Simple method for determination of dietary fiber in frozen foods

A simple method was developed for the determination of dietary fiber in multicomponent foods. The method involves dispersing the sample into pH 7.4 phosphate buffer and adding bile and pancreatic enzyme as described. Results were comparable to AOAC methods with correlation coefficients of 86% for multicomponent dinners and 89% for breakfast foods. Coefficients of variation ranged from 7.4 to 20.0% for multicomponent foods and 1.0 to 3.6% for single component foods. In addition, blind duplicate samples had a correlation of 0.99. The described method required less time, labor, and manipulation than AOAC methods.     

Determination of total dietary fiber in foods and food products by using a single-enzyme, enzymatic-gravimetric method: interlaboratory study

A simplified enzymatic-gravimetric method for total dietary fiber (TDF) determination has been published and used in the Food Composition Laboratory of the U.S. Department of Agriculture since 1988. THis method gives comparable results to AOAC Official Methods 985.29 and 991.43 but the AOAC methods use 100 degrees C (water bath) to gelatinize the sample and a combination of alpha-amylase and an amyloglucosidase to hydrolyze starches, whereas the simplified method incorporates an autoclaving step (121 degrees C) for gelatinization followed by incubation with only amyloglucosidase. The simplified method omits protease hydrolysis and does not require any pH adjustment. Overall, the simplified method cuts cost and is less labor intensive. An interlaboratory study was conducted to validate this method. Blind duplicates of six sample (baked beans, corn bran, roasted peanuts, cooked potatoes, white bread with reduced calories, and cooked white rice) were sent to 11 laboratories. The reproducibility relative standard deviations of the TDF values (without outliers) ranged from 3.46 to 27.6%. The repeatability standard deviations ranged from 0.91 to 14.6%.     

海绵锆红外吸收法测定氧和氢含量、热导法测定氮含量

应用先进的氧氮氢联测仪,同时完成高纯金属和金属材料中氧、氮、氢含量的测定,分析结果稳定可靠,仪器自动扣除空白值,可设定分析参数,进口标准样品,高纯镍篮,分析精度大且快等特点,可以准确测定海绵锆中微量氧、氮、氢的含量。     

氯化金中金量测定方法的研究

氯化金中金量的测定通常采用还原沉淀法,一般使用草酸作为还原剂,但在草酸还原金的过程中存在着还原不完全、试液外溢等问题。在借鉴国内同行的分析工作经验基础上,提出了以亚硫酸钠替代草酸还原测定氯化金中的金量。该方法与草酸还原沉淀法相比,具有准确、易操作的优点,测定结果令人满意。     

Effect of dietary corn starch intake on ruminal, small intestinal and large intestinal starch digestion in cattle

In Exp. 1, 24 yearling Holstein steers averaging 340 kg were fed either an alfalfa hay diet at a maintenance level of metabolizable energy (ME) intake or corn silage-corn diets at one, two or three times maintenance ME intake. After a 42-day adjustment period, steers were fed individually, and digestibilities of total alpha-glucosides, starch oligosaccharides and glucose were determined at 2-week intervals, with chromic oxide used as an indicator. Steers fed the alfalfa hay diet had higher (P less than .05) total tract digestibilities of total alpha-glucosides and starch than steers fed the corn diets. Fecal starch (percentage of dry matter) in steers fed the corn diets increased (P less than .05) from approximately 11 to 31% as level of ME intake increased from one to three times maintenance. Starch digestibilities for the corn diets fed at one, two and three times maintenance were 81.4, 76.4 and 76.0%, respectively. However, these trends toward reduced starch digestibilities were not significant. There appeared to be no apparent adaption of alpha-glucoside digestibility in the total digestive tract among steers fed different levels of corn over the intervals observed. In Exp. 2, four Holstein steers (350 KH) were each fitted with duodenal and ileal reentrant cannulas and fed either a low or a high level of corn. Alpha-glucoside intakes for animals given the low and high levels of cord averaged 1.7 and 3.2 kg, respectively. Steers fed the high level of corn digested more (p less than .05) alpha-glucoside in the total tract (2.9 vs 1.6 kg), reticulo-rumen (2.3 vs 1.2 kg) and large intestine level of corn. Steers fed the high level of corn also digested more corn in the small intestine (.415 vs .221 kg) than steers fed the lower level; however, differences were not significant. Although there were trends toward lower partial digestion coefficients (expressed as a percentage of alpha-glucoside presented to that segment) in the total tract, reticulo-rumen and small intestine for steers fed the high corn diet, the magnitude of the differences was not significant.     

