scholarly journals The Effect of Freeze-Drying on the Properties of Polish Vegetable Soups

2021 ◽  
Vol 11 (2) ◽  
pp. 654
Author(s):  
Ewa Jakubczyk ◽  
Aleksandra Jaskulska

The aim of this study was to investigate selected physical and biochemical properties of four vegetable freeze-dried soups. The water content, water activity, pH, color parameters, antioxidant activity (EC50), total polyphenolic content of fresh tomato, pumpkin, beetroot, and cucumber, and freeze-dried soups were measured. Sensory analysis was applied to compare sensory attributes of fresh and rehydrated soups. The sorption isotherms of freeze-dried soups were obtained with the application of the static and dynamic vapor sorption (DVS) method. The application of the freeze-drying method enabled the obtaining of dry soups with a low water content of 2–3%. The drying caused a significant change of color of all soups. The redness of soups decreased after drying for the beetroot soups from +39.64 to +21.91. The lower chroma value of 25.98 and the highest total color change ΔE*ab = 36.74 were noted for freeze-dried beetroot soup. The antioxidation activity and total polyphenolic content were reduced after drying, especially for the cucumber and tomato soups. The Peleg model was selected to describe the sorption isotherms of dried soups. The sorption isotherm of freeze-dried cucumber and beetroot soups had a sigmoidal shape of type II. The shape of the moisture sorption isotherm for freeze-dried tomato and pumpkin soups corresponded more with type III isotherms. The DVS method can be used to characterize the moisture sorption isotherms of freeze-dried products.

Author(s):  
Aslı Zungur Bastıoğlu ◽  
Safiye Nur Dirim ◽  
Figen Kaymak Ertekin

Yogurt powder was produced by freeze drying and with added candied chestnut puree at ratios of 5, 10, and 20 % by weight. Moisture sorption isotherms of yogurt powder samples, plain (YP), and containing 5, 10, 20% candied chestnut puree (CCP) were determined at 25°C using the standard, static-gravimetric method. The experimental adsorption data of yogurt powders at 25°C were fitted to 14 sorption equations which are most widely used to fit experimental sorption data of various food materials. The parameters of the sorption models were estimated from the experimental results by using the nonlinear regression analysis. The GAB model gave the closet fit to the sorption data of freeze dried yogurt powders with candied chestnut puree at 25°C. BET, Ferro Fanton, Henderson, Halsey, Oswin and Modified Oswin models are also acceptable for describing the adsorption isotherms for freeze dried yogurt with candied chestnut puree at 25°C.


Author(s):  
J Roy ◽  
MA Alim ◽  
MN Islam

The study was carried out for the purpose of determining the drying kinetics as well as moisture sorption isotherm of hybrid-81 corn. Corn at about 31% moisture content (wb) was dried in a forced convective hot air cabinet dryer at different drying conditions, such as variable air dry bulb temperature (40°C, 50°C and 60°C) and loading density (3.56 kg/m2, 7.12 kg/m2, and 10.68 kg/m2) as well as in shining sun at different layers (3.56 kg/m2, 7.12 kg/m2, and 10.68 kg/m2). The water sorption isotherm of the dried corn was developed using vacuum desiccators, which contained saturated salt solutions in the range of 11-93% RHs. The mono-layer moisture content calculated by the Brunauer–Emmett–Teller (BET) model (6.76 g/100 g solid) was lesser than that calculated by the Guggenheim–Anderson–De Boer (GAB) model (10.53 g/100 g solid). The energy constants were 10.45 and 4.64 as per BET and GAB equation, respectively. Both models gave suitable fits for corn. The activation energy (Ea) for diffusion of water was found to be 11.09 kcal/gm-mole for corn. Furthermore, it was noticed that, with the increase of corn layer, the drying rate decreased in case of both sun and mechanical drying. However, higher loading density resulted in efficient drying, at least up to 10.7 kg/m2. It was shown that the drying time to obtain stability was the lowest for moisture content (12.08 %) corresponding to aw of 0.65 in case of BET or GAB monolayer moisture content. This finding could be helpful in predicting the storage life of corn.J. Bangladesh Agril. Univ. 15(2): 309-317, December 2017


