Osmotic Dehydration Of Fruits Research Articles

Use of coconut sugar as an alternative agent in osmotic dehydration of strawberries.

This study aimed to evaluate coconut sugar (CS) as an alternative osmotic agent to sucrose for the osmotic dehydration (OD) of strawberries. OD was performed by immersing strawberries cut into 13.6±0.4mm edge cubes in osmotic solutions of CS or sucrose, at two different concentrations (40% and 60%, w/w), with and without application of vacuum (AV) in the first 20min of the process. The total OD time was 300min. Evaluations of the kinetics of solid gain (SG), water loss (WL), and weight reduction (WR) were performed at 30, 60, 120, 180, 240, and 300min. SG, WL, and WR increased over the OD time and showed values of up to 7.94%, 63.40%, and 55.94%, respectively. AV increased WL, WR, shrinkage, pH, and total color difference and decreased anthocyanin, ascorbic acid (AA), phenolic, and antioxidant contents. The higher concentration led to higher SG, WL, WR, shrinkage, hardness, and lower moisture content, water activity, anthocyanin, AA, phenolic, and antioxidant contents. The use of CS instead of sucrose had little influence on strawberry properties, except pH and color responses. The optimal treatment was using a 60% CS solution without AV, showing a very distinct color change, hardness increased by approximately 4.5 times and maintenance of acidity, anthocyanins, AA, total phenolics, and antioxidants of 38.0%, 39.6%, 11.8%, 30.0%, 31.1%, and 30.3%, respectively, compared to fresh strawberries. PRACTICAL APPLICATION: Osmotic dehydration of fruit is a process traditionally carried out using sucrose. However, increasing health concerns have made consumers seek alternative sugars to sucrose. The use of coconut sugar made it possible to produce osmo-dehydrated strawberries different from the traditional one, maintaining product quality and process efficiency.

Sugar profiles modulation of mangoes during osmotic dehydration in agave syrup solutions.

Chemical interaction and multicompound competition were investigated on solids gain and carbohydrate profiles evolution during osmotic dehydration of mangoes. Tommy Atkins mango slices (0.4cm and 1.5cm thickness) were osmotically processed at 40°C for up to 4h and 8h, respectively. Osmotic solutions (60 °Brix) were separated in two categories: single solute (sucrose, glucose, fructose) and multisolute (agave syrup, alone or with additions of 5% inulin or 0.1-0.3% xanthan gum) solutions. High performance liquid chromatography (HPLC) analysis was carried out on treated mango to determine sugar profiles evolution during osmotic dehydration and final product concentrations. Findings pointed out that composition of osmotic solution may modulate mango sugar profiles by triggering uptake or loss of sugar according to different phenomena: chemical potential gradient, lixiviation, prevailing mass transfer, formation of carbohydrate barrier, and solution viscosity. Mango was enriched with the solute present in the single solute osmotic solution, while it lost its own native sugars, which were absent in the osmotic solution. Increasing sample thickness reduces individual sugar uptake or loss in mango treated with both single and multisolute solutions. Significant differences in mono solute solution behavior were found for sucrose due to its capability to form a sugar layer outside the surface of thicker samples, which was shown by scanning electron microscopy (SEM) images, a barrier markedly hindering the sucrose uptake or loss. Addition of polysaccharides (particularly xanthan gum) was found to have an impact of lowering mango individual sugar uptake (18-30%). Practical Application These results will help in understanding the mechanisms by which gain of individual sugars could be reduced and composition could be modulated during osmotic dehydration of fruits. Thus, the findings in this work could lead to production of low-sugar content, osmotically processed mango snacks, enriched with inulin, enhancing their dietary and marketable value.

