Characterisation of Italian commercial apricot juices by high-performance liquid chromatography analysis and multivariate analysis

The modern fruit juice industry needs their products to be characterized by high-quality attributes to meet consumers’ expectation. In this view, the composition of 26 Italian commercial apricot juices obtained from organic, integrated and conventional agriculture was analysed for carbohydrates, organic acids, amino acids, phenolic compounds and furanic compounds by high-performance liquid chromatography (HPLC). The content of 5-hydroxymethylfurfural in apricot juices (range 0.1–18 mg/l) was within the regulatory limit of 20 mg/l. The lack of furanic compounds in apricot fresh fruits confirmed their importance as quality markers of heating condition during processing and storage of fruit juices. Univariate analysis disclosed some significant differences among the composition of the apricot juices in terms of glucose, fructose, malic acid, glycine, chlorogenic acid, rutin, and a^∗-parameter (redness). Principal component analysis on chemical composition of apricot juices resulted in two principal components (PCs) that accounted for 66% of the total variance. Organic apricot juices showed some separation from the other juices, whereas a lack of distinction between integrated and conventional juices appeared.     

变频电潜泵在排水采气工艺中的应用

详细阐述了电潜泵的基本工作原理,指出了电潜泵排水采气工艺的适用范围与特点,并以蜀南气矿多口电潜泵工艺井为例,对电潜泵排水采气过程中出现的诸如气体干扰、天然气渗入电缆绝缘层导致电缆损坏等问题做了详细的分析,并提出了解决这些问题的具体方法.总结了多年来电潜泵排水采气工艺成功与失败的经验,对今后该项工艺的发展与推广有指导作用.     

Seasonal effects on Ca(2+) transport of sarcoplasmic reticulum and on meat quality of pigs with different malignant hyperthermia status

The intracellular Ca(2+) concentration is mainly regulated by the sarcoplasmic reticulum (SR). A disturbed regulation leads to an increased metabolism and ultimately to inferior meat quality. In this study, pigs with normal and mutated calcium release channels (referred to as MHR and MHS, respectively) were used. One batch of pigs was slaughtered in winter months and another in summer months. The intention was to elucidate the impact of season on the Ca(2+) transport of SR and on meat quality in dependence of the MH-status. The results show an impact of MH-status and of season on the meat quality with inferior values in summer months, and in MHS pigs. Immediately after slaughter the rate of Ca(2+) sequestration of the SR with biochemically closed and with opened calcium release channels (CRC) was not different between experimental groups. However, with basic CRC (not biochemically manipulated) the Ca(2+) uptake rate of MHR muscle of summer pigs was significantly reduced and at the level of that of MHS pigs. The results indicate an impact of summer season on the ability of SR to regulate Ca(2+) concentration properly even in pigs with a normal CRC. This disturbed Ca(2+) regulation is correlated with diminished meat quality.     

Detection of cauliflower mosaic virus by the polymerase chain reaction: testing of food components for false-positive 35S-promoter screening results

 Today DNA-based techniques are very common for the detection of genetically modified organisms (GMOs) in food products. For fast and easy detection of GMOs, polymerase chain reaction (PCR) screening methods, which amplify common transgenic elements, are applied in routine analysis. These techniques do not allow differentiation between GMOs and the natural occurrence of transgenic elements, such as the 35S-promoter of cauliflower mosaic virus (CaMV) or the NOS-terminator of Agrobacterium tumefaciens, and thus may result in false-positive detection of GMOs. In this study we evaluated three different existing 35S screening systems and report the development of two new CaMV-specific PCR systems. These PCR systems based on CaMV-specific genes allow the identification of positively screened 35S food samples as naturally virus-infected products or plants. Seven food samples tested positive in routine 35S screening analysis and negative in GMO specific systems were investigated using the new virus-specific PCR systems. In all seven samples CaMV was detected. Received: 26 April 1999 / Revised version: 28 June 1999     

Investigations of peptides and proteases in green coffee beans

Cof. canephora var. robusta. The coffee types were not significantly different in peptide content, but were significantly different in peptide composition. Peptides with weakly acid pI values were mainly found in the Cof. robusta samples. In comparison, peptides from Cof. arabica samples ranged evenly from the weakly acidic up to the weakly basic pH range. The apparent molecular masses of the peptides in the two groups of samples lie between 4 kDa and 10 kDa. The cysteine content of the peptides was relatively high. Model roastings permitted the assumption that peptides make a contribution to coffee flavour. Peptides are already available in freshly harvested coffee. Model tests have suggested that processing after the coffee harvest has an influence on peptide composition but not on the amounts of peptide. All coffee samples contained some extractable proteases. The electrophoretically obtained enzyme patterns of Cof. arabica and Cof. robusta were different. Received: 6 September 1999     

Kinetics of active sucrose transport in Saccharomyces cerevisiae

The kinetic analysis of active sucrose-H+ uptake by Saccharomyces cerevisiae revealed the presence of two transport systems with high and low affinity for sucrose. The MAL2T permease has a low affinity (K(m) = 120 +/-20 mM) for sucrose, while the alpha-glucoside transporter encoded by the AGT1 gene is a high affinity sucrose-H+ symporter (K(m) = 7.9+/-0.8 mM) that increases the specific growth rate of cells growing on sucrose.     

Interaction of Vanillin with Soy and Dairy Proteins in Aqueous Model Systems: A Thermodynamic Study

ABSTRACT: Interactions of vanillin with soy, casein, and whey proteins were studied in aqueous model systems using a thermodynamic approach. Vanillin-protein binding was examined at 12 and 4 °C using 3 proteins and 6 vanillin concentrations. The results were analyzed using a Klotz plot. Number of binding sites (n) and dissociation constants (K_d) were derived from the plots. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) for the bindings were calculated. Under identical experimental conditions, whey protein was found to have higher affinity to vanillin than the other 2 proteins. Bindings of vanillin with casein and whey protein were enthalpy driven, while the interaction of vanillin with soy protein was highly entropy driven. The results inferred that conformational changes of soy protein might be important in binding of vanillin.     

Evaluation of Petroleum Impurities in Motor Spirit and Diesel Oils Using Artificial Neural Network

Studies have been conducted for the ternary mixture of motor spirit, diesel, and kerosene oil samples using artificial neural network (ANN). American standard for testing materials (ASTM) distillation data of samples were used for the evaluation of respective components. Results of such evaluation of the samples were found to comply well with experimental values.     

1-Polyhexene as a viscous additive to lubricating oils

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 6, pp. 28–30, June, 1991.     

Specific Energy Prediction for Circular Diamond Saw in Cutting Different Types of Rocks Using Multivariable Linear Regression Analysis

Circular diamond saw performance is affected by a variety of factors. The principal factors requiring consideration when predicting cutting rates are the type and operating features of a diamond saw and the rock characteristics. The laboratory experimental tests are carried out on three groups of rocks (16 types) cut with the help of three types of diamond disk saws with different feed rates and cutting depths at constant peripheral velocity. The quantitative determinations of a wide range of textural, mechanical, and intact properties of rocks are also made. The relationship between the specific cutting energy SE _cut of the sawblade operating parameters and rock properties is established. Applying multivariable linear regression analysis, the predictive model of SE _cut is developed based on the rock property data. Models verified by statistical tests prove their practical validity. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 56–80, May–June, 2005.