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Comparison of the influence of citric acid and acetic acid as simulant for acidic food on the release of alloy constituents from stainless steel AISI 201
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.ORCID iD: 0000-0003-2206-0082
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.ORCID iD: 0000-0003-2145-3650
2015 (English)In: Journal of Food Engineering, ISSN 0260-8774, Vol. 145, 51-63 p.Article in journal (Refereed) Published
Abstract [en]

To ensure the safety of metals and alloys intended for food contact, a new European test protocol (CoE protocol) using citric acid as a food simulant was published in 2013. This study investigated the influence of citric acid and exposure conditions on the metal release from an austenitic manganese stainless steel (AISI 201). Exposures in 5 g/L citric acid resulted in significantly lower metal releases compared with specific release limits set by the CoE protocol. 5 g/L (0.3 vol%) citric acid was more aggressive than 3 vol% acetic acid (Italian protocol) due to higher metal complexation. Studies on abraded surfaces revealed that most metals were released during the first 0.5 h of exposure due to surface passivation. Surface abrasion, increased temperature (40-100 degrees C), increased surface area to solution volume ratio (0.25-2 cm(2)/mL) and increased citric acid concentration (0-21 g/L) all resulted in increased released metal quantities.

Place, publisher, year, edition, pages
2015. Vol. 145, 51-63 p.
Keyword [en]
Austenitic stainless steel, Food contact, CoE protocol, Test guideline, Complexation, Metal release, Surface oxide
National Category
Food Engineering
URN: urn:nbn:se:kth:diva-156095DOI: 10.1016/j.jfoodeng.2014.08.006ISI: 000343379500007ScopusID: 2-s2.0-84907192007OAI: diva2:778271
Available from: 2015-01-09 Created: 2014-11-21 Last updated: 2016-08-30Bibliographically approved
In thesis
1. Metal Release and Corrosion of Stainless Steel in Simulated Food Contact
Open this publication in new window or tab >>Metal Release and Corrosion of Stainless Steel in Simulated Food Contact
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Knowledge on metal release behaviour of stainless steels used in food processing applications and cooking utensils is essential within the framework of human health risk assessments. Recently, a new European test guideline (the CoE protocol) has been implemented to ensure safety of metals and alloys in food contact, such as stainless steels. This guideline suggests 5 gL-1 citric acid (pH 2.4) as a food simulant for acidic foods of pH ≤ 4.5. So far, limited assessments exist that investigate the correlation between the bioaccessibility, material characteristics, corrosion behaviour and surface chemistry of stainless steel for food application tests using citric acid. Therefore, this doctoral thesis comprises an in–depth interdisciplinary and multi–analytical research effort to fill this knowledge gap.

This work includes thorough investigations of a range of stainless steel grades in simulated food contact as a function of different important parameters such as grades, surface finish, temperature, pH, solution composition, metal complexation and buffering capacity, concentration of the complex forming agents, loading, and repeated usage. This is accomplished by kinetic studies of metal release, electrochemical, and surface analytical investigations. Another focus of this thesis is to assess the dominating metal release process in citric acid or chloride containing solutions of varying pH.

This study suggests protonation (at acidic pH) and surface complexation (at weakly acidic and neutral pH) as the predominant metal release mechanisms for stainless steel in citric acid solutions. Solution complexation may also play a role by hindering metal precipitation at weakly acidic and neutral pH, and metal release from surface defects / inclusions may initially be important for non-passivated surfaces.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2016. 63 p.
TRITA-CHE-Report, ISSN 1654-1081 ; 2016:32
National Category
Materials Chemistry Metallurgy and Metallic Materials
Research subject
urn:nbn:se:kth:diva-191474 (URN)978-91-7729-067-4 (ISBN)
External cooperation:
Public defence
2016-09-22, F3, Lindstedtsvägen 26, KTH Campus, Stockholm, 10:00 (English)

QC 20160831

Available from: 2016-08-31 Created: 2016-08-30 Last updated: 2016-08-31Bibliographically approved

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Mazinanian, NedaOdnevall Wallinder, IngerHedberg, Yolanda
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