Color Formation in Nitrite‐Free Dried Hams as Related to Zn‐Protoporphyrin IX and Zn‐Chelatase Activity

Abstract

The development of red pigment Zn-protoporphyrin IX (ZPP) in nitrite-free Parma hams was investigated in 5 leg muscles at several stages of processing and the activity of muscle Zn-chelatase was concurrently assayed for its potential role in ZPP formation. A steady increase of the pigment was observed throughout the manufacturing stages at mild temperatures while no development was observed during the prior cold resting phase. The enzyme was partly inactivated according to a muscle-dependent pattern, resulting in similar ZPP contents, hence color, in finished hams. It is concluded that enzyme-dependent synthesis of ZPP in nitrite-free dried hams contributes to color development, enabling muscles in dried hams to become more similar in redness than in green thighs. Therefore, checking raw meat for the enzyme content may be a means to control color formation in nitrite-free dry-cured meat derivatives.

Salt Intake from Processed Meat Products: Benefits, Risks and Evolving Practices

“…In salted products, the pigment responsible for the typical red color is linked to the zinc protoporphyrin IX (ZPP) molecule (Wakamatsu et al, 2004), generated through a process of substitution of the iron of the heme by a zinc atom (of which pork meat contains much). Studies with model systems (Benedini et al, 2008) or on dried hams (Parolari, Benedini, & Toscani, 2009) highlight the important role of salt in the formation of this pigment by promoting the enzymatic activity of a zinc-chelatase that seems to be involved in this reaction, catalyzing iron substitution by zinc (Wakamatsu et al, 2004). The aim of a study in 2007 was to explore the relationship between lipid and pigment oxidation caused by replacing sodium chloride with potassium chloride at low salt levels (Cheng, Wang, & Ockerman, 2007).…”

Zinc-protoporphyrin content in commercial Parma hams is affected by proteolysis index and marbling

“…4.99.1.1) is the endogenous enzyme suggested as being responsible for the formation of ZnPP in meat (Benedini et al 2008). This enzyme is active throughout the processing time of dry-cured hams and is considered to some extent, responsible for the gradual formation of ZnPP (Parolari et al 2016;Parolari et al 2009;Adamsen et al 2006b). The residual activity of this enzyme, even in hams with a low water activity and a high salt concentration, would explain why many authors find a higher ZnPP content at the end of the process (Adamsen et al 2006b;Parolari et al 2009;Parolari et al 2016).…”

“…This enzyme is active throughout the processing time of dry-cured hams and is considered to some extent, responsible for the gradual formation of ZnPP (Parolari et al 2016;Parolari et al 2009;Adamsen et al 2006b). The residual activity of this enzyme, even in hams with a low water activity and a high salt concentration, would explain why many authors find a higher ZnPP content at the end of the process (Adamsen et al 2006b;Parolari et al 2009;Parolari et al 2016). However, in addition to meat endogenous enzymes, various authors have indicated the existence of other alternative and complex mechanisms that could be involved in this pigment formation and occur simultaneously (Becker et al 2012;Grossi et al 2014;Parolari et al 2016).…”

“…Therefore, a number of endogenous and exogenous factors that have not yet been completely elucidated could have an effect on the formation of ZnPP in Parma hams (Grossi et al 2014;Paganelli et al 2016). Although several factors affecting ZnPP have been studied in in vitro models, data is scarce on typical ZnPP contents in drycured Parma ham and studies dealing with the factors involved in the formation of this pigment in hams are still necessary (Wakamatsu et al 2009b;Parolari et al 2009;De Maere et al 2014). Therefore, it is important to gain a better understanding of the factors that contribute to this pigment content because they determine the characteristic colour of non-nitrified dry-cured hams.…”

Investigation of contributors to zinc protoporphyrin IX formation at optimum pH 5.5 in pork

“…When the separated soluble fractions were mixed together with insoluble fraction, ZnPP formation was rescued to a level similar to pork homogenate. Because FECH, considered to be involved in the formation of ZnPP (Becker et al., ; Benedini, Raja, & Parolari, ; Parolari, Benedini, & Toscani, ; Wakamatsu et al., ), is the terminal enzyme of the heme‐biosynthetic pathway in mitochondria, it is likely to be present in the insoluble fraction. In addition, some other insoluble components present in mitochondria, such as protoporphyrinogen oxidases, and protoporphyrinogen IX, are components in the heme‐biosynthetic pathway (Koch et al., ; Poulson, ) and might have a role in ZnPP formation.…”