1969 ◽  
Vol 77 (3-4) ◽  
pp. 113-128
Author(s):  
Humberto Vega-Mercado ◽  
Gustavo V. Barbosa-Cánovas

Moisture sorption isotherms of freeze-dried pineapple pulp were determined at 5, 25, 30, 35 and 55°C. Water activity were controlled by using preselected saturated salt solutions in evacuated glass desskators according to Wolf et al. (20), where micro crystalline cellulose is the reference material for the determination of sorption isotherms. The data were correlated in terms of some empirical models involving two single parameters: models of Henderson, Oswin, Chung-Pfost, Halsey, Iglesias-Chirife, and Smith. Also, the data was correlated by the Guggenheim-Anderson-deBoer (G.A.B.) model involving three adjustable parameters. It was found that the models proposed by Henderson and Iglesias-Chirife were the most useful ones in predicting water activities at different levels and at different temperatures.


2015 ◽  
Vol 11 (4) ◽  
pp. 573-578 ◽  
Author(s):  
Ji-Yeon Chun ◽  
Yeon-Ji Jo ◽  
Jun-Bo Shim ◽  
Sang-Gi Min ◽  
Geun-Pyo Hong

Abstract This study investigated the moisture sorption isotherm (MSI) profiles of freeze-dried (FD) and boiled-dried (BD) abalone at 15°C, 25°C, and 35°C, and compared the quality characteristics of the abalone after rehydration. The equilibrium moisture content (EMC) and the calculated monolayer moisture content of FD abalone were higher than those of BD abalone. After rehydration, FD abalone showed a higher yield and a lower shear force than BD abalone. Additionally, the appearance of FD abalone was similar to that of fresh abalone, reflecting a potential application of FD to produce value-added dried abalone.


2013 ◽  
Vol 431 ◽  
pp. 32-36 ◽  
Author(s):  
Rungsiri Suriyatem ◽  
Pornchai Rachtanapun

Rice starch/carboxymethyl cellulose from durian rind (RS/CMCd) blend films were prepared by solution casting. The effect of different ratios between rice starch and CMCd (100:0, 88:12, 67:33, 50:50, 33:67, 12:88 and 0:100) on moisture sorption isotherm of blend films was investigated. The sorption isotherm of RS/CMCd blend films was determined at various relative humidity (RH) at 25°C. The isotherm curves revealed that the highest equilibrium moisture content (EMC) was obtained from CMCd film, at aw=85. Knowledge of sorption isotherms is important to predict the moisture sorption properties of the filmsviamoisture sorption empirical models. The Lewicki, Peleg, Guggenheim-Anderson-deBoer (GAB), BrunauerEmmettTeller (BET), and Oswin models were tested to fit the experimental data. The root mean squares percentage error (%RMS) of Lewicki, Peleg, GAB, BET and Oswin was in the range of 5.3-83.1, 2.2-20.0, 6.9-20.2, 3.4-26.4 and 4.7-41.2, respectively. The Peleg model was found to be the best fitted model for RS/CMCd blend films.


Food Research ◽  
2021 ◽  
Vol 5 (6) ◽  
pp. 178-186
Author(s):  
T. Chuacharoen ◽  
J. Moolwong ◽  
T. Chyrsirichote

