Intensification of process of hydration of soybean oil with use of ultrasonic impact

. This scientific article presents the results of ultrasound on changes in the yield of phospholipids, lecithin, and cephalin in soybean oil depending on the intensity of the soybean oil hydration process and the consumption of the hydrated solution, conventional mixing, and ultrasound exposure, as well as 20-22 Due to the use of high-frequency ultrasound exposure, the amount of non-hydratable phospholipids in soybean oil was reduced.


Introduction
Vegetable oils obtained by pressing and extraction methods contain mechanical compounds, non-oily substances, toxic substances, and accompanying substances, in addition to glyceride.Also, when oil is extracted through pressing and squeezing, the unwanted particles may get into the mixture [1][2][3].Over time, the filtered oils become cloudy and precipitate.Particle oil sinks to the bottom of storage tanks during storage.Their amount is 20-25%.It consists of fusa-phosphatides, proteins, and mucilaginous substances.When heated, the particle dissolves in oil, and when cooled, it separates from oil again.Impurities that form a true or colloidal solution with vegetable oil include sterols, waxes, waxy substances, phosphatides, color and odorants, carbohydrates, proteins, and vitamins [4][5][6].
Of vegetable oils, soybean oil contains the maximum amount of phospholipids (up to 2.5%) compared to other oils, which gives preference to obtaining the latter.However, despite using various chemical reagents, some phospholipids remain in the hydrated oil.Therefore, hydrated phospholipids (HPF) yield does not exceed 70-75% of their total content in soybean oil.Increasing the yield of hydrated phospholipids from soybean oil requires selecting an effective hydrating aqueous solution, the conditions for this process, etc. [7][8][9][10].
Of vegetable oils, soybean contains more phospholipids of hydratable and nonhydratable forms, which undoubtedly affects this production's technical and economic efficiency.Moreover, the hydratable phospholipids include lecithin and the non-hydratable -cephalin, the chemical formula of which is presented below: *Corresponding author: a.ahmedov80@mail.ruwhere: R1 and R2 are saturated and unsaturated hydrocarbon residues of fatty acids.The soybean oil hydration method is rational, but its use is associated with several difficulties; in particular, the physicochemical parameters and refined oil yield do not meet the standard's requirements.Therefore, increasing the efficiency of soybean oil hydration is an urgent task.
In many parts of the world, crude soybean oil is extracted from soybean petals by washing them with a hexane solvent.The solvent is then removed, and the crude oil remains.The hydration process removes naturally occurring phospholipids from unrefined soybean oil.Although all crude vegetable oils contain phosphatides, soybean oil is currently the main source of industrial lecithin, as it contains the highest amounts of phosphatides and the largest production of lecithin in the world.This oil is produced by hydration and mechanical separation.
In practice, hydrated soybean oil is mixed with water or an aqueous solution of organic (citric, malic, acetic, etc.) acids using a turbulator that does not mix in the hydration apparatus in the required hydrodynamic mode.Therefore, biplanetary mixers, mechanochemical activators, etc., are used to perfectly mix phases [11,12].
In contrast to those noted above, taking into account the advantages of the cavitation effect, we studied the effect of ultrasonic mixing of soybean oil with a hydrated reagent on the yield of phospholipids [13].

Methods
The article uses modern chemical, physicochemical, and spectral and standardized physical, mechanical, technological, and operational test methods [13,17].

Results and Discussion
In fig. 1 presents the results of studies of the proposed effect on the yield of the obtained phospholipids [17].
Fig. 1 shows that ultrasonic action with a frequency of 20 MHz increases the yield of soy phospholipids than with conventional (50 rpm) stirring of a mixture of oil with a hydrated solution.
The purpose of intensifying the process of hydration of soybean oil is to increase the yield of hydrated phospholipids, i.e., lecithin's by reducing the amount of non-hydrated, i.e., cephalin.In practice, these indicators are controlled by increasing the temperature and the amount of injected hydration solution.Taking this into account, we studied the effect of ultrasonic action on the yield of hydrated phospholipids at an aqueous solution flow rate equal to 4.0% of the total mass of a mixture of soybean oil with water [18][19][20].
The research results are shown in Figure 2 Figure 2 shows that with an increase in the temperature of hydration of soybean oil, the yields of lecithin increase with conventional (curve 1) and ultrasonic (curve 2) stirring at a frequency of 20 MHz [19].
It is known that cephalin is a non-hydratable phospholipid, and its decrease in soybean after increases the yield of lecithin, the target product of the hydration process [20].
We have studied the yields of cephalin from soybean oils depending on the mixing time and its implementation conditions.
The results of the experiments are presented in Figure 3. Figure 3 shows that with an increase in the hydration time (τ) up to 10 minutes, the yield of cephalin decreases with conventional (curve 1) and ultrasonic (curve 2) mixing of the phases.This is due to a decrease in the intensity of mixing soybean oil with a hydrating agent in the amount of 4% of the total mass of the mixture.Moreover, ultrasonic action (curve 2) provides a greater yield of cephalin than usual (curve 1) stirring.
In terms of time consumption, the hydration process is influenced by the following factors: τ1 is mixing time of vegetable oil with a hydrating reagent, min; τ2 is swelling time of vegetable oil phospholipids, min; τ3 is time of phospholipid flakes enlargement, min; τ4 is settling time of phospholipid flakes, min; τ5 is time of separation of phospholipids from vegetable oils, minutes.
For the full-time separation of phospholipids from vegetable oils, τ1 + τ2 + τ3 + τ4 + τ5 minutes are consumed.Moreover, the resulting phospholipid contains up to 40% triacylglycerides, i.e., neutral fats, which are subjected to separation with acetone when obtaining fractions of lecithin and cephalin [20].
Moreover, the intensity of the compound phenomena in the process of hydration of vegetable oils can be shown in the following graph, which is shown in Figure 4. Figure 4 shows that until the complete precipitation of phospholipids of vegetable oils, the intensity of the previous stages is less noticeable than the subsequent ones.
4. Conclusions.Thus, we can summarize that to intensify the process of hydration of phospholipids from vegetable oils, it is necessary to improve the first 3 stages, where phospholipid flakes are formed.Moreover, the first 3 stages have practically the same flow rate, which is clearly seen in Figure 4.
In conclusion, it was found that ultrasound has a good effect on the yield of phospholipids, lecithin, and cephalin in soybean oil, depending on the intensity of the soybean oil hydration process and the consumption of the hydrated solution, conventional mixing, and ultrasound exposure.As a result, due to the use of 20-22 MHz ultrasound exposure, the amount of non-hydratable phospholipids in soybean oil decreased.

Fig. 1 .Fig. 2 .
Fig. 1.Change in the yield of phospholipids (Ph) of soybean oil depending on the flow rate of the hydrated solution (Gs), conventional (50 rpm) stirring (control, curve 1), and ultrasonic exposure (curve 2 equal to 2 MHz)

Fig. 3 .
Fig. 3. Changes in the yield of cephalin (K) depending on the time of hydration of soybean oil under normal (at 50 rpm, curve 1) and ultrasonic (at a frequency of 20 MHz, curve 2) mixing of the mixture

Fig. 4 .
Fig. 4. Curves of the intensity of extraction of phospholipids from vegetable oils at different stages of the process of their hydration