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. 2026 Apr 21;46(1):63. doi: 10.1007/s44463-026-00063-y

Effects of curing sources and high-pressure processing on quality attributes of smoked hams

Nadini H Gamage 1, Damon Ewasko 1, Yenling Yeh 1, Amilton S de Mello 1,✉
PMCID: PMC13100098  PMID: 42012757

Abstract

To address consumer demand for “clean label” meat products, naturally derived nitrite sources are increasingly used as alternatives to synthetic nitrite. This study assessed the effects of curing source and high-pressure processing (HPP; 85,000 psi) on the quality of smoked, sliced ham. Hams were produced by following four formulations: synthetic nitrite (CONV), celery powder plus antimicrobial (ALT), celery powder with spices (ALTSPI), and no nitrite plus spices (UNCSPI), each with or without HPP. Instrumental color, texture, moisture, and sensory attributes were evaluated over 29 days of refrigerated vacuum display. CONV and ALT hams exhibited comparable color stability, texture, and overall sensory acceptability, indicating that natural nitrite effectively preserves cured meat characteristics. UNCSPI hams showed lower redness, altered hue, reduced springiness, and inferior sensory scores, confirming nitrite’s functional necessity. HPP minimally affected color, texture, or acceptability in nitrite-containing hams but increased off-flavor in uncured formulations, likely due to lipid oxidation. These results demonstrate that naturally sourced nitrite performs equivalently to synthetic nitrite in maintaining quality and support regulatory recognition of naturally cured products. Additionally, HPP does not compromise quality in nitrite-containing RTE hams.

Keywords: Ham, Celery powder, Nitrite, Natural, High-pressure processing

Introduction

Over the past decade, substantial shifts have occurred in consumer dietary patterns across diverse socioeconomic sectors, particularly in developed nations (Aviles et al. 2020). Demand for convenience-oriented foods, including ready-to-cook (RTC) and ready-to-eat (RTE) meat products, has risen markedly due to increasingly hectic lifestyles and a general decline in interest in home cooking (Dave and Kelly 2012). Among RTE meats, sliced cured ham remains one of the most frequently consumed products in domestic settings and consistently ranks among the top five processed meat categories in the market (Zeng et al. 2019).

Nitrite is a key functional ingredient in the curing of meat products, contributing to color development, flavor stability, oxidative protection, and antimicrobial efficacy, especially against Clostridium botulinum (Mancino and Newman 2007). In recent years, however, public concerns have intensified regarding the source of nitrite used in processed meats and the manner in which regulatory agencies classify and label cured products. In the United States, manufacturers that replace synthetic sodium nitrite with vegetable-derived nitrite sources, such as celery juice powder, may label their products as “uncured” and indicate “no nitrate or nitrite added,” even though these natural ingredients undergo conversion into nitrite during processing. Although celery powder exerts antimicrobial effects and contributes to cured color like synthetic nitrite, the United States Department of Agriculture (USDA) does not recognize natural sources as equivalent curing agents. Consequently, the incorporation of natural nitrite sources into processed meats has resulted in a complex regulatory challenge, particularly when such products also bear “natural” or “organic” labeling claims.

Beyond labeling considerations, nitrite is a fundamental component for maintaining microbial stability in RTE meats. Despite undergoing lethality treatments (i.e., cooking), RTE products are susceptible to post-process contamination, particularly by Listeria monocytogenes, a pathogen of substantial public health importance (Szymczak et al. 2020). United States regulations (9 C.F.R. 430.4) mandate the application of post-lethality treatments (PLTs) to limit or suppress L. monocytogenes growth. High-pressure processing (HPP) represents an effective PLT for mitigating Listeria contamination in cured ham and other RTE meats (Pérez-Baltar et al. 2020). However, existing research indicates that HPP may alter quality characteristics, including texture, tenderness, color, and lipid stability (Fuentes et al. 2010).

Given ongoing debates about nitrite source equivalency and the growing commercial utilization of HPP, research is needed to determine whether hams formulated with natural and synthetic nitrite, or even with ingredients that simulate cured color and flavor, exhibit comparable sensory, textural, and visual attributes following HPP treatment.

