Effects of Reduction or Replacement of Sodium Chloride on Growth of Micrococcus, Moraxella and Lactobacillus Inoculated Ground Pork

Three replications each of ground pork inoculated with either a Moraxella, Micrococcus, or a Lactobacillus species were used to determine effects of reduction or replacement of NaCl on viable counts of these bacteria. Type or level of chloride salt did not affect (P > 0.05) Micrococcus counts. Likewise, Moraxella counts were not affected (P > 0.05) by type or level of chloride salt. However, with Lactobacillus as inoculum, reducing NaCl by 50% slightly increased these counts. Data suggest that reduction or replacement of NaCl influenced the development of the Lactobacillus culture but had no significant effect on the growth characteristics of the other two bacterial cultures.     

OXIDATIVE STABILITY, COOKING YIELD AND TEXTURE OF PORK TREATED WITH A LOW-SODIUM SALT

The effect of a low-sodium salt mixture (LSSM) on the characteristics of cooked ground pork was investigated. LSSM, similar to NaCl, exhibited a minor but definite prooxidative effect in the system examined. The cooking yield of meat containing 1% LSSM was 69.8% compared to 74.3% for 1% NaCl. The cooking yields of samples with 2 and 3% LSSM were similar to those containing 2 and 3% of NaCl, respectively (p > 0.05). Maximum shear force values of samples containing 1% LSSM and 1% NaCl were similar. However, the maximum shear force values of meats treated with LSSM at 2 and 3% LSSM (19.1 and 24.8 kg) were lower (P < 0.05) than those containing 2 and 3% NaCl (21.9 and 27.0 kg). Addition of LSSM or NaCl to ground pork also enhanced the cooking yield and firmness over those containing no salt. The color characteristics of cooked pork remained generally unaffected by LSSM.     

Effect of Salt Reduction on Growth of Listeria monocytogenes in Meat and Poultry Systems

Abstract: Reducing sodium in food could have an effect on food safety. The objective was to determine differences in growth of Listeria monocytogenes in meat and poultry systems with salt substitutes. For phase 1, fresh ground beef, pork, and turkey with NaCl, KCl, CaCl₂, MgCl₂, sea salt, or replacement salt added at 2.0% were inoculated with L. monocytogenes to determine growth/survival during 5 d at 4 °C to simulate a pre‐blend process. L. monocytogenes populations significantly decreased (0.41 log CFU/g) during the storage time in beef, but no differences (P > 0.05) were observed over time in pork or turkey. Salt type did not affect (P > 0.05) L. monocytogenes populations during pre‐blend storage. MgCl₂ and NaCl allowed significant growth of aerobic populations during storage. For phase 2, emulsified beef and pork products were processed with 2% NaCl, KCl, sea salt, or a NaCl/KCl blend and post‐process surface‐inoculated with L. monocytogenes to determine growth/survival at 4 °C for 28 d. Pork products showed significantly greater L. monocytogenes population growth at all sampling times (0, 7, 14, 21, and 28 d) than beef products, but salt type had no effect on L. monocytogenes populations with sampling times pooled for data analysis. Although salt types had no impact on L. monocytogenes populations in preblend and emulsified meat products, pork and turkey preblends and emulsified pork had greater L. monocytogenes populations compared with beef products. These studies demonstrate that sodium may not affect the safety of preblends and emulsified meat and poultry products. Practical Application: odium reduction in food is an important topic because of sodium's unfavorable health effects. This research shows that reducing sodium in pre‐blends and emulsified meat and poultry products would have no effect on Listeria monocytogenes populations, but replacement of NaCl with MgCl₂ may affect growth of aerobic populations.     

EFFECT OF SOLUBLE POLYLACTIC ACID DURING REFRIGERATED STORAGE OF GROUND MEATS INOCULATED WITH ESCHERICHIA COLI O157:H71

Ground beef, ground pork, and commercial breakfast sausage were inoculated (6.5 log₁₀ CFU/mL) with a five strain mixture of Escherichia coli 0157:H7 and treated either with sterile water, or 1% or 2% solutions of soluble polylactic acid (SPLA) in sterile water and stored at 4C for 1, 24, 72 and 168 h. After 168 h, 2% SPLA was significantly (p0.05) more effective than both 1% SPLA and sterile water in reducing E. coli 0157:H7 and resulted in overall reductions of 1.68, 1.70, and 1.32 log₁₀ CFU/mL for beef, pork, and pork sausage, respectively, when compared to control samples. The meat samples treated with 1% and 2% SPLA maintained significantly (p 0.05) lower pH values throughout refrigerated storage of 168 h with the higher concentration sustaining pH values from 3.83 to 3.92. Although the inhibitory effect of this acid increased with storage time, E. coli 0157:H7 survived these acidic conditions, with water activity levels ranging from 0.972 to 0.991.     

