarp slices during osmotic dehydration were investigated. The effective diffusivities for mass transfer were determined using the slope method based on the Fickian diffusion model. Water loss and sucrose uptake were proportional to the square root of osmotic contact time, implying that the process is Fickian. The specific mass transfer rate constants and effective diffusivities (D_e), derived from Fick's unsteady‐state diffusion equation, increased with temperature and sucrose syrup concentration. D_e values for water loss and sucrose uptake, which ranged between 2.59 × 10^?6 to 5.12 × 10^?6 m²/h and 1.70 × 10^?6 to 4.14 × 10^?6 m²/h, respectively, were related to absolute temperature using an Arrhenius‐type relationship. The activation energies, which fell in the range previously reported for diffusion‐controlled processes, increased with sucrose syrup concentration and varied from 9.74 to15.16 KJ/mol.     

INFRARED SPECTROSCOPIC DETERMINATION OF DEGREE OF UNSATURATION OF FATS AND OILS

SUMMARY– Infrared spectra of various fats and oils were determined. Ratios of absorbance at 3.3μ (olefinic C—H stretching band) to absorbance of other characteristic triglyceride absorption bands were calculated. Relationships between these ratios and unsaturation, as estimated by iodine value, were determined. Analyses of 25 fats and oils showed that the ratio of absorbance at 3.3μ to absorbance at 3.5μ (aliphatic C—H stretching band) and iodine value were linearly related and exhibited a correlation coefficient of 0.98. Estimation of degree of unsaturation of 19 additional fats and oils revealed an average deviation of ± 0.97 iodine value units or ± 1.12% between measured values and values calculated from infrared absorption patterns.     

APPLICATION OF CRYOSCOPY FOR THE MEASUREMENT OF ENZYMATIC HYDROLYSIS OF LACTOSE

In an earlier report we proposed a new rapid method based on the measurement of the depression of the freezing point of a solution due to the hydrolysis of lactose. In addition, this report describes the influence of acidification on the accuracy and the reproducibility of this method.