جستجوی مقالات مرتبط با کلیدواژه « Foam mat drying » در نشریات گروه « صنایع غذایی »

In this research, cress seed gum in three concentrations (0.1, 0.2 and 0.3%) as a stabilizer and egg white powder in four levels (1, 2, 3 and 4%) was used to produce orange juice foam and then the optimal foam sample (minimum density, maximum stability and overrun) was selected. Next, the optimal sample for drying by foam mat drying method was dried at three different temperatures (40, 55 and 70 C) by hot air dryer. The results showed that by decreasing the concentration of cress seed gum and increasing the concentration of egg white protein, the overrun increased significantly and the density decreased (p<0.05). Also, by increasing the concentration of cress seed gum and egg white protein, the stability of the foam improved. Among all the treatments, the sample containing 4% egg white powder and 0.1% cress seed gum, in addition to low drainage (drainage volume 0.5 ml), has low density (0.321 gr/cm) and high overrun (308 percent) which was selected as the best treatment for the production of orange powder. The drying time of orange pulp at temperatures of 40, 55 and 70 degrees Celsius was 100, 150 and 280 minutes, respectively. The effective diffusion coefficient in the temperature range of 40 to 70 degrees Celsius was in the range of 1.38 x 10-7 to 2.938 x 10-7 m2/s. The results showed that by increasing the temperature from 40 to 70 degrees Celsius, the solubility of the powder increased, while the water activity of the powder, density and reabsorption of water decreased significantly (p˂0.05). Also, the results of color analysis showed that with increasing drying temperature, color indices (L*) and (a*) increased significantly and color index (b*) decreased. Our results showed that food powders with good properties can be gained by foam mat drying.

Production of powdered beverage, especially based on local products and with the aim of optimal use of waste, is one of the research fields considered by the food industry. In this studt the effect of different foam mat drying condition on orange beverage powder was investigated. In order to prepare the beverage foam, egg white and basil gum solution were used according to the experimental design and were mixed with an electric mixer at the highest speed for 6 minutes. Drying was performed under different treatments of the oven with (45, 65 and 80) temperatures and microwave with (360, 600 and 900) power, with (3 and 5 mm) thicknesses. Some properties of the beverage powder including moisture content, water activity, solubility, water binding capacity, rehydrating the powder, hygroscopy, flowability, pH, color, DSC,FTIR, and sensory characteristics were investigated. Almost all properties indicate a increasing trend with increasing the drying temperature.

One of the products that its production has not been investigated well and is an imported product is cream powder. Foam mat drying is a widespread technique to dehydrate liquid or semi-liquid foods with high viscosity, adhesion and high sugar content, which are usually difficult to dry. Evaluating moisture content over time is the first indication of how the drying process is performed and can be used as a tool to compare the drying behavior of food. The rate of drying, which is expressed as a function of time or moisture content, is also a very important parameter that helps to understand drying properties of a material. Color can also indicate chemical changes in food during the thermal process such as browning and caramelization. Therefore, since in the drying industry, process time, product quality, optimization and equipment design are directly affected by the rate of drying of food, hence, in this study, in the process of drying the camel milk cream by the foam mat drying method, drying operation at temperatures of 45, 60 ,and 75 °C and thicknesses of 1, 3 and 5 mm was performed in a non-continuous cabinet dryer to evaluate the kinetics of drying , structure and color of the dried foam.   

Camel milk cream was mixed with carboxymethyl cellulose (0.1%), cress seed gum (0.1%) and 80% whey protein concentrate (5%) at 25 ° C. After pasteurization, the samples were stirred with a mixer at a maximum speed of 1500 rpm (5 minutes) for proper aeration. The foam samples were poured into a plate in a thin layer with thicknesses of 1, 3 and 5 mm and then dried in a dryer at temperatures of 45, 60 and 75 ° C until a constant moisture was reached. The process treatments were performed in a completely randomized central composite design (CCD) (5 replications at the center point) for 2 variables at three levels. The effective diffusion coefficient was calculated based on the second Fick's law of diffusion. Then, using Arrhenius equation, which shows the relationship between temperature and effective diffusion coefficient, activation energy was also calculated. After the drying stage, in order to investigate the changes in moisture during the drying, by determining MR, we have used some experimental models that were previously used for drying agricultural products, to fit the experimental data using the statistical software MATLAB 2016. 

The results showed that increasing the temperature from 45 to 75° C reduced the drying time of the samples by almost 50%. Reducing the thickness from 3 to 1 mm led to an 80% reduction in drying time of the samples. The overall effective diffusion coefficient of the tested samples varied between 7.09×10-10 and 8.11× 10-9  m2/s. The increase in the temperature led to an increase in the effective diffusion coefficient of the samples. The activation energy of the samples varied between 25.59 and 38.22 kJ /mol, and  comparison of the means showed that the activation energy of the samples was also increased by increasing the foam thickness. Totally, 17 models were evaluated to investigate the drying kinetics of the samlses and in all cases of foam drying , page and Midilli models with R2 values above than 0.99 and the lowest values of RMSE indicate the best fit with the experimental data among the 17 fitted model. Examining the digital images of the samples also showed that at low temperatures, the structure of the dried foams was smooth and it became more uneven and porous as a result of increasing the temperature. Also, the trend of changes in the parameters of the gray level co-occurrence matrix (GLCM) (energy, correlation, and homogeneity) of the samples was almost the same with the changes in temperature and thickness so that, the increase in the drying temperature and a decrease in the thickness of the samples led to a decrease in these parameters. Increasing the foam thickness at high temperatures led to a decrease in the browning index and at low temperatures, led to an increase in the browning index of the samples.

