Sanitizing effect of salts on experimentally inoculated organisms on pork carcasses

Pork forequarters procured from freshly slaughtered animals were decontaminated with hot water and inoculated with Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Yersinia enterocolitica, Listeria monocytogenes, Serratia marcescens, Pseudomonas aeruginosa and Proteus vulgaris. The forequarters were individually spray washed with 5% potassium sorbate and a combination of 5% sodium chloride and 2.5% each of sodium acetate, sodium citrate, sodium lactate and potassium sorbate solutions. The total viable count (TVC) of the treated meat samples was reduced by 0.96 and 1.31 log units by spraying with salt and salt combination respectively with marginal changes in colour and odour scores. Inoculated organisms were found to be highly sensitive to salt combination treatment as compared to potassium sorbate alone. Shelf-life of salt and salt combination treated samples was increased to 8 and 11 days as against 4 days in untreated samples. Carcass washing with salt and salt combination was found to be suitable for extension of shelf-life and improvement in the sensory and microbiological quality of meat.     

Microbial and Sensory Quality of Fresh Camel Meat Treated with Organic Acid Salts and/or Bifidobacteria

Fresh camel meat samples were treated by dipping in solutions of sodium acetate (10% w/w), potassium sorbate (1.5% w/w), sodium lactate (5% v/v of 60% solution), or trisodium citrate (1.5%w/w) alone or combined with Bifidobacterium breve cell suspension (5%) and stored at 4°C. The pH, psychrotrophs, and sensory attributes were evaluated. Sodium acetate alone or combined with bifidobacteria maintained pH level, extended microbial shelf life (>12 days) and minimized surface discoloration. Bifidobacteria cell suspension when applied alone had negligible effects on microbial and sensory attributes. However, when combined with sodium acetate or potassium sorbate, bifidobacteria exhibited an additive effect on suppressing spoilage microorganisms.     

Evaluation of the effects of sodium chloride,potassium sorbate,nisin and lysozyme on the probability of growth of Clostridium sporogenes

The aim of this study was to evaluate the combined effect of salt (sodium chloride, 0–8% w/v), sorbate (potassium sorbate, 0–4.5% w/v), nisin (0–500 ppm) and lysozyme (0–500 ppm) on the survival of Clostridium sporogenes as a non‐toxigenic surrogate of Clostridium botulinum in terms of the probability of growth by using a central composite rotatable design. The results indicated that salt and sorbate were the most effective factors in preventing the growth of Cl. sporogenes in high‐moisture (>95%) and low‐acid conditions. The probability of growth of Cl. sporogenes in broth was reduced by combinations of salt and sorbate. Nisin and lysozyme had insignificant effects on the probability of growth of Cl. sporogenes (P > 0.05). Lysozyme individually and in combination with nisin had no inhibitory effect on Cl. sporogenes. Overall, the addition of sorbate and lysozyme may allow the salt concentration to be reduced while preventing growth.     

Effect of chemical preservatives on shelf life of mushroom (Pleurotus ostreatus) cultivated on cassava peels

Short shelf life is a major impediment to the processing and distribution of mushroom. The effect of chemical preservatives on some quality attributes of mushroom during storage was investigated. Mushroom were soaked in four preservatives at two concentrations for 10 mins, packaged, stored at 4 °C for 30 days and analysed at intervals for their microbial population, colour, firmness and weight loss. Sodium benzoate (0.05%, 0.1%) lost its preservative effect on all the micro‐organisms enumerated after 3 days, and samples treated with 0.1% potassium sorbate had the lowest microbial load at the end of the storage period. Change in colour of the potassium sorbate (0.1%)‐treated sample was lower than and significantly different from the citric acid (2%, 4%)‐treated samples. The values of the firmness of the 4% citric acid preserved mushroom were significantly different (P ≤ 0.05) from other samples throughout the storage period. There was a significant negative correlation (r = ?0.807, P < 0.01) between the firmness and weight loss of the preserved mushroom. Potassium sorbate (0.1%) and citric acid (4%) extended the shelf life of mushroom for 24 days.     

Chemical sprays as a method for improvement in microbiological quality and shelf-life of fresh sheep and goat meats during refrigeration storage (5-7°C)

The shelf-life of meats from freshly slaughtered sheep and goat carcasses at 5-7?°C was extended after spraying (pressure 3 kg/cm(2)) the carcasses with solution 'B' containing potassium sorbate, sodium acetate, sodium citrate, sodium lactate each at 2.5% and sodium chloride at 5% (prepared w/v in potable water), when compared with solution 'A' (without potassium sorbate). Solution B treatment inhibited Bacillus spp. to minimum and were not detected up to sixth day. It extended the lag phase of all organisms including psychrotrophes (pseudomonads) and reduction of differential counts in sheep and goat meat were noted throughout the refrigerated storage. On sixth day (control) and seventh day (solution "A treated") meat samples developed off odour and discoloration with total viable count (TVC)>10(7) cfu/g. Solution B treated meat samples showed no spoilage at seventh or eighth day, indicating an extended shelf-life of 3 and 2 days when compared with control and solution A treated meat, respectively.     