The present investigation examined the effects of four curing treatments: synthetic nitrite (CONV), celery powder plus antimicrobial (ALT), celery powder with spices (ALTSPI), and no nitrite plus spices (UNCSPI), in combination with HPP or no HPP treatment on instrumental color, texture, moisture, and sensory perception. The objective was to determine whether naturally cured and uncured hams treated with ingredients that simulate cured characteristics demonstrate equivalent quality attributes to conventionally cured hams after all being treated with HPP.

Materials and methods

Fresh pork procurement and brine preparation

Fresh pork legs (IMPS 402 F; M. semimembranosus and M. adductor) were obtained from a USDA-inspected harvest facility and transported under refrigeration to a USDA-inspected manufacturer of heat-treated, shelf-stable meats. All brine preparation, injection, curing, cooking, and packaging procedures were performed at this facility in accordance with commercial protocols and USDA-FSIS regulatory guidelines.

Four brine formulations (Table 1) were developed to evaluate the effects of different curing systems. These included: (1) conventional synthetic nitrite (CONV); (2) celery powder plus MOstatin® V, a buffered vinegar antimicrobial (ALT); (3) celery powder plus spices as an alternative natural curing system (ALTSPI); and (4) no nitrite source plus spices (UNCSPI). These formulations were designed to reflect current industry trends toward naturally labeled and minimally synthetic ingredients (Calo et al. 2015). The approximate total concentration of pumped nitrite in hams cured with synthetic nitrite or celery powder was 120 ppm. Buffered vinegar MOstatin® V was included in the ALT formulation to mimic common commercial formulations that use celery powder as a curing source and to enhance flavor. Sugars, red wine, apple cider, and spices were used according to common formulations for smoked hams in North American markets. Annatto paste was used as a coloring source to mimic cured product color. Overall, the recipes were similar or identical to those used in existing commercial products found in stores labeled as cured or uncured.

Table 1.

Composition of brines used for the manufacture of hams: conventional (CONV), celery powder (ALT), celery powder plus spices (ALTSPI), uncured plus spices (UNCSPI)

Ingredients (%) Treatments
CONV ALT ALTSPI UNCSPI
Water 85.41 83.92 83.41 77.26
Sea salt 6.86 6.74 6.7 6.21
*Curing mixture (Nitrite + **sodium erythorbate) 0.57
*Celery powder (2% nitrite) 1.75 1.74
MOstatin® V 0.56
Granulated sugar 3.97 3.88
Brown sugar 3.18 3.1
Turbinado sugar 7.02 6.47
Red wine 5.39
Garlic fresh, chopped 0.78 3.59
Garlic powder 0.09
Onion powder 0.17
Apple cider 0.36
Annatto paste 0.72
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*Curing mixture and celery powder, achieving 120 ppm mg/kg of sodium nitrite

**550 ppm of sodium erythorbate

Pork legs were injected with brine to reach 115% of their green weight, held under refrigeration, and immersed in the brine for five days. Cooking was conducted in a commercial electric smoker according to FSIS compliance guidelines for the control of Trichinella and other parasitic hazards, followed by stabilization procedures for fully cooked RTE meats (USDA-FSIS. FSIS Compliance Guideline for Stabilization (Revised Appendix B) and Guideline 2021). Hams were smoked at 108 °C for 10 h until reaching an internal temperature of 71 °C. After cooking, hams were rapidly chilled to 1 °C for approximately 12 h, fabricated, and vacuum-packaged in high-barrier bags, with a thickness of 75 to 80 μm (3 mil) and oxygen transmission rate (OTR) of less than 15.5 cc/m2/24 hr. (Cryovac, Sealed Air Corporation).

High-pressure processing and sample allocation

Each curing treatment was further subdivided into HPP and no-HPP (NOHPP) groups. For instrumental color, Warner-Bratzler shear force (WBSF), and texture profile analysis (TPA), eight 2.54-cm chops were collected from each ham. One unpressurized chop was used to determine post-cook moisture. For all remaining analyses, matched HPP and NOHPP chops were used. The remaining portion of each ham was divided into two 8-cm sections for sensory analysis, again with HPP and NOHPP pairing.

