Estimation of theaflavin content in black tea using electronic tongue

Biochemical components like theaflavins (TF) play very important role in the quality of finished CTC (cut, torn, and curled) variety of tea. TF are known to provide characteristic astringency to the taste of finished CTC tea. The quality indicators like brightness, briskness, strength, color and overall quality of tea liquor are also due to the amount of TF present. A positive correlation is normally observed between the amount of TF and the quality scores of finished tea. Biochemical tests that yield the percentage of TF are often time consuming, require meticulous effort of sample preparation, storage and measurement. This paper proposes an alternative approach of quality evaluation of CTC tea by predicting the amount of TF that may be present in a given tea sample, using a voltammetric electronic tongue.     

Production of podophyllotoxin by plant cell cultures of Podophyllum hexandrum in bioreactor

Submerged cultivation of Podophyllum hexandrum for the production of podophyllotoxin was carried out in a 3l stirred tank bioreactor fitted with a low-shear Setric impeller. The specific requirements of the medium, such as carbon source (sugar) and light, were established for the growth of and podophyllotoxin production by P. hexandrum in suspension cultures. Substitution of sucrose by glucose resulted in higher growth and podophyllotoxin production. The biosynthesis of podophyllotoxin was favored when plant cells were cultivated in the dark. An agitation speed of 100 rpm was sufficient to mix the culture broth in the bioreactor without causing any significant cell damage. Biomass and podophyllotoxin accumulation in 3 l bioreactor under batch growth conditions were 6.5 g/l and 4.26 mg/l, respectively, in 22 d. This resulted in an overall podophyllotoxin productivity of 0.19 mg/(l.d), which represented an increase of 27% in comparison to its productivity in a shake flask. Podophyllotoxin production was found to be a combined growth-associated and non-growth associated process.     

Removal of E. coli from water using surface-modified activated carbon filter media and its performance over an extended use

Modification of activated carbon (AC) by aluminum hydroxychloride (AHC), and diatomaceous earth by zinc hydroxide changed the zeta potentials of these filter media from negative to positive. The modification method is amenable to room temperature, and eliminates the essential requirement of strong base treatment for making metal hydroxide coated filter media. Solid-state MAS 27Al NMR spectra suggested the presence of Al13-mer in the AHC-treated AC. AHC-modified AC samples were further treated with silver halide, and two antibacterial compounds to prevent microbial growth on filter media. In situ precipitation of silver bromide on AC resulted in formation of nanosized AgBr crystals. Bacteria removal performances of the modified media were tested in columns. For the first time, we demonstrated that only 30 g of either AHC-treated AC (60 x 200 mesh) or nano AgBr supported AC could provide >6 log E. coli removal over approximately 1000 L when the input water had a bacterial load of 10(7) CFU/mL. The filter media were robust enough to perform even when water was passed at superficial velocities 3-10 times the typical velocity (6 cm/min) of water treatment processes. Metal leaching from the modified media was found to be less than the USEPA specified Maximum Contaminant Level.     

Flavour production in plant cell cultures of basmati rice (Oryza sativa L)

Callus cultures of naturally flavoured rice (Oryza sativa var 370) called basmati were obtained on Murashige and Skoog medium with 2,4-dichlorophenoxyacetic acid and kinetin. There was a perceptible basmati flavour in fresh callus. The volatile flavour components of basmati rice and callus were obtained by steam distillation-solvent extraction and were analysed on GC-MS. A qualitative comparison of volatile flavour components of callus cultures and natural basmati rice was also made. The results show the presence of 29 major compounds in rice and 23 in callus. The identified compounds include hydrocarbons, ketones, aldehydes, alcohols and esters. This demonstrated the potential of callus of basmati rice for flavour development.     

Estimation of rubber content of guayule (Parthenium argentatum) using low-resolution proton magnetic resonance

Low-resolution proton magnetic resonance (p.m.r.) has been investigated as a rapid screening method for the determination of rubber in guayule. Regression equations have been derived relating p.m.r. measurements to rubber content in the original material and in acetone extracted material, and to the amount of rubber extracted. Linear relationships have been established for all three variables with r² values of 0.92, 0.94 and 0.92 (P < 0.001) respectively. Sample pretreatment was found to be important, with grinding and heating resulting in a loss of rubber, as determined by both p.m.r. and extraction.     

