Lifetime Distribution of Clusters in Binary Mixtures Involving Hydrogen Bonding Liquids

Hydrogen bonded liquids are associated liquids and tend to exhibit local inhomogeneity in the form of clusters and segregated sub-nano domains. It is an open question as to whether Hbonded clusters in pure water have common features with the water segregated pockets observed in various aqueous binary mixtures, such as water-alcohol mixtures, for example. In the present study, we demonstrate through classical molecular dynamics studies of the lifetime distributions of the hydrogen bonds in different types of binary mixtures, that these lifetimes exhibit the same universal features in the case of the pure liquids, independently of the species concentrations. The same types of three distinct lifetimes are observed, all of them in the sub picosecond regime. The primary lifetime concerns that of Hbonded dimers, and strongly depends on Hbonding criteria such as the bonding distance. The two others are independent of bonding criteria. The secondary lifetime concerns Hbonded cluster lifetimes, while the tertiary lifetime concerns the topology of these clusters, such as chains or globules, for example. This surprizing separation in three distinct lifetimes suggests the existence of associated three distinct kinetic mechanisms in the very short sub-picosecond time scales.

Chemical Composition and Polyphenolic Compounds of Red Wines: Their Antioxidant Activities and Effects on Human Health—A Review

Red wine, an alcoholic beverage is composed of a spectrum of complex compounds such as water, alcohol, glycerol, organic acid, carbohydrates, polyphenols, and minerals as well as volatile compounds. Major factors that affect the levels of phenolic compounds in red wines are the variety of grapes and the storage of the wines. Among the constituents of red wine, phenolic compounds play a crucial role in attributes including color and mouthfeel and confer beneficial properties on health. Most importantly, phenolic compounds such as flavanols, flavonols, flavanones, flavones, tannins, anthocyanins, hydroxycinnamic acids, hydroxybenzoic acids, and resveratrol can prevent the development of cardiovascular diseases, cancers, diabetes, inflammation, and some other chronic diseases.

JELLY FOOD CONCENTRATE WITH ENCAPSULATED HIBISCUS EXTRACT

Background. Taking into consideration the intense rhythm of life, the development of technologies for instant food products of increased nutritional value is urgent. Typically, food concentrates for desserts include fruit or fruit and berry fillings and require cooking to prepare ready-made meals. In this case, heat treatment of the mixture (boiling) negatively affects the thermolabile biologically active compounds. The aim of the work was to develop a recipe for instant food jelly concentrates of increased nutritional value based on encapsulated powdery hibiscus extract. Materials and methods. To encapsulate the aqueous-alcoholic extract of hibiscus and obtain a powdered semi-finished product, swelling potato starch was used. Rheological studies were carried out using a "REOTEST-2" rotational viscometer. Results. In order to enrich food concentrates of instant kissel with biologically active substances, we studied a method for extracting dry hibiscus flowers with aqueous-alcoholic solutions of various concentrations. It was found that the extractivity and the transfer of polyphenolic compounds, including anthocyanins, to the extract are improved when a water-alcohol mixture with an ethyl alcohol concentration of 30 % is used as an extractant. For the preparation of a powdery hibiscus extract, modified swelling starch was used, which has the property of swelling in cold water, which makes it possible not to subject the mixture to prolonged heat treatment for preparing a ready-made dish and to preserve the biologically active substances of the hibiscus extract. In addition, this starch is an effective solid carrier that plays a protective role for thermolabile vitamins and bioflavonoids. On the basis of experimental studies, formulations of instant jelly have been developed, which include fructose, powdered hibiscus extract, apple pectin and ascorbic acid. The study of the rheological properties of semi-finished products based on hibiscus extract, as well as ready-made jelly, testifies to the receipt of a finished dessert with a delicate creamy consistency. Conclusion. A method for obtaining a powdery encapsulated hibiscus extract based on swelling potato starch and a composition of a food jelly concentrate using this semi-finished product have been developed. It was found that for the extraction of raw materials it is better to use a water-alcohol mixture with an ethanol content of 30 %, since most of the anthocyanins are converted into the extract under these conditions. The developed semi-finished product of dry hibiscus extract can be used as a thickener, acidifier and colorant in recipes for food concentrates for instant dessert dishes. Due to the use of swelling starch, food concentrates of jelly do not need to be boiled, and the presence of vitamins, organic acids, flavonoids and especially anthocyanins in the hibiscus extract increases the nutritional value of the finished product.

