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Detalles de la revista
Formato
Revista
eISSN
2256-0939
Publicado por primera vez
30 Aug 2012
Periodo de publicación
2 veces al año
Idiomas
Inglés

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Volumen 35 (2016): Edición 330 (June 2016)

Detalles de la revista
Formato
Revista
eISSN
2256-0939
Publicado por primera vez
30 Aug 2012
Periodo de publicación
2 veces al año
Idiomas
Inglés

Buscar

5 Artículos
Acceso abierto

Fungal Diversity of Maize (Zea Mays L.) Grains

Publicado en línea: 10 Aug 2016
Páginas: 2 - 6

Resumen

Abstract

Maize is becoming more and more important crop for dairy farming as forage and as substrate for biogas production. The mycotoxin producing fungi can spoil feed, reduce cattle productivity and cause health problems. The aim of this research was to study the mycoflora of maize grains in order to clarify the fungal composition and verify the presence of potential mycotoxin producing fungi. The grain samples were collected from different maize hybrid performance trial in Research and Study farm “Vecauce” of Latvia University of Agriculture in 2014. The fungi from 14 genera were isolated from surface sterilized grains. The most abundant were Alternaria, Fusarium and Penicillium spp. Mycotoxin producing fungi are present in maize grain mycoflora, and there is a risk that maize production can contain mycotoxins.

Palabras clave

  • mycoflora
  • mycotoxins
  • Fusarium
  • ear rot
  • kernels
Acceso abierto

Impact of Water on Rheological Behavior of Polyurethane Glues

Publicado en línea: 10 Aug 2016
Páginas: 7 - 18

Resumen

Abstract

Gluing of wood with great moisture content has challenge of water interaction with glue to give unwanted changes in glue properties and formed bond-line. Rheological measurements of polyurethane glues are sufficiently effective method to understand the polymer curing process and viscoelastic properties. Gel formation point is important parameter for a glue from the point of its application. When glue reaches the gel formation point, its viscosity drastically increases so that it could not properly wet the wood and it can result in poor bonds. One-component moisture curing polyurethane glues require water molecules for the polyadditional reaction. When water is involved in the curing reaction, it reacts with the isocyanate groups of glue and can lead to the formation of excessive carbon dioxide and thus can lead to glue penetration out of bond-line, additional backpressure. The dynamic viscoelastic parameters such as complex dynamic viscosity (ή), phase angle (δ), elastic storage modulus (G”), the viscous loss modulus (G”) of two kinds of polyurethane glues depending on added water amount (from 0.9% to 10.0%) at a constant frequency and deformation (oscillation mode) were determined using rheometer. The aim of the present study was to investigate impact of added water on rheological behavior of polyurethane glues. At the end of this study it was concluded that tested glues indicated various behavior depending on chemical composition and added water content. Gel formation point is higher in case of GlueI. However, gel formation time was higher in case of GlueII and was not dependent on added water content. Gel formation time was faster for GlueII. Nevertheless, faster formed gel is stronger than longer formed gel of GlueI.

Palabras clave

  • polyurethane glue
  • rheological behavior
  • curing process
  • green gluing
Acceso abierto

The Effect of Cocoa Beans Heavy and Trace Elements on Safety and Stability of Confectionery Products

Publicado en línea: 10 Aug 2016
Páginas: 19 - 23

Resumen

Abstract

The aim of the study was to evaluate cocoa beans quality produced in Cameroon, Ecuador, Nigeria and Ghana from safety position determining heavy and trace metals concentration and evaluating the oxidative stability of confectionery products prototypes (trials) with analysing cocoa beans. For evaluation of oxidative stability of confectionery products, the main ingredients - butter and cocoa beans kernels were tested making trials as milk chocolate prototype.

