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Studies on Mass Transfer and Diffusion Coefficients in Elephant Foot Yam (Amorphophallus spp.) during Osmotic Dehydration in Sodium Chloride Solution

Sangeeta,, Hathan, Bahadur Singh
Journal of food processing and preservation 2016 v.40 no.3 pp. 521-530
Amorphophallus, crops, diffusivity, drying, geometry, mass transfer, models, osmotic treatment, pickles, raw materials, sodium chloride, solutes, temperature, value-added products, water content, yams
The aim of this work was to study the osmotic dehydration kinetics of elephant foot yam (Amorphophallus spp.) cubes in different concentrations (5, 10 and 15% w/w) and temperatures (40, 50 and 60C) of sodium chloride solutions. Water loss and solid gain ranged from 16.69 to 33.97 and 6.65 to 12.95 g/100 g, respectively, for all the process parameters applied. The mass transfer rate was initially higher and becomes negligible after 150 min. The normalized moisture and normalized solid content vary from 0.74 to 0.88 and 1.38 to 1.72 g/g, respectively, at the end of osmotic dehydration. Azuara model was the best‐fitted model among all the models applied for both water loss and solute gain and also used to predict equilibrium values. The effective diffusivity of water loss as well as solute gain was estimated for parallelepiped/slab geometry and varied from 7.380–8.564 × 10⁻⁰⁹ and 6.780–7.921 × 10⁻⁰⁹ m²/s, respectively, for the earlier conditions of osmotic dehydration. PRACTICAL APPLICATIONS: Elephant foot yam (EFY) is a medicinal and nutritional tuber crop mainly consumed as vegetable, pickles and Ayurvedic preparations. Because of its culinary properties, therapeutic values and medicinal utility, it is also referred to as “king of tuber crops.” In spite of its valuable properties, a large‐scale production in any processed form is not carried out. It can be converted into a number of value‐added products if processed properly and can effectively enhance the consumption by utilizing its functional benefits. For converting into value‐added products or preserving it for a long time, drying is necessary as EFY contain high moisture content, but bioactive compounds significantly degrade. A good idea in this regard is osmotic dehydration, which minimizes nutritional losses of raw materials, without causing too much increase in process costs. For increasing shelf stability and processing on a commercial level, the primary step is to study mass transfer behavior and diffusion coefficients.