Osmotic dehydration of fruits using unconventional natural sweeteners and non‐thermal‐assisted technologies: A review

In the food preservation process, drying or dehydration reduces the moisture content that is needed for the growth and multiplicity of microorganisms that cause food spoilage. Among the most effective and appropriate methods for extending the shelf life of fruits and vegetables is osmotic dehydration. This process encourages the movement of water molecules from the food to the osmo-active solution and a small amount of solute from the solution into the food, resulting in an organoleptic and functional product. Sugar, which is the most popular osmotic agent, presents many health risks. Therefore, this review discusses the mechanisms of osmotic dehydration and the use of unconventional natural sweeteners like honey, jaggery, coconut sugar, stevia, and sugar beet molasses as an osmotic agent. Furthermore, certain non-thermal methods to help osmotic dehydration have been reviewed that may improve the drying and quality parameters of different fruits. Practical applications The osmotic dehydration process in fruits reduces postharvest losses, as well as maintaining the initial fruit characteristics such as color, aroma, texture, and nutritional content. The uses of natural sweeteners viz. jaggery and honey as osmotic agents have numerous health benefits. Due to these benefits, it can be used at small scales, home-scale industries, and large-scale industries. Various methods can be used to enhance osmotic dehydration, such as pulsed electric fields, high pressure, vacuum, microwave, centrifugal force, or ultrasound, which can be applied to large-scale industries.

Mass Transfer During Osmotic Dehydration of Fruits and Vegetables: Process Factors and Non-Thermal Methods

Osmotic dehydration of fruits and vegetables is a slow process due to resistance in mass transfer (MT). This resistance can be modified by varying the osmotic solution or process conditions, or by employing non-thermal treatments (NTT). Some NTT modify the tissue structure by formation of pores in the cell membrane (such as pulse electric fields) or microchannels (such as ultrasound and osmosonication), and others increase the contact surface area with the tissue through a decrease in atmospheric pressure (such as vacuum pulses) or an increase of the system pressure (such as high hydrostatic pressures). Changes in the rate of MT caused by modifications in experimental conditions can be described with mathematical models, such as Fick’s second law. The aims of this review are to analyze the different factors that modify MT rate during osmotic dehydration, examine the application of NTT to modify MT, and to study models that describe these processes.

Osmotic dehydration of bottle gourd (Legeneria siceraria)

Osmotic dehydration of fruits and vegetables an effective method for preservation. The Bottle gourd (Legeneria siceraria) belongs to Cucurbitaceous family. Average composition of fresh bottle gourd is constituted by water (96.0%), carbohydrates (2.5%), fibre (0.6%), proteins (0.2%) and calcium (20mg). The bottle gourd is a common vegetable in India subcontinental. It is moderately perishable vegetable. In this report, efforts were made to analyze the effect of different concentration, temperature and mass ratio of fruit to osmotic solution on osmotic dehydration process of bottle gourd cubes. comparative study for different parameters variables (solid gain weight reduction, water loss) was also studies. Five concentration levels of salt solution were 5, 10, 15, 20, and 25% (w/w) used in this study to compare the effect of the concentration of the osmotic agents on osmotic dehydration. Bottle gourd cubes were immersed in the osmotic reagents with a fruit to osmotic solution mass ratio of 10:1, 20:1 and 30:1 soaking experiment were conducted at 40, 50 and 600C in a 500 mi capacity water bath. The osmotic dehydration was done for a period of 1, 3, 5, 7 and 9 h and replicated thrice. Quality analysis of osmotically dehydrated bottle gourd cubes was done according to ISI (1971) and Ranganna (1991) with 9-point hedonic scale. The moisture content of bottle gourd cubes observed decreases with higher concentration, temperature and mass ratio. The weight reduction, water loss and solid gain were very fast during initial period of osmosis but equilibrium did reach even after 9h. The solid gain, water loss and weight reduction were observed higher for higher temperature, concentration and mass ratio of bottle gourd cubes. The sensory evaluation performed for the approximately central conditions processing parameters gave average scores of 7 or above.