Effect of selected generally recognized as safe preservative sprays on growth of Listeria monocytogenes on chicken luncheon meat

The ability of selected generally recognized as safe (GRAS) chemical preservatives to reduce populations or inhibit growth of Listeria monocytogenes on chicken luncheon meat was evaluated. Slices of luncheon meat were treated by evenly spraying onto their surfaces 0.2 ml of a solution of one of four preservatives (sodium benzoate, sodium propionate, potassium sorbate, and sodium diacetate) at one of three different concentrations (15, 20, or 25% [wt/vol]). Each slice was then surface inoculated with a five-strain mixture of 10(5) CFU of L. monocytogenes per ml, held at 4, 13, or 22 degrees C, and assayed for L. monocytogenes immediately after inoculation and at 3, 7, 10, and 14 days of storage. Initial reductions of L. monocytogenes populations ranged from 0.78 to 1.32 log10 CFU g(-1) at day 0 for sodium benzoate- or sodium diacetate-treated meat, whereas reductions for the sodium propionate or potassium sorbate treatments were only 0.14 to 0.36 log10 CFU g(-1). After 14 days of storage at 4 degrees C, L. monocytogenes populations on all treated slices were 1.5 to 3 log10 CFU g(-1) less than on the untreated slices. At 13 degrees C and after 14 days of storage, L. monocytogenes populations were 3.5 and 5.2 log10 CFU g(-1) less on luncheon meat slices treated with 25% sodium benzoate or 25% sodium diacetate, respectively, and ca. 2 log10 CFU g(-1) less when treated with 25% sodium propionate or 25% potassium sorbate than on untreated control slices. Only sodium diacetate was highly inhibitory to L. monocytogenes on meat slices held at 22 degrees C for 7 days or longer. Untreated luncheon meat held at 22 degrees C was visibly spoiled within 10 days, whereas there was no evidence of visible spoilage on any treated luncheon meat at 14 days of storage.     

Effect of food grade organic acids on inoculated S. aureus, L. monocytogenes, E. coli and S. Typhimurium in sheep/goat meat stored at refrigeration temperature

Sheep/goat forequarters procured from freshly slaughtered animals were decontaminated with hot water and inoculated with Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salmonella typhimurium. The forequarters were individually spray washed with 2% lactic acid and 1.5% acetic + 1.5% propionic acid combination. Total viable count (TVC) of the treated meat samples was reduced by about 0.52 and 1.16 log units with marginal changes in colour and odour scores. Inoculated organisms were found to be highly sensitive to acid combination treatment as compared to lactic acid alone. Shelf-life of acid and acid combination treated samples was increased to 8 and 11 days as against 3 days in untreated samples. Carcass washing with acid alone or acid combination was found to be suitable for extension of shelf-life and improvement in the sensory and microbiological quality of meat.     

Effect of high pressure processing on physicochemical and microbiological properties of marinated beef with reduced sodium content

High pressure processing (HPP) is one of the newer technologies that has shown great potential for manufacturing meat products with reduced sodium content. The aim of this study was to evaluate the effect of HPP applied at different levels in the inactivation of Listeria innocua and Enterococcus faecium inoculated in marinated beef (Longissimus lumborum) with reduced sodium content, as well as its influence on the physicochemical properties of the meat. Samples were inoculated with 10⁶ CFU/g of L. innocua and E. faecium, and marinated with solutions in different concentrations of NaCl (1 or 2%) and citric acid (1 or 2%) for 18 h and treated with high pressure (300, 450 or 600 MPa). Samples treated with 600 MPa were also evaluated regarding physicochemical stability after 14 days of refrigerated storage. Different marinating solutions were not sufficient to reduce initial microbial loads in the non-pressurized samples, but the combination with high pressure caused six log cycle reductions of both microorganisms. The treatment with 2% salt/2% citric acid was the most effective for each pressure considered for both bacteria. No significant changes were observed in the water activity of the samples, however samples with higher concentration of citric acid showed lower (p < 0.05) pH and lower (p < 0.05) lipid oxidation after 14 days of storage under refrigeration. Only samples treated with 600 MPa showed an increase (p < 0.05) in hardness. The results showed that HPP was able to process a safe meat product with reduced sodium concentration.Industrial relevanceThe result from this study shows the benefits of using HPP as an alternative meat processing technology to develop a meat product with reduce sodium content. Meat processed by this method have better nutritional quality and extended shelf life as compared to conventional processing. The step taken in this study will aid the meat processing industry for the development of microbiologically safe meat product with low sodium content by the application of high pressure processing.     

