Isotermas de adsorción en harina de maíz (Zea mays L.)

Gálvez, Antonio; Aravena, Elena Lara; Mondaca, Roberto Lemus

doi:10.1590/s0101-20612006000400017

Cited by 33 publications

(26 citation statements)

References 24 publications

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“…Some of the above-mentioned studies, found isotherm crossovers due to the effect of temperature at elevated water activities (usually above 0.75) when thymol was used as an antimicrobial agent. 14,16,17,[20][21][22] Other studies did not show isotherm crossovers but no sorption data was presented at elevated temperature for water activities above 0.80-0.85 and therefore possible isotherm crossovers were not evidenced. [10][11][12] Some of these products contained a significant fat content (sardines, chickpea, corn flour, sesame flour, distillers dried grains, and oat flour), therefore absorption of thymol by fat in the product was possible since thymol has affinity for lipids, being soluble in organic compounds as indicated previously.…”

Section: Introductionmentioning

confidence: 93%

“…Some authors have used thymol as an antimicrobial agent in food moisture sorption isotherm determinations by the SG technique in temperature ranges that included elevated temperatures: Menkov 10 in lentil seeds (5-60°C); Sablani et al 11 in freeze-dried sardines (25-50°C); Moreira et al 12 in fresh chickpea (25-45°C); Durakova and Menkov 13 in rice flour (10-30°C); Durakova and Menkov 14 in chickpea flour (10-40°C); Cassini et al 15 in texturized soy protein (10-40°C); Vega-Gálvez et al 16 in corn flour (7 to 45°C); Menkov and Durakova 17 in sesame flour (10-40°C); Goula et al 18 in spray-dried tomato pulp (20-70°C); Vega-Gálvez et al 19 in Chilean papaya (5-45°C); Ganesan et al 20 in distillers dried grains (10-40°C); Perdomo et al 21 in cassava starch (5-45°C) and Brett et al 22 in oat and rice flours (5 to 45°C). Some of the above-mentioned studies, found isotherm crossovers due to the effect of temperature at elevated water activities (usually above 0.75) when thymol was used as an antimicrobial agent.…”

Section: Introductionmentioning

confidence: 99%

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Determination of Moisture Sorption Characteristics of Oat Flour by Static and Dynamic Techniques with and Without Thymol as an Antimicrobial Agent

et al. 2011

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The effectiveness of thymol as an antimicrobial agent during the determination of equilibrium moisture sorption data at high-water activities (0.50-0.98) was studied at 5, 23, and 45°C in oat flour. The static gravimetric (SG) method (with and without added thymol) and the dynamic vapor sorption technique (DVS) were used. Microbial growth in samples conditioned in these environments at temperatures of 5 and 45°C was null indicating no need for the use of thymol at these temperatures. However, samples confined in environments kept at 23°C, when the SG method was used, needed addition of thymol since mold growth took place in its absence. The statistical comparison between experimental equilibrium moisture content (EMC) mean values showed that, at 45°C, EMC values obtained using the SG technique with added thymol were significantly higher than those obtained without thymol by both SG and DVS techniques. This could indicate an interaction of thymol with food components or absorption by lipids present. Therefore, caution must be exerted when using thymol as an antimicrobial agent at elevated temperatures and high equilibrium relative humidity. Moisture adsorption isotherms for oat flour were determined using a DVS technique and no isotherm crossover with temperature, as previously reported for this product using thymol as an antimicrobial agent, was exhibited. Moisture sorption data obtained in this work by DVS can be considered more accurate than those previously reported for oat flour, since no external agent was involved during isotherm determinations.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Determination of Moisture Sorption Characteristics of Oat Flour by Static and Dynamic Techniques with and Without Thymol as an Antimicrobial Agent

et al. 2011

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“…(4)). Such experimental data, were taken from literature and previous work [20,21], and fitted using the Oswin model, which has been reported to provide satisfactory fitting in several works [22][23][24][25]: (8) where the fitting parameters A and B are specific to each material.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Determination of hygrothermal parameters of experimental and commercial bio-based insulation materials

