Communication Record: Leif Horsfelt Skibsted


Dr Peter Ford shared his work with me on the solution chemistry of nitric oxide and other reactive nitrogen species. The relevance to meat curing of such a study is immense. Not just for the general reaction sequence and broadly relevant considerations, but particularly related to meat curing, the following question is postulated. If it is possible to produce the cured reaction with Nitric Oxide directly without the use of nitrite or nitrite, does nitrite and nitrate-free bacon follow? The reason for this is that nitrate and nitrite form in the presence of nitric oxide. If you then cured meat without the use of nitrite or nitrate and these species form in any event, is it ethical to declare on the bacon label, “contains no nitrites/ nitrites” on the basis that none was added?

I posed this question to Dr. Ford who referred my question to Dr. Skibsted in Denmark who is a meat scientist. So relevant is the question that I present Dr. Skibsted’s answer below.

For our quest for nitrite-free bacon, using bacterial fermentation for the curing reaction where bacteria access the nitrogen in proteins to effect curing, the meeting of Dr. Skibsted was of supreme importance as it turns out that he and his research teams have elucidated the underlying mechanisms over many years. I therefore not only present his reply to my question, but also the many papers he graciously made available to me for consideration. In his reply, he mentions Dr. Jens Møller whom I quested years ago when I did my review of the curing reaction, Reaction Sequence: From nitrite (NO2-) to nitric oxide (NO) and the cooked cured colour.

Record of Communication

I publish the record of private communication between myself and Dr. Leif Horsfelt Skibsted related to curing through bacterial fermentation and if it is possible to have curing and no NO2- or NO3- in the meat, even if NO is created through fermentation.

On Mon, 17 Oct 2022 at 10:05, Leif Horsfelt Skibsted <xxxxxx.xx> wrote:

Dear Eben

The cured meat pigment MbFe(II)NO will oxidize to nitrate, which may be reduced to nitrite by bacterial enzymes. In real meat systems, I agree with you, nitrite will develop even when no nitrite was added

Jens Møller was my PhD-student many years ago. We wrote the Chem.Rev. paper together some 20 years ago. He did some post-doc work later with others on bacterial meat curing.

Best regards


Leif H. Skibsted

Professor emeritus

University of Copenhagen

Department of Food Science

Rolighedsvej 26

DK-1958 Frederiksberg C

DIR +45 29 21 89 49

A. Colour formation in fermented sausages by meat-associated staphylococci with different nitrite- and nitrate-reductase activities

B. Relationship between nitrate/nitrite reductase activities in meat associated staphylococci and nitrosylmyoglobin formation in a cured meat model system

C. Microbial formation of nitrite-cured pigment, nitrosylmyoglobin, from metmyoglobin in model systems and smoked fermented sausages by Lactobacillus fermentum strains and a commercial starter culture

D. Nitric Oxide and Myoglobins

E. Nitric Oxide

F. Plant derived ingredients rich in nitrates or phenolics for protection of pork
against protein oxidation

My Complete Work on Nitrites