Effects of Potassium Sorbate, Sodium Acetate, Phosphates and Sodium Chloride Alone or in Combination on Shelf Life of Vacuum-Packaged Pork Chops

Microbiological and some physical and chemical effects of treating pork chop surfaces with sodium acid pyrophosphate, a commercial phosphate blend, potassium sorbate and phosphate/sorbate/sodium acetate solutions, with or without sodium chloride, before packaging were studied in pork chops vacuum-packaged and stored at 2–4°C for 10 weeks. All treatments containing potassium sorbate reduced (P<0.05) counts of mesophiles, psychrotrophs, EnterobacteriaCeae, facultative anaerobes, and lactobacilli. Treatment of chops with 10% phosphates/ 10% potassium sorbate solutions improved pork color and decreased purge. Potassium sorbate alone reduced microbial counts more than it did when combined with phosphates, but chops were darker and had more exudate (P<0.05). Combined use of 10% phosphates/10% potassium sorbate extended shelf life in vacuum-packaged fresh pork chops to 10 weeks at 2–4°C compared with 4 weeks for untreated pork and protected meat color.     

Optimisation of preservatives for dealcoholised red wine using a survival model for spoilage yeasts

To optimise the application of preservatives in a new commercial dealcoholised red wine (DRW), a survival model of Rhodotorula mucilaginosa and Saccharomyces cerevisiae was developed. A factorial design included three variables, each at three levels: potassium sorbate, sodium metabisulphite and dimethyl dicarbonate (0, 100 and 200 mg L^?1). DRW samples were inoculated with a cocktail of yeasts and counts were performed after 1, 2, 3, 4, 6 and 8 weeks of incubation. Logistic regression analysis was used to create survival models. Potassium sorbate and sodium metabisulphite did not show any fungicide effect alone, while the model predicts that dimethyl dicarbonate at 185 mg L^?1 has fungicide activity. The interaction of potassium sorbate and dimethyl dicarbonate was statistically significant, so both could act as synergic preservatives. The logistic model obtained was validated with a 100% of accuracy for the conditions tested. Combining use of the studied preservatives reduced the individual dose for preservation of DRW.     

Inhibitory effect of organic acid salts on spoilage flora in culture medium and cured cooked meat products under commercial manufacturing conditions

Lactobacillus curvatus, isolated from a spoiled vacuum-packaged 'pariza' type meat product, was used to inoculate modified MRS broth containing sodium lactate, sodium acetate and potassium sorbate in different concentrations, alone or in inter se combinations. Two commercial preparations (MIX 1 and MIX 2) were also used containing combinations of the above antimicrobials. Results from the preservatives addition to the culture medium showed highest antimicrobial activity in the case of the sodium lactate (2%, 3% or 4%), sodium acetate (0.5%) and potassium sorbate (0.15%) combination. Results from the preservatives addition to two types of thermally processed meats showed that sodium lactate and the combination of sodium lactate, sodium acetate and potassium sorbate were the most effective; extending the products shelf life an additional 10 days. Finally, MIX 1 and MIX 2 suppressed the lactic acid bacteria (LAB) growth in the culture medium but not in the final product.     

Effects of Potassium Sorbate Alone and in Combination with Sodium Chloride on the Growth of Salmonella typhimurium 7136

The effects of potassium sorbate alone and in combination with 2 or 3% sodium chloride (NaCl) on the growth of Salmonella typhimurium ATCC 7136 were examined. Growth studies were performed in tryptic soy brogh (adjusted to a final pH 6.3) at 22°C for 15 days and 35°C for 48 hr without shaking. A dual plating procedure was employed to monitor growth (tryptic soy agar) and development of injury in the cell population (Levine's eosine methylene blue agar + 2% NaCl + 0.05% sodium desoxycholate). The difference between these two plate counts served as a measure of the number of injured organisms. It was found that combinations of sorbate and NaCl were more effective in the inhibition of S. typhimurium than sorbate alone under the conditions and variables studied. No injury was observed in the cell population as determined by our assay procedure. The combination of 3% NaCl + 0.3% potassium sorbate was the most effective in inhibiting growth of S. typhimurium at either storage temperature.     