Effects of NaCl Concentration and Potassium Chloride Substitutions on the Thermal Properties and Lipid Oxidation of Dry‐Cured Pork

The thermal properties of cured meat are important for determining storage life and nutritional quality. However, few studies have focused on the thermal properties of dry‐cured pork, particularly in relation to salt level and type. In order to study the thermal properties of dry‐cured pork, we used differential scanning calorimetry (DSC) to evaluate the net heat energy (enthalpy, ΔH), onset (T_onset), and maximum (T_max) temperatures of different pork cuts salted with mixtures of chloride (NaCl and KCl) salts within the curing and ripening temperature range. Within the curing temperature range (?5 to 20 °C), the T_onset, T_max, and ΔH of cured meat treated with different NaCl : KCl mixtures were generally lower than for fresh meat, which indicates that the addition of NaCl or KCl can reduce the melting of lipids and water (especially lipids), in different pork cuts. Within the ripening temperature range (5 to 50 °C), heat absorption peaks in belly and leg cuts were between 29 and 33 °C. However, no obvious heat absorption peak was found in loin cuts. Compared to non‐KCl substitutions, a slightly higher KCl substitution could significantly (P < 0.05) enhance ΔH values of dry‐cured belly and leg cuts. The likely cause of this phenomenon is that high KCl substitutions promote lipid oxidation (r = 0.98, for belly; r = 0.95, for leg cuts). Therefore, KCl substitution should be no more than 30% (wt/wt), especially for high lipid pork, to prevent excessive melting and oxidation of lipids during the dry‐curing process.     

Comparison of Milk Mineral, Sodium Tripolyphosphate, and Vitamin E as Antioxidants in Ground Beef in 80% Oxygen Modified Atmosphere Packaging

The antioxidant effects of milk mineral (MM), sodium tripolyphosphate (STP), and vitamin E (E) were tested in raw ground beef packaged in 80% O₂ modified atmosphere packaging, and held 1, 4, 7, or 14 d at 2 °C. Two levels of each antioxidant (0.75% and 1.5% MM, 0.25% and 0.5% STP, 50 or 100 ppm E) were compared with control samples without added antioxidants. Vitamin E was mixed with mineral oil or ethanol before mixing with meat samples. Thiobarbituric acid (TBA) values were highest (P < 0.05) in controls without antioxidants, and samples with added vitamin E. Lowest TBA values (<0.5) were in samples treated with 0.75% or 1.5% milk mineral. All ground beef samples maintained redness (a* > 10) through 4 d of storage. By day 7, ground beef treatments with added E were brown. After 14 d, ground beef with 0.75% MM was more red (P < 0.05) than other treatments or controls. Thus, 0.75% MM has possible application to prolong red color stability and inhibit lipid oxidation in ground beef packaged in high oxygen atmospheres.     

Microbiological and chemical quality of ground beef treated with sodium lactate and sodium chloride during refrigerated storage

The effects of sodium lactate (NaL) and sodium chloride (NaCl), either alone (30 g/kg) or in combination (20+20 g/kg), on the microbiological and chemical quality of raw ground beef during vacuum-packaged storage at 2°C were investigated. The results showed that addition of NaL alone or in combination with NaCl significantly delayed the proliferation of aerobic plate counts, psychrotrophic counts, lactic acid bacteria and Enterobacteriaceae and extended the shelf life of the product up to 15 and 21 days, respectively, versus 8 days only for control. Over the storage time (21 days), NaL maintained the ground beef at almost constant pH, while the pH of control or NaCl-treated samples significantly decreased. Lipid oxidation (TBA value) was not affected by addition of NaL. At storage day 21 however, TBA values of both NaL-treated (0.309) and control (0.318) samples were significantly lower than those of samples treated with NaCl (0.463). The combination of NaCl with NaL significantly reduced the oxidative changes caused by NaCl (0.384 versus 0.463). Therefore, NaL alone or in combination with NaCl could be utilized successfully to reduce the microbial growth, maintain the chemical quality, and extend the shelf life of ground beef during refrigerated storage.     

