Jeffrey J. Sindelar

Determining the impact of varying levels of cherry powder and starter culture on quality and sensory attributes of indirectly cured, emulsified cooked sausages

Indirect curing is a process that utilizes ingredients high in naturally occurring nitrate and a nitrate reducing bacterial starter culture (SC) to provide quality and sensory attributes similar to nitrite-added cured meats. The objective of this study was to determine the effects varying concentrations of starter culture and the addition of cherry powder (CP) had on improving quality and sensory attributes of indirectly cured sausages. Four treatments (TRTs) (TRT 1: low SC+no CP; TRT 2: low SC+CP; TRT 3: high SC+no CP; and TRT 4: high SC+CP) and a sodium nitrite-added (156 ppm) control were investigated. Residual nitrite levels throughout storage declined most rapidly in TRTs 2 and 4 (P<0.05). Few differences existed between TRTs and C for pH, objective color, or cured pigment concentrations. Consumer sensory panel scores revealed all treatment combinations were comparable (P>0.05) to the C for all sensory attributes.

Dietary nitrate and nitrite: Benefits, risks, and evolving perceptions

Consumers have an illogical relationship with nitrite (and its precursor, nitrate) in food. Despite a long history of use, nitrite was nearly banned from use in foods in the 1970s due to health concerns related to the potential for carcinogenic nitrosamine formation. Changes in meat processing methods reduced those potential risks, and nitrite continued to be used in foods. Since then, two opposing movements continue to shape how consumers view dietary nitrate and nitrite. The discovery of the profound physiological importance of nitric oxide led to the realization that dietary nitrate contributes significantly to the nitrogen reservoir for nitric oxide formation. Numerous clinical studies have also demonstrated beneficial effects from dietary nitrate consumption, especially in vascular and metabolic health. However, the latest wave of consumer sentiment against food additives, the clean-label movement, has renewed consumer fear and avoidance of preservatives, including nitrite. Education is necessary but may not be sufficient to resolve this disconnect in consumer perception.

Reducing sodium levels in frankfurters using a natural flavor enhancer

Sodium chloride (NaCl; salt) contributes to important quality and food safety properties of processed meats. However, renewed interest exists in reducing sodium in the human diet. This study investigated quality and sensory impacts associated with partial replacement and/or reduction of normally added NaCl using a natural flavor enhancer (NFE) in frankfurters. Varying levels of NFE were used with NaCl and/or potassium chloride (KCl) to comprise treatments (TRT) which investigated flake salt replacement (Phase I) and sodium reduction (Phases II and III). Phase I sensory and quality results identified a 50% replacement of NaCl with NFE as the baseline for subsequent phases. Phase II indicated that the inclusion of NFE could allow for a 20% NaCl reduction without adverse effects on quality or sensory attributes. Phase III results demonstrated that it was feasible to reduce NaCl by 35% via the inclusion of KCl in NFE containing frankfurters without major quality or sensory changes.

Identifying ingredients that delay outgrowth of Listeria monocytogenes in natural, organic, and clean-label ready-to-eat meat and poultry products.