QUALITATIVE AND QUANTITATIVE ANALYSIS OF FLAVONOIDS DURING DEVELOPMENT OF ANTIDIABETIC EXTRACT

During development of antidiabetic extract in blueberry shoots (Vaccinium myrtillus L.), ginseng leaves (Panax ginseng C.A.Mey.) and water-alcohol extraction from this plant material the flavonoid content is studied because this group of biologically active substances has hypoglycemic effect. Qualitative reactions for different groups of flavonoids has confirmed their presence in blueberry shoots and ginseng leaves. In addition, qualitative analysis of water-alcohol extraction on their base using spectrophotometry has also showed presence of this group of biologically active substances. Along with that, quantitative content of flavonoids has been detected using differential spectrophotometry in blueberry shoots, ginseng leaves and water-alcohol extraction on their base.

ANALYSIS OF THE COMPOSITION OF WATER-ALCOHOL MIXTURES USING THE INFRARED ABSORPTION SPECTRA OF THEIR VAPORS

The article presents the results of studies of infrared absorption spectra of saturated vapors of alcohols and alcohol-containing mixtures in the range of 1.3—1.5 μm. A method was developed for the quantitative determination of the composition of water-alcohol mixtures based on the use of multiple linear regression, and a range of methanol concentrations was determined, in which the nonlinearity of the dependence of the concentration of alcohols in saturated vapors over a liquid mixture on the concentration of alcohols in this liquid mixture does not significantly affect the results of analysis of the mixture composition. A method for optimizing a set of wavelengths for multiple linear regression, based on minimizing the mean-square error in determining the concentration is proposed and implemented. The developed methods make it possible to determine the presence of small (<1%) amounts of methanol against the background of large amounts of ethanol and water using relatively inexpensive and accessible spectroscopic equipment.

Investigating the effect of submerged impingement jet on heat transfer in water-alcohol mixtures

This paper presents new results of experiments on spherical sample cooling with submerged impingement jet in subcooled water-alcohol mixtures. The influence of the ethanol concentration on the occurrence of intensive boiling regime is detected. Experiments are carried out on a stainless-steel sample in a water-ethanol mixture, in a wide range of concentrations and temperatures. The result includes an increase of the heat transfer intensity at exposure of the submerged impingement jet. The intensive boiling regime is detected with a higher ethanol content compared to experiments in a calm liquid.

CHEMICAL CHARACTERIZATION OF BARK COMPOUNDS FROM CAATINGA SPECIES

This study aimed to chemically characterize the bark extracts from three tree species: Anacardium occidentale L., Ziziphus joazeiro Mart. and Mimosa caesalpiniaefolia Benth., in addition to obtaining the soluble extract content in water, alcohol and hexane from the bark of these species. The bark was collected from branches of the three species and subsequently pre-dried and milled. The extract content was then determined using the Sohxlet method aiming to quantify the total extractives in the samples, and determine the extract content soluble in water, ethyl alcohol and hexane. The extracts were further analyzed by Near Infrared Spectroscopy (NIRS) analysis to determine their chemical composition. The extract contents in the three species behaved in a similar way, with hexane being the solvent which extracted more compounds and juazeiro the species that displayed the highest total extract content. With the chemical characterization of the extracts, it was possible to identify the presence of functional groups characteristic of carbohydrates and proteins in the aqueous extracts; the presence of characteristic hydroxyl group, for example in alcohols, aldehydes, ketones and ethers in the ethanolic extracts; and the presence of fatty acids and aromatic compounds (essential oils) in hexanolic extracts. The essential oils were the compounds which presented larger quantities, and can be exploited by the pharmaco-chemical industry.