Phytic acid, in vitro protein digestibility, dietary fiber, and minerals of pulses as influenced by processing methods

In this study we have shown that an antibody to CD18 identified a population of cells in the rabbit retina that resembled the perivascular macrophage found in other regions of the central nervous system. In the normal retina these cells possessed a ramified morphology and presented in an ordered array on the vitreal surface in association with the epiretinal vessels. Approximately 50% of the perivascular macrophages constitutively expressed MHC class II. In response to interleukin-1 beta (IL-1 beta)-induced inflammation, these cells became activated, as evidenced by a change from a ramified to an ameboid morphology and increased expression of MHC class II, and migrated away from the vessels. These changes were first detected around 3 h post-intraocular challenge coincident with the onset of inflammation. At the peak of the inflammatory response (approximately 24 h post-challenge), many activated perivascular macrophages were no longer associated with the vessels and formed long "cord" of MHC class II+ cells associated with underlying deposits of fibrin. In eyes challenged with heat-inactivated IL-1, no change in the morphology or distribution of the perivascular macrophage was noted. At 3 weeks post-challenge with IL-1, the number and distribution of the perivascular macrophages were restored to baseline values, although with a reduced cell size. Since these changes closely resemble those that occur in non-lymphoid dendritic cells in the skin, heart, and/or kidney following activation with cytokines or bacterial products, the results suggest that the perivascular macrophage represents the dendritic cell of the retina and may thus play an important role in immune surveillance in the eye and maintenance of the blood-retina barrier.     

Effect of various commercially available enzymes in the liquid chromatographic determination with external standardization of thiamine and riboflavin in foods

The efficacy of various commercially available enzymes in the determination of thiamine and riboflavin in foods was studied by liquid chromatography (LC) using external standards. Different enzymes, as well as the same enzyme produced by different manufacturers, very strongly affected the determination of both vitamins. The recoveries for different foods ranged from 85 to over 100% for thiamine and from 80 to 100% for riboflavin. The present LC method was accurate and precise when tested on a food and a feed reference material, and coefficients of variation were 5.5% for thiamine and 10% for riboflavin in a rye flour reference material tested for 8 months.     

Effect of dietary fat, fiber, and monensin on cecal activity in turkeys

Two experiments were conducted to determine the physical, chemical, and microbial properties of turkey cecal droppings and relate them to intake of common dietary components, namely fat, fiber, and the anticoccidial, monensin. Experiment 1 involved collection and analysis of physical and chemical properties of cecal and regular droppings from commercial turkey flocks. Experiment 2 tested the effect of dietary fat, fiber, and monensin on growth performance and cecal activity in male turkeys. Compared to regular excreta, cecal droppings analyzed in Experiment 1 were higher in viscosity and fat content, and lower in dry matter, nitrogen, and fiber content (P < 0.05). High dietary fiber and fat significantly (P < 0.05) improved growth performance in Experiment 2. Prolonged feeding of monensin significantly (P < 0.05) reduced cecal evacuation. Results of chemical composition showed that higher dietary fat and fiber significantly (P < 0.01) reduced the fat percentage of cecal contents, whereas prolonged feeding of monensin increased the fat in both cecal contents and droppings. There was no significant effect of any of the treatments on pH, viscosity, and microbial counts of cecal contents. There is the need to identify and characterize the compound responsible for the high viscosity of cecal droppings.     

