Mass balance on extraction of phospholipids from organic raw material

Abstract

Phospholipids are found in nature in all tissues of vegetable and animal origin. However a particularly high level, up to 1-1.5%, may be reached in the seeds of oily plants, or up to 10% in animal tissues (egg yolk, bovine brain). One of the most important functions of phospholipids (particularly lecithin) is their involvement in the permeability of cell membranes. When assessing nutritive fats, preference is therefore given to fat containing a high quantity of phospholipid. This opinion also applies to medicinal fats. Phospholipids are valuable in medicine and as substances possessing a high emulsifying ability. This property leads to their use in the food, pharmaceutical, and perfume industries. The ability of phospholipids in the presence of water to form closed membrane structures, liposomes, enables their use in the preparation of liposomal forms of chemotherapeutic preparations [2]. A liposome is a container for the directed transport of a drug to the focus of the disease [3]. More careful study is needed of the possibilities of extending the range of sources for obtaining and extracting phospholipids. We have studied the kinetics of extracting phospholipids from powdered egg yolk, seeds of flax and oats, and soya beans in an apparatus with a mixer. Ethyl alcohol (95%) was used as extractant. The ratio of solid to liquid phases was 1:8 and 1:5. The extraction temperature for the process was 20~ Test samples were taken at set time intervals and were analyzed. The quantitative content of phospholipid in the extract was determined by photocolorimetric analysis of the lipid phosphorus after preliminary treatment with mineral acid and subsequently with molybdenum blue in the presence of sodium acetate solution [4]. The kinetic curves obtained at various phase ratios are shown in Figs. 1 and 2. It is evident from Fig. 1, in which the dependence of phospholipid phosphorus concentration in the extract on time is shown at a ratio of solid and liquid phases of 1:8 (curve 1) and 1:5 (curve 1'), that the accumulation of the desired components does not become maximal for about 3 h. This indicates the significant diffusion resistance of the membranes of the lipid containers which the desired components overcome during diffusion to the phase separation boundary. An analogous picture is observed when extracting oat seeds (see Fig. 2, curves 3 and 3'). In both cases molecular diffusion is the factor determining the rate of the process. It was also established that the process occurs by an intradiffusion mechanism. The kinetic curves 1 and 1', 2 and 2' in Fig. 2 were constructed from the experimental data of extracting soya beans and flax seed. When extracting soya beans it follows from Fig. 2 that the concentration of phospholipid in the extract reaches a certain level after 10 min and stays at this level for about 1 h. It then slowly increases to 0.02 mg/ml after 3 h. Something similar is also observed on extracting flax seed. A certain concentration of the desired components in the extract is reached comparatively rapidly and then an insignificant growth is recorded for 3 h. Such a picture is explained by the anatomical structure of flax seed and soya beans. When grinding the flax seed and soya bean we open a significant quantity of endosperm ceils where the fat containers are mainly localized. Initially, washing out of phospholipid occurs and then the remainder of the desired components diffuse outward, by overcoming the resistance of the membranes of the unopened cells. The typical kinetic curves obtained are described well by the equation: