Effect of chitosan–lemon essential oil coatings on storage-keeping quality of strawberry

In recent years much attention has been focused on maintaining the freshness of fruits and vegetables by immersion of cellular materials containing water in an osmotic solution. It results in the development of intermediate moisture products having lower water activity, which is imparted by solute gain and water loss. During the process, chemical, physical and biological activities, which deteriorate the foods, are lowered considerably; hence extends the shelf life of food products. In this process moisture is withdrawn from the product at ambient temperature by diffusion, so phase change has been avoided. Besides, it helps to improve the nutritional and sensory attributes of food products and is less energy intensive process as compared to other drying techniques. Osmotic dehydration is influenced by various factors such as osmotic agent, time and temperature, solute concentration, solution to sample ratio, agitation and geometry of the materials. Recently, osmotic dehydration has been combined with several other methods namely, pulsed high electric field, high hydrostatic pressure, ultrasound, centrifugal force, vacuum and gamma irradiation. These techniques have been employed during or after osmotic treatment to enhance osmotic dehydration performance by increasing the cell membrane permeability and mass transfer rate. These combined operations reduce the drying time, minimizing further energy costs. In this study, various segments of osmotic dehydration techniques and its application in food processing as well as recent advances in osmotic dehydration have been reviewed. Industrial relevance The osmotic dehydration technique is gaining popularity as a mean of obtaining minimally processed food. This review paper deals with the kinetics and mechanisms of osmotic dehydration technique for the preservation of fruits and vegetables. The various factors effecting osmotic mass transfer rate in food have been reviewed. In this paper, the combined effect of osmotic dehydration and several other innovative techniques (pulsed high electric field, high hydrostatic pressure, ultrasound, centrifugal force, vacuum and gamma irradiation) on the quality and shelf life of fruits and vegetables have been reviewed. These techniques have been employed during or after osmotic treatment to enhance osmotic dehydration performance by increasing the cell membrane permeability. These combined operations reduce the drying time, minimizing further energy costs as well as improving the quality of fruits and vegetables during storage.

Developments in osmotic dehydration technique for the preservation of fruits and vegetables

Freezing plays an important role in food preservation and the emergence of rapid freezing technologies can be highly beneficial to the food industry. This paper reviews some novel food freezing technologies, including high-pressure freezing (HPF), ultrasound-assisted freezing (UAF), electrically disturbed freezing (EF) and magnetically disturbed freezing (MF), microwave-assisted freezing (MWF), and osmo-dehydro-freezing (ODF). HPF and UAF can initiate ice nucleation rapidly, leading to uniform distribution of ice crystals and the control of their size and shape. Specifically, the former is focused on increasing the degree of supercooling, whereas the latter aims to decrease it. Direct current electric freezing (DC-EF) and alternating current electric freezing (AC-EF) exhibit different effects on ice nucleation. DC-EF can promote ice nucleation and AC-EF has the opposite effect. Furthermore, ODF has been successfully used for freezing various vegetables and fruit. MWF cannot control the nucleation temperature, but can decrease supercooling degree, thus decreasing the size of ice crystals. The heat and mass transfer processes during ODF have been investigated experimentally and modeled mathematically. More studies should be carried out to understand the effects of these technologies on food freezing process.

Emerging Techniques for Assisting and Accelerating Food Freezing Processes─A Review of Recent Research Progresses

Vacuum impregnation (VI) is considered as a useful technique to quickly introduce external liquids in the porous structures of animal and plant tissues, in a controlled way. As consequence some mass transfer processes (as dewatering) are improved and also some changes in food composition may be produced. VI has broad applications in fruit and vegetable processing and provides many unique advantages. This review analyzes the main factors and responses of porous fruits and vegetables to VI processing, summarizes important developments related to VI applications in the fruit and vegetable industry, and discusses quality aspects of VI processed fruits and vegetables, as well as technical challenges and future research needs in this field.

Practical applications of vacuum impregnation in fruit and vegetable processing

The drying of foods is hugely important technique for the food industry and offers possibilities for ingredient development and novel products to consumers In recent years, there have been many advances in technology associated with the industrial drying of food including pre-treatments, techniques, equipment and quality Recent research has revealed that novel drying approaches such as microwave- or ultrasound-assisted drying, high electric field drying, heat pump drying and refractance window drying can be now taken to improve the efficiency and efficacy of drying so that energy consumption can be reduced whilst at the same time preserving the quality of the end product However, whilst research has showed these technologies to be successful, commercial practitioners do not often know what techniques have the greatest potential in industry The current work highlights recent developments of valuable novel drying techniques to promote sustainability in the food industry and points towards

A.A. Ayala

Papers

Changes in mechanical properties throughout osmotic processes: Cryoprotectant effect

Drying characteristics of mango slices using the Refractance Window™ technique