Palumbo

Palacio

Holcroft

et al. 2016

Construction and Building Materials

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The development and application of bio-based insulation materials can contribute to the minimization of the environmental impacts of buildings through reduction of embodied and in-use energy demand, in addition to many other major impacts such as resource depletion and waste generation. The hygrothermal performance of natural building materials has direct and indirect impacts on moderating indoor environmental conditions and can contribute to energy savings provided that such aspects are taken into account during the design and construction phases. This requires in-depth knowledge of the thermal and hygroscopic properties of the materials and their dependence on the moisture content. In this paper, the hygrothermal properties of six insulation materials is determined; four are commercially available materials while the other two are experimental materials based on crop byproducts and natural binders. The influence of relative humidity on such properties is analysed.Moreover, the experimental Moisture Buffer Values are obtained for the six insulations, according to the protocol of the standard ISO 24353. Finally, a mass and heat coupled model is numerically solved to simulate this protocol for two of the materials, obtaining a good agreement with the experimental results.

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“…In this study, 10 mathematical models were used to describe the adsorption isotherms of chitosan films at different temperatures (Aviara et al, 2004;Ayala Aponte et al, 2011;Furmaniak et al, 2007;Gálvez et al, 2006;Timmermann et al, 2001). From these 10 equations (Equations 1-10; Table 2), 5 are the original models and 5 are modified versions of each model where the temperature is taken into account.…”

Section: Mathematical Moisture Sorption Modelsmentioning

confidence: 99%

“…In the case of chitosan, when it is hydrated at low values of RHeq (< 50%) the rate of relaxation of the solvent Table 2. Isotherm models used for experimental data fitting (Aviara et al, 2004;Ayala Aponte et al, 2011;Furmaniak et al, 2007;Gálvez et al, 2006;Timmermann et al, 2001 Where a w is water activity, X is the moisture content on a dry base and T is temperature.…”

Section: Moisture Adsorption Isothermsmentioning

confidence: 99%

Modelling the effect of temperature on the water sorption isotherms of chitosan films

2016

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The interaction of the water molecules from the environment with foods and other materials can be evaluated using sorption isotherms. Films and biodegradable films are susceptible to changes in their functional characteristics due to adsorbed water. The amount of moisture that biodegradable films can adsorb depends on the temperature, relative humidity of the storage area and chemical composition. Several mathematical models can be used to describe the behavior of sorption isotherms in biodegradable films and some of them have been modified to include the temperature parameter into the equation. In this research, the original and modified BET, GAB, Halsey, Henderson and Dswin models were assessed to determine their suitability describing the behavior of moisture adsorption isotherms of chitosan films at 15, 20, 25 and 30 °C. The modified models of GAB, Dswin and Halsey gave the best fit to the experimental sorption data of the chitosan films, with R 2 values higher than 0.97 demonstrating that those models describe better the sorption isotherms at the temperatures studied.Keywords: chitosan film; moisture adsorption isotherm; GAB model. Practical Application:The knowledge of the relationship between the equilibrium moisture content, equilibrium relative humidity and temperature is very important in order to describe the effect of water activity on storage of foods. Several mathematical models were used to describe the water sorption behavior of chitosan edible films involving water activity, moisture content and temperature.

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Isotermas de adsorción en harina de maíz (Zea mays L.)

Cited by 33 publications

References 24 publications

Determination of Moisture Sorption Characteristics of Oat Flour by Static and Dynamic Techniques with and Without Thymol as an Antimicrobial Agent

Determination of Moisture Sorption Characteristics of Oat Flour by Static and Dynamic Techniques with and Without Thymol as an Antimicrobial Agent

Determination of hygrothermal parameters of experimental and commercial bio-based insulation materials

Modelling the effect of temperature on the water sorption isotherms of chitosan films

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