原子吸收光谱法测定锌精矿中镉不确定度评定

对锌精矿化学分析方法——火焰原子吸收光谱法测定镉量时的不确定度进行评定。根据分析过程,对其不确定度来源进行量化表述,评定原子吸收光谱法测定锌精矿中镉的不确定度。评估出的不确定度范围,适用于评价不同实验室人员或不同实验室之间测定结果的质量。     

New method for determination of free amino groups in intact pure proteins: relationship to available lysine

A new rapid method for the quantitative and routine determination of free amino groups in intact pure proteins has been developed. Primary amino groups are labeled with fluorescamine and the labeled groups are detected by absorption spectroscopy in the range 375-390 nm. The amino group concentration can be determined in a few minutes without hydrolyzing the labeled protein and extracting a lysine derivative. The method was tested with the following proteins: lysozyme, alpha-lactalbumin, beta-lactoglobulin, bovine serum albumin, ribonuclease, ribonuclease-S-peptide, and alphasl-casein B. Application of this method to the estimation of available lysine is discussed.     

Study on determination method of iron content in galvanized coating of zinc-iron alloy

The iron content in the galvanized coating of zinc-iron alloy was determined by atomic absorption spectrometry and two kinds of X-ray fluorescence(XRF) methods.Results show that the chemical method exhibits the highest accuracy.However, this method presents low detection efficiency and is thus unsuitable for production quality control.Fundamental parameter and empirical coefficient methods in XRF can be used for the quality control of iron content in the galvanized coating of zinc-iron alloys.Th...     

Determination of total fat in foods and feeds by the caviezel method, based on a gas chromatographic technique

This peer-verified method specifies a fast, easy, and reliable quantitative method to determine total fat in foods and feeds in compliance with the new definition of fat from the U.S. Food and Drug Administration. The method takes into consideration all fatty acids, from C4 to C24, and when fat is present at 0.3-100%. The validation study included 9 matrixes, with fat levels ranging from 1 to 79%. Sample and internal standard (IS; tridecanoic acid) are added to solvent (n-butyl alcohol). Fat is extracted and simultaneously saponified by potassium hydroxide. The fatty acid potassium salts are converted to fatty acids by adding an acidic aqueous salt solution, which produces a 2-phase system. The upper phase, containing the fatty acids and IS, is injected into the fat determination system. After gas chromatographic separation, the fat content is calculated from IS and fatty acid peak areas. The fat content is automatically converted to triglyceride content with a pre-determined factor. Ten replicates of 9 different food samples, which cover the whole range of different contents in fat, proteins, and carbohydrates, were analyzed by the submitting and the peer laboratories. Repeatability relative standard deviation (RSDr) values ranged from 0.47 to 4.62%. Reproducibility relative standard deviation (RSDR) values ranged from 0.85 to 9.52%. These estimates include between-run variability. The method shows good accuracy. Values for standard reference materials (SRMs) are in agreement with certified values. Regression analysis of the correlation between observed fat and certified value over all matrixes and fat levels indicated good precision and absence of method bias (5 SRMs; 1-30% fat; correlation coefficient, R2 = 99.98%).     

锌铁合金钢板镀层中铁含量的检测方法探讨

采用标准化学法和两种X射线荧光法对锌铁合金钢板镀层中的铁含量进行了测定研究.试验结果表明,对于锌铁合金样板镀层中铁含量的测定,标准化学法是准确性最佳的方法,但是该方法检测效率低,不适用于生产质控检测.X射线荧光法中的基本参数法和经验系数法均可用于锌铁合金钢板镀层中铁含量的生产质控检测,检测重复性分别可达0.2％和0.4％,均优于原子吸收法的0.6％.但是,这两种X射线荧光法均有各自的使用限制,对于不同机组生产的锌铁合金钢板的检测准确性较标准化学法差,需谨慎限制使用.     