响应面法优化植物抗氧化剂降低培根亚硝胺残留量的工艺

为探讨植物抗氧化剂降低培根中亚硝胺残留量的最适添加量,在单因素实验的基础上,采用Box-Behnken响应面法研究了培根腌制风干过程中茶多酚添加量、葡萄籽提取物与亚硝酸钠添加量对亚硝胺的影响,模拟得到了二次多项式回归方程的预测模型。结果表明植物抗氧化剂能有效降低亚硝胺残留量,最佳添加量为:茶多酚310mg/kg,葡萄籽提取物420mg/kg,亚硝酸钠120mg/kg。在此条件下,N-二甲基亚硝胺的残留量为0.325μg/kg,与模型预测值0.3395μg/kg吻合良好,说明优化出的回归方程对于生产实际有一定的理论指导意义。     

Differentiation of intracellular peptidases of starter and adjunct cultures using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Selection of starter and adjunct cultures is important to minimize bitterness of Cheddar and Gouda cheeses. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry may be useful for rapid screening of cheese cultures for propensity to produce bitter cheese. The objective of this study was to demonstrate the application of MALDI-TOF for differentiating intracellular peptidase activities of starter and adjunct cultures on β-CN f193-209 under simulated cheese condition. Bovine β-casein was incubated with chymosin in 9.55 g/l citrate buffer (pH 5.4, 40 g/l sodium chloride) at 30°C for 24 h, followed by incubation with cell-free extract (CFE) of starter or adjunct culture. Mixed strains of Lactococcus lactis ssp. lactis and L. lactis ssp. cremoris designated as 56 and 105 were the sources of nonbitter and bitter starter cultures, respectively. Lactobacillus helveticus WSU-19 and W900R represented adjunct cultures having high and low debittering activities, respectively. The degradation pattern of β-CN f193-209 by CFE of WSU-19 indicates general aminopeptidase and endopeptidase activities, while degradation of the peptide by CFE of W900R, 56, and 105 are mainly from endopeptidase activity. The rates of β-CN f193-209 hydrolysis by CFE of WSU-19, W900R, 56, and 105 are 6.90, 0.38, 0.39, and 0.23 mg/l per h, respectively.     

植物油中脂肪酸成分的调查与分析

通过对植物油中脂肪酸成分的调查,了解多种不同植物油中的脂肪酸含量及组成比,从而为研制符合国家推荐的脂肪酸比例的保健调和油提供数据参考。方法:取一定量的油脂样品,通过碱法甲酯化后用气相色谱分析。结果:实验结果显示,植物油中含有大量的不饱和脂肪酸,主要为油酸和亚油酸,同时还发现存在少量的共轭亚油酸,而饱和脂肪酸则以棕榈酸和硬脂酸为主。在不饱和脂肪酸中n-6/n-3的比值除了亚麻子油和精炼菜子油分别为0.44、2.84以外,其他植物油的比值均较高,从11.15到286.37不等。     

Estimation of circulating bovine leukemia virus levels using conventional blood cell counts

Bovine leukemia virus (BLV) is widely prevalent in Japanese dairy farms. To control BLV infections in Japan, segregating or managing cows according to their proviral load (PVL) is a rational strategy. This study was conducted to establish a quantitative procedure for estimating blood PVL per microliter using a statistical model to offer a cost-effective alternative to the conventional quantitative real-time PCR method. In total, 250 Holstein cows infected with BLV were identified from 10 commercial dairy farms. Information on age was collected and blood samples were tested for white blood cell and lymphocyte counts and PVL using PCR. Generalized linear models with quasi-Poisson errors were used to estimate PVL by selecting age, logarithm of lymphocyte count, and their interaction term as explanatory variables. To evaluate the model, blood samples of 92 BLV-infected Holstein cows from 2 other commercial dairy farms were tested, and measured PVL values were compared with estimated PVL values by the model. The logPVL per microliter was modeled by positive associations with log lymphocyte count and age and a negative association with the interaction term. In the evaluation, measured PVL values had a strong correlation with estimated PVL values (Spearman's ρ = 0.87). In conclusion, our model provides a cost-effective and more rapid alternative to the conventional method to facilitate test and segregation or management of BLV-suspected cows.     

