Abstract
Solvent extraction as a method of extracting protein from oilseed meals offers the advantage of higher efficiency. Unfortunately, the published literature points to the gap in the work concerned with the necessary equilibrium diagram to design due process equipment for such extracts. Initiated by this lack of basic knowledge, the present study has been undertaken to provide the equilibrium data for three different ternary systems, namely: sesame protein / sodium hydroxide solution system, soybean protein / sodium hydroxide solution system and lupine protein / sodium hydroxide solution system. These oilseed meals were selected because of their high protein content (53.4 %, 46.2 % and 42.3 % protein, respectively). The study also concentrated on the evaluation of the major parameters affecting the extraction process, i.e. the normality of the sodium hydroxide solution used as extracting solvent and the initial oilseed solvent to meal feeding ratio. The results obtained indicate that the best normality of sodium hydroxide solution used for extracting soybean and lupine protein is 0.02N, while 0.04N solution is required for extracting sesame protein. Also, operating at a liquid to solid feed ratio of 30:1 and 50:1 for soybean, sesame and lupine, respectively, is enough to reach a high protein extract. Correlations were presented for each locus of under flow compositions, graphically acquired, and the data are compared with those calculated by analytical solutions.
Highlights
Oilseed proteins rank high among the unconventional sources of protein proposed by the Protein Advisory Group of the United Nations (1968) to bridge the protein gap in developing countries.Oilseeds in general, after the extraction of the oil, yield a product known as meal, which is considerably rich in protein
Other factors- such as the solvent to meal ratio, temperature, contact time and particle-size play an important role during the extraction of the protein from the meal, yet the separation of soluble matter from its mixture with insoluble solid depends primarily on the equilibrium distribution of the solute between the miscella and the leached residue. Knowledge of these distribution relationships is essential for a common process design as well as for selecting the ratio of extraction solvent to feed that enters an existing extraction battery and for evaluating the mass transfer rates or theoretical stage efficiencies achieved in process equipment
The locus of underflow compositions shows a linear relationship as observed in the graphical representations of the ternary diagram corresponding to the three systems respectively (Figure 2 to Figure 4)
Summary
Oilseed proteins rank high among the unconventional sources of protein proposed by the Protein Advisory Group of the United Nations (1968) to bridge the protein gap in developing countries.Oilseeds in general, after the extraction of the oil, yield a product known as meal, which is considerably rich in protein. Other factors- such as the solvent to meal ratio, temperature, contact time and particle-size play an important role during the extraction of the protein from the meal, yet the separation of soluble matter from its mixture with insoluble solid depends primarily on the equilibrium distribution of the solute between the miscella and the leached residue. Knowledge of these distribution relationships is essential for a common process design as well as for selecting the ratio of extraction solvent to feed that enters an existing extraction battery and for evaluating the mass transfer rates or theoretical stage efficiencies achieved in process equipment
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