The objective of this study was to identify ingredients that inhibit Listeria monocytogenes in natural, organic, or clean-label ready-to-eat meat and poultry products. Fourteen ingredients were screened in uncured (no-nitrate-or-nitrite-added), traditional-cured (156 ppm of purified sodium nitrite), cultured (alternative cured, natural nitrate source, and Staphylococcus carnosus), or preconverted (alternative cured, natural nitrite source) turkey slurries. Slurries were cooked, cooled, inoculated to yield 3 log CFU/ml L. monocytogenes, stored at 4°C, and tested weekly for 4 weeks. Three antimicrobial ingredients, 1.5 % vinegar-lemon-cherry powder blend, 2.5 % buffered vinegar, and 3.0 % cultured sugar-vinegar blend, were incorporated into alternative-cured ham and uncured roast beef and deli-style turkey breast. Controls included all three meat products without antimicrobial ingredients and a traditional-cured ham with 2.8 % sodium lactate-diacetate. Cooked, sliced products were inoculated with 3 log CFU/g L. monocytogenes, vacuum packed, and stored at 4 or 7°C, for up to 12 weeks. For control products without antimicrobial agents stored at 4°C, a 2-log L. monocytogenes increase was observed at 2 weeks for ham and turkey and at 4 weeks for roast beef. Growth (>1-log increase) in the sodium lactate-diacetate was delayed until week 6. Compared with the control, the addition of either vinegar-lemon-cherry powder blend or buffered vinegar delayed L. monocytogenes growth for an additional 2 weeks, while the addition of cultured sugar-vinegar blend delayed growth for an additional 4 weeks for both ham and turkey. The greatest L. monocytogenes delay was observed in roast beef containing any of the three antimicrobial ingredients, with no growth detected through 12 weeks at 4°C for all the treatments. As expected, L. monocytogenes grew substantially faster in products stored at 7°C than at 4°C. These data suggest that antimicrobial ingredients from a natural source can enhance the safety of ready-to-eat meat and poultry products, but their efficacy is improved in products containing nitrite and with lower moisture and pH.

Reducing sodium levels in frankfurters using naturally brewed soy sauce

Sodium chloride (NaCl; salt) serves important functions in processed meats, contributing to desirable quality and food safety characteristics; however, renewed interest exists in reducing sodium in the human diet despite sodium being a required component of the diet for physiological regulation. This study investigated consumer sensory and quality impacts from replacement of normally added NaCl (flake salt) with naturally brewed soy sauce (SS). Varying levels of SS were used with NaCl and/or potassium chloride (KCl) to comprise treatments (TRT) which investigated flake salt replacement (Phase I) and sodium reduction (Phases II and III). Phase I identified a 50% replacement of NaCl with SS as the baseline for subsequent phases. Phase II indicated that the inclusion of SS could allow for a 20% NaCl reduction without adverse effects on quality or sensory attributes. Phase III results demonstrated that it was feasible to reduce NaCl by 35% via the inclusion of KCl in SS containing frankfurters without major quality or sensory changes.

Comparison of the Effect of Curing Ingredients Derived from Purified and Natural Sources on Inhibition of Clostridium perfringens Outgrowth during Cooling of Deli-Style Turkey Breast.

The antimicrobial impact of purified and natural sources of both nitrite and ascorbate were evaluated against Clostridium perfringens during the postthermal processing cooling period of deli-style turkey breast. The objective of phase I was to assess comparable concentrations of nitrite (0 or 100 ppm) and ascorbate (0 or 547 ppm) from both purified and natural sources. Phase II was conducted to investigate concentrations of nitrite (50, 75, or 100 ppm) from cultured celery juice powder and ascorbate (0, 250, or 500 ppm) from cherry powder to simulate alternative curing formulations. Ground turkey breast (75% moisture, 1.2% salt, pH 6.2) treatments were inoculated with C. perfringens spores (three-strain mixture) to yield 2.5 log CFU/g. Individual 50-g portions were vacuum packaged, cooked to 71.1°C, and chilled from 54.4 to 26.7°C in 5 h and from 26.7 to 7.2°C in 10 additional hours. Triplicate samples were assayed for growth of C. perfringens at predetermined intervals by plating on tryptose-sulfite-cycloserine agar; experiments were replicated three times. In phase I, uncured, purified nitrite, and natural nitrite treatments without ascorbate had 5.3-, 4.2-, and 4.4-log increases in C. perfringens, respectively, at 15 h, but <1-log increase was observed at the end of chilling in treatments containing 100 ppm of nitrite and 547 ppm of ascorbate from either source. In phase II, 0, 50, 75, and 100 ppm of nitrite and 50 ppm of nitrite plus 250 ppm of ascorbate supported 4.5-, 3.9-, 3.5-, 2.2-, and 1.5-log increases in C. perfringens, respectively. In contrast, <1-log increase was observed after 15 h in the remaining phase II treatments supplemented with 50 ppm of nitrite and 500 ppm of ascorbate or ≥75 ppm of nitrite and ≥250 ppm of ascorbate. These results confirm that equivalent concentrations of nitrite, regardless of the source, provide similar inhibition of C. perfringens during chilling and that ascorbate enhances the antimicrobial effect of nitrite on C. perfringens at concentrations commonly used in alternative cured meats.