Estimation of viable Salmonella cell numbers in meat and meat product using real-time PCR

Recently we developed a novel method for estimating viable Salmonella cell numbers by means of a 5'-nuclease real-time PCR [Fujikawa et al., J. Food Hyg. Japan, 47, 151-156 (2006)]. The method was based on the increase kinetics of the target DNA region (inv A) of the microorganism growing in a culture medium during incubation. The index for the PCR was the threshold cycle. In this study, we validated the method for application in food. Namely, Salmonella cells spiked into ground chicken, pork, and beef and raw hamburger patty at various cell concentrations were cleaned up using buoyant density centrifugation and the Salmonella cell numbers were estimated with our method. Linear decreases in the threshold cycle value were observed during incubation of the samples. The standard curves for the cell number in all food samples were almost identical. With a standard curve using the mean parameter values, we successfully estimated viable Salmonella cell concentrations of the foods. The results indicate that our method is applicable for viable cell number estimation of the target microorganism in foods. Further, we used this method to study Salmonella growth in ground chicken stored at a constant temperature.     

Changes in water content of high plus hydrogel lenses worn on an extended wear basis in a geriatric aphakic population.

PURPOSE: To investigate the water content of hydrogel lenses of relatively high plus power hydrogel lenses after 3 months extended wear and compare values with unused lenses. METHOD: Geriatric aphakic extended wear soft lens patients were fitted with one of four different brands of hydrogel lenses (A) Incanto 78 (Cantor and Nissel, UK), (B) PSL72 (Prospect lenses, UK), (C) ES70 (Ocular Sciences), (D) Proclear (Coopervision). After 3 months continuous wear the lens was removed and water content (WC) was determined at both lens surfaces using an Abbé refractometer. The water content was also measured for 40 unused lenses (+10 to +20D, 10 lenses per brand). RESULTS: One hundred and thirty-two lenses were checked after 3 months extended wear. Mean (+/-S.D.) WC values for front (f) and back (b) surfaces of worn and unworn lenses were, respectively, (A) Worn (n=45): f 73.2(4.13) b 73.8(4.33); unworn f 80.5(0.68) b 81.1 (0.80). (B) Worn (n=37); f 70.5(4.49) b 70.9 (3.89); unworn f 72.5(0.94) b 72.3 (0.89). (C) Worn (n=34); f 68.3(3.18) b 68.4(3.63); unworn f 70.6 (0.48) b 71.1 (0.55). (D) Worn (n=16); f 63.4(3.68) b 63.3(3.19); unworn f 60.9 (1.56) b 61.5 (1.92). There was a significant correlation between WC measured from front and back surfaces (p < 0.01). In worn A-C lenses, front surface WC tended to be lower than back surface WC. For lenses A and C at both surfaces the WC of worn lenses was significantly lower than unworn lenses (p < 0.05). For lens D, mean WC of worn lenses was significantly higher than unworn lenses (p < 0.05). In 80% of B lenses, surface WC of worn lenses were significantly lower than WC of unworn lenses (p < 0.05). There was no relationship between WC and lens power. CONCLUSION: On average, A and C lenses tended to desiccate but D lenses tended to swell as did 20% of B lenses. The front surface of worn lenses measured lower water content than the back surface suggesting the front surface is drier than the back. This apparent difference in water content between the surfaces could be an artefact emanating from differential rates of surface deposition.     

分光光度法对超浓缩粉中磷含量的测定研究

在常用的分光光度法基础上对超浓缩洗衣粉中磷酸盐进行定量测试研究。采用条件试验法进行了标准溶液吸取量、显色剂加入顺序、显色剂加入量、选取分析试样的探索,用正交试验法对试样称取量、加入的ＨＮＯ３量、煮沸时间、试液吸取量等各种因素进行优选,探索出了适用于超浓缩洗衣粉中磷酸盐的定量分析方法,准确率达９９％以上。     

Determination of the phosphorus content in potato starch using an energy-dispersive X-ray fluorescence method

Potato starch is unique because of its high starch phosphorus content. The textural characteristics of potato starch change due to the presence of the starch phosphate. Thus, the measurement of phosphorus in potato starch is needed, but conventional methods require a considerable amount of time and labour. In this investigation, a simple and fast analytical procedure has been developed for the determination of the phosphorus content of potato starch with a non-destructive energy dispersive X-ray fluorescence (ED-XRF) technique. Potato starch samples were analyzed as pressed pellets using detection times of 200 s. Reference values, measured by a conventional method, namely, wet chemical analysis, were used to calibrate the ED-XRF. Calibration was done using 20 potato starch samples, and the results were validated using a second set of 15 samples. The results indicated the validity of ED-XRF as a rapid and non-destructive method for the quantitative determination of phosphorus content of potato starch. Based on the combined results of ED-XRF and Rapid Visco-Analyzer (RVA), ED-XRF is promising for predicting the peak viscosity, by RVA, of potato starch paste through the measurement of starch phosphorus content.     

