Analysis of modes of heat transfer in baking Indian rice pan cake (Dosa,) a breakfast food

Heat transfer by individual modes is estimated during baking of rice (Oryza sativa) pan cake (Dosa), a traditional food. The mathematical expressions proposed could be used to modify the baking oven for controlling the individual modes of heat transfer to obtain the desired product texture, colour and flavour. Conduction from the rotating hot plate is found to be the most prominent mode of heat transfer and is critical for obtaining the desired product characteristics such as texture and flavour. Temperature profiles along the thickness of Dosa are obtained and compared with those obtained experimentally. Heat transfer parameters such as thermal conductivity and emissivity of Dosa are determined (0.42 W/m K and 0.31, respectively). The effect of material of construction of the hot plate such as alloy steel, teflon coated aluminum, cast iron and stainless steel on product texture was studied and stainless steel was found to give good surface finish to the product, which was confirmed by scanning electron microscope. Sensory evaluation was carried out to evaluate the product acceptability. The thermal efficiency of the baking oven was 51.5%

Kinetics of osmotic dehydration of coconut

Osmotic dehydration rates were determined for coconut over a range of osmotic solution concentration (40–70°B) and temperature (25–45C). A semi-empirical relation for kinetics of osmotic dehydration has been proposed, which indicates the moisture diffusion as a function of concentration of osmotic solution and its temperature. Good agreement was observed between the observed and predicted values (correlation coefficient 0.90). the effective diffusion coefficients of water in coconut during osmotic dehydration were estimated and also the activation energy of the osmotic dehydration process of coconut was found as 1.75 × 104 J/kg-mole

Differential partitioning for purification of anthocyanins from Brassica oleracea L.

Aqueous two phase extraction was employed as an alternate method for the downstream processing of anthocyanins. Polyethylene glycol (PEG) 4000/magnesium sulphate (14.8%/10.3% w/w) was found to be the most suitable system. Tie line length of 32.61% and volume ratio of 0.73 have resulted in maximum partitioning of anthocyanins to the PEG-rich phase (yield – 98.19%) and sugars to the salt-rich phase (yield – 73.16%). Multistage aqueous two phase extraction resulted in an increase in removal of sugars (to about 96.5%) with 91.9% yield of anthocyanins. The phase forming polymer (PEG 4000) was successfully separated from anthocyanins employing organic–aqueous extraction resulting in 2.3 fold increase in the concentration of anthocyanins. High performance liquid chromatography (HPLC)–Mass spectroscopy (MS)/MS was carried out to confirm the structural stability of anthocyanins

Extraction and purification of C-phycocyanin from spirulina platensis employing aqueous two phase systems

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Water and solute diffusion coefficients of carrot as a function of temperature and concentration during osmotic dehydration

Mass transfer was quantitatively investigated during osmotic dehydration of fresh carrot over a range of concentration (40–70 °B) and temperature (30–50 °C) of osmotic solution. Effective diffusion coefficients of water as well as sucrose were estimated using the solution of Fick's unsteady state law. Multilinear analysis of the estimated effective diffusion coefficients of water and solute revealed that these values depend upon temperature and concentration of the osmotic solution as well as the combined effect of temperature and concentration