USAGE OF ETHANOLAMINES IN SOYBEAN OIL DEGUMMING PROCESS

ABSTRACT

The article discusses the results of a non-standard method of degumming soybean oil with ethanolamines. Various degumming methods, such as water degumming and TOP degumming, were compared with ethanolamine degumming, specifically monoethanolamine, diethanolamine, and triethanolamine. The effectiveness of removing phosphorus, iron, and tocopherols in soybean oil was compared among different degumming methods. Among the ethanolamines, monoethanolamine proved to be the most effective in removing phosphorus. Degumming soybean oil with monoethanolamine reduced the phosphorus content to less than 1.6 mg.kg^-1, which is significantly better than the current TOP degumming method.

АННОТАЦИЯ

В статье проанализированы результаты нестандартного метода гидратации соевого масла этаноламинами. Разные методы гидратации, такие как водная гидратация, ТОП гидратация были сравнены с гидратацией этаноламинами, в частности мноэтаноламином, диэтаноламином и триэтаноламином. Были сопоставлены эффективность удаления фосфора, железа и токоферолов при разных методах гидратации соевого масла. Среди этаноламинов самым эффективном в удаления фосфора оказался моноэтаноламин. Гидратация моноэтаноламином соевого масла снизила содержание фосфора на менее чем 1.6 mg.kg^-1 , что намного лучше  чем современный метод ТОП гидратации.

Keywords: Soybean oil, degumming, ethanolamines, phosphorus, iron, tocopherol.

Ключевые слова: Соевое масло, гидратация, этаноламины, фосфор, железо, токоферол.

Introduction

During the last period, there have been numerous discoveries in the fats and oils industry, particularly in the field of degumming. These factors provide opportunities for selecting an efficient, cost-effective, and environmentally friendly process. Crude vegetable oils contain both hydratable forms and non-hydratable forms of phospholipids. Non-hydratable forms of phospholipids, due to their stable solubility in oil, do not diminish during water degumming and cannot be separated by precipitation or centrifugation (1). Modern hydration processes should target non-hydratable forms of phospholipids, converting them into hydratable forms and facilitating its efficient removal. A simplified scheme for the hydration (acidic) of vegetable oils includes: The breakdown of phosphate-metal complexes by adding acid. Degumming of phospholipids by adding water. Partial neutralization by adding alkali (2). Today, there are several methods for degumming vegetable oils (Table 1), such as water degumming, acid degumming, Super/Uni, SOFT, TOP, ultrafiltration degumming and degumming with ethanolamines (3-7)."Начало формы

Table 1.

Degumming methods of vegetable oils

The use of ethanolamines in the refining process of vegetable oils has a long history. Ethanolamine is an organic compound widely employed in various industrial sectors, including the food and petroleum industries. In 1925, Wilhelm proposed the refinement of vegetable oils using ammonia in micelles (8). One of the reasons for using ammonia was its easy regeneration from soapstock (9). A year later, Rosenstein suggested the use of ethanolamines as neutralizing agents (10, 11). Additionally, Thengumpilli proposed the use of ethanolamines for the refining of vegetable oils from rice bran only (12). It is also known that monoethanolamine was used to reduce the gossypol content in cottonseed oil (13). Ethanolamine’s effectively used during degumming process of sunflower and rapeseed oils. Monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) decreased phosphorus, magnesium and calcium content in sunflower and rapeseed oils. Among ethanolamine’s MEA shoved the better result than DEA and TEA (14). Also, MEA was used during pretreatment of cottonseed, it shoved the better effect on refining process comparing with standard pretreatment (15).

Начало формы

Materials and methods

Materials

Soybean oil samples were collected from local oil factory Kattakurgan Oil Plant in Uzbekistan.

Degumming

In the water degumming process, the initial step involved heating crude soybean oils to 80°C. Subsequently, a 6% volume of water was introduced into the oils, and the mixture was stirred for 30 minutes using a magnetic stirrer. The next step comprised centrifugation for a duration of 15 minutes, effectively eliminating impurities from the crude soybean oils.

For the TOP degumming process, water-degummed oil was heated to 80°C. Then, 0.1% volume of phosphoric acid (at 15% weight concentration) was added, and the mixture was stirred for 5 minutes. After partial neutralization with a 0.3% volume of NaOH (using a 20% water solution) and a 5-minute mixing stage, the hydrated phosphatides were subsequently removed via centrifugation, which lasted for 20 minutes.

In the degumming process involving ethanolamine, the water-degummed oil was initially treated by adding 0.5% ethanolamines and stirring for 60 minutes. This was followed by the addition of water, equivalent to 2% of the oil's volume, and stirring for an additional 30 minutes. Finally, the mixture was subjected to centrifugation for a duration of 20 minutes.