Osmotic dehydration of fruit and berry raw materials in the food industry

Osmotic dehydration has recently received more attention as an effective method of preserving fruits and berries. Osmosis is a simple process that facilitates the processing of fruits and berries in order to preserve the original characteristics, namely nutritional value and organoleptic properties: color, aroma and texture. Osmotic dehydration has found wide application in the preservation of food products, as the activity of water in fruits and berries decreases, in some of them up to 90% of water is contained. The process of osmotic dehydration with the help of various agents is less energy-intensive than the process of drying or freezing, since it can be processed at ambient temperature. Osmotic dehydration has potential advantages in preserving the quality of food and in maintaining healthy food for the food industry. Treatment includes dehydration of fruits and berries by an osmotic agent followed by dehydration in dry or frozen apparatus where the moisture content decreases and the product becomes more stable. This process is a partial dewatering process to provide improved product quality compared to conventional drying processes or freezing. The purpose of studying osmotic dehydration is to identify the advantages and disadvantages in the treatment of osmotic agents. Various aspects of osmotic dehydration technology are considered, namely the solutions used, the characteristics of solutions, the effect of variable processes and the qualitative characteristics of osmo-dehydrated products. Factors of osmotic dehydration that depend on the osmotic agent, concentration of solute, temperature, time, size, shape and compactness of the material, mixing and the ratio of the solution to the samples.

Solute Transfer in Osmotic Dehydration of Vegetable Foods: A Review.

While various mechanisms have been proposed for the water transfer during osmotic dehydration (OD), little progress has been made to understand the mechanisms of solute transfer during osmotic dehydration. The transfer of solutes has been often described only by the diffusion mechanism; however, numerous evidences suggest the participation of a variety of mechanisms. This review deals with the main issues of solute transfer in the OD of vegetables. In this context, several studies suggest that during OD of fruits and vegetables, the migration of solutes is not influenced by diffusion. Thus, new theories that may explain the solute transport are analyzed, considering the influence of the plant microstructure and its interaction with the physicochemical properties of osmotic liquid media. In particular, the surface adhesion phenomenon is analyzed and discussed, as a possible mechanism present during the transfer of solutes in OD.

A Review on Osmotic Dehydration of Fruits and Vegetables: An Integrated Approach

AbstractOsmotic dehydration is a simultaneous mass transfer process which mainly promotes the flow of water molecules from the food to osmo‐active solution and some migration of solutes from the solution into the food, thus maintaining good organoleptic and functional properties in the finished product. This paper presents mechanism of osmotic dehydration and recent developments regarding the factors affecting osmotic dehydration process viz., pretreatment factors (blanching, coating, ultrasound treatment, high pressure processing, pulsed electric field effect, etc.), product‐related factors and osmotic solution related factors (temperature of osmotic solution, concentration of osmotic agent, type of osmotic agent, agitation/stirring process during osmotic process, osmotic solution and food mass ratio). The details on mathematical modeling of mass transfer during osmotic dehydration of foods and benefits of osmotic dehydration which includes energy saving methods and quality of final product are reviewed.Practical ApplicationOsmosis is a physical phenomenon that has been extensively studied in various disciplines of science and engineering. Osmotic dehydration has diverse applications in fruits and vegetables. Thus it can be used to decrease the post harvest losses. Being a simple process, it facilitates processing of fruits and vegetables with retention of initial fruit characteristics viz., colour, aroma, texture and nutritional composition. Since no preservative was used, it does not adversely affect the human body. This process could be used on small scale for development of self‐entrepreneurs and home scale industries. The mathematical models can be used for understanding the mass transfer phenomenon during the process. The economic interest relates to the reduced energy consumption as compared to conventional drying. This review serves to provide an updated status on osmotic dehydration and its research gap which is useful for academics, research purpose and processing industries.

Fundamentals and Application of Osmotic Dehydration

Osmotic dehydration is a water removal process that consists of placing foods, such as pieces of fruits and vegetables, in a hypertonic solution. Both mass fluxes lead to a decrease of the water activity in the product, increasing its shelf life. It can be used as a single dehydration process or as a pre-treatment of other processes such as drying, pasteurization or freezing. Heat and mass transfer gradients associated to the process produce changes in the chemical, physical and structural characteristics of the vegetable tissue. The knowledge and prediction of these changes are very important because they affect the quality of the final product, process modelling and design of process equipment. This work presents some new experimental data during osmotic dehydration of fruits. Some models were used so as to obtain predicted values during osmotic dehydration.