The effect of maltodextrin on the moisture sorption isotherm, glass transition temperature (Tg), and degree of caking of freeze-dried avocado samples at room temperature (25°C) was investigated. The incorporation of maltodextrin reduced the water sorption capacity of the powder due to its less hygroscopic nature. Parameters derived from the Guggenheim, Anderson, and de Boer (GAB) model describing the properties of absorbed water are discussed. The water absorption isotherm possessed the characteristic sigmoid-shaped type II isotherm curves and the model gave the best fit over the whole range of aw tested. The differential scanning calorimetric method was used to measure the Tg of freeze-dried avocado samples. Increasing the water content decreased the Tg, and Tg was increased with increasing maltodextrin content. Increased maltodextrin content to solid material in the freeze-dried sample was associated with less sensitivity to caking as evidenced by Tg values. In addition, increased maltodextrin content in the powders caused brighter, less yellowish, and more greenish coloration and protected color change including browning index. The antioxidant capacity was significantly decreased with increasing maltodextrin content. Thus, the effect of maltodextrin concentration on physicochemical properties was a promising way to preserve the physical property and chemical compounds in freezedried avocado powder.


2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohammad Shafiur Rahman ◽  
Mohammed Khalfan Al-Khusaibi ◽  
Kutaila Abbas AL-Farsi ◽  
Ismail Mohamed Al-Bulushi ◽  
Aisha Abushelaibi ◽  
...  

Water activity is considered an important factor in assessing the stability of food. Understanding the relationship between water activity and equilibrium moisture content (moisture sorption isotherm) benefits food processing in terms of modeling of drying and estimation of shelf life. In addition, glass transition helps to quantify molecular mobility which helps in determining the stability of food. The aim of this study was to determine the moisture sorption isotherm and thermal characteristics of freeze-dried tuna. These characteristics will help in determining the monolayer moisture and glassy state of the product, at which food is considered most stable. Moisture sorption isotherm at 20°C and thermal characteristics (over a wide temperature range i.e. from -90 to 250 °C) of freeze-dried tuna flesh were measured. Isotherm data were modeled by BET (Brunauer-Emmett-Teller) and GAB (Guggenheim-Anderson–De Boer) models. The GAB and BET monolayer water values were determined as 0.052 and 0.089 g g-1 dry-solids (dry-basis), respectively. In the case of samples at moisture contents above 0.10 g g-1 (wet basis), DSC (Differential Scanning Calorimetry) thermograms showed two-step state changes (i.e. two glass transitions), one exothermic peak (i.e. molecular ordering) and another endothermic peak (i.e. solids-melting). However, the sample at moisture content of 0.046 g g-1 showed three-step state changes (i.e. three glass transitions). The multiple glass transition could be explained by the natural heterogeneity of tuna flesh and inhomogeneity due to molecular incompatibility of the different compositions. The moisture content did not affect the first glass transition temperature nor the exothermic peak (p>0.05), whereas the third glass transition temperature decreased (i.e. plasticized) with increasing moisture content (p<0.05). The solids-melting peak temperature decreased, and enthalpy increased with decreasing moisture content (p<0.05).


2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
M. S. Alamri ◽  
A. A. Mohamed ◽  
S. Hussain ◽  
M. A. Ibraheem ◽  
Akram A. Abdo Qasem

Epoxy resin was prepared by crosslinking epoxidized oil and millet flour. The reaction was carried out at three different temperatures (25, 40, and 55°C) and zinc chloride levels (1, 2, and 3%). Moisture sorption isotherms were determined at 0.1 to 0.9 water activity (aw) using a gravimetric sorption analyzer (Q 2000). The sigmoidal shape (type II) of the resin isotherms exhibited lower equilibrium moisture content (EMC) at higher temperature. The experimental data were modeled using GAB (Guggenheim–Anderson–de Boer) and BET (Brunauer–Emmett–Teller). The EMC of the resin was significantly lower than that of the flour, which could be attributed to the decrease in the number of water-binding sites due to the creation of dense areas during crosslinking. The low root-mean-square error (RMSE) indicates that GAB and BET were suitable for predicting the water sorption isotherm for millet flour resin. The heat of sorption of the resin was large at low moisture content and increased at higher relative humidity. It is recommended that millet flour resin be used at relative humidity below 60%.


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