Water adsorption isotherms and isosteric sorption heat of spray-dried and freeze-dried dehydrated passion fruit pulp with additives and skimmed milk

Moisture equilibrium data of passion fruit pulp powders with maltodextrin and gum arabic were obtained by two different drying methods (spray drying and freeze drying) and determined at 20, 30, 40 and 50º C. Skimmed milk was used to substitute part of these additives in the samples. One formulation using passion fruit pulp/maltodextrin/skimmed milk (PMS) was prepared, and another using passion fruit pulp/gum arabic/skimmed milk (PGS). The behavior of curves was type III, according to Brunauer's classification. GAB models were fitted to experimental equilibrium data. The parameters obtained from GAB models was affected by the presence of additives. The behavior of the sorption isotherms for different temperatures are similar, noting only a small effect of temperature. There were little differences between both drying methods and additives used in relation to equilibrium moisture content. The parameters obtained with the addition of the skimmed milk were considered satisfactory (Xm values ranged from 0,04084 to 0,06488 in dry basis), demonstrating that it is an effective and cheap alternative for regular additives. A progressive increase in the heat of sorption in relation to decreasing moisture content was observed and the heat of sorption values of different samples are all similar, comparing the relative equilibrium moisture content.

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Heat of sorption and free energy change of freeze-dried pineapple pulp

The Journal of Agriculture of the University of Puerto Rico ◽

10.46429/jaupr.v77i3-4.4198 ◽

1969 ◽

Vol 77 (3-4) ◽

pp. 101-111

Author(s):

Humberto Vega-Mercado ◽

Gustavo V. Barbosa-Cánovas

Keyword(s):

Free Energy ◽

Moisture Content ◽

Equilibrium Moisture Content ◽

Free Energy Change ◽

Energy Change ◽

Heat Of Sorption ◽

Freeze Dried ◽

Adsorption Data ◽

Pineapple Pulp ◽

Two Parameters

Two thermodynamic properties, the heat of sorption (Qs) and the Gibbs free energy change (∆G) were evaluated at several temperatures (5, 25, 30, 35 and 55°C) on freeze-dried pineapple pulp. It was found that 1) the heat of sorption follows the Clauslus-Clapeyron relationship; 2) the shape of the heat of sorption vs. the equilibrium moisture content curve was sigmoid; 3) the heat of sorption from adsorption data gave higher values than those from desorption data; and 4) the free energy change (∆G) is linearly related to the equilibrium moisture content. These two parameters are very important in dealing with food stability because it is possible to predict the water activity at any given temperature of either of these values is known.

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Equilibrium moisture content and heat of sorption of Gelidium sesquipedale

Journal of Stored Products Research ◽

10.1016/j.jspr.2004.03.001 ◽

2005 ◽

Vol 41 (2) ◽

pp. 199-209 ◽

Cited By ~ 58

Author(s):

L.Ait Mohamed ◽

M. Kouhila ◽

S. Lahsasni ◽

A. Jamali ◽

A. Idlimam ◽

...

Keyword(s):

Moisture Content ◽

Equilibrium Moisture Content ◽

Heat Of Sorption ◽

Gelidium Sesquipedale

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Effects of Enzymatic Liquefaction, Drying Techniques, and Wall Materials on the Physicochemical Properties, Bioactivities, and Morphologies of Zinc-Amaranth (Amaranthus viridis L.) Powders

International Journal of Food Science ◽

10.1155/2021/1819104 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Siti Faridah Mohd Amin ◽

Roselina Karim ◽

Yus Aniza Yusof ◽

Kharidah Muhammad

Keyword(s):