An index to predict outcome of surgery for reflux esophagitis based on the AFP classification

Fifteen patients with reflux esophagitis were treated surgically from July 1990 to April 1994. We evaluated these patients using the anatomic-functional-pathologic (AFP) classification both prior to and following the operation. An objective index for surgical outcome was devised. By using the grades Ai, Fj, and Pk, the i2 + j2 + k2 score was determined. The scores ranged from 3 to 22 (mean 9.1 +/- 5.4) prior to the operation. Postoperatively, 12 (80%) of 15 patients showed a complete recovery with a numerical score of 0, and their symptoms also disappeared. The scores of these 12 patients prior to the operation ranged between 3 and 11. However, the other 3 patients did not exhibit a complete recovery. Their scores prior to the operation ranged between 17 and 22, and the symptoms in 2 of these 3 patients persisted following the operation. These results suggest that surgical treatment for reflux esophagitis can be expected to be successful if the preoperative AFP score is less than 11.     

Evaluation and confirmation of an alkylation-gas-liquid chromatographic method for the determination of carbamate and urea herbicides in foods

A method is described for the direct analysis of the urea herbicides linuron, monuron, diuron, chlorbromuron, fluometuron, chloroxuron, and fenuron in cabbage, corn, potatoes, turnip, and wheat at 0.01-1.0 ppm. The samples are extracted with acetone; the filtrate is partitioned with hexane-methylene chloride (1+1) followed by 2 other extractions with methylene chloride. The organic phases are dried and concentrated for column chromatographic cleanup on 2% deactivated Florisil. The column fractions are evaporated just to dryness and redissolved in 10 ml isooctane for high-pressure liquid chromatography on a 25 cm silica gel (5 mum) column. Isopropanol in isooctane is the mobile phase, and compounds are measured by ultraviolet absorption at 254 nm. Recoveries are greater than 80% in most cases. These results are confirmed by alkylation with sodium hydride-methyl iodide in dimethyl sulfoxide to form the methyl products which are analyzed by the same chromatographic system or by gas-liquid chromatography.     

Tandem-in-time mass spectrometry method for the sub-parts-per-trillion determination of 2,3,7,8-chlorine-substituted dibenzo-p-dioxins and -furans in high-fat foods

Phosphorylation of the nucleosome core histone H3 (H3) on Ser-10 is thought to be a prerequisite for chromatin condensation at mitosis. Although during interphase, cell differentiation, or mitogenic activation of quiescent cells, changes in chromatin structure that involve local chromatin condensation/decondensation also occur, little is known about H3 phosphorylation during these transitions. Using the recently developed sensitive marker to monitor H3 phosphorylation, namely, the mAb that recognizes the phosphorylated epitope of H3 (anti-H3-P mAb), the status of H3 phosphorylation was assayed in individual human lymphocytes after their mitogenic stimulation (G0 to G1 transition) and in human leukemic HL-60 cells induced to differentiate by all-trans-retinoic acid (RA), 1,25-dihydroxyvitamin D3 (vit D3), dimethyl sulfoxide (DMSO), or phorbol myristate acetate (PMA). Multiparameter flow cytometry was used to correlate H3 phosphorylation with cell cycle position. The specificity of the anti-H3-P mAb was confirmed by the loss of its binding following cell treatment with alkaline phosphatase. The presence of phosphorylated H3 was detected during interphase in HL-60 cells and in normal lymphocytes at a level severalfold lower than during mitosis. No significant changes in H3 phosphorylation were observed during lymphocyte stimulation. Unexpectedly, the level of H3 phosphorylation was over fourfold higher in monocytes than in lymphocytes or granulocytes from peripheral blood. The punctate pattern of labeling with anti-H3-P mAb in monocyte nuclei suggests that H3 is phosphorylated in small clusters of adjacent nucleosomes. Differentiation of HL-60 cells was accompanied by a rise in H3 phosphorylation, which was higher after induction by RA, vit D3, and PMA (approx. threefold) than after DMSO (approximately 20%). The data indicate that in addition to being a critical event during chromatin condensation at mitosis, H3 phosphorylation plays a role during chromatin changes accompanying differentiation of HL-60 cells, in particular, along the monocytic lineage. The high level of H3 phosphorylation in monocytes may serve as a marker of these cells and is being explored as a possible diagnostic and prognostic tool in monocytic leukemias.     

工业片碱中NaOH含量的一种简便测定方法

提出工业片碱中NaOH含量的一种简便测定方法 ,并探讨了它的合理性