The foam mat drying is a process in which liquid food is converted into stable foam by combining gas into it, and then dried at a relatively low temperature. In current research, shrimp foam was prepared using 0.25% Cress seed gum and dilution with ratio of 1 shrimp to 4 water after 4 min whipping and then foam with 4mm thickness dried in a drier with 70°C. Shelf life of powders for 6 months and two storage temperatures (ambient and refrigerate) were measured. The experiments included density, water activity, water absorption, oil absorption, total volatile base nitrogen (TVB-N), thiobarbituric acid, peroxide and microbial count including coliform bacteria, mold and yeast, and total count. The count of mesophilic, psychrotroph, total coliforms, vibrios, mold and yeast was increasing during shelf-life time. On the other hand, fecal coliform and escherichia coli and Salmonella were not found in shrimp powder samples during shelf-life period. During the shelf-life period of water absorption, oil absorption, water activity, decreasing trend and TVB-N, thiobarbituric acid, peroxide and density were increasing. In refrigerated samples at the end of the 6-month period, there was a lower level of TVB-N, thiobarbituric acid, peroxide and water activity than those stored in the ambient temperature.

Due to the nutritional status and health effects of raspberry as a fruit rich in nutrients such as anthocyanins and phenolic compounds, the resulting powder can while have these compounds, increasing the variety and consumption of raspberry products (Si et al., 2016). However, because of its high moisture content and vulnerable texture, raspberry fruit corrupts very quickly and is difficult to keep fresh, even in cold storage conditions. Therefore, maintaining the quality of raspberry fruit after harvest and also increasing its storage time is one of the goals of raspberry growers around the world (Palonen and Weber, 2019). The drying process of fruits and vegetables prevents chemical and biochemical spoilage of the products and increases their shelf life by reducing the moisture content. However, some undesirable physical and chemical changes such as loss of color, texture and nutritional value may also occur during drying, which reduce consumer acceptance (Dehghannya et al., 2017; Kayran and Doymaz, 2017). Foam mat drying is an alternative method of drum dryer, spray dryer and freezer dryer for the production of food powder. Food products become a stable foam by adding foaming agents and stirring in the presence or absence of foam stabilizers and are dried using different heat streams. Therefore, with the proper selection of foaming agents and drying conditions, a high quality powder can be obtained (Qadri et al., 2010; Javed et al., 2018). Despite the impact of air velocity on drying kinetics and other process parameters and consequently on the qualitative and functional characteristics of the dried product, few studies have been done on the effect of air velocity on foam mat drying of agricultural and food products. Therefore, according to the potentials of raspberry fruit and foam mat drying method, the aim of the present study was to evaluate the effect of drying air velocity (2 to 4 m/s) on the effective moisture diffusion coefficient, drying kinetics and also on the physicochemical properties of raspberry powder produced by the foam mat drying method.

Black raspberry fruit after being prepared from the local market in the north of the Iran (Gilan province) was stored at a temperature of 4C. The raspberry fruit was first completely crushed by a food processor and passed through mesh number 30. Ovalbumin and methylcellulose with a concentration of 0.5% were used as foaming agent and foam stabilizing agent, respectively and added to the raspberry pulp. The resulting mixture was mixed with an electric stirrer at maximum speed for 10 minutes and the resulting foam was spread in a thickness of 7 mm on an aluminum plate. Drying was performed with a convective hot air dryer at a temperature of 70C and an air velocity of 2 to 4 m/s. Drying kinetics and effective moisture diffusion coefficient, as well as physicochemical properties of raspberry powder such as bulk and tap density, powder flowability, absolute density, water solubility index (WSI) and water absorption index (WAI), powder mass porosity, moisture content and color were evaluated according to the methods described by Dehghannya et al (Dehghannya et al., 2018, 2019).

In the present study, the drying kinetics of raspberry by the foam mat drying method and the physicochemical properties of the resulting powder under the influence of air velocity were investigated. The results showed that the effective moisture diffusion coefficient (Deff) was in the range of 1.391  10-8 to 1.723  10-8 m2/s and the increase of drying air velocity from 2 to 3 m/s and 3 to 4 m/s had a significant effect on it (p < 0.05). However, increasing the drying air velocity had no significant effect (p> 0.05) on moisture content, moisture ratio and drying rate of the product during drying. Changes in Carr index and Hausner ratio at different drying velocities were statistically significant (p <0.05) and increasing the air velocity from 2 to 3 m/s reduced their values, which indicated the improvement of the powder flowability at air velocity of 3 m/s. Furthermore, the mean values of MC, WSI, WAI, Chroma index and brightness of raspberry powder significantly increased with increasing drying air velocity (p <0.05). However, the bulk and tap density and absolute density and the overall color difference of raspberry powder decreased with increasing drying air velocity (p> 0.05).

The results of this study showed that the hot air velocity used in the drying process can be effective on the effective moisture diffusion coefficient and thus on the quality characteristics of the produced powder. So that, its effect on effective moisture diffusion coefficient, bulk and tap density, flowability, absolute density, WSI, WAI, moisture content and brightness of powder were significant. It should be noted, that the effect of air velocity in different values and in accordance with other process conditions, on different parameters is variable. Raspberry powder produced by foam mat drying method, due to its high anthocyanin content, can be used as a natural additive in dairy products, desserts, jams, jellies and other food products and the results of this study can increase the quality of the powder and improve its nutritional and functional properties by optimizing the drying process.