Sugar beet molasses: Properties and applications in osmotic dehydration of fruits and vegetables

Sugar beet molasses: Properties and applications in osmotic dehydration of fruits and vegetables

Characteristic Process Variables during the Osmotic Dehydration of Stone Fruits: Experimental Values and Correlations between Components Content

Stone fruits (plums, peaches, nectarines, cherries and apricots) are widely consumed fresh or processed. Osmotic dehydration – immersion of food pieces in hypertonic solutions – is often used as a pretreatment to further conservation procedures for these fruits. Usually, it is characterized determining the variation with time of water loss and solution solids gain. Both variables depend on food size, shape, structure and process conditions, and there are no general correlations for their variation. As an alternative, it is important to develop relations between water and soluble solids content independent of product characteristics and process conditions. In this work, we developed experimental values of relevant variables for stone fruits dehydrated in glucose or sorbitol and included them in linear correlations between water content and soluble solids for different stone fruits dehydrated in sugar or polyalcohol solutions and in a general linear correlation that allows to characterize both properties with only one rapid determination (of any of both). Practical Applications Linear correlations for the variation of soluble solids content as a function of water content during osmotic dehydration were generalized to a unique linear regression equation independent of type of fruit and/or solute and valid for any process condition, which allows to characterize both properties with only one rapid determination (of any of both). This correlation can be easily used under process conditions to monitor the advance of osmotic dehydration of fruits.

Recent Development in Osmotic Dehydration of Fruit and Vegetables: A Review

Osmotic dehydration of fruits and vegetables is achieved by placing the solid/semi solid, whole or in pieces, in a hypertonic solution (sugar and/or salt) with a simultaneous counter diffusion of solutes from the osmotic solution into the tissues. Osmotic dehydration is recommended as a processing method to obtain better quality of food products. Partial dehydration allows structural, nutritional, sensory, and other functional properties of the raw material to be modified. However, the food industry uptake of osmotic dehydration of foods has not been extensive as expected due to the poor understanding of the counter current flow phenomena associated with it. However, these flows are in a dynamic equilibrium with each other and significantly influence the final product in terms of preservation, nutrition, and organoleptic properties. The demand of healthy, natural, nutritious, and tasty processed food products continuously increases, not only for finished products, but also for ingredient to be included in complex foods such as ice cream, cereals, dairy, confectionaries, and bakery products.

Hydrothermal Carbonization of Spent Osmotic Solution (SOS) Generated from Osmotic Dehydration of Blueberries

Hydrothermal carbonization of spent osmotic solution (SOS), a waste generated from osmotic dehydration of fruits, has the potential of transformation into hydrochars, a value-added product, while reducing cost and overall greenhouse gas emissions associated with waste disposal. Osmotic solution (OS) and spent osmotic solution (SOS) generated from the osmotic dehydration of blueberries were compared for their thermo-chemical decomposition behavior and hydrothermal carbonization. OS and SOS samples were characterized for total solids, elemental composition, and thermo-gravimetric analysis (TGA). In addition, hydrothermal carbonization was performed at 250 °C and for 30 min to produce hydrochars. The hydrochars were characterized for elemental composition, Brunauer-Emmett-Teller (BET) surface area, particle shape and surface morphology. TGA results show that the SOS sample loses more weight in the lower temperature range than the OS sample. Both samples produced, approximately, 40%–42% (wet-feed basis) hydrochar during hydrothermal carbonization but with different properties. The OS sample produced hydrochar, which had spherical particles of 1.79 ± 1.30 μm diameter with a very smooth surface. In contrast, the SOS sample produced hydrochar with no definite particle shape but with a raspberry-like surface.