The composition of confectionery ingredients affects quality of products; therefore it is very important to evaluate quality of raw materials in confectionery industry, as they are purchased practically in all regions of the world. Mercury, arsenic, lead, cadmium concentration was determined in whole cocoa beans as their presence in foods have toxic effect on human beings and their concentration are strictly limited as maximum residue limits for processing. Cocoa shells can be used as additive to confectionery products recipes therefore the object of the study was cocoa beans and cocoa shells.

Analyzing cocoa beans quality indices there was established that lead, cadmium, aluminium and zinc concentrations vary in cocoa beans significantly. Differences in lead concentration in cocoa beans from Ghana, Cameroon and Ecuador were significant (p < 0.05) compared with concentration of lead in cocoa beans from Nigeria (p > 0.05). Cadmium concentration in cocoa beans from Cameroon was significantly different comparing with cocoa beans from Nigeria, Ecuador and Ghana (p > 0.05). Differences in aluminium concentration in cocoa beans kernels were significant (p < 0.05) in all analyzed samples. Concentration of zinc was higher in shells of cocoa beans, especially in shells of cocoa beans from Ecuador (p < 0.05). The presence of cocoa products in milk chocolate prototypes inhibited the speed of lipid peroxidation. The different trace and heavy metals concentrations in cocoa beans should be taken into account choosing ingredients and components for confectionary products production particularly those with high content of cocoa (chocolates, sweets, cocoa fillings, cocoa creams and others) with the aim to prevent oxidation process during shelf-life of products.

Palabras clave

  • cocoa beans
  • heavy
  • trace metals
  • peroxides
Acceso abierto

The Effect of Egg Yolk Oil on The Chemical, Physical and Sensory Properties of Mayonnaise

Publicado en línea: 10 Aug 2016
Páginas: 24 - 31

Resumen

Abstract

Egg yolk oil (EYO) is an essence of egg bioactive compounds. Extracted from egg yolk it can be used in various food products increasing their nutritional and biological value. Mayonnaise is a kind of a semi-solid oil-inwater emulsion containing 60-80% fat. Mayonnaise typically contains oil, egg yolk, vinegar, salt, sugar and thickening agents. Mayonnaise is the product where application of EYO can be evaluated. The aim of this study was to evaluate the effect of egg yolk oil on the chemical, physical and sensory properties of mayonnaise. EYO was added to mayonnaise in the concentrations of 1, 3, 5 and 7%. The main parameters of mayonnaise were determined using standard methods: lipid, protein, fatty acids, vitamin D, pH, viscosity, colour and acceptance of sensory properties (viscosity, egg aroma, egg taste, yellow colour, sour taste and creaminess). At analyzed concentrations EYO has no influence (p > 0.05) on mayonnaise pH, lipid and protein content, but an increase in EYO content decreases the viscosity of mayonnaise. Increasing amount of EYO additive resulted in more intensive yellow colour of mayonnaise. Additions of EYO enrich mayonnaise with vitamin D and docosahexaenoic acid. Sensory evaluation of mayonnaise samples showed panellists’ preference for mayonnaise with 3% and 5% EYO additive.

Palabras clave

  • egg yolk oil
  • mayonnaise
  • physical properties
  • sensory evaluation
Acceso abierto

Analysis of the non Isothermal Distributed Activation Energy Model for Biomass Pyrolysis by Fuzzy Gaussian Distribution

Publicado en línea: 10 Aug 2016
Páginas: 32 - 41

Resumen

Abstract

The main aim of this paper is to fuzzify the kinetic parameters, which have crisp nature, in order to obtain the realistic and accurate results. In the present study, the variance, upper limit of ‘dE’ and the frequency factor are assumed to be fuzzy numbers. The Gaussian distribution is considered as the distribution function, f (E), of Distributed Activation Energy Model (DAEM). The membership and the non-membership functions are evaluated by the trapezoidal fuzzy number. Thermo-analytical data has been found experimentally with the help of TGA/DTG analysis. The approximated solution of DAEM is obtained with the help of asymptotic expansion.

