Adsorbents to tackle 3-MCPD

With the EU currently looking at legislation to control levels of 3-MCPD esters, bleaching earths play an important role in migitating this critical process contaminant Vinicius Celinski

Adsorbents to

tackle 3-MCPD

The role of bleaching earths in mitigating 3-monochloropropane-1,2-diol ester (3-MCPDE) formation is an important one, especially with the EU currently considering legislation to control its level in food.

Humans are exposed to 3-MCPDEs from consuming refined oils or food products containing refined oils, such as infant formula, dietary supplements, fried potato products and bakery products.

The occurrence of 3-MCPDEs in food oils was first reported in the mid-2000s. The EU is proposing two maximum thresholds for vegetable and fish oils and fats intended for consumers or for use as food ingredients: oils and fats from coconut, maize, rapeseed, olives (except olive pomace oil) sunflower, soyabean and palm kernel and mixtures of oils and fats from this category only. 2,500µg/kg for other refined vegetable oils (including olive pomace oil), fish oil and oils of other marine organisms and mixtures of oils and fats from this category only.

Research has shown that 3-MCPDEs are primarily formed during the deodorisation step of edible oil refining. There, the high temperatures that are applied unlock the potential of key factors – such as acidity, chlorine precursor nature and content – to become active.

Even before this step is reached, good u

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u agricultural practi ce can help miti gate higher temperatures, such as above 200 0 C where their characterisati on, genesis, 3-MCPDE formati on. to reduce free fatt y acids (FFAs), cannot quanti ty and miti gati on have been a For example, palm oil and palm fats be avoided. source of debate in the past years. have the highest levels of MCPDEs Due to the very diff erent physical among vegetable oils and reducing the Inorganic vs organic chlorides nature of inorganic and organic chlorines, handling of palm fruits to prevent the It is common to fi nd varying amounts of effi cient miti gati on of these substances formati on of free fatt y acids (FFAs) is inorganic chlorine as part of the natural calls for individual strategies. recommended, along with sterilisati on mineral structure of bleaching earths. at temperatures at or below 140 0 C to Furthermore, it can accumulate in an Chlorine precursors and BEs inacti vate lipases. adsorbent if special care is not taken Clariant has conducted research to To reduce the amount of chlorine between the many steps involved in examine whether inorganic and organic precursors, farmers can limit the use of producing the fi nished product such as chlorines turn equally into 3-MCPDEs and substances such as ferti lisers, pesti cides mining, transportati on, acti vati on and feature similar conversion rates. and water that have excessive amounts of chlorine-containing compounds. washing. Using greater amounts of well Dr. Vinicius Celinski, BU Functional Minerals, Application Development, 21.10.2019 Confidential The company’s Research & Development department also looked During the refi ning stage, processors processed bleaching clay may reduce the at whether a complete miti gati on of should work at the lowest possible formati on of 3-MCPDEs in all vegetable inorganic chlorine leads to zero 3-MCPDE temperatures (ideally at or below 140 0 C) and less acidic conditi ons. and fi sh oils. Organochlorine precursors are mainly formati on. Although trivial, it is important to recall Systematic addition of inorganic chlorine (salt) to palm oil prior to

However, in practi ce, the applicati on of bleaching step found in crude oil prior to processing, what makes up the total chlorine content u • 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 0 20 40 60 80 100 120 Amount of 3 - MCPD esters in 100 g of deodorized oil/µmol Amount of total chlorine during bleaching (org. + inorg.)/µmol with BE 0,0 2,0 4,0 6,0 8,0 10,0 12,0 14,0 0 20 40 60 80 100 120 Amount of 3 - MCPD esters in 100 g of deodorized oil/µmol Amount of total chlorine during bleaching (org. + inorg.)/µmol with BE without BE Dependencydoes not cross the y-axis at 0 and is not linear. • High quality BE can adsorb a good portion of free inorganic chlorine, contributing to the mitigation strategy. • Dependency does not cross the y-axis at 0 and is not linear This speaks for the presence of other chlorine precursors • High quality bleaching earth can adsorb a good porti on of free inorganic chlorine, conti buti ng to a miti gati on Figure 1: Systemati c additi on of inorganic chlorine (salt) to palm oil prior to bleaching Dr. Vinicius Celinski, BU Functional Minerals, Application Development, 21.10.2019 Systematic addition of inorganic chlorine (salt) to palm oil prior to bleaching step Confidential Source: Clariant BU FM, Applicati on and Development Dept

This speaks forthe presence ofotherchlorine precursors. Does 1 mol Cl precursors lead to 1 mol 3-MCPD esters?