Samples designated for NOHPP were immediately transported to the University of Nevada, Reno (UNR) Meat Quality Laboratory. Samples assigned to HPP were shipped to a commercial high-pressure facility in the southeastern United States and subjected to 85,000 psi (≈ 586 MPa) for 2 min at 5 °C in an AV-10 HPP system (Avure Technologies). All samples were maintained under consistent refrigeration throughout transport, processing, and storage. Laboratory and sensory analyses began nine days after production.

Retail display and instrumental color evaluation

Instrumental color was evaluated in refrigerated vacuum-packaged products. Samples were maintained in a refrigerated display case (4 °C ± 2 °C; Master-Bilt VOAM48-79). Fluorescent lights provided approximately 1614 lx illumination. Color measurements were obtained on days 1, 5, 9, 13, 17, 21, 25, and 29 after production using a HunterLab Miniscan XE Plus colorimeter (45/0°, 25-mm aperture, D65 illuminant, 2° observer). L* (lightness), a* (redness), b* (yellowness), hue angle [hue = arctan(b*/a*)], and chroma [= (a² + b²)¹/²] values were recorded from three random areas of the chop. Instrument calibration followed manufacturer instructions using vacuum-packaged standard tiles.

Texture profile analysis and Warner-Bratzler shear force

A TMS-PRO texture analyzer (Food Technology Co.) with a 100-kg load cell was used for both TPA and WBSF. For TPA, three cubes (2.54 cm²) per ham were double-compressed to 50% of their original height. Hardness, springiness, adhesiveness, cohesiveness, gumminess, and chewiness were calculated from force–time curves. For WBSF, six 1.27-cm cores parallel to muscle fibers were sheared using a V-blade (60°; 1.016-mm thickness) at 8 mm/s. Maximum load and displacement limits were set at 100 kg and 1000 mm, respectively.

Moisture content and sensory evaluation

Moisture was determined from liquid-nitrogen-pulverized samples following AOAC protocols. Sensory evaluation was approved by the University of Nevada, Reno IRB (IRB# 966040-1). Eight consumer sensory sessions were conducted, each involving 30 panelists aged 21–64. For each 8-cm ham section, thirty 16-g slices were prepared 1 h before each session, and eight samples (one from each fixed effect combination) were served per session.

Panelists scored color, odor, flavor, texture, and overall desirability on a 9-point hedonic preference scale. Off-flavor intensity was evaluated using a 9-point preference scale. Samples were coded with random 3-digit numbers and served at room temperature in randomized order under lighting of about 1,000 lx. Deionized water was provided as a palate cleanser.

Statistical analysis

The study followed a completely randomized design (CRD). Thirty-two hams were assigned to four curing treatments, and slices were subsequently split into HPP and NOHPP groups, yielding 64 samples (n = 8 per treatment combination). Curing treatment was the whole-plot factor, and HPP was the split-plot factor in a 4 × 2 factorial design. Sensory models included the panelist as a random effect. Color data (4 × 2 × 8 factorial) were analyzed as repeated measures using the best-fit covariance structure (Toeplitz) per AIC/BIC criteria. All analyses were conducted in SAS® 9.4 using the GLIMMIX procedure, with significance set at P ≤.05.

Results and discussion

All P-values for main effects and their interactions are summarized in Table 2.

Table 2.

P-values of individual fixed effects and their interactions for instrumental color, texture profile (TPA), WBSF, and sensory analysis