Palabras clave

  • Fuzzy number
  • Gaussian distribution
  • distributed activation energy model (DAEM)
  • kinetic parameters
  • biomass pyrolysis
  • asymptotic expansion
5 Artículos
Acceso abierto

Fungal Diversity of Maize (Zea Mays L.) Grains

Publicado en línea: 10 Aug 2016
Páginas: 2 - 6

Resumen

Abstract

Maize is becoming more and more important crop for dairy farming as forage and as substrate for biogas production. The mycotoxin producing fungi can spoil feed, reduce cattle productivity and cause health problems. The aim of this research was to study the mycoflora of maize grains in order to clarify the fungal composition and verify the presence of potential mycotoxin producing fungi. The grain samples were collected from different maize hybrid performance trial in Research and Study farm “Vecauce” of Latvia University of Agriculture in 2014. The fungi from 14 genera were isolated from surface sterilized grains. The most abundant were Alternaria, Fusarium and Penicillium spp. Mycotoxin producing fungi are present in maize grain mycoflora, and there is a risk that maize production can contain mycotoxins.

Palabras clave

  • mycoflora
  • mycotoxins
  • Fusarium
  • ear rot
  • kernels
Acceso abierto

Impact of Water on Rheological Behavior of Polyurethane Glues

Publicado en línea: 10 Aug 2016
Páginas: 7 - 18

Resumen

Abstract

Gluing of wood with great moisture content has challenge of water interaction with glue to give unwanted changes in glue properties and formed bond-line. Rheological measurements of polyurethane glues are sufficiently effective method to understand the polymer curing process and viscoelastic properties. Gel formation point is important parameter for a glue from the point of its application. When glue reaches the gel formation point, its viscosity drastically increases so that it could not properly wet the wood and it can result in poor bonds. One-component moisture curing polyurethane glues require water molecules for the polyadditional reaction. When water is involved in the curing reaction, it reacts with the isocyanate groups of glue and can lead to the formation of excessive carbon dioxide and thus can lead to glue penetration out of bond-line, additional backpressure. The dynamic viscoelastic parameters such as complex dynamic viscosity (ή), phase angle (δ), elastic storage modulus (G”), the viscous loss modulus (G”) of two kinds of polyurethane glues depending on added water amount (from 0.9% to 10.0%) at a constant frequency and deformation (oscillation mode) were determined using rheometer. The aim of the present study was to investigate impact of added water on rheological behavior of polyurethane glues. At the end of this study it was concluded that tested glues indicated various behavior depending on chemical composition and added water content. Gel formation point is higher in case of GlueI. However, gel formation time was higher in case of GlueII and was not dependent on added water content. Gel formation time was faster for GlueII. Nevertheless, faster formed gel is stronger than longer formed gel of GlueI.

Palabras clave

  • polyurethane glue
  • rheological behavior
  • curing process
  • green gluing
Acceso abierto

The Effect of Cocoa Beans Heavy and Trace Elements on Safety and Stability of Confectionery Products

Publicado en línea: 10 Aug 2016
Páginas: 19 - 23

Resumen

Abstract

The aim of the study was to evaluate cocoa beans quality produced in Cameroon, Ecuador, Nigeria and Ghana from safety position determining heavy and trace metals concentration and evaluating the oxidative stability of confectionery products prototypes (trials) with analysing cocoa beans. For evaluation of oxidative stability of confectionery products, the main ingredients - butter and cocoa beans kernels were tested making trials as milk chocolate prototype.

The composition of confectionery ingredients affects quality of products; therefore it is very important to evaluate quality of raw materials in confectionery industry, as they are purchased practically in all regions of the world. Mercury, arsenic, lead, cadmium concentration was determined in whole cocoa beans as their presence in foods have toxic effect on human beings and their concentration are strictly limited as maximum residue limits for processing. Cocoa shells can be used as additive to confectionery products recipes therefore the object of the study was cocoa beans and cocoa shells.