Artificial neural networks are a set of nonlinear equations that have the ability to adapt to establish complex nonlinear relationships between input and output variables. Artificial neural network modeling was used to predict the production of Ricotta cheese powder with the desired quality. In this study, a 4-class artificial neural network with a multilayer perceptron model was used to predict foam and Ricotta cheese powder data prepared by foam mat drying. This modeling was performed by pattern recognition method and using machine learning algorithm. Pattern recognition is the ability to recognize the order of properties or data that gives information about a system or data set. The model used for this study had 10 neurons in the hidden layer. 4 different ratios of milk and whey (treatments) were considered as input and foam density, powder density, hygroscopy, water activity, water absorption and oil absorption as model outputs. In this model, 70% of the data were used for training, 15% for testing and 15% of the data for validation. The best validation performance occurred in the 20th period. The final results showed that the model used was able to accurately predict the data related to each class with 94.8% accuracy.

Celery is one of the most consumed and highly nutritious vegetables with high dietary fiber, phytochemicals, vitamins, and minerals, which offers great benefits for utilization as a functional food ingredient. Fruit and vegetable juice powders have many benefits and economic advantages over their liquid precursors such as reduced volume/weight, reduced packaging, easier handling/ transportation, and much longer shelf-life. Also, powders can be reconstituted to produce juice and used for preparation of products such as snacks, chutney, soups, baby foods, etc. In‏ foam-mat drying, food liquids and pastes are first whipped into stable foam by the addition of different foaming agents or stabilizing agents and then dried in the form of thin layer. This foam structure dries rapidly due to the increase of the surface area of the material by incorporating air/gas and forms a porous structure which gives high quality and instant properties of the dried product.‏ The dried product is scraped off from the drying surface in the form of flakes, which is then converted to a fine powder. Response surface methodology (RSM) is a combination of mathematical and statistical techniques used to investigate the interaction effects of independent variables on responses. There is considerable information on foam-mat dried food powders, but there is no scientific literature related to foam-mat drying of celery juice. The present research was thus focused on optimizing the foaming conditions (WPC as a foaming agent, Xanthan gum (XG) concentration as the stabilizer and whipping time (WT)) to minimize foam density (FD) and drainage volume (DV) using RSM. The effects of drying temperatures on some physicochemical properties of powder were also investigated.  

Celery was purchased from the‏ local market.XG and WPC powders were‏ purchased from Sigma Chemical Company (St. Louis, MO)‏ and Milei Company Germany, respectively. Celery juice was extracted by using a juicer machine (Robert Bosch Stand mixer MMB 2000 /05 FD 8611 Type CNSM03EV, 600W, Slovenia). Based on preliminary tests, XG solutions were prepared by dissolving the appropriate amount of the defined gum powder in distilled water and stirring with a magnetic stirrer to achieve a uniform solution. This solution was refrigerated at 4°C overnight to complete hydration. RSM was used to estimate the main effects of the process variables on FD and DV in celery juice foam. The experiment was established based on a face-centred central composite design (FCCD). According to the experimental design, to prepare 100 g of samples, the appropriate amount of celery juice, WPC, and XG solution were poured to a 250 mL beaker. Then the mixture was placed into a water bath for 5 minutes at 55 °C temperature. The mixture was then taken out of water bath and was whipped by a mixer (Gosonic, model No. GHM- 818, 250W, China) with the maximum speed of 5400 rpm at ambient temperature during the given time. The density of foamed celery juice was determined in terms of mass over volume and expressed in g/cm3. To assess foam stability, the drainage test was performed for 1h. Furthermore, the effects of drying temperatures on some physicochemical properties of powders were investigated.  

The quadratic model was selected as a suitable statistical model for both FD and DV. ANOVA showed that this model is significant for both responses. Moreover, lack-of-fit was not significant for response surface models at a 95% confidence level, indicating that this model is adequately accurate for predicting responses. Based on the constrain criteria, the optimized foaming parameters were: XG concentration of 0.42% (w/w), WPC concentration of 6% (w/w), and WT of 9.30 min. The amount of FD and FDV for foam at these optimum conditions were 0.4 g/cm3 and 0 ml, respectively. The results showed the moisture content and water activity of the celery powders decreased with the‏ increase in drying temperature. By increasing drying temperature from 40 to 70 °C, bulk density also decreased. Increase in drying temperature results in decrease in moisture content and bulk density. Tapped density generally behaves similar to bulk density because by shaking powder, the space between the particles is filled and occupied volume by the powder is reduced. By increasing in temperature, particle density decreased. Overall, with increasing drying temperature, the porosity of powder increased. Increasing temperature and reducing moisture content, the possibility of approaching and join together of particles is increased and the space between the particles becomes less. The numerical value of the car index parameter in this study was 15.3% to 24.67%. The highest value of flowability related to the sample was dried at 70°c. With decreasing in drying temperature, the moisture content of powders increased and due to forming liquid bridges between particles making them less flowable. The numerical value of the Hausner parameter in this study was 1.15 to 1.32. Except for powder produced at 70 °C, the powder was placed in the intermediate cohesiveness powder class. By increasing drying temperature, the cohesiveness of powder decreased significantly.

