Osmotic Dehydration of Yacon Using Glycerol and Sorbitol as Solutes: Water Effective Diffusivity Evaluation

Exploring Osmotic Dehydration for Food Preservation: Methods, Modelling, and Modern Applications

This study summarizes the most recent findings on osmotic dehydration, a crucial step in food preservation. The many benefits of osmotic dehydration are listed, including longer shelf life and preserved nutritional value. Mass transfer dynamics, which are critical to understanding osmotic dehydration, are explored alongside mathematical models essential for comprehending this process. The effect of osmotic agents and process parameters on efficacy, such as temperature, agitation and osmotic agent concentration, is closely examined. Pre-treatment techniques are emphasized in order to improve process effectiveness and product quality. The increasing demand for sustainability is a critical factor driving research into eco-friendly osmotic agents, waste valorization, and energy-efficient methods. The review also provides practical insights into process optimization and discusses the energy consumption and viability of osmotic dehydration compared to other drying methods. Future applications and improvements are highlighted, making it an invaluable tool for the food industry.

Review of osmotic dehydration: Promising technologies for enhancing products' attributes, opportunities, and challenges for the food industries

Osmotic dehydration (OD) is an efficient preservation technology in that water is removed by immersing the food in a solution with a higher concentration of solutes. The application of OD in food processing offers more benefits than conventional drying technologies. Notably, OD can effectively remove a significant amount of water without a phase change, which reduces the energy demand associated with latent heat and high temperatures. A specific feature of OD is its ability to introduce solutes from the hypertonic solution into the food matrix, thereby influencing the attributes of the final product. This review comprehensively discusses the fundamental principles governing OD, emphasizing the role of chemical potential differences as the driving force behind the molecular diffusion occurring between the food and the osmotic solution. The kinetics of OD are described using mathematical models and the Biot number. The critical factors essential for optimizing OD efficiency are discussed, including product characteristics, osmotic solution properties, and process conditions. In addition, several promising technologies are introduced to enhance OD performance, such as coating, skin treatments, freeze-thawing, ultrasound, high hydrostatic pressure, centrifugation, and pulsed electric field. Reusing osmotic solutions to produce innovative products offers an opportunity to reduce food wastes. This review explores the prospects of valorizing food wastes from various food industries when formulating osmotic solutions for enhancing the quality and nutritional value of osmotically dehydrated foods while mitigating environmental impacts.

The Influence of Polyols on the Process Kinetics and Bioactive Substance Content in Osmotic Dehydrated Organic Strawberries

In recent years, an increasing interest in reducing sugar consumption has been observed and many studies are conducted on the use of polyols in the osmotic dehydration process to obtain candied or dried fruits. The studies in the literature have focused on the kinetics of the process as well as the basic physical properties. In the scientific literature, there is a lack of investigation of the influence of such polyol solutions such as sorbitol and mannitol used as osmotic substances during the osmotic dehydration process on the contents of bioactive components, including natural colourants. Thus, the aim of the study was to evaluate the impact of polyols (mannitol and sorbitol) in different concentrations on the process kinetics and on chosen physical (colour and structural changes) as well as chemical (sugars and polyol content, total anthocyanin content, total polyphenol content, vitamin C, antioxidant activity) properties of osmotic-dehydrated organic strawberries. Generally, the results showed that the best solution for osmotic dehydration is 30% or 40% sorbitol solutions, while mannitol solution is not recommended due to difficulties with preparing a high-concentration solution and its crystallization in the tissue. In the case of sorbitol, the changes of bioactive compounds, as well as colour change, were similar to the sucrose solution. However, the profile of the sugar changed significantly, in which sucrose, glucose, and fructose were reduced in organic strawberries and were partially replaced by polyols.

Osmotic Dehydration, Drying Kinetics, and Quality Attributes of Osmotic Hot Air-Dried Mango as Affected by Initial Frozen Storage

Using frozen mango for osmotic hot air drying is still uncommon due to a lack of knowledge on the effect of the freezing process on the final product's quality attributes. This study aimed to investigate the effect of the freezing method (slow and quick freezing) and frozen storage time at -18 °C (0, 1, and 2 months) on mass transfer kinetics during osmotic dehydration, drying kinetics during hot air drying, and final quality attributes of the dried mango. The results indicated that Peleg's model could describe the water loss and solid gain during the osmotic dehydration in a 38° Brix sugar solution. Freezing before osmotic dehydration reduced the water loss rate while increasing the solid uptake content. Frozen mangoes showed slightly higher drying rates at 50 and 60 °C than the fresh ones. Freezing and frozen storage also retarded the browning reaction and polyphenol oxidase activities. The osmotic-dried mango obtained from frozen mangoes showed a chewy and gummy texture, which could be considered a distinctive texture characteristic for dried mango.