Treatments1
Curing HPP day Curing*HPP Curing*day HPP*day Curing*HPP*day
Instrumental color L* 0.093 0.210 < 0.001 0.974 0.583 0.440 0.861
a* < 0.001 0.779 < 0.001 0.912 < 0.001 < 0.001 0.417
b* < 0.001 0.232 < 0.001 0.964 < 0.001 < 0.001 0.404
hue < 0.001 0.844 < 0.001 0.831 < 0.001 < 0.001 0.563
Chroma < 0.001 0.591 < 0.001 0.933 < 0.001 0.006 0.460
TPA and WBSF Hardness 0.143 0.495 * 0.551 * * *
Springiness 0.033 0.741 * 0.453 * * *
Adhesiveness 0.975 0.542 * 0.973 * * *
Cohesiveness 0.194 < 0.001 * 0.478 * * *
Gumminess 0.447 0.313 * 0.415 * * *
Chewiness 0.296 0.703 * 0.630 * * *
WBSF 0.092 0.141 * 0.916 * * *
Sensory analysis Color < 0.001 0.931 * 0.118 * * *
Odor < 0.001 0.925 * 0.022 * * *
Flavor < 0.001 0.690 * 0.066 * * *
Texture < 0.001 0.596 * 0.086 * * *
Overall desirability < 0.001 0.995 * 0.078 * * *
Off-flavor < 0.001 0.633 * 0.005 * * *
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1curing = CONV, ALT, ALTSPI and UNCSPI, and; HPP = HPP and NO HPP; day (of display) = 1, 5, 9, 13, 17, 21, 25 and 29

*Not applicable, day of display effect not included in the model.

Instrumental color

No three-way interactions were detected for any color parameter. For L*, only the display-day fixed effect was significant. Lightness values measured on days 1, 5, 9, 13, 17, 21, 25, and 29 were 61.47CB, 63.13ᴬ, 62.96ᴬ, 62.89ᴬ, 61.04C, 61.34CB, and 61.76ᴮ, respectively (S.E.M. = 0.40). Overall, L* values ranged from 61 to 63, with noticeable variation primarily on days 5, 9, and 13. Sindelar et al. (Sindelar et al. 2007) similarly reported a small yet significant increase in L* across a 28-day display period. Increases in L* after HPP application are typically attributed to alterations in muscle fiber structure and potential myoglobin oxidation during pressurization. Nonetheless, these changes are generally considered to have limited practical relevance, as the human eye perceives lightness differences only across a relatively broad reflectance range.

Two-way interactions between curing treatment and display day, and between HPP and display day, were observed for all color attributes except L*. Across display days (Table 3), a* values declined slightly in all hams. The characteristic pink color of cured products is primarily stabilized by nitrosyl hemochromogen. During curing, nitric oxide reacts with myoglobin to form nitrosylmyoglobin (NO–Mb), which is subsequently converted to nitrosyl hemochromogen upon thermal denaturation (Pegg and Shahidi 1997). Heat exposure reveals the heme prosthetic group, a porphyrin ring with a central Fe2+ bound to NO, producing the typical cured pink hue. The intensity of this color depends on the proportion of NO–Mb converted to nitrosyl hemochromogen. The absence of HPP effect on color may be attributed to the short period time that the intervention was applied and the robustness of the nitrosyl hemochromogen molecule in true-cured products, since the compound usually presents some stability when pressure is applied.

Table 3.

Least square means of a*, b*, hue angle, and chroma values affected by the interaction between curing and day of display fixed effects (P-values in Table 2)