In this research, physical properties in instant drink powder made from red beetroot, quince fruit and cinnamon extract by foam-mat drying were investigated. The effect of independent variables regarding maltodextrin level and the method of drying (foam mat hot air drying and freeze-drying) on the moisture content, hygroscopicity; caking degree; bulk, tapped and particle density and solubility of powders were determined. Results showed as the maltodextrin level increased, hygroscopicity and caking degree of powders decreased. The highest values of bulk (0.62 ± 0.008 g/cm3) and tapped density (0.77 ± 0.007 g/cm3) belong to powders contain 20% of maltodextrin, prepared with foam mat hot air drying and the lowest values (0.25 ± 0.003 g/cm3, 0.31 ± 0.005 g/cm3 respectively for bulk and tapped density) observed in powders contain 20% of maltodextrin, prepared with foam mat freeze-drying. Powders contain 20% of maltodextrin in both methods of drying had the lowest values of particle density (1.04 ± 0.008 g/cm3 and 1.23 ± 0.02 g/cm3 respectively for 20% maltodextrin hot air foam mat dried and freeze foam mat dried samples). Powder solubility increased as the maltodextrin level increased. Hygroscopicity, caking degree, solubility and particle density in powders prepared from foam mat freeze-drying were higher than that of powders prepared with foam mat hot air drying. Bulk and tapped density of powder samples prepared with foam mat hot air drying (0.52 ± 0.1 g/cm3 and 0.67 ± 0.11 g/cm3 respectively) were higher than that of foam mat freeze-dried samples (0.36 ± 0.07 g/cm3 and 0.47 ± 0.1 g/cm3 respectively). Both independent variables (maltodextrin level and drying method) had a significant effect on hygroscopicity; caking degree; bulk, tapped and particle density and solubility. Results showed that the powder sample contains 20% maltodextrin prepared with foam mat hot air drying can be introduced as an optimal sample.

The purpose of this study was to produce red beetroot pulp powder using foam-mat drying technique and to investigate the effect of foam thickness on drying kinetics and physicochemical and microstructural properties of the resulting powder. To prepare foam, ovalbumin as foaming agent at a concentration of 2% (w / v) was added to the red beetroot pulp and was stirred for a specific time and speed. Prepared foam was spread on aluminum plates at thicknesses of 5, 6 and 7 mm and then dried in a hot air cabinet dryer at 50 ºC and constant air velocity of 1 m/s. Results showed that increasing foam thickness from 5 to 7 mm had no significant effect on moisture content and moisture ratio but significantly (p <0.05) reduced the drying rate by about 29.63%. The effective moisture diffusion coefficient was significantly affected by the foam thickness and ranged between 5.550 × 10−9 and 7.388 × 10−9 m2/s. Also, with increasing foam thickness, due to increasing drying time and more denaturation of proteins, an increase in Carr index and Hausner ratio was observed, resulting in a decreasing trend in the flowability of the powders. Bulk and tapped densities of powders were significantly decreased due to the change in moisture content, caused by the increase in foam thickness. Thickness had no significant effect on water solubility index and water absorption index. The microstructure analysis of the produced powders by field emission scanning electron microscope showed that with increasing foam thickness, cracking and surface roughness of powder particles increased. The results of this study and further studies can lead to optimization of red beetroot powder production as a natural food coloring and better preservation of its nutritional and functional properties.

The foam mat drying is a process in which liquid food is converted in to stable foam by combining gas into it, and then dried at a relatively low temperature. The effect of drying temperature (50, 60 and 70 °C) and thickness (4 and 8 mm) on foam mat drying kinetics of shrimp under hot-air drying was investigated. The drying curves obtained were processed for drying rates to find the most convenient model among the 12 different expressions proposed by earlier authors. In addition, the various statistical parameters such as: R2, reduced chi-square, SSE and root mean square error (RMSE) were used to determine the quality of the fit. The colour change during concentration processes was investigated. Total colour differences parameter was used to estimate the extent of colour loss. The zero-order, first-order and a combined kinetics model were applied to the changes in colour parameters. Based on the results, Midilli model was found to be the best model fitted to the experimental hot air drying data at all temperature levels. These models exhibited the highest value of R2 and the least RMSE, χ2 and SSE comparing to the other models. Results indicated that variation in TCD followed combined kinetics model. This model implied that the colour formation and pigment destruction occurred during foam mat drying process of shrimp.

Cluster analysis (CA) is a multivariate tool used to organize a set of multivariate data (observations, objects) into groups called clusters. The cluster analysis method was carried out on characteristics of Ricotta cheese powder, with the effect of milk/whay ratio (formulation) and foam mat drying temperature. In this study, 4 types of formulations and 6 drying temperature were used to study the density, hygroscopic and color factors to find the formulation and optimal temperature that created the proper physical properties. The results of analysis of variance showed high temperature due to higher vapor velocity, decreased density and increased hygroscopicity (p<0.05). Also, with increasing temperature, the index "L" decreased and the indices "a" and "b" decreased. According to the results of cluster analysis, cluster 2 was selected as the best cluster for the least disparity between treatments and also due to the lowest Within-group variance. In this cluster, cheeses with a high percentage of whey in the formulation combination and low temperatures are found to foam mat drying. According to the results, the Lightness (L) of the powders of this cluster is higher, and at lower temperatures the density and hygroscopy are lower. Based on the results in general, the use of cluster analysis to select formulations for foam mat drying of ricotta cheese is a suitable method.

In this study, the effect of chia seed gum (0.1-0.3%) and albumin (5-15%) on physicochemical properties of barberry powder (stability and density of foam, pH, density of powder, total anthocyanin content, Hygroscopic, water solubility index and Water absorption index) produced by foam-mat drying was evaluated. Results showed the increase of albumin and chia seed gum increased the stability of the foam and the solubility of the powder, while the foam density and hygroscopic of powder decreased. Increasing the concentration of albumin reduced the density and total anthocyanin content of the samples. Increasing the chia seed gum (0.1-0.2%) increased the density of powder, while increasing the chia seed gum (0.2-0.3%) reduced the density of powder and incorporated chia seed gum had no significant effect (P<0.05) on total anthocyanin content. Based on the results, pH of powders produced in the range of 3.35-3.31. The incorporation of albumin to 10%, had no significant effect (P<0.05) on pH, while incorporation of albumin (10 to 15%) significantly increased pH. Also, increasing chia seed gum (0.1-0.3 %) significantly increased the pH of the powders.