Effect of Nitrite and Sorbate on Total Number of Aerobic Microorganisms in Chicken White and Dark Meat Patties

The effects of nitrite, sorbate and combinations of these two ingredients plus salt on the number of aerobic microorganisms in chicken white and dark meat patties were examined. All patties were stored at 4–5°C for 12 days. Nitrite concentrations of 400 and 2500 ppm were effective in preventing bacterial growth in chicken white meat patties while 2500 ppm was required to prevent growth in dark meat. A reduction in bacterial growth (4–10 days) was demonstrated with 100 and 150 ppm nitrite in chicken white meat patties. Four hundred ppm nitrite reduced bacterial growth in dark meat patties for 6 days. In white meat patties, the use of sorbate (0.26%) in combination with nitrite (40 ppm) was as effective in reducing bacterial growth as higher concentrations of nitrite, salt (2.5%) alone or in combination with sorbate (0.26%) or nitrite (40 ppm) inhibited bacterial growth in both white and dark meat patties during the first 4–6 days of storage.     

Microbiological and Some Physical and Chemical Changes in Vacuum-Packaged Beef Steaks Treated with Combinations of Potassium Sorbate, Phosphate, Sodium Chloride and Sodium acetate

Fresh rib eye steaks were examined for microbiological, lipid oxidation, pH, color and weight changes after immersion in water or in aqueous solutions of a phosphate blend and of a mixture of potassium sorbate, phosphates, sodium chloride and sodium acetate and subsequent vacuum packaging. Keeping characteristics of steaks were monitored during 12-wk storage at 2–4°C. Mesophilic, psychrotrophic, anaerobic and facultative anaerobic bacteria and lactobacilli were strongly inhibited (P<0.05) in steaks treated with the composition that contained potassium sorbate, whereas growth of Enterobacteriaceae was suppressed (P<0.01). Compared with controls, compositions containing phosphates with or without potassium sorbate protected lipids, increased solution uptake and decreased purge in steaks without affecting meat color.     

Effect of Sodium Acid Pyrophosphate in Combination with Sodium Nitrite or Sodium Nitrite/Potassium Sorbate on Clostridium botulinum Growth and Toxin Production in Beef/Pork Frankfurter Emulsions

Combinations of sodium acid pyrophosphate (SAPP) with added sodium nitrite and/or potassium sorbate were tested at various pH levels to determine effectiveness in delaying Clostridium botulinum growth and toxin production in frankfurter emulsions. Formulations containing sodium nitrite (40 ppm), potassium sorbate (0.26%) and SAPP (0.4%) resulted in a greater delay of toxin production (12–18 days) than other combinations (6–12 days) having similar pH values. Treatments containing 0.4% SAPP appeared to be more inhibitory than their counterparts without SAPP, displaying less numbers of toxic samples during the 53-day storage period at 27°C. Aerobic mesophilic colony counts and residual nitrite data showed little difference among treatments.     

Sensory evaluation of high-moisture dried prunes preserved with sodium benzoate

Both sodium benzoate and potassium sorbate were significantly detected (P < 0.05) in prune juice at levels of 500 to 600 parts/million. Detection levels for both preservatives in high-moisture dried prunes were higher (about 800 parts/million). No significant flavour differences were found between prunes treated with similar amounts of sodium benzoate and potassium sorbate. Since it was necessary to use more sodium benzoate than potassium sorbate to preserve prunes, comparisons were made between prunes containing equally effective levels of the two preservatives. No significant flavour differences were found between prunes effectively preserved with sodium benzoate and potassium sorbate. This suggests that sodium benzoate could be used as a preservative for high-moisture dried prunes with essentially no flavour problem.     

Effect of partial replacement of potassium lactate and sodium diacetate by natural green tea and grape seed extracts and postpackaging thermal treatment on the growth of Listeria monocytogenes in hotdog model system

Low‐ (5%) and high‐fat (20%) chicken and turkey hotdogs were formulated in three groups: no antimicrobials (control), chemical preservatives (potassium lactate and sodium diacetate) alone and partial replacement of chemical preservatives by green tea (GTE) and grape seed extracts (GSE), surface inoculated (c. 10³ CFU g^?1) with Listeria monocytogenes, treated with or without heat treatment (65 °C for 104 s) to determine the growth of L. monocytogenes until spoilage (28 days). Maximum growth inhibitions (c. 2.0 CFU g^?1) were observed in the treatments having chemical preservatives and plant extracts regardless of the meat and fat type. Furthermore, plant extracts along with chemical preservatives demonstrated additional inhibitory effect on the growth of L. monocytogenes survivors in chicken hotdog samples followed by postpackaging heat treatment. Results demonstrated that natural GTE and GSE can partially replace the chemical preservatives and further enhance the antilisterial activities when combined with heat treatment.     