Evaluation of Antioxidant Effects of Raisin Paste in Cooked Ground Beef, Pork, and Chicken

ABSTRACT:  The objective of this study was to evaluate the possible antioxidant activity of raisin paste added to raw ground beef, pork, or chicken before cooking to 163 °C. Samples were held at 2 °C for up to 14 d. TBA values were measured using a distillation method, to avoid yellow color interference found in "wet" TBA methods. Sample meat flavor intensity, rancid flavor intensity, and raisin flavor intensity were evaluated by a trained panel (n = 6). Addition of raisin paste lowered ( p < 0.05) TBA values and decreased panel scores for rancid flavor scores of all meat samples in a concentration-dependent manner. Highest antioxidant effects were obtained with a minimum of 1.5%, 2.0%, or 2.0% raisin paste in cooked ground beef, pork, or chicken, respectively. There was a high correlation (0.93, 0.94, 0.94) between TBA values and sensory rancid flavor scores in beef, pork, and chicken samples respectively. Addition of a reducing sugar (glucose) was nearly as effective as raisins for maintenance of low TBA values and rancid flavor scores, probably due to antioxidant effects of Maillard browning products. There was no detectable raisin flavor in cooked ground beef samples with added raisins. However, all meats with added glucose had a higher raisin flavor intensity score than controls, indicating that panelists associated sweetness with raisin flavor. Maillard browning (sample darkening) was evident after cooking of ground chicken with either raisins or glucose.     

Effect of Fe2+, Salt, Cooking and Shredded CoffiR on Thiobarbituric Acid (TBA) Numbers in Ground Beef

Presence of ferrous iron (Fe²⁺) and/or salt (NaCl) in ground beef followed by cooking and storage resulted in marked increases in lipid oxidation as measured by TBA values. Addition of an edible collagen film (Coffi^R) to minced fresh beef did not influence TBA values. Cooking fresh ground beef resulted in lowering of TBA values (when compared to raw beef), but TBA values increased more rapidly and to a greater extent in cooked beef than in raw samples during 7 days refrigerated storage.     

Effects of Chloride Salts on Physical, Chemical and Sensory Properties of Frankfurters

Triplicate 4.5 kg batches of frankfurters formulated with either pork/beef or mechanically deboned turkey (MDT) were made to replace all (100%) or part (35%) of the sodium chloride (NaCl) with either potassium chloride (KCl), magnesium chloride (MgCl₂) or lithium chloride (LiCl). Regardless of storage period or formulation, replacing all of the NaCl with either KCl or MgCl₂ was detrimental to flavor. This same replacement with LiCl was not detrimental to flavor in pork/beef formulations. Data suggest that MgCl₂ would not be a satisfactory substitute for NaCl in these formulations; however, replacing 35% of the NaCl with KCl may be possible. Because of its toxicity, LiCl is not GRAS-approved and we do not recommend its use but, its use in this study more closely approximated the sensory properties of NaCl than either KCl or MgCl₂.     

EFFECTS OF SESAME LIGNAN EXTRACT ON LINOLEIC ACID, LIPID OXIDATION, COLOR AND TEXTURAL PROPERTIES OF GROUND PORK, AND SAUSAGE PRODUCTS

Sesame lignan extract was prepared from roasted sesame oil and added at 0.02, 0.05, 0.10 and 0.20% (w/w) to linoleic acid and ground pork products. Cooked ground pork containing more than 0.02% of lignan extract showed TBA values lower than those containing butylated hydroxyanisole (BHA) during storage. Sausages containing 0.05% of lignan extract had lower thiobarbituric acid (TBA) values when stored at 4C for 14 days; they also showed higher CIE color values than the control meat sample (P < 0.05). There were no differences in textural properties such as hardness, cohesiveness and chewiness between the control and the sausages containing lignan extract when determined by Instron Testing Machine. Thus, lignan extract prepared from roasted sesame oils was highly antioxidative when used in cooked ground pork at > 0.02% or in sausages at > 0.05%.     