Ricotta cheese has a limited shelf life due to its nutritional properties, and foam drying can, in addition to increasing the shelf-life, have better properties and less cost than other drying methods. In this research, two types of ricotta cheese were prepared from whole milk and whole whey. The effect of egg white powder and whey protein concentrate in two levels of 1 and 3% in the foaming ability of cheese was investigated. In order to stabilize the foam, cress seed and xanthan gum were tested in three levels of 0.5, 1 and 1.5%. Density, drainage volume and overrun and Foam bubbles of different treatments were measured. According to the results, the best foam production conditions is 1% concentration of xanthan gum and 3% egg white powder that it had the lowest density and drainage volume and the highest overrun.

Kilka Fish is one of the most popular seafood products available for aquaculture development. It is a rich source of proteins, vitamins and minerals such as calcium and phosphor. The highly perishable nature of Kilka fish has strongly attracted researchers to find new methods to extend its shelf life. Kilka fish powder can be used in many foods, such as soups, sauces, snacks, etc. Foam-mat drying is a new effective technique has recently gained much attention because it does not suffer from major problems associated with traditional dehydration methods, such as poor rehydration characteristics, unfavorable sensory profile, and long drying time. The main objectives of this study were: (1) to optimize the effective parameters (egg white powder and xanthan gum concentration, and whipping time) on foaming properties of Kilka fish; (2) to study the effects of drying temperature and foam thickness on the drying characteristics and select a suitable model for thin-layer drying of foam; (3) to compute effective moisture diffusivity and activation energy of foam during drying; and (4) to study the effects of drying conditions on moisture content, water activity, hygroscopicity and color of powders and microstructure of dried Kilka fish foams.
Fresh Kilka fish (C. delicatula) was obtained from the Pak Samar Miroud Company (Mazandaran, Iran). Xanthan gum and egg white powders were purchased from Sigma Chemical Company and Gol Powder Company (Golestan Province, Iran) respectively. The Kilka fish skin removed and cleaned, and then crushed using a kitchen blender to obtain a homogeneous and uniform mixture. Based on preliminary tests, xanthan gum solution was prepared by dissolving a suitable amount of the selected gum powder in distilled water and mixed with a magnetic stirrer to obtain a uniform solution. The resulted solution was cooled at 4°C for 18–24h to complete hydration. According to the experimental design, to prepare 100 g of samples, appropriate amount of fish, egg white powder, xanthan gum solution and distilled water were mixed a 250-mL beaker. The mixture was then whipped with a mixer (Gosonic, model No. GHM- 818, 250W, China) with maximum speed at ambient temperature during given time, which was recommended by Design-Expert software version 6.02 (Stat-Ease, Inc., Minneapolis, MN). Foaming conditions, namely amount of egg white powder, xanthan gum and whipping time, optimized using response surface methodology (RSM) for minimizing foam density (FD) and drainage volume (DV). To evaluate drying behavior of the optimized foam, drying was carried out in a batch-type thin-layer dryer at three drying temperatures (45, 60 and 75°C) on 3- and 5-mm thicknesses. Ten thin-layer drying models were evaluated in the kinetics research. The higher values of R2 and lower values of χ2 and RMSE were selected as the basis for goodness of fit. The effective moisture diffusivity was calculated using method of slopes. A Fick’s diffusion model with slab geometry was used to describe the transport of moisture during drying inside a single Kilka fish foam mat. Activation energy was calculated by a simple Arrhenius-type relationship, by plotting the ln (Deff) against the reciprocal of absolute temperature (1/T). The microstructure of the dried fish foam-mats was analyzed by a scanning electron microscope. Finally, the effects of drying conditions on physicochemical properties of fish powder including moisture content, water activity, hygroscopicity and color were investigated.
The optimum values of variables for best product quality in terms of minimum FD and DV corresponded to egg white powder 3.67 % (w/w), xanthan gum 0.28% (w/w) and whipping time 8.93 min. The amount of FD and DV for foam at these optimum conditions were 0.92 g/cm3 and 0 ml, respectively. As expected, the increase in drying temperature and decrease in foam load led to acceleration of the dehydration of Kilka fish foam. Based on the statistical tests performed, Weibull distribution model can describe drying behavior of foams for all drying processes. Moreover, Fick’s second law was employed to calculate the effective moisture diffusivity that varied from 7.266×10-8 to 1.31×10-7 m2/s and from 7.404×10-8 to 1.693×10-7 m2/s with activation energy values of 18.201 and 25.615 kJ/mol for foam thicknesses of 3 and 5 mm, respectively. It was noted that the effective moisture diffusivity was increased when the drying temperature increased. Results showed that at the higher thickness, the internal moisture migration occurs along a longer distance rather than lower thickness. Therefore, an increase in moisture diffusivity occurs both with increase in drying temperature and sample thickness. The analysis of scanning electron microscopy (SEM) micrographs showed that there is wide porous structure of dried foams at higher speeds drying. With increasing drying temperature (due to reduction of drying times), combination of adjacent bubbles and therefor, collapse of foam structure occur less. Higher temperature reduced moisture content and aw , and thickness rise increased moisture content and aw under the same thickness and drying temperature, respectively. This is due to the fact that at higher temperatures, the rate of heat transfer to the sample would increase, therefore, it provides greater driving force for moisture evaporation which results the dried foams with reduced moisture content and aw. Moreover, with increasing foam thickness due to increased drying times and probably collapsed structure of foams and therefor weak pore structure, drying was performed difficultly which causes to retain more water in dried foams. Drying conditions had significant effect on hygroscopicity of powders. Results of color investigation showed that in both thicknesses, powder produced at 60°C have higher L* and lower a*.