Validation of pepperoni process for control of Shiga toxin-producing Escherichia coli.

The objective of this study was to compare the survival of non-O157 Shiga toxin-producing Escherichia coli (STEC) with E. coli O157:H7 during pepperoni production. Pepperoni batter was inoculated with 7 log CFU/g of a seven-strain STEC mixture, including strains of serotypes O26, O45, O103, O111, O121, O145, and O157. Sausages were fermented to pH ≤4.8, heated at 53.3°C for 1 h, and dried for up to 20 days. STEC strains were enumerated at designated intervals on sorbitol MacConkey (SMAC) and Rainbow (RA) agars; enrichments were completed in modified EC (mEC) broth and nonselective tryptic soy broth (TSB). When plated on SMAC, total E. coli populations decreased 2.6 to 3.5 log after the 1-h heating step at 53.3°C, and a 4.9- to 5-log reduction was observed after 7 days of drying. RA was more sensitive in recovering survivors; log reductions on it were 1.9 to 2.6, 3.8 to 4.2, and 4.6 to 5.3 at the end of cook, and at day 7 and day 14 of drying, respectively. When numbers were less than the limit of detection by direct plating on days 14 and 20 of drying (representing a 5-log kill), no more than one of three samples in each experiment was positive by enrichment with mEC broth; however, STEC strains were recovered in TSB enrichment. Freezing the 7-day dried sausage for 2 to 3 weeks generated an additional 1- to 1.5-log kill. Confirmation by PCR revealed that O103 and O157 had the greatest survival during pepperoni productions, but all serotypes except O111 and O121 were occasionally recovered during drying. This study suggests that non-O157 STEC s trains have comparable or less ability than E. coli O157 to survive the processing steps involved in the manufacture of pepperoni. Processes suitable for control of E. coli O157 will similarly inactivate the other STEC strains tested in this study.

Validating the Inhibition of Staphylococcus aureus in Shelf-Stable, Ready-to-Eat Snack Sausages with Varying Combinations of pH and Water Activity.

Shelf-stable, ready-to-eat meat and poultry products represent a large sector of the meat snack category in the meat and poultry industry. Determining the physiochemical conditions that prevent the growth of foodborne pathogens, namely, Staphylococcus aureus postprocessing, is not entirely clear. Until recently, pH and water activity (a(w)) criteria for shelf stability has been supported from the U.S. Department of Agriculture training materials. However, concern about the source and scientific validity of these critical parameters has brought their use into question. Therefore, the objective of this study was to evaluate different combinations of pH and aw that could be used for establishing scientifically supported shelf stability criteria defined as preventing S. aureus growth postprocessing. Snack sausages were manufactured with varying pH (5.6, 5.1, and 4.7) and a(w) (0.96, 0.92, and 0.88) to achieve a total of nine treatments. The treatments were inoculated with a three-strain mixture of S. aureus, with populations measured at days 0, 7, 14, and 28 during 21 °C storage. Results revealed treatments with a pH ≤ 5.1 and a(w) ≤ 0.96 did not support the growth of S. aureus and thus could be considered shelf stable for this pathogen. The results provide validated shelf stability parameters to inhibit growth of S. aureus in meat and poultry products.

Modeling the Impact of Ingoing Sodium Nitrite, Sodium Ascorbate, and Residual Nitrite Concentrations on Growth Parameters of Listeria monocytogenes in Cooked, Cured Pork Sausage.