Trisodium Phosphate Treatment of Pork Carcasses

Pork skin samples, naturally contaminated or inoculated with Salmonella typhimurium, were treated with varying levels of trisodium phosphate (TSP). Aerobic plate counts (APC) of the samples were unaffected by treatment; however, S. typhimurium was reduced (P < 0.05). Using levels most effective for reducing S. typhimurium on skin, TSP was investigated for use on whole pork carcasses during slaughter/processing and did not affect APC of pork carcasses. Due to a lack of detectable presence, any effects of TSP on native Salmonella contamination of pork carcass surfaces could not be determined. TSP had negligible effect on visual pork color, texture or odor.     

EFFECT OF INOCULATION ON THE QUALITY OF DRY-CURED HAMS

Twenty paired pork legs were vacuum tumbled with cure adjuncts at 18 revolutions per minute (RPM) and 94.5 k Pa vacuum for 30 min. Following 40 days of curing, those legs from the right side were inoculated (I) with a mixed culture of microorganisms obtained from commercially cured ham and those from the left were not inoculated (C). All samples were evaluated at 56 days and 73 days for sensory traits. Water, NaCl, NO₃ and NO₂ determinations were also made. Inoculation increased (P <0.05) cured color development of uncooked samples cured for 56 days. Cure time and inoculation had no effect (P > 0.05) on juiciness or flavor. Aging increased tenderness (P <0.05), as evidenced in the samples at 73 days, and reduced the moisture content. Microbial inoculation did not accelerate the cure penetration rate and had no consistent effect on the amount of NO₃ and NO₂.     

Retardation by Glandless Cottonseed Flour of Lipid Oxidation and Discoloration in Raw Ground Beef Containing Salt

Salt (NaCl) was added to raw ground beef at levels of 0, 0.5, 1, 2 or 3% of the weight of the meat and defatted glandless cottonseed flour (GCF) was added at 0 or 3% levels. Patties were made with these mixes and stored for 3 or 6 days at 4°C or for 30 or 60 days at –20°C. Lipid oxidation (TBA values) in samples stored at 4° and –20°C and discoloration in samples stored at 4°C were determined. In samples made with salt only, TBA values within each storage period for each storage temperature increased with increasing salt levels up to 2%; increasing salt from 2 to 3% decreased TBA values. GCF markedly reduced TBA values at each salt level. Discoloration of samples stored at 4°C was also decreased by GCF.     

TBA Values, Sensory Characteristics, and Volatiles in Ground Pork During Long-term Frozen Storage: Effects of Packaging

Ground pork (30% fat) was packaged in vacuum bags (V), polyvinyl chloride film (P), Saran Wrap?(S), aluminum foil (A), or Saran?-aluminum foil combination (SA) and frozen at - 17°C for 13, 26, and 39 wk. Samples were analyzed for TBA value and pH. Volatiles were steam distilled, volatilized at 60°C, and 1 mL samples of headspace gas was analyzed using gas chromatography and mass spectrometry. Spectra for individual peaks on the total ion chromatograms were identified with spectra from known standards. Ground pork (cooked to 75°C) was evaluated by a trained sensory panel for flavor and texture. Rancid and acid odor and flavor scores and TBA values increased over time regardless of packaging treatment; however, V-packaged pork had lower scores and P-packaged had higher scores at all time periods than did that in other materials. Eighteen volatiles were identified and quantified using GC/MS; 3-hydroxy-2-butanone had the highest correlation coefficients with TBA value, odor, and flavor scores.     

Comparison of antioxidant effects of milk mineral, butylated hydroxytoluene and sodium tripolyphosphate in raw and cooked ground pork

The antioxidant effects of 0.5-2.0% milk mineral (MM) was tested in raw and cooked ground pork stored at 2?°C or -20?°C, compared to butylated hydroxytoluene (BHT) and sodium tripolyphosphate (STP). TBA numbers were low and not different between raw meat treatments. TBA numbers were lower (P<0.01) for cooked treatments with MM or STP compared to controls or treatments with BHT. Experiments were also done to determine acceptability of pork samples with various TBA values, and to determine effect of holding time before serving on TBA values. Cooked pork patties held at 71?°C for 90 or 120 min had higher (P<0.05) TBA values than patties held for 0-60 min. Thus patties could be warmed for 60 min after cooking without significantly increasing TBA number. For paired-preference sensory testing, patties were cooked and stored at 2?°C for 0, 1, 2 and 3 days to obtain TBA numbers of 0.4, 1.5, 3.4 and 3.9 respectively. Panelists preferred (P<0.001) patties with TBA number <0.5, compared to patties with TBA numbers >1.4.     

