Effect of Nitrite Source & Reducing Compounds on Cured Color Development in an All-Beef Model System

Authors: Leila G. Venzor, Graduate Student and Research Technician; Grace C. Johnson, Ashley A. Hahn, Graduate Students; Benjamin L. Weinandt, Undergraduate Student; Jordan C. Wicks, Assistant Professor; Gary A. Sullivan, Associate Professor, Animal Science, Lincoln.

Summary with Implications

This study evaluated the effects of nitrite source (sodium nitrite, celery powder, beet powder) and reducing agents (none, sodium erythorbate, acerola) on cured color development, cured meat pigment formation, and residual nitrite in an all-beef emulsion as a model system for frankfurters and smoked sausage. Treatments were prepared and analyzed for color, pigment concentration, and nitrite retention. Nitrite source did not significantly affect cured pigment or residual nitrite. The inclusion of reducing compounds significantly increased cured pigment and redness in cooked samples while lowering residual nitrite. No treatment differences were found for initial raw color. These results suggest that natural nitrite sources and reductants perform comparably to synthetic options for cured color development, with reducing agents being essential for optimal cured color, regardless of their origin. 

Introduction

Sodium nitrite, sodium erythorbate and ascorbic acid, have been used as the primary curing and reducing agents or cure accelerators in cured meat products due to their importance in producing consistent cured color, flavor, as well as imparting preservative properties essential for the shelf stability and consumer appeal of cured meat products. Growing consumer trends demanding naturally derived food ingredients and cleaner labels have led to the use of ingredients from plant sources in processed meat products. Celery and beet juice, rich in nitrates, are incubated with specific bacterial starter cultures which allow the microbial conversion from nitrate to nitrite. Additionally, acerola cherry is rich in ascorbic acid, making it a natural reducing compound. Together, these dried ingredients are commonly used for alternative meat curing. More recently, other alternative plant sources have also been adopted as research into these bio actives continues to advance. Prior research has reported varying effectiveness of these alternative curing ingredients depending on their sources, composition, and interaction with natural or synthetic reducing agents. As development of these ingredients progresses, it is to be expected that efficacy does as well. Therefore, this study aimed to investigate the combined effects of nitrite source and reducing compound on cured color development, residual nitrite levels, and pigment formation using an all-beef emulsion model system. Our results provide insight into their use for natural and conventional curing strategies.

Procedure

Fresh beef top round was trimmed free of external fat and ground (3/16 in) at the Loeffel Meat Laboratory. Treatments were assigned in a 3x2 factorial arrangement to evaluate the effect of nitrite source (156 ppm nitrite or molar equivalent) [sodium nitrite, celery powder (SafePlate CP300, Wenda Ingredients, Naperville, IL), or beet powder (SafePlate BP300, Wenda Ingredients, Naperville, IL)] and addition of reducing compounds (495 ppm ascorbic acid or molar equivalent) [no reducing compound or reducing compound from either sodium erythorbate or acerola (SafePlate ACP34, Wenda Ingredients, Naperville, IL)] in a beef model system. Ground beef (680 g), salt (13.6 g), and ice (136 g) were added to a RoboCoupe food processor with respective nitrite and reducing compound treatments, chopped for 30 s, scraped, and chopped for an additional 30 s. The resulting emulsified batters were placed into five 100 mL glass beakers, pressed with a rounded spoon to remove air pockets, covered in plastic wrap, and placed in a cooler (37 °F) for 30 min. A sample of the raw batter was spread onto a flat-bottom weigh boat to measure initial raw instrumental color  (L*, a*, b*). Samples were cooked in a water bath (105 °F) for 30 min and transferred to a 176°F water bath for an additional 30 min to reach a final temperature of 175 °F. Samples were cooled in an ice water bath for 30 min and kept under refrigeration. The following day, beaker sausages were sliced into 4 medallions and cooked instrumental color was measured in triplicate. Absorbances of cured and total meat pigments were measured at 540 nm and 640 nm, respectively (Model Epoch Spectrophotometer, Biotek, Winooski, VT). Residual nitrite concentrations were measured (540 nm) using the spectrophotometric method. Three full replicates were produced. Data were analyzed as a completely randomized design using PROC GLIMMIX of SAS (version 9.4) for interactions and main effects of nitrite source and addition or absence of a reducing compound. Significance was determined at P < 0.05 and tendency was determined at 0.05 < P < 0.10. 

Results

There was no interaction of nitrite source by reducing compound (P = 0.43) for any parameter measured (Table 1). Nitrite source (P = 0.17) did not impact the development of total meat pigment, cured pigment or residual nitrite, though there was a tendency (P = 0.06) for total meat pigment to be higher with sodium nitrite (145.8 ppm) than with beet powder (123.1 ppm). Celery powder (136.9 ppm) was intermediate for total meat pigment and similar to all other treatments.  Collectively, these indicate similar cured color development regardless of nitrite source.

No significant differences (P = 0.38) were observed in initial raw color values (L*, a*, b*) for any treatments (Table 2). Treatments with reducing compounds had lower total meat pigment (P = 0.02) but higher cured (P = 0.03) and percentage of cured pigment (P < 0.001) compared to those without reducing compounds, regardless of nitrite source. Additionally, residual nitrite was lower when a reducing agent was used (P = 0.004). Use of a reducing agent significantly increased redness of final cooked color in the all-beef model system (P < 0.0001).

Conclusions

The results of this study indicate that formulas including reducing agents, regardless of nitrite source, had improved cured meat characteristics. This suggests that the nitrite sources used had a similar impact on cured color development and naturally sourced curing agents were interchangeable with synthesized sodium nitrite for color traits in an all-beef model system. Moreover, these data highlight the importance of using a reducing agent, regardless of source, to produce a higher quality cured meat product. These findings show that naturally sourced nitrite sources and reducing agents are approaching equivalence to synthetic sources for cured color traits.

Acknowledgment

Curing ingredients were provided by Wenda Ingredients, Naperville, IL. 

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