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According to the long-term plan accepted by the Editorial Board, in the first days of October 2018 we present to our readers the 57th issue of the Polish Journal of Commodity Science. Continuing the efforts to widen the group of our readers all the papers are published in English. We would like to remind that now, only papers written in English are accepted by the editors. As before, each paper contains a wide summary in Polish and English. The summaries in both language versions of all the works published one can find on our web page Moreover, at the web page an open-access to all the papers published up to 2017 is offered. A series of 14 articles in the current issue of our magazine is opened by the work by Lotko et al. regarding bibliometric analysis of service quality attributes. The authors of this study have identified the frequency of quality attributes of services used in models available in the literature. The research results presented in the paper include the analysis of 24 models of quality of services described in both Polish and foreign literature. On the basis of the results it was found that almost half of the analyzed attributes refer directly to the staff having contact with the client. At the same time, it was observed that communication with a client is the most often indicated attribute of the quality of services. The next article deals with verification of the reliability of information about the presence of soy allergens in selected food products and dishes. Derewiaka and co-authors investigate the presence of allergens in self-produced model foodstuffs and packaged food products and dishes available on Polish market. Reliability of the information given by producers was checked by application of ELISA immunoassay based on trypsin inhibitor detection. The quality control of a new food product is the subject of Halagarda's interests. The author discusses the possibilities of choosing the elements of the process of developing a new food product that can be used to improve the quality of the product. The models for the development of new products and consumer research techniques together with the success factors of new products. It has been confirmed that the use of tools to optimize quality contributes to the success of the product on the market, but it is not clearly defined which methods should be used in a specific case. Ensuring high-quality raw materials and food products sensitive to oxidative changes requires the development of fast and effective methods for monitoring these processes. In the next paper, Wójcicki presents the results of his research on monitoring the oxidative changes of olive oils using the absorption spectra in the visible range and compares this information with classic chemical parameters, eg changes in the peroxide number, acid number, contents of carotenoid and chlorophylls. The results were analyzed using statistical methods (PCA and PLS). It was found that visible spectroscopy can be a valuable tool for assessing the oxidative changes of various olive oils. In the consecutive paper also new food raw materials important from the point of view of the production of gluten-free products are concerned. Żbikowska and co-authors deal with the assessment of the quality parameters of biscuit-fat products made with the addition of flour from papaya leaves. On the basis of conducted physicochemical and sensory tests it was found that it was possible to replace gluten-free flours with papaya leaf flour. It was observed that this addition had the greatest impact on the color parameters of the raw and the baked product Moreover, the increase in the proportion of papaya flour led to darker products and a drop in sensory quality. It was also found that the addition of flour from papaya leaves did not affect the quality of the raw dough and most of the physical parameters of the final product tested.  The subject of Palka's research interests is the assessment of the quality of avocado and mango based sorbets on. The paper presents the results of the assessment of sorbets made with the addition of various stabilizers. Physicochemical and organoleptic tests as well as evaluation of antiradical activity of sorbets were carried out. It was found that the tested products differed in terms of physico-chemical and organic-physical properties. It was also shown that the addition of stabilizers significantly affected sorbent characteristics. The best characteristics was revealed by sorbet containing guar gum as stabilizer.   In the next paper, Wilczyńska and Żak present the results of their research on the quality of less common honey varieties such as: faceli, dandelion, raspberry and goldenrod. Physical and chemical parameters, color, antioxidant properties and sensory attributes of these honeys were evaluated. It was found that all varieties of honey tested met the requirements for water content, reducing sugars content and free acid content. It has been shown that the tested honey varieties have a clear color and are characterized by a relatively low content of 5-HMF, low diastase number and low antioxidant activity. There were clear differences between the individual varieties, both in the chemical composition and the sensory characteristics of the honeys examined. Although the antioxidant properties of beer have been known for a long time, it seems that some natural flavorings for beer can affect these properties. In the next work Kozak et al. focused on the experimental determination