| Parma hams | Proteolysis enhances ZnPP formation by increasing zinc availability for insertion into heme structures. | Proteolysis significantly correlates with ZnPP levels, promoting stable red coloration. | Variability in proteolysis can impact consistency in ZnPP formation. | Standardize curing processes to enhance uniform ZnPP production. | Bou et al. (2018) |
| Parma hams and pork muscles | ZnPP-Hb complexes form non-enzymatically, driven by hemoglobin dissociation. | ZnPP-Hb complexes dominated in experimental models of Parma ham, enabling natural coloration. | Strict control of pH levels and temperature is required. | Develop scalable protocols to enhance ZnPP-Hb formation for broader applications in meat processing. | Zhai et al. (2022) |
| Dry cured hams | ZnPP forms under low temperature curing conditions. | Red color formation was observed at 3°C–4°C, though slower than at warmer conditions | Slower ZnPP formation compared to warm curing processes. | Investigate low-temperature pathways for industrial scalability | Parolari et al. (2016) |
| Parma ham, Iberian ham, and nitrite-cured hams | ZnPP forms through enzymatic activity influenced by salt and nitrite levels. | Lower salt content promotes ZnPP formation, while nitrite inhibits it. | Balancing salt levels for optimal ZnPP without compromising product safety. | Develop alternative curing agents, such as natural acids or plant-derived compounds, that simultaneously enhance ZnPP formation and ensure microbial safety. | Adamsen et al. (2006) |
| Nitrite-free dry fermented sausages | ZnPP forms at pH>4.9 and increases significantly during long-term drying. | Natural red color achieved without nitrites; optimal results obtained after extended drying periods of up to 177 d. | Drying up to 177 d limits scalability and increases production costs. | Investigate alternative methods to accelerate ZnPP formation for industrial feasibility. | De Maere et al. (2016) |
| Cooked hams | ZnPP and protoporphyrin IX (PPIX) form independently and contribute to reddish color in nitrite-free products. | Demonstrated natural red color development with polyphenols achieving comparable coloration to nitrite-treated controls. | Consistency of pigment formation across production batches. | Optimize processing conditions to stabilize ZnPP and PPIX levels for consistent natural color development. | Giménez-Campillo et al. (2022) |
| Longissimus muscles | ZnPP forms through Fe-Zn substitution in myoglobin without significant degradation. | Efficient natural red color formation achieved during short-term storage (72 h). | Variability in ZnPP levels under different storage conditions. | Investigate the role of myoglobin availability in ZnPP formation pathways. | Khozroughi et al. (2017) |
| Porcine muscles | ZnPP forms at optimal pH 4.75 and 5.5, varying by muscle fiber type. | ZnPP production optimized using slow-twitch (type I) fibers in acidic pH conditions. | pH variability requires precise adjustments for consistency. | Develop methods to enhance consistent ZnPP production across different muscle types. | Wakamatsu et al. (2019) |
| Pork homogenates | ZnPP forms through parallel enzymatic and non-enzymatic pathways, inhibited by nitrite. | Highlighted key enzymatic and non-enzymatic pathways for ZnPP formation, favoring nitrite-free processing. | Inhibition by nitrite poses challenges for industrial adaptation. | Identify alternative additives to enhance ZnPP formation while ensuring product safety. | Becker et al. (2012) |
| Minced pork muscles | ZnPP formation driven by high-ZnPP forming lactic acid bacteria (LAB) under controlled fermentation. | LAB strains enhanced natural color, serving as a substitute for conventional curing agents such as nitrites. | Optimization required for diverse meat products to ensure consistent color improvement. | Evaluate LAB strains across various meat matrices to enhance scalability of ZnPP-based color enhancement. | Kauser-Ul-Alam et al. (2021) |
| Porcine and chicken organs | ZnPP forms through zinc-chelatase activity influenced by organ type and pH conditions. | Porcine liver demonstrated the highest ZnPP formation, while chicken organs showed limited capacity. | Limited ZnPP formation in specific organs such as chicken liver and spleen. | Optimization of pH, temperature, and enzyme activity for broader organ application. | Wakamatsu et al. (2015) |
| Ultrasound-treated porcine liver | Ultrasound treatment intensifies ferrochelatase (FECH) extraction, promoting ZnPP formation in liver tissues. | ZnPP production increased by 33% with ultrasound treatment compared to conventional methods. | Precise control over ultrasound intensity is required to avoid enzyme degradation. | Optimize ultrasound parameters for large-scale applications, balancing enzyme stability and process efficiency. | Abril et al. (2021) |
| Porcine liver homogenates | ZnPP formation promoted by ascorbic and acetic acids under controlled pH and temperature. | ZnPP levels significantly increased under optimal conditions (pH 4.8, 45°C, 24 h), with microbial safety maintained. | Requires precise pH and temperature control for consistent results. | Scale natural acid-based methods for commercial applications. | Llauger et al. (2023) |