Organic acids and their salts as dipping solutions to control listeria monocytogenes inoculated following processing of sliced pork bologna stored at 4 degrees C in vacuum packages.

Postprocessing contamination of cured meats with Listeria monocytogenes has become a major concern for the meat processing industry and an important food safety issue. This study evaluated aqueous dipping solutions of organic acids (2.5 or 5% lactic or acetic acid) or salts (2.5 or 5% sodium acetate or sodium diacetate, 5 or 10% sodium lactate, 5% potassium sorbate or potassium benzoate) to control L. monocytogenes on sliced, vacuum-packaged bologna stored at 4 degrees C for up to 120 days. Organic acids and salts were applied by immersing (1 min) in each solution inoculated (10(2) to 10(3) CFU/cm2) slices of bologna before vacuum packaging. Growth of L. monocytogenes (PALCAM agar) on inoculated bologna slices without treatment exceeded 7 log CFU/cm2 (P < 0.05) at 20 days of storage. No significant (P > 0.05) increase in L. monocytogenes populations occurred on bologna slices treated with 2.5 or 5% acetic acid, 5% sodium diacetate, or 5% potassium benzoate from day 0 to 120. Products treated with 5% potassium sorbate and 5% lactic acid were stored for 50 and 90 days, respectively, before a significant (P < 0.05) increase in L. monocytogenes occurred. All other treatments permitted growth of the pathogen at earlier days of storage, with sodium lactate (5 or 10%) permitting growth within 20 to 35 days. Extent of bacterial growth on trypticase soy agar plus 0.6% yeast extract (TSAYE) was similar to that on PALCAM, indicating that the major part of total bacteria grown on TSAYE agar plates incubated at 30 degrees C was L. monocytogenes. Further studies are needed to evaluate organic acids and salts as dipping solutions at abusive temperatures of retail storage, to optimize their concentrations in terms of product sensory quality, and to evaluate their effects against various other types of microorganisms and on product shelf life. In addition, technologies for the commercial application of postprocessing antimicrobial solutions in meat plants need to be developed.     

Nucleotide degradation of sodium acetate and potassium sorbate dip treated and vacuum packed Black Pomfret (Parastromateus niger) and Pearlspot (Etroplus suratensis) during chill storage

Quality changes of vacuum packed Black Pomfret (Parastromateus niger) and Pearlspot (Etroplus suratensis) treated with sodium acetate and potassium sorbate, respectively, and subsequently stored in vacuum packs in ice during chill storage were evaluated by measuring the volatile base nitrogen values, K-values and sensory parameters. The effects of sodium acetate (2% w/v) and potassium sorbate (2% w/v) dip treatments on vacuum packed Black Pomfret and Pearlspot were also examined. Total volatile base nitrogen values were found to increase slowly with time, whereas the K-values were found to increase linearly with time in samples of both the species and exceeded the acceptability limit on the day of sensory rejection. The K-values, representing the ratio between the sum of inosine and hypoxanthine to the sum of all other ATP breakdown products, was found to be a more reliable method for estimation of the quality of fresh/preserved fish. Sodium acetate/potassium sorbate dip treated and vacuum packed Black Pomfret and Pearlspot exhibited lower K-values compared to untreated samples. Treated vacuum packed samples of Black Pomfret were found to be in good and acceptable condition up to 16 days whereas treated vacuum packed samples of pearlspot remained in good condition up to 15 days compared to vacuum packed and air packed samples which were acceptable only up to 10 and 8 days, respectively. The sensory characteristics correlated well with the K-values for both the species.     

Inhibition of Salmonella by Sodium Nitrite and Potassium Sorbate in Frankfurters

All beef frankfurters and beef-pork frankfurters containing various levels of sodium nitrite (0, 50, or 156 ppm) or potassium sorbate (0, 0.26, or 0.39%) alone or in combination (50 ppm nitrite + 0.26% sorbate) were prepared. Frankfurters were inoculated with nalidixic acid resistant Salmonella and incubated at 15°C and 27°C for up to 21 days. Frankfurters formulated with 50 or 156 ppm nitrite and incubated at 27°C, or 50 ppm nitrite and incubated at 15°C failed to inhibit the growth of Salmonella. Sorbate alone and sorbate in combination with 50 ppm nitrite were equally effective in inhibiting Salmonella at either temperature and were equivalent to 156 ppm nitrite in inhibiting Salmonella at 15°C.