Day of display
Curing 1 5 9 13 17 21 25 29 S.E.M.
a* CONV 12.23Aa 11.77CBa 11.65Ca 11.73BCa 11.62CDa 11.87Ba 11.85Ba 11.45Da 0.25
ALT 12.24Aa 11.66Ba 11.65Ba 11.58Ba 11.64Ba 11.68Ba 11.63Ba 11.18Ca 0.22
ALTSPI 11.78Aa 11.49BCDa 11.50BCDa 11.45CDa 11.54BCDa 11.68ABCa 11.71ABa 11.33Da 0.28
UNCSPI 6.50Ab 6.38Ab 6.16Ab 5.76Bb 5.68Bb 5.78Bb 5.69Bb 5.48Bb 0.25
b* CONV 9.44Ac 8.99Bc 8.90BCc 8.94Bc 8.55DEc 8.43Ec 8.71CDc 8.03Fc 0.10
ALT 10.30Ab 9.80Bb 9.79Bb 9.72Bb 9.19Db 9.22Db 9.51Cb 8.82Eb 0.10
ALTSPI 10.30Ab 9.87Bb 9.90Bb 9.90Bb 9.61Cb 9.50Cb 9.70BCb 8.93Db 0.10
UNCSPI 16.02Aa 15.62Ba 15.64Ba 15.56Ba 14.50Ca 14.10Da 14.41Ca 13.55Ea 0.18
hue CONV 37.73Ac 37.43Ac 37.45Ac 37.40Ac 35.46Bc 35.46Cc 36.42Bc 35.15Cc 0.51
ALT 40.02Ab 40.09Ab 40.11Ab 40.09Ab 38.35Bb 38.37Bb 39.32Ab 38.36Bb 0.64
ALTSPI 41.32Ab 40.80Ab 40.85Ab 40.94Ab 39.90Bb 39.27Bb 39.75Bb 38.34Cb 0.67
UNCSPI 68.00Ba 67.80Ba 68.54Ba 69.74Aa 68.67ABa 67.76Ba 68.51Ba 67.99Ba 0.83
Chroma CONV 15.46Ab 14.82Bb 14.67BCb 14.75Bb 14.43Dbc 14.56CDb 14.72BCb 14.00E 0.24
ALT 16.00Ab 15.24Bb 15.23Bb 15.13BCb 14.84Ebc 14.90DEbc 15.04CDbc 14.26F 0.18
ALTSPI 15.67Ab 15.16Bb 15.18Bb 15.14Bb 15.03Bab 15.07Bbc 15.22Bbc 14.49C 0.25
UNCSPI 17.33Aa 16.91Ba 16.84BCa 16.61Ca 15.58Da 15.26Eac 15.52DEac 14.62F 0.20
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ABCDMeans within a row with different superscripts are statistically different

abMeans within a column with different superscripts are statistically different

S.E.M = Standard error of the mean

Color stability during display is primarily determined by oxygen and light exposure. Oxygen induces oxidation of NO–Mb and nitrosyl hemochromogen, contributing to reductions in a*. Significant declines in a* in cooked cured meats have been attributed to heme oxidation and porphyrin degradation, yielding sulfhydryl and carbonyl derivatives (Ma et al. 2017). Light exposure may further contribute to pigment degradation through peroxynitrite-mediated reactions and other free radical pathways (Møller et al. 2004), and photo-oxidation of NO–Mb may also occur via formation of a nitrosyl–dioxyl radical species (Munk et al. 2010).

In the present study, color changes over the display period were minimal because samples were stored under vacuum, mimicking standard commercial packaging conditions. Although chemical pigment changes and myoglobin oxidation were not directly evaluated, the minimal variation in a*, b*, hue angle, and chroma suggests that photo-oxidation was also negligible. Thus, any changes occurring under 30 days of vacuum display are unlikely to be perceptible to consumers.

Significant differences were observed among curing treatments. Uncured hams with spices (UNCSPI) had the lowest a* values and the highest b*, hue angle, and chroma values. Because UNCSPI hams did not receive synthetic or natural nitrites, annatto paste and red wine were added to the brine to mimic a pinkish tone. Annatto (Bixa orellana L.) contains carotenoid pigments producing yellow-orange-red colors and provides antioxidant and antimicrobial properties due to phenolic and flavonoid constituents (Martín-Sánchez et al. 2017). Although our preliminary tests suggested that this combination might approximate cured-meat color, the final concentrations applied did not yield an acceptable pink color, as determined by instrumental measurements and sensory evaluation (Table 6).

Table 6.

Color, flavor, texture, and overall desirability scores of hams cured with conventional or natural ingredients and uncured (P-values in Table 2)

Sensory attributes1 Curing Methods
CONV ALT ALTSPI UNCSPI S.E.M.
Color 7.38a 7.40a 7.19b 3.23c 0.07
Flavor 7.07a 7.04a 6.51b 4.46c 0.09
Texture 6.95ab 7.04a 6.79b 5.77c 0.09
Overall desirability 7.00a 7.10a 6.59b 4.36c 0.09
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1Hedonic scale for color, flavor, texture, and overall desirability: 9-Like extremely, 8-Like very much, 7-Like moderately, 6-Like slightly, 5-Neither like or dislike, 4-Dislike slightly, 3-Dislike moderately, 2-Dislike very much, 1-Dislike extremely