Determination of phosphorus, iron and tocopherols

The content of phospholipids was determined as the total phosphorus on a vegetable oil according to AOCS Official Method Ca 12-55 (16). Iron was  determined by ICP following AOAC Official Method 990.08 (17). The total tocopherol content in cottonseed oil was determined be AOCS Official Method Ce 8-89 (18).

Results and discusion

During degumming process many impurities in crude oils are removing. Table 2 illustrates the influence of water degumming, monoethanolamines (MEA), diethanolamines (DEA), triethanolamines (TEA), and TOP degumming methods on the phosphorus, iron, and tocopherol content in soybean extracted and pressed oils.

As evident from the data, soybean extracted oil contains higher levels of phospholipids (724.3 mg.kg^-1), tocopherols (1103.1 mg.kg^-1), and iron (4.3 mg.kg^-1) compared to pressed oil. This discrepancy can be attributed to the fact that during the extraction process, a larger portion of accompanying substances is transferred into the extracted oil.

Water degumming significantly reduced the phosphorus content in soybean oil, reaching levels of 72.6 mg.kg^-1 in extraction oil and 57.8 mg.kg^-1 in pressed oil. Water degumming also decreased tocopherol content by 9-10% and iron content by nearly three times.

 Degumming of soybean oil with ethanolamines demonstrated favorable outcomes in reducing phosphorus and iron in the oils. In the realm of vegetable oil refining, ethanolamine serves as a noteworthy agent for neutralization and complexation. Ethanolamine forms emulsions with these components, facilitating their removal during phase separation. Ethanolamine's pivotal role in eliminating impurities from vegetable oils is closely associated with its function as a regulating and complexing agent. It forms complexes with phospholipids, aiding in their removal during degumming.

Among the ethanolamines, MEA exhibited remarkable effectiveness in reducing phosphorus in the oil. When oils were treated with DEA (extracted oil - 4.2 mg.kg^-1, pressed oil - 1.1 mg.kg^-1) and TEA (extracted oil- 7.6 mg.kg^-1, pressed oil- 2.2 mg.kg^-1), the phosphorus content in soybean oil was higher compared to MEA treatment (extracted oil- 1.6 mg.kg^-1, pressed oil - 0.5 mg.kg^-1).

Table 2.

Influence of degumming methods on phosphorus,
tocopherols and iron content in soybean oils

Ethanolamine forms complexes with iron ions through chelation. The amino group of ethanolamine can establish hydrogen bonds with iron ions, while the ethyl group facilitates hydrophobic interactions with these ions. This interaction enables the formation of a stable complex between ethanolamine and iron.

These factors collectively allow ethanolamines to reduce the iron content in soybean oil. Among the ethanolamines, MEA demonstrated the most significant reduction in iron content. When MEA was employed, the iron content decreased to 0.3 mg/kg in extracted oil and 0.1 mg/kg in pressed oil. Importantly, ethanolamines only moderately reduced the tocopherol content, accounting for just 10% of the total tocopherol content in crude oil.

In the case of TOP degumming of soybean oil, the phosphorus content (extracted - 9.9 mg/kg, pressed - 5.6 mg/kg) and iron content (extracted- 0.2 mg/kg, pressed - 0.1 mg/kg) diminished. Tocopherol content also exhibited the most significant reduction compared to other degumming methods.

Conclusion

The goal of this paper is analysing the usage of ethanolamines during degumming processes of soybean oils. Soybean extracted oil contains notably higher levels of phospholipids compared to pressed oil. The degumming of soybean oil with ethanolamines demonstrates favorable outcomes in reducing phosphorus and iron levels. Among the ethanolamines, MEA proves remarkably effective in reducing phosphorus content in the oil. Treatment with DEA and TEA results in higher phosphorus levels compared to MEA treatment. Ethanolamines, particularly MEA, to significantly reduce iron content in soybean oil. Importantly, ethanolamines cause only a moderate reduction in tocopherol content, accounting for just 10% of the total tocopherol content in crude oil. TOP degumming of soybean oil, decreased amount of phosphorus (extracted - 9.9 mg/kg, pressed - 5.6 mg/kg) and iron (extracted - 0.2 mg/kg, pressed - 0.1 mg/kg) significantly. Tocopherol content exhibits the most significant reduction among all degumming methods. The choice of degumming method significantly influences the composition of soybean oils, particularly with regard to phosphorus, iron, and tocopherol content. MEA, in particular, stands out as a highly effective agent for reducing both phosphorus and iron levels while preserving the essential tocopherols, ultimately enhancing the quality and stability of soybean oil.

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