of the antioxidant potential of pasteurized and unpasteurized beer. The influence of the addition of fruit-rich syrups (chokeberry and raspberry) to beer on changes in antioxidant properties of beer was also evaluated. It has been found that unpasteurised beer has a higher antioxidant potential than a bevery beer. It was also observed that beer with the addition of chokeberry juice had a higher antioxidant capacity than beer with the addition of raspberry juice. Obtaining natural antioxidant substances that can be applied as food supplements or ingredients of cosmetic products requires the use of an extract of a vegetable raw material. The effectiveness of this process in relation to a specific raw material depends not only on the type of raw material and duration of the extractcion, but also on the type of solvent used in this process. In the next paper, Kwaśna et al. analyze the possibilities of using the Hansen Solubility Parameter (HSP) to select the best composition of the mixture used for extracting phenolic compounds from marigold flowers. The paper presents the results of the research on water-alcohol mixtures as effective extractants of these ingredients based on the HSP values of active substances present in marigold flowers.  In the consecutive article, Wolak et al. present the results of their research regarding the assessment of the content of metals present in used motor oils. The authors employed the Xray fluorescence method. It was found that the type and concentration of metals in the tested samples of used engine oils depended on the type of oil applied and engine capacity. Higher average concentrations of chromium, iron, nickel and lead were found in oils used in lowercapacity engines and higher concentration of copper in engine oils with higher capacity. No differences were observed in the concentrations of manganese and molybdenum in oils operating in engines with different capacities. It was found that the results might be useful in determining the method of wear of engines of different capacities. The subject of research by Woźniak et al. was to determine the crystal microstructure of fat blends containing tallow and hemp oil. The physical mixtures of these fat components and the products of their esterification carried out in the presence of enzymes have been assayed. In the case of mixtures of these components, a phenomenon of dilution of the crystal structure was observed, followed by an increase in the oil content in the mix. A significant modification of the density of the crystal structure, size of crystals and their morphology in fatty mixtures has been found. The authors claim that the mixtures obtained may constitute an attractive fat base for emulsion food and cosmetics. Oiling skins is an important element of the process of controlling their functional properties. Żarłok presents the results of research that was supposed to determine the effect of the type of fat liquoring agents used on the hygienic properties of the hides.  Agents based on natural and synthetic fats as well as hydrophobic agents were used as fat spreading substances. The effect of the type of agent appliedon skin softness, time of water drop penetration and sorption, desorption and water vapour permeability were assessed. It has been shown that the type of lubricating agent used has a significant impact on the skin's resistance to water which is measured by the penetration time of a drop of water into the skin. Tests on the modification of the natural properties of starch polymers with natural substances and the possibility of using them as packaging materials are the subject of the Morawska research. The paper presents tests of biodegradable films from kuzu starch obtained by casting plastified with glycerol and polyethylene glycol (400). The influence of natural extracts (extract from yerba mate, aloe gel, eucalyptus oil) on the thickness, density, hardness, thermal properties and water vapor permeability of the produced starch films was investigated. It was found that the natural extracts present in the kuzu starch films limit the increase in crystallinity and recrystallization of starch. In turn, the presence of yerba mate extract and aloe gel in these films slightly increases the water vapour permeability, while the addition of eucalyptus oil degrades the water vapour permeability. In the last work, Zięba presents the results of her research on the rheological properties of shampoos. Liquid hair shampoos made according to original recipes containing modifiers of rheological properties: agar, arabic gum, carrageen gum, xanthan gum and guar gum were tested. It was found that the use of xanthan, carrageenan and guar gums allowed to obtain shampoos with high viscosity, which led to reduce the rate of the products flowing from the hair. In turn, the use of arabic gum and agar allows to obtain shampoos with lower viscosity. It has been shown that the test substances of natural origin modifying rheological properties allow  the formulation of hair shampoos suitable for products intended for different groups of consumers. The fifty-seventh issue of our quarterly is closed by the section “TPJ Information”. It contains information about the next international commodity science conference “Current Trends in Commodity Science” organized by the Faculty of Commodity Science at the University of Economics in Poznan, which will be held in June 2019.
I wish you a nice reading
 PJCS Editor  Prof. dr hab. inż. Ryszard Zieliński




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