Optimization of Osmotic Dehydration of Tomatoes in Solutions of Non-Conventional Sweeteners by Response Surface Methodology and Desirability Approach

The osmotic dehydration (OD) of tomatoes in solutions of alternative sweeteners was investigated using Response Surface Methodology (RSM), while selected desirability functions were implemented in order to define the optimum process parameters (temperature/duration of osmotic treatment, osmotic solution composition and concentration). Mass exchange, color and texture were measured during the process. Changes in color occurred rapidly at the beginning of the process, while firmness was significantly increased, indicating that OD processing led to tomato texture improvement. Color and firmness changes were adequately modeled using a polynomial model. RSM coupled with desirability functions was applied to optimize OD procedure in terms of color retention and maximum solid gain, a requirement for candied products. A maximum desirability was obtained by incorporating oligofructose into the osmotic solution, at relatively short treatment times. Results were validated and sensory analysis was conducted at the optimized conditions to assess samples’ organoleptic acceptance.

Quality of ‘Royal Gala’ cut apple during osmotic dehydration

Abstract The present work aimed to evaluate quality parameters of ‘Royal Gala’ apple cubes during osmotic dehydration (OD). We investigated the following OD conditions: osmotic agent, pressure, and temperature. The osmotic agent, being lower after OD with sorbitol than sucrose solutions, mainly influenced the water activity of the product. The color changes increased with increased temperature and were higher in vacuum experiments than at atmospheric pressure. In general, we recommend OD at 25 °C and atmospheric pressure for the preservation of the total phenolic content (TPC) and antioxidant activity (AA) of apple cubes during the process. Peleg’s model was found to provide the best fit of TPC and AA data.

Evaluation and modelling of osmotic pre-treatment of peach using alternative agents in a multiple-component solution

BACKGROUND

Peach is a perishable fruit of great importance for the Greek food export market which is prone to rapid deterioration after harvesting. Its short shelf life can be substantially prolonged by applying an appropriate osmotic dehydration (OD) pre-treatment, which is a mild, non-thermal procedure. The aim of this study was to describe mass transfer and quality retention induced by the OD process.

RESULTS

Peach pieces were immersed in tertiary solutions of glycerol, erythritol, steviol glucosides and mineral salts at pre-selected OD conditions (25-45 °C for 3-240 min, w_fruit /w_solution = 1:5). Water loss (WL), solid gain (SG), water activity (a_w ) as well as representative quality indices (colour, texture) were measured during OD, showing that osmotically dehydrated peach presented significant a_w reduction (from 0.97 to 0.88) combined with quality retention.

CONCLUSION

This research showed that OD can be an effective pre-processing step in the production of intermediate moisture novel products. A second-degree polynomial model was developed describing adequately the effect of OD time and temperature and glycerol concentration on WL, SG, a_w , colour and texture of osmotically dehydrated peach, and analysis of variance was applied to identify those factors that significantly affect the aforementioned parameters. It was concluded that OD using alternative osmotic agents is an efficient method with respect to product colour and texture retention, allowing for the production of novel products with extended shelf life. © 2018 Society of Chemical Industry.

Study of osmotic dehydration of kiwi fruit using sucrose solution

Abstract Osmotic dehydration of kiwi was evaluated using 45, 55 and 65 °Brix sucrose solutions. Free moisture, water activity and solutes gain decreased in fruit during the process. Water loss rates were higher in the beginning of drying. Water activity decrease was higher when the product was in 65 °Brix solution. The equilibrium moisture content estimated by the Peleg model decreased significantly with increasing concentration of the osmotic solution, and the diffusivity values of water loss were in the range from 1.5 × 10-9 to 1.9 × 10-9 m2 s-1. The osmotic pressures of the solutions were also predicted.

Mathematical modelling of the osmotic dehydration of physalis

Abstract Physalis was osmotically dehydrated with 60 °Bx sucrose or sorbitol solutions at 60 °C and with a mass ratio of sample to solution of 1:4, at atmospheric pressure or under vacuum at 150 mbar. The Crank’s, Peleg’s and Page’s models were tested to describe the mass transfer kinetics for water loss (WL) and solids gain (SG). The effective diffusivities of both water and solute were around 10-11 m2 s-1 under all conditions. Peleg’s model presented the best fit. The use of sorbitol as the osmotic agent resulted in an increase in the WL rate. In experiments with sucrose solutions, a higher WL was obtained under vacuum than at atmospheric pressure. The SG was particularly low during osmotic dehydration. Thus, the use of sorbitol as the osmotic agent was shown to be a promising alternative to sucrose.