Antioxidant Activities ◽

Gum Arabic ◽

Leafy Vegetables ◽

Drying Methods ◽

Cell Wall Degrading Enzymes ◽

Green Leafy Vegetables ◽

Enzymatic Liquefaction ◽

Freeze Dried ◽

Wall Materials ◽

Spray Dried

The demand for vegetable powder has been escalating considerably due to its various health benefits and higher shelf life compared to fresh green leafy vegetables. Thus, much research emphasised manufacturing vegetable powder at a lower operational cost and higher efficiency while preserving the nutritive values of the vegetables. In this study, zinc- (Zn-) amaranth puree was liquefied with three types of cell wall degrading enzymes (i.e., Viscozyme L, Pectinex Ultra SP-L, and Rapidase PAC) with varying concentrations (0–3% v/w) and incubation time (0.5–24 h) at pH 5 and 45°C before the drying process. The results showed that enzymatic liquefaction using 1% (v/w) of Viscozyme L for 3 h was the optimal procedure for the reduction of the viscosity of the puree. The liquefied puree was then microencapsulated through either spray- or freeze-drying with different wall materials, e.g., 10% of maltodextrin (MD) DE 10, resistant maltodextrin (RMD), N-octenyl succinate anhydride (OSA) starches from waxy maize, HI CAP 100 (HICAP), Capsul (CAP), and gum Arabic (GA). The results showed that all freeze-dried powders generally had higher process yield (except for that encapsulated by HICAP), higher moisture content (but similar water activities), higher retention of total Zn-chlorophyll derivatives, lower hygroscopicity with slab-like particles, larger particle size, and lower bulk density than those of spray-dried powders. In contrast, the spray-dried powders exhibited irregular spherical shapes with relatively high encapsulation efficiency and antioxidant activities. Nonetheless, encapsulation using different wall materials and drying methods had no significant effect on the powder’s cohesiveness and flowability.

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EFFECT OF DRYING METHODS ON THE EQUILIBRIUM MOISTURE CONTENT ISOTHERMS OF SOY PULP (OKARA) POWDER

The Proceedings of the 5th Asia-Pacific Drying Conference ◽

10.1142/9789812771957_0078 ◽

2007 ◽

Author(s):

IWAN TARUNA ◽

SURYANTO ◽

SRI ASTUTI

Keyword(s):

Moisture Content ◽

Equilibrium Moisture Content ◽

Drying Methods

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Enhanced Microencapsulation of C-Phycocyanin from Arthrospira by Freeze-Drying with Different Wall Materials

Food Technology and Biotechnology ◽

10.17113/ftb.58.04.20.6622 ◽

2020 ◽

Vol 58 (4) ◽

Author(s):

Wanida Pan-utai ◽

Siriluck Iamtham

Keyword(s):

Thermal Stability ◽

Antioxidant Activity ◽

Moisture Content ◽

Water Activity ◽

Freeze Drying ◽

Antioxidant Properties ◽

Gum Arabic ◽

Water Soluble ◽

Freeze Dried ◽

Wall Materials

Research background. C-phycocyanin (C-PC) as a water-soluble blue pigment was extracted from microalga Arthrospira. C-PC could be a good substitute for synthetic pigments with high antioxidant activity. However, C-PC is unstable due to sensitivity to temperature, light, pH, and oxygen; therefore applications of C-PC in food and other products are limited. Microencapsulation of C-PC using freeze-drying is a solution to this problem and is considered a suitable method for drying heat-sensitive pigment. Experimental approach. C-phycocyanin was extracted from Arthrospira platensis. C-phycocyanin microcapsules were modified by freeze-drying, with different ratios at 0-100 % of maltodextrin (MD) and gum Arabic (GA) used as microencapsulation wall materials. The powders produced were evaluated for physical properties including moisture content and water activity, solubility, hygroscopicity, bulk density, colour appearance, particle morphology and size distribution. Thermal stability and antioxidant activity of freeze-dried C-PC microencapsulated powders were also assessed. Results and conclusions. Freeze-dried C-PC microencapsulated powders with maltodextrin and gum Arabic as wall materials gave high encapsulation efficiency of around 99 %. At higher gum Arabic percentage, moisture content decreased and water activity improved. Maltodextrin gave higher solubility of C-PC powders whereas gum Arabic led to a similar colour of C-PC without microencapsulation. Freeze-dried C-PC microencapsulated powders were composed of different sized microparticles regardless of the combination of wall materials with amorphous glassy shapes. Thermal stability of encapsulated C-PC increased and also showed high antioxidant properties. Novelty and scientific contribution. C-PC microcapsules that maintain colourant stability with high antioxidant levels and resistance to high temperatures can be applied in a wide variety of products and also in the food industry.

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Physical quality analysis of drying beluntas leaves (Pluchea indica L.) using variations of drying methods

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/922/1/012053 ◽

2021 ◽

Vol 922 (1) ◽

pp. 012053

Author(s):

A S Telaumbanua ◽

J N W Karyadi ◽

Pravitajaty ◽

A N I Kusumastuti ◽

K Ma’Rufah ◽

...