a,bMeans within rows having different superscripts are statistically different

S.E.M = Standard error of the mean

The interaction between HPP and display day is shown in Table 4. Although the interaction was statistically significant for a*, b*, hue angle, and chroma, pairwise testing (P ≤.05) revealed differences only for b* and hue angle. Hams treated with HPP exhibited higher b* values on days 21, 25, and 29, and a greater hue angle on day 29. Previous studies reported that HPP may increase pH or prevent its typical decline in meat products (Utama et al. 2017). High pressure can denature myofibrillar proteins, increase ionization, and reduce the number of free acidic groups (Ma and Ledward 2013). Changes in pH and redox potential are directly related to a* and inversely associated with hue angle. Pavli et al. (Pavli et al. 2017) documented higher pH values in HPP-treated sliced hams on days 18, 24, and 31 compared with non-treated controls. Consequently, lower a* values and narrower hue angles would typically be expected following HPP.

Table 4.

Least square means of a*, b*, hue angle, and chroma values affected by the interaction between HPP and day of display fixed effects (P-values in Table 2)

Day of display
HPP 1 5 9 13 17 21 25 29 S.E.M.
a* HPP 10.74A 10.41B 10.30BCD 10.15D 10.22CD 10.32BC 10.24CD 9.72E 0.46
NOHPP 10.63A 10.24B 10.18BC 10.10BC 10.02C 10.17BC 10.19BC 10.00C 0.49
b* HPP 11.41A 11.05B 11.05B 11.09B 10.57DC 10.47Da 10.73Ca 10.01Ea 0.45
NOHPP 11.61A 11.08B 11.05B 10.96B 10.35C 10.16Db 10.43Cb 9.65Eb 0.44
hue HPP 46.37BC 46.26BCD 46.52B 47.14A 45.77DE 45.27E 46.35BCD 45.93CDa 2.31
NOHPP 47.22A 46.80A 46.95A 46.94A 45.92B 45.15C 45.65BC 43.99Db 2.40
Chroma HPP 16.05A 15.58B 15.52B 15.45B 15.10C 15.08C 15.24C 14.35D 0.18
NOHPP 16.18A 15.49B 15.44B 15.36B 14.85C 14.80C 15.01C 14.31D 0.18
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ABCDMeans within a row with different superscripts are statistically different

abMeans within a column with different superscripts are statistically different

S.E.M = Standard error of the mean

However, in this study, a* and hue angle values were slightly higher in HPP-treated samples than in NOHPP samples. Although the magnitude of change was minimal (a maximum of 0.36 for a* and 1.94 for the hue angle), HPP may induce slight increases in these color parameters. Given the minimal variation observed, such differences are unlikely to influence product appearance during retail display. Overall, HPP had no significant effect on a*.

Texture profile, Warner–Bratzler shear force, and moisture

Effects of HPP on meat texture have been previously documented, as high pressure can alter protein conformation, induce denaturation, and promote aggregation or gelation (Sun and Holley 2010). These structural modifications may influence instrumental texture parameters and, ultimately, consumer perception. Previous work applying 87,000 psi for 3 min reported that HPP produced hams that were softer, less cohesive, less springy, and less chewy than non-HPP controls (Pietrasik et al. 2016).

In the present study, HPP-treated samples exhibited lower deformation values than NOHPP samples (P <.001; 0.38a vs. 0.34b, for NOHPP and HPP, respectively S.E.M. = 0.006), suggesting potential effects on hardness, Warner–Bratzler shear force (WBSF), and chewiness. However, no significant HPP effects were detected for these traits. Thus, the protein modifications resulting from 85,000 psi did not substantially influence instrumental or sensory texture measures (Table 2). Those minimal effects were possibly due to the post-cooking state of the hams, in which proteins were thermally denatured and do not undergo further transformation under pressure. In addition, the short 2-minute treatment led to no structural collapse in cooked products.

