Formation of naturally occurring pigments during the production of nitrite-free dry fermented sausages

• Zn(II)PPIX was able to form in nitrite-free dry fermented sausages.
• Also PPIX accumulated in nitrite-free dry fermented sausages.
• Both pH and time were found to be crucial factors for their formation.
• Heme breakdown occurred more gradually, irrespective of the different pH conditions.
• Zn(II)PPIX formation and product redness were significantly correlated.

This study investigates the potential of producing red coloured dry fermented sausages without the addition of nitrite and/or nitrate. Therefore, the formation of zinc protoporphyrin IX (Zn(II)PPIX) as naturally occurring pigment, and the interrelated protoporphyrin IX (PPIX) and heme content were evaluated during nitrite-free dry fermented sausage production at different pH conditions. Zn(II)PPIX was only able to form in dry fermented sausages at pH conditions higher than approximately 4.9. Additionally, the presence of Zn(II)PPIX increased drastically at the later phase of the production process (up to day 177), confirming that in addition to pH, time is also a crucial factor for its formation. Similarly, PPIX also accumulated in the meat products at increased pH conditions and production times. In contrast, a breakdown of heme was observed. This breakdown was more gradual and independent of pH and showed no clear relationship with the formed amounts of Zn(II)PPIX and PPIX. A statistically significant relationship between Zn(II)PPIX formation and product redness was established.