Can nitrite-embedded packaging film induce curing reactions in meat post-thermal processing?

Abstract

Nitrite-embedded film (NEF) was evaluated for compositional, quality, and safety attributes of conventionally-cured, alternatively-cured, and nitrite-free bologna. Nitrite is a key ingredient for quality attributes (color, flavor, antioxidant) and antimicrobial protection in cured meat products. The objectives were to determine the effects of NEF following thermal processing of conventionally-cured, alternatively-cured and nitrite-free bologna for compositional characteristics including; instrumental color, cured pigment concentration and migration, residual nitrite, and lipid oxidation, quality characteristics including cured meat color, flavor, and aroma attributes, and protection against Listeria monocytogenes. For evaluation of compositional characteristics important for cured meat, instrumental color (surface and internal color during lighted and dark storage), cured pigment concentration and migration, residual nitrite, and lipid oxidation were investigated. Three bologna formulations, each packaged into two package types were produced: a conventionally cured (with sodium nitrite) control formulation vacuum-packaged in (1) conventional (CON-CF), and (2) nitrite-embedded (CON-NEF) film, a nitrite free formulation vacuum-packaged in (3) conventional (UC-CF), and (4) nitrite-embedded (UC-NEF) film, and another nitrite free formulation with an added reductant, cherry powder, which is a natural source of ascorbic acid, vacuum-packaged in (5) conventional (UCC-CF), and (6) nitrite-embedded (UCC-NEF) film. In-package and internal instrumental a* values, residual nitrite, cured pigment concentration, and cured pigment migration were significantly greater (P < 0.05) for UC-NEF and UCC-NEF compared to conventional film counterpart, UC-CF, or UCC-CF, respectively. Lipid oxidation (TBARS values) was significantly greater (P < 0.05) for UC and UCC formulation however, not different (P > 0.05) over storage time. Purge (%) was significantly lower (P < 0.05) for CF packaged formulations and increased (P < 0.05) over storage time. The added reductant in the UCC formulation increased the rate of change and degree of difference for color attributes, and residual nitrite, as well as pigment concentration and migration of color, between respective packaging films (NEF or CF), however the same differences were observed for the nitrite-free formulation (UC) without any added reductant, consequently, a reductant was not required to generate cured meat attributes when packaged in NEF. Quality characteristics of NEF following thermal processing impact on cooked bologna was evaluated in an additional three bologna formulations, each packaged into two package types were produced; a conventionally cured control formulation (with nitrite from sodium nitrite) packaged in (1) conventional (CON-CF), and (2) nitrite-embedded (CON-NEF) film, a nitrite-free formulation packaged in (3) conventional (UCC-CF), and (4) nitrite-embedded (UCC-NEF) film, and an alternatively cured formulation (nitrite from cultured celery juice powder) packaged in (5) conventional (AC-CF), and (6) nitrite-embedded (AC-NEF) film. Instrumental a* values (light and dark storage accessed at regular intervals of 7 or 14 d over 126 d of storage) and cured pigment concentration (measured at 14 d intervals over 84 d of storage) were significantly greater (P < 0.05) for UCC-NEF compared to conventional film counterpart, UCC-CF. No significant differences (P > 0.05) for lipid oxidation (TBARS values) were observed with NEF. Trained sensory panelists, who evaluated samples at 14 d intervals over 70 d of storage, found significantly greater (P < 0.05) cured aroma, cured flavor, pink color and less off-flavor for uncured bologna packaged in NEF. NEF provided comparable cured meat attributes to the control formulation that included nitrite in the formulation. To determine the effects of NEF following thermal processing towards protection against Listeria monocytogenes growth, two bologna formulations, each packaged into two package types were produced: a conventionally-cured control formulation (with nitrite from sodium nitrite) vacuum-packaged in (1) conventional (CON-CF), and (2) nitrite-embedded (CON-NEF) film, a nitrite-free formulation vacuum-packaged in (5) conventional (UCC-CF), and (6) nitrite-embedded (UCC-NEF) film. CON-NEF and UCC-NEF treatments resulted in significantly lower (P < 0.05) growth of L. monocytogenes, than CON-CF and UCC-CF. Residual nitrite was significantly greater (P < 0.05) for NEF treatments than for CF. Cured pigment migration to the product interior was significant (P < 0.05) for the UCC-NEF product.