Potato is one of the most consumed and highly nutritious vegetables with high energy, dietary fiber, phytochemicals, vitamins, and minerals which offer great benefit for utilization as functional food ingredient. The dried potato powder can be used in formulation of many foods like soups, snacks, sauces, noodles, etc. The foam mat drying involves the dehydration of a thin layer of foam followed by its disintegration in order to obtain a powder which can be easily reconstituted in water when added to other foods. Because of the porous structure of the foamed materials, mass transfer is enhanced leading to shorter drying times and consequently acquiring higher quality in the dried product. Food foams can be considered as biphasic systems where a gas (dispersed phase) is embedded in a continuous liquid phase. The foam properties such as structure, density and stability have important influence on moisture migration during drying and accordingly, the quality of final product. Foams that do not collapse for at least 1h are mechanically or thermally stable for the entire drying process. Response surface methodology (RSM) is a combination of mathematical and statistical techniques which used to investigate the interaction effects of independent variables on responses. There is considerable information on foam-mat dried food powders, but there is not any scientific literature that related to study on foam-mat drying of potato puree. The present research was thus focused on optimizing the foaming conditions (potato puree: gum solution ratio; Arabic gum (AG) concentration as the stabilizer and whipping time [WT]) to minimize foam density (FD) and drainage volume (DV) using RSM. Likewise, choosing a suitable model for thin-layer drying of foam and the effect of different drying temperatures (45, 60 and 80°C) on drying behavior were investigated, and the effective moisture diffusivity and activation energy were calculated. The effects of drying temperatures on water activity (aw) and water binding capacity (WBC) were also investigated.
Material and Fresh potato was purchased from a local market (Mashhad, Iran). Arabic gum was procured from Sigma Chemical Company (USA). For preparation of potato puree, fresh potatoes were washed and peeled by steel knife and were washed again and additional water was taken absolutely and then crushed by Phillips home crusher (600W) with maximum speed for 3 minutes to get a homogeneous puree. Based on preliminary tests, AG solutions were prepared by dissolving a suitable amount of the selected gum powder in distilled water and stirring with a magnetic stirrer to obtain a uniform solution. This solution was refrigerated at 4°C overnight to complete hydration. RSM was used to estimate the main effects of the process variables on FD and DV in potato puree foam. The experiment was established based on a face-centered central composite design (FCCD). The experimental range was chosen on the basis of the results of preliminary tests. The independent variables were consisted of potato puree: gum solution ratio (1:1 –2:1 w/w), AG concentration (0.1–0.9% w/w) and WT (3–9 min). According to the experimental design, to prepare 100 g of samples, appropriate amount of potato puree and AG solution were mixed in a 250-mL beaker. The mixture was then whipped with a kitchen mixer (model no. SM88, Sonny, China) at a maximum speed of 1,500 rpm at ambient temperature during given time which was recommended by Design-Expert software. The density of foamed potato puree was determined in terms of mass over volume and expressed in g/cm3. In order to assess foam stability, the drainage test was performed for 1h. To evaluate drying behavior of the optimized foam, drying was carried out in a batch-type thin-layer dryer at temperatures of 45, 60 and 80°C on 3 mm thickness. Ten thin-layer drying models were evaluated in the kinetics research. The higher value of R2 and lower values of χ2, RMSE and SSE were selected as the basis for goodness of fit. Fick’s diffusion equation for particles with a slab geometry was used for calculation of effective moisture diffusivity. The foamed potato puree spread on a tray was considered as slab geometry. Activation energy was calculated by a simple Arrhenius-type relationship, by plotting the ln (Deff) against the reciprocal of absolute temperature (1/T). Furthermore, the effects of drying temperatures on aw and WBC of powders were investigated.
The quadratic model was selected as a suitable statistic model for both FD and DV. ANOVA showed that this model is significant for both responses. Moreover, lack-of-fit was not significant for response surface models at 95% confidence level, indicating this model is adequately accurate for predicting responses. The optimum values of variables for best product quality in terms of minimum FD and DV corresponded to potato puree to gum solution ratio 2:1(w/w), AG 0.77% (w/w) and WT 6.80 min. The amount of FD and DV for foam at these optimum conditions were 0.30 g/cm3 and 5 ml, respectively.
The result showed that when the drying temperature increased, the drying time decreased. This was due to the quick removal of moisture at higher temperature. Drying rate (DR) versus moisture content of potato puree foam-mats figure showed that DR was higher during the initial stage as compared with the final stage and foam-mat drying was occurred principally in the constant rate period. Due to the increase in surface area and the porous structure, removal of water from the inner surface of potato puree foam to the outer surface was fast enough to preserve the surface moisture. The rate of movement of moisture from the inner surface to the exposed surface decreased with decreasing moisture content, which indicates that the DR decreased and the falling rate period started. The effective moisture diffusivity varied from 3.286×10-9 to 8.032×10-9 m2/s with activation energy value of 30.97 kJ/mol. Statistical analysis results showed that the Weibull distribution model provide the highest R2 and lowest values of χ2, RMSE and SSE at all drying temperatures. The temperature elevation reduced aw. This is due to the fact that at higher temperatures, the rate of heat transfer to the sample would increase, therefore, it provides greater driving force for moisture evaporation which results the dried foams with reduced aw. Drying temperatures did not show any significant effect on WBC of powders.