Analyzing cocoa beans quality indices there was established that lead, cadmium, aluminium and zinc concentrations vary in cocoa beans significantly. Differences in lead concentration in cocoa beans from Ghana, Cameroon and Ecuador were significant (p < 0.05) compared with concentration of lead in cocoa beans from Nigeria (p > 0.05). Cadmium concentration in cocoa beans from Cameroon was significantly different comparing with cocoa beans from Nigeria, Ecuador and Ghana (p > 0.05). Differences in aluminium concentration in cocoa beans kernels were significant (p < 0.05) in all analyzed samples. Concentration of zinc was higher in shells of cocoa beans, especially in shells of cocoa beans from Ecuador (p < 0.05). The presence of cocoa products in milk chocolate prototypes inhibited the speed of lipid peroxidation. The different trace and heavy metals concentrations in cocoa beans should be taken into account choosing ingredients and components for confectionary products production particularly those with high content of cocoa (chocolates, sweets, cocoa fillings, cocoa creams and others) with the aim to prevent oxidation process during shelf-life of products.

Palabras clave

  • cocoa beans
  • heavy
  • trace metals
  • peroxides
Acceso abierto

The Effect of Egg Yolk Oil on The Chemical, Physical and Sensory Properties of Mayonnaise

Publicado en línea: 10 Aug 2016
Páginas: 24 - 31

Resumen

Abstract

Egg yolk oil (EYO) is an essence of egg bioactive compounds. Extracted from egg yolk it can be used in various food products increasing their nutritional and biological value. Mayonnaise is a kind of a semi-solid oil-inwater emulsion containing 60-80% fat. Mayonnaise typically contains oil, egg yolk, vinegar, salt, sugar and thickening agents. Mayonnaise is the product where application of EYO can be evaluated. The aim of this study was to evaluate the effect of egg yolk oil on the chemical, physical and sensory properties of mayonnaise. EYO was added to mayonnaise in the concentrations of 1, 3, 5 and 7%. The main parameters of mayonnaise were determined using standard methods: lipid, protein, fatty acids, vitamin D, pH, viscosity, colour and acceptance of sensory properties (viscosity, egg aroma, egg taste, yellow colour, sour taste and creaminess). At analyzed concentrations EYO has no influence (p > 0.05) on mayonnaise pH, lipid and protein content, but an increase in EYO content decreases the viscosity of mayonnaise. Increasing amount of EYO additive resulted in more intensive yellow colour of mayonnaise. Additions of EYO enrich mayonnaise with vitamin D and docosahexaenoic acid. Sensory evaluation of mayonnaise samples showed panellists’ preference for mayonnaise with 3% and 5% EYO additive.

Palabras clave

  • egg yolk oil
  • mayonnaise
  • physical properties
  • sensory evaluation
Acceso abierto

Analysis of the non Isothermal Distributed Activation Energy Model for Biomass Pyrolysis by Fuzzy Gaussian Distribution

Publicado en línea: 10 Aug 2016
Páginas: 32 - 41

Resumen

Abstract

The main aim of this paper is to fuzzify the kinetic parameters, which have crisp nature, in order to obtain the realistic and accurate results. In the present study, the variance, upper limit of ‘dE’ and the frequency factor are assumed to be fuzzy numbers. The Gaussian distribution is considered as the distribution function, f (E), of Distributed Activation Energy Model (DAEM). The membership and the non-membership functions are evaluated by the trapezoidal fuzzy number. Thermo-analytical data has been found experimentally with the help of TGA/DTG analysis. The approximated solution of DAEM is obtained with the help of asymptotic expansion.

Palabras clave

  • Fuzzy number
  • Gaussian distribution
  • distributed activation energy model (DAEM)
  • kinetic parameters
  • biomass pyrolysis
  • asymptotic expansion

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