Keyword(s):

Moisture Content ◽

Quality Analysis ◽

Physical Parameters ◽

Drying Methods ◽

Rehydration Ratio ◽

Freeze Dried ◽

Drying Conditions ◽

The Impact ◽

Freeze Dryer

Abstract Beluntas leaves are medicinal plants with pharmacological effects, such as antioxidant, antidiarrheal, antidiabetic, and antibacterial. Drying is one of the processes before the beluntas leaves are consumed. However, drying could degrade the quality of beluntas leaves. This research aims to investigate the impact of drying conditions on the physical qualities of dried beluntas leaves. Beluntas leaves with a moisture content of 83-90% were dried using drying methods, namely the greenhouse effect dryer (ERK), cabinet dryer (CD) at 40, 50, 60, and 70°C, and freeze dryer (FD) at 35, 45, and 55°C. The physical parameters measured were moisture content, color, shrinkage, rehydration ratio, and bulk density. The results showed that the final moisture content of the dried beluntas leaves were 8.40; 4.92-10.70; 4.73-6.77%w.b for ERK, CD, and FD, respectively. Page’s model was suitable for explaining the changes in moisture ratio during the drying process (R 2 = 0.9934 − 0.9999). The freeze-drying method can preserve the leaves’ color and obtain the lowest moisture content with a low drying temperature compared to other methods. Freeze-dried beluntas leaves also exhibited the highest rehydration ratio, which was 2.03 – 2.25.

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Changes in Physicochemical Properties and Volatile Compounds of Roselle (Hibiscus sabdariffa L.) Calyx during Different Drying Methods

Molecules ◽

10.3390/molecules26206260 ◽

2021 ◽

Vol 26 (20) ◽

pp. 6260

Author(s):

Nurul Hanisah Juhari ◽

Helle Jakobe Martens ◽

Mikael Agerlin Petersen

Keyword(s):

Moisture Content ◽

Physicochemical Properties ◽

Volatile Compounds ◽

Freeze Drying ◽

Cell Structure ◽

Vacuum Drying ◽

Drying Methods ◽

Oven Drying ◽

Sun Drying ◽

Freeze Dried

Fresh roselle are high in moisture and deteriorate easily, which makes drying important for extending shelf-life and increasing availability. This study investigated the influence of different drying methods (oven-drying, freeze-drying, vacuum-drying, and sun-drying) on the quality of roselle calyx expressed as physicochemical properties (moisture content, water activity, soluble solids, color), volatile compounds, and microstructure. Oven-drying and freeze-drying reduced moisture content most while vacuum-drying and sun-drying were not as efficient. All drying methods except sun-drying resulted in water activities low enough to ensure safety and quality. Vacuum-drying had no impact on color of the dry calyx and only small impact on color of water extract of calyx. Drying reduced terpenes, aldehydes, and esters but increased furans. This is expected to reduce fruity, floral, spicy, and green odors and increase caramel-like aroma. Sun-drying produced more ketones, alcohols, and esters. Scanning electron microscopy revealed that freeze-drying preserved the cell structure better, and freeze-dried samples resembled fresh samples most compared to other drying techniques. The study concludes that freeze-drying should be considered as a suitable drying method, especially with respect to preservation of structure.

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Modeling sorption isotherms and isosteric heat of sorption of roasted coffee beans

Proceedings of 21th International Drying Symposium ◽

10.4995/ids2018.2018.7668 ◽

2018 ◽

Author(s):

Gentil Andres Collazos-Escobar ◽

Nelson Gutiérrez-Guzmán ◽

Henry Alexander Vaquiro-Herrera ◽

Erika Tatiana Cortes-Macias

Keyword(s):

Moisture Content ◽

Equilibrium Moisture Content ◽

Sorption Isotherms ◽

Isosteric Heat ◽

Dew Point ◽

Roasted Coffee ◽

Sorption Data ◽

Heat Of Sorption ◽

Coffee Beans ◽

Roasted Coffee Beans

The aim of this work was determine the sorption isotherms in roasted beans of specialty coffee at temperatures of 25, 30 and 40 °C and water activities between 0.1 and 0.8 using the dynamic dew point method. The experimental sorption data were modeled using 12 different equations to represent the dependence of equilibrium moisture content with aw and temperature. The net isosteric heat of sorption was determined from the experimental sorption data using the Clausius-Clapeyron equation. The Weibull model satisfactorily modeled the effect of the temperature on the hygroscopic equilibrium in roasted coffee beans (R2adj =0.902 and RMSE = 0.00550 kg·kg-1d.b.). The net isosteric heat of sorption increase with increased moisture content. Keywords: water activity; sorption properties; equilibrium moisture content; hygroscopicity

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