Kilka Fish is one of the most popular seafood products available for aquaculture development. It is a rich source of proteins, vitamins and minerals such as calcium and phosphor. The highly perishable nature of Kilka fish has strongly attracted researchers to find new methods to extend its shelf life. Kilka fish powder can be used in many foods, such as soups, sauces, snacks, etc. Foam-mat drying is a new effective technique has recently gained much attention because it does not suffer from major problems associated with traditional dehydration methods, such as poor rehydration characteristics, unfavorable sensory profile, and long drying time. The main objectives of this study were: (1) to optimize the effective parameters (egg white powder and xanthan gum concentration, and whipping time) on foaming properties of Kilka fish; (2) to study the effects of drying temperature and foam thickness on the drying characteristics and select a suitable model for thin-layer drying of foam; (3) to compute effective moisture diffusivity and activation energy of foam during drying; and (4) to study the effects of drying conditions on moisture content, water activity, hygroscopicity and color of powders and microstructure of dried Kilka fish foams.
Fresh Kilka fish (C. delicatula) was obtained from the Pak Samar Miroud Company (Mazandaran, Iran). Xanthan gum and egg white powders were purchased from Sigma Chemical Company and Gol Powder Company (Golestan Province, Iran) respectively. The Kilka fish skin removed and cleaned, and then crushed using a kitchen blender to obtain a homogeneous and uniform mixture. Based on preliminary tests, xanthan gum solution was prepared by dissolving a suitable amount of the selected gum powder in distilled water and mixed with a magnetic stirrer to obtain a uniform solution. The resulted solution was cooled at 4°C for 18–24h to complete hydration. According to the experimental design, to prepare 100 g of samples, appropriate amount of fish, egg white powder, xanthan gum solution and distilled water were mixed a 250-mL beaker. The mixture was then whipped with a mixer (Gosonic, model No. GHM- 818, 250W, China) with maximum speed at ambient temperature during given time, which was recommended by Design-Expert software version 6.02 (Stat-Ease, Inc., Minneapolis, MN). Foaming conditions, namely amount of egg white powder, xanthan gum and whipping time, optimized using response surface methodology (RSM) for minimizing foam density (FD) and drainage volume (DV). To evaluate drying behavior of the optimized foam, drying was carried out in a batch-type thin-layer dryer at three drying temperatures (45, 60 and 75°C) on 3- and 5-mm thicknesses. Ten thin-layer drying models were evaluated in the kinetics research. The higher values of R2 and lower values of χ2 and RMSE were selected as the basis for goodness of fit. The effective moisture diffusivity was calculated using method of slopes. A Fick’s diffusion model with slab geometry was used to describe the transport of moisture during drying inside a single Kilka fish foam mat. Activation energy was calculated by a simple Arrhenius-type relationship, by plotting the ln (Deff) against the reciprocal of absolute temperature (1/T). The microstructure of the dried fish foam-mats was analyzed by a scanning electron microscope. Finally, the effects of drying conditions on physicochemical properties of fish powder including moisture content, water activity, hygroscopicity and color were investigated.
The optimum values of variables for best product quality in terms of minimum FD and DV corresponded to egg white powder 3.67 % (w/w), xanthan gum 0.28% (w/w) and whipping time 8.93 min. The amount of FD and DV for foam at these optimum conditions were 0.92 g/cm3 and 0 ml, respectively. As expected, the increase in drying temperature and decrease in foam load led to acceleration of the dehydration of Kilka fish foam. Based on the statistical tests performed, Weibull distribution model can describe drying behavior of foams for all drying processes. Moreover, Fick’s second law was employed to calculate the effective moisture diffusivity that varied from 7.266×10-8 to 1.31×10-7 m2/s and from 7.404×10-8 to 1.693×10-7 m2/s with activation energy values of 18.201 and 25.615 kJ/mol for foam thicknesses of 3 and 5 mm, respectively. It was noted that the effective moisture diffusivity was increased when the drying temperature increased. Results showed that at the higher thickness, the internal moisture migration occurs along a longer distance rather than lower thickness. Therefore, an increase in moisture diffusivity occurs both with increase in drying temperature and sample thickness. The analysis of scanning electron microscopy (SEM) micrographs showed that there is wide porous structure of dried foams at higher speeds drying. With increasing drying temperature (due to reduction of drying times), combination of adjacent bubbles and therefor, collapse of foam structure occur less. Higher temperature reduced moisture content and aw , and thickness rise increased moisture content and aw under the same thickness and drying temperature, respectively. This is due to the fact that at higher temperatures, the rate of heat transfer to the sample would increase, therefore, it provides greater driving force for moisture evaporation which results the dried foams with reduced moisture content and aw. Moreover, with increasing foam thickness due to increased drying times and probably collapsed structure of foams and therefor weak pore structure, drying was performed difficultly which causes to retain more water in dried foams. Drying conditions had significant effect on hygroscopicity of powders. Results of color investigation showed that in both thicknesses, powder produced at 60°C have higher L* and lower a*.

