Osmotically dehydrated

Osorio, C. et al., Application of tristimulus colorimetry to obtain natural additives from fruits. 1. Color evaluation during osmotic dehydration, in Proceedings of 4th International Congress on Pigments in Food, Hohenheim, Germany, Carle, R. et al., Eds., Shaker Verlag, Aachen, 2006, Yll. 

Ade-Omowaye BIO, Rastogi NK, Angersbach A and Knorr D. 2002. Osmotic dehydration of bell peppers influence of high intensity electric field pulses and elevated temperature treatment. J Food Eng 54 35—43. Ajlouni S, Kremer S and Masih L. 2001. Lycopene contents in two different tomato cultivars. Food Aust... 

Tonon RV, Baroni AF and Hubinger MD. 2007. Osmotic dehydration of tomato in ternary solutions influence of process variables on mass transfer kinetics and an evaluation of the retention of carotenoids. J Food Eng 82 509-817. 

PRESENT AND FUTURE IN PROCESS CONTROL AND OPTIMIZATION OF OSMOTIC DEHYDRATION... 

The process involves placing the solid food (whole or in pieces) into solutions of high sugar or salt concentration. Le Maguer (1988), Raoult-Wack (1994), Fito and Chiralt (1997), Behsnilian and Spiess (1998), Spiess and Behsnilian (1998), Lazarides et al. (1999), and Torreggiani and Bertolo (2002) have reviewed the basic principles, modeling and control, and specific applications of osmotic dehydration on fruit and vegetables. Additionally, the most recent research advances in this field can be obtained from the European-founded network on osmotic treatments (FAIR, 1998). 

The main unique feature of osmotic dehydration, compared to other dehydration processes, is the penetration of solutes into the food material. Through a calculated incorporation of specific solutes into the food system, it is possible, to a certain extent, to change nutritional, functional, and sensory properties, making it more suitable to processing by... 

The nature of the plant material subjected to osmotic dehydration is the key point for both modeling and optimizing the osmosis in itself and as a pretreatment to further processing. The same osmotic medium, applied to different raw materials, under identical process conditions causes substantially different rates of dehydration and solute uptake. Data on these findings were reviewed previously (Lazarides et al., 1999 Torreggiani, 1995) and have been confirmed by recent research. 

During osmotic dehydration of apple, pumpkin, and carrot in sugar solution at 30 °C, the rate of water loss was 5-10 times higher than the rate of solid gain and depended on advancement of the dewatering process (Kowalska and Lenart, 2001). Under the same dewatering conditions, pumpkin and carrot reached smaller water contents than apple (Figure 3). 

FIG. 3 Water loss (WL) and solid gain (SG) expressed on initial dry matter (idm) of strawberry (ST) slices (Brambilla et al., 2000) and apple (AP), carrot (CA), and pumpkin (PU) cubes (Kowalska and Lenart, 2001) after 60 min osmotic dehydration in a 60% (w/w) sucrose solution at 30 °C at atmospheric pressure. 

Looking more deeply into these ongoing studies, for example, the application of ultrahigh hydrostatic pressure, leads to significant changes in the tissue architecture. This resulted in increased mass transfer during the osmotic dehydration of pineapple and potato slices due to the combined effect... 

FIG. 4 Effects of varying raw material treatments prior to osmotic dehydration on moisture (MC) and solid (SC) content expressed on initial dry matter (idm). Potato slices, high hydrostatic pressure (Rastogi et al., 2001) carrot slices, PFE (Rastogi et al., 1999) bell pepper disks, PFE (Ade-Omowaye et al., 2002b) and apple slices, edible coatings (Lenart and Dabrowska, 1998). 

Another promising technique is ultrasound application during osmotic dehydration. Used on porous fruit such as apple cubes, it affects mass... 

Osmotic dehydration, both at atmospheric pressure or preceded by the application of subatmospheric pressure for a short time, has been proposed in the production of minimally processed fruits and vegetables, which are convenient, ready-to-eat, high-moisture but ambient stable foods. The consumer prefers minimally processed foods, as these foods have appealing fresh-like characteristics and thus superior sensory quality. However, at the same time, these foods must be microbiologically safe and stable. These somewhat conflicting goals are achievable by the application of... 

FIG. 7 Effect of 90-min osmotic dehydration (OD) in 40% (w/w) glucose solution at 25 °C at atmospheric pressure on drying rates (M/M0 moisture content/initial moisture content) at 60 °C of infinite plate-shaped mango (Nieto et al., 2001) and apple (Nieto et al., 1998). 

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