Uncured hams (UNCSPI) did not recover their shape as effectively as CONV and ALTSPI hams following compression (springiness values, Table 5). Because UNCSPI hams received less sodium chloride than other treatments, reduced salt-mediated protein solubilization may have contributed to these effects. As sodium chloride levels increase, scanning electron microscopy shows that fiber swelling and WHC decrease (Graiver et al. 2006); therefore, we hypothesize that lower salt levels may have affected the springiness of UNCSPI hams, as fibers could be more swollen and hold more water. Moisture content did not differ among curing treatments (P =.133; 64.98, 64.61, 63.39, and 64.82% for CONV, ALTSPI, UNCSPI, and ALT, respectively; S.E.M. = 0.51), indicating that other brine ingredients likely contributed to the reduced springiness observed in UNCSPI hams.

Table 5.

Texture Parameters (TP) and WBSF values of hams cured with conventional or natural ingredients and uncured (P-values in Table 2)

TP and WBSF Curing Methods
CONV ALT ALTSPI UNCSPI S.E.M.
Hardness (N) 169.48 137.14 160.44 156.88 9.94
Adhesiveness (J) 1.24 1.14 1.15 1.15 0.25
Springiness (m) 6.21a 5.90ab 6.28a 5.78b 0.13
Gumminess (N) 61.00 51.65 53.72 56.21 4.24
Chewiness (J) 374.56 304.05 361.49 328.01 28.32
WBSF (N) 17.64 19.35 18.81 17.35 0.63
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a,bMeans within springiness having different superscripts are statistically different

S.E.M = Standard error of the mean

Sensory analysis

Curing treatments significantly influenced color, flavor, texture, and overall desirability, while curing × HPP interactions were detected for odor and off-flavor (Table 2). Detailed sensory results are shown in Tables 6 and 7.

Table 7.

Odor and off flavor intensity scores of hams cured with conventional or natural ingredients and uncured (P-values in Table 2)

Curing Methods
CONV ALT ALTSPI UNCSPI
Odor1 S.E.M.
HPP 6.85B 7.35A 6.47C 4.09D 0.12
NOHPP 7.12A 7.03A 6.31B 4.29C
Off-flavor 2
HPP 2.43C 2.34Cb 3.10B 6.03Aa 0.15
NOHPP 2.43C 2.78Ca 3.31B 5.59Ab
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1Hedonic scale for odor: 9-Like extremely, 8-Like very much, 7-Like moderately, 6-Like slightly, 5-Neither like or dislike, 4-Dislike slightly, 3-Dislike moderately, 2-Dislike very much, 1-Dislike extremely

2Hedonic scale for off-flavor intensity: 9-extremely intense, 8-very intense, 7-moderately intense, 6-slightly intense, 5-slightly mild, 4-moderately mild, 3-very mild, 2-extremely mild, 1- no off-flavor

A,B,CMeans in rows within HPP having different superscripts are statistically different

a,bMeans in columns within curing methods for different attributes having different superscripts are statistically different

S.E.M = Standard error of the mean

As discussed previously, annatto paste and red wine failed to impart a cured-like pink color to UNCSPI hams. Consequently, panelists rated UNCSPI ham color as the least desirable, consistent with a*, b*, and hue angle values. While annatto paste and red wine provide vibrant pigments, those were not visually functional as the nitrosyl hemochromogen. Consequently, those ingredients did not generate a characteristic pink color commonly found in conventionally cured products. The cured color was not replicated possibly because Annatto provides an orange-yellow to deep brick-red tone and is prone to fading in light. Regarding red wine, the anthocyanins, which provide color, may have been oxidized during cooking. Therefore, those ingredients cannot replicate the specific “cool” rosy pink that comes from the nitrogen-iron bond of nitrites.

Flavor scores were highest for CONV and ALT hams, while ALTSPI and UNCSPI received lower ratings due to their spice-containing brines. Although spices were added to uncured formulations to emulate the tangy flavor of cured products, panelists clearly preferred the traditional cured flavor profile over seasoned alternatives. This preference strongly influenced overall desirability scores, with CONV and ALT again ranking highest. The similar rates of CONV and ALT indicate that nitrite, whether from synthetic or natural sources, leads to similar flavor and color development during processing.