Osmotic dehydration of fruits in food industrial: A review

Osmotic dehydration (OD) is an operation used for the partial removal of water from plant tissues by immersion in a hypertonic solution, sugar and/or salt solution, to reduce the moisture content of foods before actual drying process. Research applications of osmotic dehydration to food processing in technology and in component transfer mechanisms are being carried out in several countries. This technique is a partial dehydration process to give the product a quality improvement over the conventional drying process. Osmotic dehydration is affected by several factors such as osmotic agent, solute concentration, temperature, time, size, and shape and tissue compactness of the material, agitation and solution/sample ratio. The osmotic dehydration step can be done before, during or after the conventional drying process to enhance the mass transfer rate or to shorten the duration of drying time the quality of osmotically dehydrated products is better and shrinkage is considerably lower as compared to products from conventional drying processes. This technique helps to conserve the overall energy relative to other drying procedures. In this review, the mechanism of osmotic dehydration is described. In addition, some factors that affect on mass transfer during osmotic dehydration reviewed. The major objective of this paper is to discuss the advantage of osmotic dehydration in terms of energy reduction.

Modeling of Osmotic Dehydration Kinetics of Banana Slices using Artificial Neural Network

Osmotic dehydration of fruits is one of the oldest forms of food preservation techniques known to man. Osmotic dehydration is affected by several factors such as osmotic agent, solute concentration, temperature, time, size, and shape and tissue compactness of the material, agitation and solution/sample ratio. The application of osmotic dehydration includes musk melon, banana, papaya, mango, onion slices cucumber and carrot. Artificial Neural Network is a black box tool for the modeling of processes involving multivariable non linear relationships. The present work is aimed at the study of effect of time, temperature and concentration of osmotic solution on the weight reduction for the process of osmotic dehydration of banana slices. The experimental data of osmotic dehydration kinetics generated have been used to develop a mathematical model using regression analysis. Artificial neural network models having different topologies are developed. The comparison between ANN models is carried out based on the relative error values of all the output data points. ANN model 1 is observed to be superior than model 2. The comparison is also carried out between the output values obtained by ANN model 1 and the mathematical model using regression analysis.

Osmotic dehydration of fruits and vegetables: a review.

The main cause of perishability of fruits and vegetables are their high water content. To increase the shelf life of these fruits and vegetables many methods or combination of methods had been tried. Osmotic dehydration is one of the best and suitable method to increase the shelf life of fruits and vegetables. This process is preferred over others due to their vitamin and minerals, color, flavor and taste retention property. In this review different methods, treatments, optimization and effects of osmotic dehydration have been reviewed. Studied showed that combination of different osmotic agents were more effective than sucrose alone due to combination of properties of solutes. During the experiments it was found that optimum osmosis was found at approximately 40°C, 40 °B of osmotic agent and in near about 132min. Pretreatments also leads to increase the osmotic process in fruits and vegetables. Mass transfer kinetics study is an important parameter to study osmosis. Solids diffusivity were found in wide range (5.09-32.77kl/mol) studied by Fick's laws of diffusion. These values vary depending upon types of fruits and vegetables and osmotic agents.

Use of Osmotic Dehydration to Improve Fruits and Vegetables Quality During Processing

Osmotic treatment describes a preparation step to further processing of foods involving simultaneous transient moisture loss and solids gain when immersing in osmotic solutions, resulting in partial drying and improving the overall quality of food products. The different aspects of the osmotic dehydration (OD) technology namely the solutes employed, solutions characteristics used, process variables influence, as well as, the quality characteristics of the osmodehydrated products will be discussed in this review. As the process is carried out at mild temperatures and the moisture is removed by a liquid diffusion process, phase change that would be present in the other drying processes will be avoided, resulting in high quality products and may also lead to substantial energy savings. To optimize this process, modeling of the mass transfer phenomenon can improve high product quality. Several techniques such as microwave heating, vacuum, high pressure, pulsed electric field, etc. may be employed during or after osmotic treatment to enhance performance of the osmotic dehydration. Moreover new technologies used in osmotic dehydration will be discussed. Patents on osmotic dehydration of fruits and vegetables are also discussed in this article.