30,0

Conditions: acid + water degum. at 95°C; wet + dry bleaching at BE dosage: 1,4%; deso at 270°C 0,0 5,0 10,0 15,0 20,0 25,0 0 20 40 60 80 100 120 Conversion efficiency (Total chlorine to 3 - MCPD esters)/% Amount of total chlorine (org. + inorg.)/µmol with BE without BE R 1 R 2 R 1 R 2 R 2 • The conversion efficiency of chlorine precursors is surprisingly low under common refining conditions. • Inorganic chlorine’s conversion efficiency is not constant and appears to be lower than that of organochlorides. • High quality bleaching earths can efficiently adsorb inorganic chlorine. Figure 2: Systemati c additi on of inorganic chlorine (salt) to palm oil prior to bleaching – does 1 mol Cl lead to 1 mol 3-MCPD esters? • The conversion effi ciency of chlorine precursors is surprisngly low under common refi ning conditi ons • Inorganic chlorine’s conversion effi ciency is not constant and appears to be lower than that of organochlorides • High performance bleaching earths can effi ciently adsorb inorganic chlorine Source: Clariant BU FM, Applicati on and Development Department

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of an oil sample, since that influences the mitigation strategy.

In this part of Clariant’s research, the total amount of chlorine represented the sum of organic and inorganic chlorine without differentiating between them.

Chlorine (salt) was systematically added to palm oil prior to bleaching in order to examine whether a complete conversion would be the result (for example, does one mol of chloride lead to one mol of 3-MCPDEs).

It was found that the conversion rate dependency was not linear, speaking for the presence and importance of other chlorine precursors (see Figure 1, previous page).

Furthermore, the conversion efficiency of the inorganic chlorine precursor was surprisingly low under common refining conditions, at 30% even without bleaching earths (see Figure 2, previous page).

The conclusion is that inorganic chlorine’s conversion efficiency is not constant and appears to be lower than that of organochlorines.

Other factors also point to the existence and importance of organochlorines.

For example, washing filter oil with water to reduce the content of inorganic chlorine does not significantly reduce the formation of 3-MCPDEs.

In addition, performing the bleaching step with natural bleaching earths (thermally activated, without acid) still often leads to 3-MCPD formation.

Organochlorines

Organochlorines have been identified as the main contributor to the formation of 3-MCPDEs, with a sphingolipid-based organochlorine compound shown as the most active precursor, according to research carried out by Malaysia’s Sime Darby Plantation.

Crude palm, soyabean, rapeseed, sunflower, corn, coconut and olive oils were tested for the presence of organochlorine compounds as possible precursors for 3-MCPDEs.

The compounds were found in all the vegetable oils tested, according to the study, ‘Natural Organochlorines as Precursors of 3-Monochloropropanediol Esters in Vegetable Oils’, published in December 2017 by the American Chemical Society (AOC).

Further study was made on oil palm products, and analysis of the chlorine isotope mass pattern exhibited in high-resolution mass spectrometry enabled organochlorine compound identification in crude palm oils as constituents of wax esters, fatty acid, diacylglycerols and sphingolipids, which are produced endogenously in oil palm mesocarp throughout ripening.

“Analysis of the thermal decomposition and changes during refining suggested that these naturally-present organochlorine compounds in palm oils, and perhaps in other vegetable oils, are precursors of 3-MCPD esters,” the researchers said.

“Enrichment and dose-response showed a linear relationship to 3-MCPD ester formation and indicated that the sphingolipid-based organochlorine compounds are the most active precursors of 3-MCPDEs.”

Conclusions

The conversion efficiency of inorganic chlorine into 3-MCPDEs is not constant and can be much lower than that of organochlorines.

High performance bleaching earths, produced by paying attention to qualitative and technical prerequisites, can efficiently mitigate inorganic chlorine.

A naturally present organochlorine compound in crude palm oil is an important contributor to the formation of 3-MCPDEs.

Better understanding the dynamics of 3-MCPDE formation and accounting for the different physical nature of organic and inorganic chlorines are key to develop tailor-made solutions to efficiently mitigate both types of chlorine precursors.

Therefore, with respect to its entire Tonsil bleaching earth portfolio, Clariant takes various measures to ensure low levels of inorganic chlorine.

These include selective mining with strict specification limits for chlorine levels, the monitoring of transportation and stringent quality control of raw materials and products, in conjunction with rigorous washing of activated bleaching earths as an essential part of the production process.  Dr Vinicius Celinski is the Application Development Manager of the Competence Center Purification of BU Functional Minerals at Clariant AG, Switzerland. This article is based on a presentation made at the 17th Euro Fed Lipid Congress and Expo in Seville in 2019 Visit www.clariant.com/OilPurification to view the Tonsil bleaching earth portfolio