Retail Shelf-Life of Pork Dipped in Organic Acid before Modified Atmosphere or Vacuum Packaging

Modified atmosphere packaging (MAP) is increasingly popular for meat, but raw, chilled pork in vacuum or anoxic environments has a purple color. The retail shelf‐life of pork chops dipped in 500 ppm ascorbic acid, 250 ppm citric acid, or no acid dip and stored at 1 °C before simulated retail display in MAP with gas exchange or air‐permeable packaging after vacuum pouch storage was determined. The 80% N₂:20% CO₂ in MAP was exchanged with 80% O₂:20% CO₂, and chops were removed from vacuum packages and overwrapped with permeable film (VP‐PVC) on the 7th day before simulated retail display at 4 °C. Shelf‐life traits were determined at 1, 7, 8, 10, 12, and 14 d postpackaging. The pH values changed with time, but returned to post‐dipped, prepackaged levels at the end of simulated retail storage. Weight loss of chops increased (P < 0.05) in VP‐PVC compared with MAP. The a* values increased (P < 0.05) and L* and b* values decreased during simulated retail display, with higher L*, a*, and b* color values for chops in MAP than VP‐PVC. Log numbers of psychrotrophic microorganisms were higher (P < 0.05) on VP‐PVC samples than for chops in MAP on days 12 and 14. Psychrotrophic counts on ascorbic acid‐treated samples were decreased compared with citric acid or no dipping on pork during simulated retail display. Pork chops in MAP with gas exchange had lighter and redder color, increased weight retention, decreased psychrotrophic counts, and increased lipid oxidation compared with conventional vacuum and overwrap packaging systems.     

Heating and Storage Conditions Affect Survival and Recovery of Listeria monocytogenes in Ground Pork

The effect of heating rate, heating atmosphere, and meat age on survival of Listeria monocytogenes was examined in ground pork, as well as the ability of injured cells to recover during storage under air and vacuum packaging at 4 and 30°C. Significantly more survivors were observed when samples were heated at 1.3°C/min than at 8.0°C/ min. Cells inoculated into 3-month-old pork were more sensitive to heating than cells inoculated into fresh ground pork (D_62°C= 5.2 min and 7.7 min, respectively). More survivors were detected when the meat was heated aerobically than anaerobically. However, storage under vacuum at 4 or 30°C resulted in faster recovery compared with cells packaged in air. Thus, heating and packaging conditions affected ability of this pathogen to survive and recover after a heat process in pork.     

Control of lipid oxidation in cooked meats by combinations of antioxidants and chelators

The degree of oxidation in cooked meats treated with phosphates or polyphosphates and sodium ascorbate (SA) or one of its related compounds was determined using the 2-thiobarbituric acid (TBA) test. Combinations of ascorbates with a polyphosphate effectively retarded lipid oxidation in cooked pork during a 5-week storage period at refrigerator temperature. Addition of a phenolic antioxidant—butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG), tert-butylhydroquinone (TBHQ) or trihydroxybutyrophenone (THBP)—to the above mixtures did not affect the TBA numbers substantially (≤0·1 TBA unit). Ethylenediaminetetraacetic acid disodium salt (Na₂EDTA) with sodium ascorbate, with or without a phenolic antioxidant, was effective in protecting cooked pork from oxidation (TBA numbers of ≤1). Commercial antioxidant systems, Tenox A and Tenox II, were also effective in retarding meat rancidity, but Ronoxan A and Ronoxan D20 were only slightly effective.     

Survival of Listeria monocytogenes and Salmonella typhimurium and Quality Attributes of Cooked Pork Chops and Cured Ham after Irradiation

Cooked pork chops (pumped with salt/polyphosphate brine or untreated) and cured hams were inoculated with Listeria monocytogenes and Salmonella typhimurium. The samples were irradiated at low (0.75 to 0.90 kGy) or medium doses (1.8 to 2.0 kGy), and each dose was delivered at either a low (2.5 M/min conveyor speed) or high (5.4 M/min) dose rate. Low-dose irradiation reduced L. monocytogenes by more than 2 log and S. typhimurium by 1 to 3 log. Pathogen populations and total plate counts (TPC) were reduced to undetectable levels by medium doses. No meat quality attributes were affected, and no dose rate effect was observed. Nitrite reduced (P < 0.05) both pathogens and TPC during 7°C storage in ham, especially when combined with low-dose irradiation.