USE OF VACUUM IMPREGNATION FOR MINIMALLY PROCESSED FRUITS AND VEGETABLES

Vacuum impregnation (VI) is a recent development in the osmotic treatment of foods. VI of a porous product consists of exchanging the internal gas or liquid occluded in open pores for an external liquid phase by the action of hydrodynamic mechanisms promoted by pressure changes. This process is carried out by applying vacuum pressure (P1) to the tank which contains the product immersed in a solution for a time (t1) sufficient for it to be de-aired, and subsequently restoring the pressure to atmospheric pressure (P2) while the product remains immersed for time (t2). VI can be useful introducing dissolved or dispersed substances directly into the porous structure of the food matrix. Moreover, VI can increase the mass transfer rate, as a result of shorter diffusive paths after the impregnation step, in processes in which solid-liquid operations are present, such as salting of meats, osmotic dehydration of fruits, oil extraction by liquid solvents and the incorporation of preservatives or additives to food items. VI has broad applications in fruit and vegetable processing and provides many unique advantages. This technique is being investigated to incorporate physiological active compounds (minerals, probiotics, vitamins and firming agents such as hydrocolloids) into the structure of fruits and vegetables. Impregnated products can be commercialized as minimally processed fresh functional foods or can be dried osmotically or by air in order to obtain more stability. In this study, the main factors and responses of fruits and vegetables to VI processing are explained and quality aspects of VI applied to minimally processed fruits and vegetables were discussed.

INFLUENCE OF PROCESS CONDITIONS ON THE MASS TRANSFER DURING OSMOTIC DEHYDRATION OF COATED PINEAPPLE SAMPLES

ABSTRACT The study investigated the combined treatment of edible coatings and osmotic dehydration (OD) of pineapple samples. Pineapple samples were coated with 0.5% to 5.0% (w/v) sodium alginate solution by dipping for 60 s and 120 s and then dried at 50C for 10 and 40 min. OD in sucrose solution was carried out for coated and uncoated samples and water loss (WL), solid gain (SG), performance ratio (PR) and weight reduction (WR) were measured. There was a difference of 13.76 (g/100 g fresh sample) in the rates of WL between its highest and lowest value. The lowest value of 6.15 (g/100 g fresh sample) of SG and the highest value of PR of 7.32 was observed in the sample dipped in coating solution of 2% concentration for 120 s followed by drying for 40 min. WL increased whereas SG decreased up to a certain level of concentration of coating solution. PRACTICAL APPLICATIONS The treatment of coating may provide a solution to the problem of solid gain without affecting water removal during osmotic dehydration. The application of coating before osmotic dehydration (OD) will help in retaining nutrients and flavor than those without coating. The coated osmotically dehydrated fruits after rehydration can be added in ice cream, yogurt and confectionary products. Limited information is available in the literature combining coating with OD of fruits. Results of this study will be helpful in exploring the application of coating in pineapples. The combination of coating and OD may provide a practical method for the preservation of pineapple with better quality characteristics.

A Comparison of Some Mathematical Models Used for the Prediction of Mass Transfer Kinetics in Osmotic Dehydration of Fruits

Mass transfer in osmotic dehydration of fruits at atmospheric pressure has been modeled either by a phenomenological approach using Crank's model (which is a Fick's law solution) or empirically, using models developed from polynomial equations, mass balances, or relations between process variables (i.e., Magee's, Azuara's, and Page's models). For all of these models, experimental data are required to determine the values of their adjustable parameters for specific processing conditions. From a wide variety of published data, the parameters for moisture loss (ML) and solid gain (SG) were calculated for the above-mentioned models, and a comparison of their correlation capability was made. Azuara's and Page's models yield better correlations (with mean absolute errors less than 1.26% for ML and 0.46% for SG) than Magee's and Crank's models (with mean absolute errors of up to 2.98 and 1.68% for ML and SG, respectively).