Sodium nitrite has been identified as a key antimicrobial ingredient to control pathogens in ready-to-eat (RTE) meat and poultry products, including Listeria monocytogenes. This study was designed to more clearly elucidate the relationship between chemical factors (ingoing nitrite, ascorbate, and residual nitrite) and L. monocytogenes growth in RTE meats. Treatments of cooked, cured pork sausage (65% moisture, 1.8% salt, pH 6.6, and water activity 0.98) were based on response surface methodology with ingoing nitrite and ascorbate concentrations as the two main factors. Concentrations of nitrite and ascorbate, including star points, ranged from 0 to 352 and 0 to 643 ppm, respectively. At one of two time points after manufacturing (days 0 and 28), half of each treatment was surface inoculated to target 3 log CFU/g of a five-strain L. monocytogenes cocktail, vacuum packaged, and stored at 7°C for up to 4 weeks. Growth of L. monocytogenes was measured twice per week, and enumerations were used to estimate lag time and growth rates for each treatment. Residual nitrite concentrations were measured on days 0, 4, 7, 14, 21, and 28, and nitrite depletion rate was estimated by using first-order kinetics. The response surface methodology was used to model L. monocytogenes lag time and growth rate based on ingoing nitrite, ascorbate, and the residual nitrite remaining at the point of inoculation. Modeling results showed that lag time was impacted by residual nitrite concentration remaining at inoculation, as well as the squared term of ingoing nitrite, whereas growth rate was affected by ingoing nitrite concentration but not by the remaining residual nitrite at the point of inoculation. Residual nitrite depletion rate was dependent upon ingoing nitrite concentration and was only slightly affected by ascorbate concentration. This study confirmed that ingoing nitrite concentration influences L. monocytogenes growth in RTE products, yet residual nitrite concentration contributes to the antimicrobial impact of nitrite as well.

Impact of Clean-Label Antimicrobials and Nitrite Derived from Natural Sources on the Outgrowth of Clostridium perfringens during Cooling of Deli-Style Turkey Breast

Organic acids and sodium nitrite have long been shown to provide antimicrobial activity during chilling of cured meat products. However, neither purified organic acids nor NaNO2 is permitted in products labeled natural and both are generally avoided in clean-label formulations; efficacy of their replacement is not well understood. Natural and clean-label antimicrobial alternatives were evaluated in both uncured and in alternative cured (a process that uses natural sources of nitrite) deli-style turkey breast to determine inhibition of Clostridium perfringens outgrowth during 15 h of chilling. Ten treatments of ground turkey breast (76% moisture, 1.2% salt) included a control and four antimicrobials: 1.0% tropical fruit extract, 0.7% dried vinegar, 1.0% cultured sugar-vinegar blend, and 2.0% lemon-vinegar blend. Each treatment was formulated without (uncured) and with nitrite (PCN; 50 ppm of NaNO2 from cultured celery juice powder). Treatments were inoculated with C. perfringens spores (three-strain mixture) to yield 2.5 log CFU/g. Individual 50-g portions were vacuum packaged, cooked to 71.1°C, and chilled from 54.4 to 26.7°C in 5 h and from 26.7 to 7.2°C in an additional 10 h. Triplicate samples were assayed for growth of C. perfringens at predetermined intervals by plating on tryptose-sulfite-cycloserine agar. Uncured control and PCN-only treatments allowed for 4.6- and 4.2-log increases at 15 h, respectively, and although all antimicrobial treatments allowed less outgrowth than uncured and PCN, the degree of inhibition varied. The 1.0% fruit extract and 1.0% cultured sugar-vinegar blend were effective at controlling populations at or below initial levels, whether or not PCN was included. Without PCN, 0.7% dried vinegar and 2.0% lemon-vinegar blend allowed for 2.0- and 2.5-log increases, respectively, and ∼1.5-log increases with PCN. Results suggest using clean-label antimicrobials can provide for safe cooling following the study parameters, and greater inhibition of C. perfringens may exist when antimicrobials are used with nitrite.