Potato is one of the most consumed and highly nutritious vegetables with high energy, dietary fiber, phytochemicals, vitamins, and minerals which offer great benefit for utilization as functional food ingredient. The dried potato powder can be used in formulation of many foods like soups, snacks, sauces, noodles, etc. The foam mat drying involves the dehydration of a thin layer of foam followed by its disintegration in order to obtain a powder which can be easily reconstituted in water when added to other foods. Because of the porous structure of the foamed materials, mass transfer is enhanced leading to shorter drying times and consequently acquiring higher quality in the dried product. Food foams can be considered as biphasic systems where a gas (dispersed phase) is embedded in a continuous liquid phase. The foam properties such as structure, density and stability have important influence on moisture migration during drying and accordingly, the quality of final product. Foams that do not collapse for at least 1h are mechanically or thermally stable for the entire drying process. Response surface methodology (RSM) is a combination of mathematical and statistical techniques which used to investigate the interaction effects of independent variables on responses. There is considerable information on foam-mat dried food powders, but there is not any scientific literature that related to study on foam-mat drying of potato puree. The present research was thus focused on optimizing the foaming conditions (potato puree: gum solution ratio; Arabic gum (AG) concentration as the stabilizer and whipping time [WT]) to minimize foam density (FD) and drainage volume (DV) using RSM. Likewise, choosing a suitable model for thin-layer drying of foam and the effect of different drying temperatures (45, 60 and 80°C) on drying behavior were investigated, and the effective moisture diffusivity and activation energy were calculated. The effects of drying temperatures on water activity (aw) and water binding capacity (WBC) were also investigated.
Material and Fresh potato was purchased from a local market (Mashhad, Iran). Arabic gum was procured from Sigma Chemical Company (USA). For preparation of potato puree, fresh potatoes were washed and peeled by steel knife and were washed again and additional water was taken absolutely and then crushed by Phillips home crusher (600W) with maximum speed for 3 minutes to get a homogeneous puree. Based on preliminary tests, AG solutions were prepared by dissolving a suitable amount of the selected gum powder in distilled water and stirring with a magnetic stirrer to obtain a uniform solution. This solution was refrigerated at 4°C overnight to complete hydration. RSM was used to estimate the main effects of the process variables on FD and DV in potato puree foam. The experiment was established based on a face-centered central composite design (FCCD). The experimental range was chosen on the basis of the results of preliminary tests. The independent variables were consisted of potato puree: gum solution ratio (1:1 –2:1 w/w), AG concentration (0.1–0.9% w/w) and WT (3–9 min). According to the experimental design, to prepare 100 g of samples, appropriate amount of potato puree and AG solution were mixed in a 250-mL beaker. The mixture was then whipped with a kitchen mixer (model no. SM88, Sonny, China) at a maximum speed of 1,500 rpm at ambient temperature during given time which was recommended by Design-Expert software. The density of foamed potato puree was determined in terms of mass over volume and expressed in g/cm3. In order to assess foam stability, the drainage test was performed for 1h. To evaluate drying behavior of the optimized foam, drying was carried out in a batch-type thin-layer dryer at temperatures of 45, 60 and 80°C on 3 mm thickness. Ten thin-layer drying models were evaluated in the kinetics research. The higher value of R2 and lower values of χ2, RMSE and SSE were selected as the basis for goodness of fit. Fick’s diffusion equation for particles with a slab geometry was used for calculation of effective moisture diffusivity. The foamed potato puree spread on a tray was considered as slab geometry. Activation energy was calculated by a simple Arrhenius-type relationship, by plotting the ln (Deff) against the reciprocal of absolute temperature (1/T). Furthermore, the effects of drying temperatures on aw and WBC of powders were investigated.
The quadratic model was selected as a suitable statistic model for both FD and DV. ANOVA showed that this model is significant for both responses. Moreover, lack-of-fit was not significant for response surface models at 95% confidence level, indicating this model is adequately accurate for predicting responses. The optimum values of variables for best product quality in terms of minimum FD and DV corresponded to potato puree to gum solution ratio 2:1(w/w), AG 0.77% (w/w) and WT 6.80 min. The amount of FD and DV for foam at these optimum conditions were 0.30 g/cm3 and 5 ml, respectively.
The result showed that when the drying temperature increased, the drying time decreased. This was due to the quick removal of moisture at higher temperature. Drying rate (DR) versus moisture content of potato puree foam-mats figure showed that DR was higher during the initial stage as compared with the final stage and foam-mat drying was occurred principally in the constant rate period. Due to the increase in surface area and the porous structure, removal of water from the inner surface of potato puree foam to the outer surface was fast enough to preserve the surface moisture. The rate of movement of moisture from the inner surface to the exposed surface decreased with decreasing moisture content, which indicates that the DR decreased and the falling rate period started. The effective moisture diffusivity varied from 3.286×10-9 to 8.032×10-9 m2/s with activation energy value of 30.97 kJ/mol. Statistical analysis results showed that the Weibull distribution model provide the highest R2 and lowest values of χ2, RMSE and SSE at all drying temperatures. The temperature elevation reduced aw. This is due to the fact that at higher temperatures, the rate of heat transfer to the sample would increase, therefore, it provides greater driving force for moisture evaporation which results the dried foams with reduced aw. Drying temperatures did not show any significant effect on WBC of powders.

The aim of this study was an evaluation of the possibility of foam mat drying method for preparing of pomegranate powder with maintaining of it’s physicochemical properties. Then some properties of pomegranate powder produced by foam mat drying such as particle size, solubility, water activity, transition point, antioxidant capacity and total anthocyanin (TAC), were investigated. The statistical results analysis of the data showed that different drying temperatures on all of the properties had a significant effect (p