MOstatin® V was included in the ALT brine formulation due to prior concerns that celery juice powder might increase pH and compromise antimicrobial efficacy. Vandewalle (VanDeWalle 2010) demonstrated that this antimicrobial had no negative impact on flavor in beef and turkey products, supporting its inclusion in ALT hams. Panelists also perceived CONV, ALTSPI, and ALT hams as having superior texture relative to UNCSPI hams.

The lower texture scores for UNCSPI hams were unexpected because only slight differences in springiness were observed instrumentally. However, undesirable flavor or aroma can influence mastication behavior, potentially reducing oral processing duration and negatively affecting texture perception. Rheological properties of foods also shape muscle activity and jaw movement during chewing (Selway and Stokes 2014, Foster et al. 2011); thus, spice combinations in ALTSPI and UNCSPI formulations may have indirectly altered perceived texture.

For odor, ALT hams were rated most desirable under both HPP and NOHPP conditions, followed by CONV, ALTSPI, and UNCSPI. Although a curing × HPP interaction was detected, no significant pairwise differences between HPP and NOHPP were observed. The interaction likely resulted from a trend (P =.060) in ALT hams, where HPP-treated samples showed slightly improved odor scores. As with flavor, undesirable odors in ALTSPI and UNCSPI hams were driven by garlic and onion additions and, for UNCSPI, the absence of nitrite.

Off-flavor intensity was highest in UNCSPI hams, followed by ALTSPI, CONV, and ALT, mirroring odor and flavor results. Within the ALT treatment, HPP reduced off-flavor intensity, consistent with Vandewalle (VanDeWalle 2010), who found that buffered vinegar improved flavor perception in restructured beef. Conversely, HPP increased off-flavor intensity in UNCSPI hams. Prior studies report that HPP pressures above 400 MPa (~ 58,000 psi) can markedly increase lipid oxidation in uncured pork (Cheah and Ledward 1996, Cheah and Ledward 1997). At the same time, nitrite inhibits oxidation by stabilizing heme iron and preventing the release of catalytic pro-oxidants (Karwowska et al. 2019). Although lipid oxidation was not measured in this study, the elevated off-flavor intensity in HPP-treated UNCSPI hams suggests that the combination of high pressure and absence of nitrite may have compromised lipid stability. The absence of HPP effect on sensory attributes may also be attributed to the fact that hams were vacuum packaged. Removing the oxygen before packaging significantly mitigates the risk of lipid and protein oxidation.

Conclusion

Hams cured with synthetic nitrite and those cured with natural nitrite sources showed equivalent sensory, textural, and visual qualities, confirming that natural nitrite performs comparably to synthetic nitrite in both product quality and antimicrobial function. In contrast, nitrite-free hams failed to develop typical cured-meat characteristics, even with added colorants and spices, highlighting nitrite’s essential functional role. High‑pressure processing (85,000 psi; ≈586 MPa) had minimal impact on the quality and acceptability of cured hams but increased off-flavors in uncured products, likely due to lipid oxidation in the absence of nitrite. In this study, lipid oxidation was not estimated. Therefore, future studies must consider estimating lipid oxidation and residual nitrite as additional parameters to correlate with flavor and color parameters. In addition, the effects of combining different nitrite sources and HPP on food safety indicators, including Listeria contamination, should also be investigated. Overall, HPP did not alter the attributes of hams cured with either synthetic or natural nitrite, and the similarity between these products suggests that the “uncured” labeling of hams made with natural nitrite sources should be reconsidered by U.S. regulatory agencies.

Author contributions

Conceptualization: de Mello AS, Ewasko D. Gamage NH, Data curation: de Mello AS, Yeh Y. Formal analysis: de Mello AS, Gamage NH. Methodology: de Mello AS, Ewasko D., Gamage NH, Yeh, Y. Software: de Mello AS. Validation: de Mello AS. Investigation: de Mello AS, Gamage NH. Writing - original draft: Yeh Y., de Mello AS. Writing - review & editing: de Mello AS Gamage NH.

Funding

This research received no external funding support.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Conflict of interest

The authors declare no competing interests.

Footnotes

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Data Availability Statement

No datasets were generated or analysed during the current study.

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