Abstract
Dry cured hams were investigated for their ability to develop red color even at low temperature (3–4 °C) and in the absence of added nitrites; results were compared with those obtained from nitrite-free hams made at conventional warm maturing temperatures. Colorimetric parameters (L*, a*, b*, and hue) and concentration of the main pigments Zn protoporphyrin IX (ZnPP) and heme were measured at three stages of preparation (six, nine, and 12 months), showing that red color was successfully formed at low temperatures, though at a slower rate and less intensively than under warm conditions. Major differences in the pattern of color development were found with the two processing temperatures. While the typical features of an enzyme-dependent mechanism, with a progressive drop in enzyme activity paralleling the synthesis of Zn protoporphyrin IX, were observed at warm temperatures, the same did not occur in cold-made hams, where the enzyme activity was almost unchanged throughout the process. These results, along with data from a descriptive sensory analysis, are supportive of a non-enzymatic mechanism leading to ZnPP (hence the red color) under cold conditions, with an estimated three-month delay compared with nitrite-free hams manufactured in a warm maturing regimen.
Highlights
Nitrite as a food additive has been in the spotlight for decades because of its broad implications in meat technology, including its conflicting effects in the context of consumer health: it acts as a beneficial microbial preservative [1] and a source of potentially harmful N-nitroso compounds [2].Reviewing nitrite’s functions, Honikel [3] pointed out that with no other molecule exerting the same functions, discontinuing its addition in meats would require the combined use of several chemical and technological strategies
After Zn protoporphyrin IX was identified as the main contributor to color in nitrite-free hams [4], studies have addressed the reaction by which, in an inherently endogenous mechanism, the muscle heme undergoes a progressive substitution of zinc for iron
Estimated means from the General Linear Model (GLM) analysis of proximate composition data are reported in Table 2 for both muscles tested at four sampling times
Summary
Nitrite as a food additive has been in the spotlight for decades because of its broad implications in meat technology, including its conflicting effects in the context of consumer health: it acts as a beneficial microbial preservative [1] and a source of potentially harmful N-nitroso compounds [2]. Reviewing nitrite’s functions, Honikel [3] pointed out that with no other molecule exerting the same functions, discontinuing its addition in meats would require the combined use of several chemical and technological strategies In this respect, dried hams in the last few years have become a case study for their ability to develop red color even without nitrites, as is the case with Parma hams, traditionally prepared with sea salt only, excluding any other additives. The removed iron was proven [10] to end up in an irreversible colloidal form of Fe (III) hydroxide, making it easy for the free zinc ion to fit into the loose heme pouch This reaction would be encouraged by partial hydrolysis of the globin moiety, supported by the proteolytic muscle enzymes [11]. The resulting color properties and the potential use of the low-temperature option in the meat industry are described
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