浸出油厂废水中溶剂含量的测定

开发了一种测定废水中溶剂含量的方法.将样品放入密封的平衡瓶中,在一定温度下,使溶剂汽化达到平衡,取液上气体注入气相色谱中测定,与标准曲线比较定量,取得了理想的分析结果.     

Estimation of residual energy intake for lactating cows using an animal model.

Residual energy intake is defined as the remaining energy from total net energy intake after accounting for all energy uses. Residual energy intake is proposed as a measure of feed efficiency because animal efficiency increases as the proportion of accountable energy intake increases or the residual energy intake decreases. Residual energy intake was estimated for each of 247 Holstein cows, daughters of 127 sires and 226 dams distributed in five herds across the US. Data consisted of daily milk production and net energy intake, biweekly measures of milk components, and BW measures taken at varied intervals throughout a lactation. Average daily net energy intake in a lactation was the dependent variable in a model that contained fixed effects of parity and herd-season subclass; covariates of lactation average daily SCM, metabolic BW, and weight change in a lactation; and random animal effect. From this model, residual energy intake was a sum of animal and residual effects. Partial energy requirements for SCM, maintenance, and weight change estimated for all cows were .54, .15, and 1.52 Mcal/kg, respectively. Heritability estimate for residual energy intake was .016; phenotypic standard deviation was 2.455. The proportion of the phenotypic standard deviation in net energy intake that was due to residual energy was 68%.     

Estimation of water sampling rates and concentrations of PAHs in a municipal sewage treatment plant using SPMDs with performance reference compounds

Semipermeable membrane devices (SPMDs) were exposed at ten sampling points, each representing a different stage in the treatment process, in a municipal sewage treatment plant. Differences in SPMD uptake kinetics of polycyclic aromatic hydrocarbons (PAHs) due to variations in conditions at the sampling sites were evaluated by using five performance reference compounds (PRCs) with log K(ow) values of 4.20 to 6.34. PRC release rate constants (k(e,PRC) values) were calculated for PRCs for which 50-98% of the initial amounts were lost during the sampling period. The k(e,PRC) values were high, ranging from 0.08 to 0.11 day(-1) for the studied PRCs, at sampling site W1 (raw sewage), the only sampling site where significant amounts of the PRCs with log K(ow) values > 5 were released from the SPMDs. At the other sampling sites, only PRCs with log K(ow) values between 4.20 and 4.50 were released in significant amounts. The release rates at these sites were lowest (0.04 day(-1)) at sampling site W9 (the secondary clarifier) and highest (0.18 day(-1)) at W8 (the active sludge aeration basin). Differences between sampling rates (R(s)) obtained using published laboratory-calibrated data and PRC-corrected R(s) values were visualized by principal component analysis (PCA). The water concentrations of 24 studied PAHs fell substantially during the course of the sewage treatment process. However, low molecular weight PAHs were more effectively removed than high molecular weight PAHs. Significant deviations between actual and estimated water concentrations may arise unless PRC-corrected R(s) values are applied.     

Enhanced cell aggregation and liver functions using polymers modified with a cell-specific ligand in primary hepatocyte cultures

Hepatocytes cultured as multicellular aggregates called spheroids exhibit enhanced liver functions and maintain them over a long period compared with monolayer culture. We previously reported the induction of hepatocyte spheroids using the synthetic polymer Eudragit (a copolymer of methacrylic acid and methylmethacrylate) as an artificial matrix in a cell suspension system (Yamada et al., J. Biochem., 123, 1017-1023, 1998). In this method, hepatocyte aggregation was promoted by the effects of electrostatic and hydrophobic interactions between cells and the polymer. To enhance the cell aggregation ability and cell-specificity of the polymer, in the present study, we prepared hepatocyte-targeting polymers containing lactone, a ligand of the asialoglycoprotein receptor. Addition of the lactone-modified polymers to the medium promoted cell aggregation and spheroid formation more effectively than unmodified Eudragit. The spheroids induced by the polymers exhibited enhanced liver functions, i.e., albumin secretion, ammonia removal, and urea synthesis, from early in the culture. We also investigated the induction of hetero-spheroids composed of various liver constitutive cells by this method. The hetero-spheroids induced by the polymers showed improved liver functions.