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Equilibrium Moisture Content Importance in Safe Maritime Transport of Black Tea

Dmowski P., Ruszkowska M.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2018

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Vol. 12, no. 2

399--404

EN

In sea transport, a very important thing is an assignment of cargo to a particular class of storage climate conditions and it is carried out on the basis of the requirements that cargo places upon its storage atmosphere. The water content of black tea must not fall below 2%, as the product otherwise becomes haylike and its essential oils readily volatilize, while on the other hand, it must not exceed 9% as it then has a tendency to grow mould and become musty. Therefore, tea requires particular temperature, humidity/moisture and possibly ventilation conditions. In this context, tea is a hygroscopic material that has the ability to absorb or desorb water in response to temperature and relative humidity of the atmosphere surrounding it. The moisture content of tea is one of the most important variables affecting its chemical and sensory properties. Therefore, to explore and predict the behaviour during transport of tea, its equilibrium moisture content must be determined for a range of transport temperatures and relative humidities. The present paper focuses on the evaluate the hygroscopic properties of tea from Rwanda with different degree of fragmentation based on isotherms of water vapour sorption and characteristics selected parameters of the surface microstructure determining transport conditions and therefor microbiological stability of teas.

2

Dimensional stability and fungal durability of acetylated wood

Rowell R.

Drewno : prace naukowe, doniesienia, komunikaty

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2016

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vol. 59, nr 197

139--150

EN

The reaction of wood to acetic anhydride greatly reduces moisture sorption and improves the dimensional stability of the wood due to the esterification of the accessible hydroxyl groups in the cell wall, reducing hydrogen bonding with water and bulking the cell wall back to its green volume. The sorption of both primary and secondary water are reduced. Dimensional stability is not 100% since the water molecule is smaller than the acetyl group, therefore water can access hydroxyl sites even when the wood is fully acetylated. The equilibrium moisture content is reduced in a linear relationship to the level of acetyl content. This means that the reduction in moisture content is not dependent on where the acetylation reaction takes place in the cell wall. Resistance to fungal attack increases as the level of acetylation increases. Resistance to attack by white-rot fungus occurs at a much lower level of acetylation (7-10%) than that to brown-rot fungal attack (17-19%). The cell wall moisture content may be too low at high levels of acetylation to support fungal attack, therefore initial colonization does not take place.

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Izotermy sorpcji maltodekstryny przemysłowej o różnym stopniu scukrzenia

Stępień A., Witczak M., Witczak T., Czader M.

Postępy Techniki Przetwórstwa Spożywczego

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2015

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nr 2

51--56

PL

Celem pracy przedstawionej w artykule było określenie właściwości sorpcyjnych maltodekstryny przemysłowej o różnych wartościach równoważnika glukozowego (DE). Izotermy sorpcji w 25°C wyznaczono w zakresie aktywności wody od 0,11 do 0,90 za pomocą metody statyczno - eksykatorowej. Dane opisano za pomocą trzech modeli matematycznych: BET, GAB i Pelega. Oceny dopasowania dokonano w oparciu o wartości: współczynnika determinacji (R2) oraz średniego błędu kwadratowego (RMS). W celu wyeksponowania różnic pomiędzy poszczególnymi próbkami przeprowadzono Analizę Głównych Składowych (PCA).

EN

The aim of the work presented in this article was to determine moisture sorption characteristics of commercial maltodextrins with different dextrose equivalent (DE). Moisture sorption isotherms at 25°C were studied for water activities ranging from 0,11 to 0,90 using static -desiccator method. The moisture sorption data were used to fit three mathematical models: BET, GAB and Peleg’s. The goodness of fit was measured by calculation of coefficient of determination (R2) and root mean square (RMS). In order to show the differences between analyzed samples of maltodextrins Principal Component Analysis (PCA) was performed.

4

An experimental study on drying characteristics and kinetics of figs (Ficus carica)

Sarvestani F. Sabet, Rahimi A., Hatamipour M. S.

Polish Journal of Chemical Technology

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2014

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Vol. 16, nr 4

60--65

EN

In this study, the thin-layer drying characteristics of Figs (Ficus carica) are investigated in a pilot scale forced convective dryer. Experiments carried out under various operating conditions including air temperature (40, 50, 60, 70°C), air velocity (0.65, 2.1, 3.45, 4.85 m/s) and air humidity (0.005, 0.010, 0.015 kg/kg) and the effects of these operating conditions on the drying kinetics and the drying time determined. The obtained kinetics data are fitted into a conceptually developed model. The equilibrium moisture content of the dried figs is determined at different values of temperature and relative humidity of air. The values of effective moisture diffusivity (Deff) are obtained from the Fick’s second law and a temperature-dependent relation is proposed for this parameter.

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Vliânie režimov termičeskogo modificirovaniâ na fiziko-mehaničeskie svojstva graba

Pinčevskaâ E., Golovač V., Gorbačeva A.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2014

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No. 88

193--197

EN

Influence of thermal modification schedules on the physical and mechanical properties of hornbeam wood. The results of investigations of the physical and mechanical properties of dry and thermo modified by different schedules hornbeam wood are given