Received: 29 August 2019 Accepted for publication: 13 November 2020 Slov Vet Res 2021: 58 (2): 47 – 54 DOI 10.26873/SVR-955-2020 UDC 579.62:637.51:636.5:579.842.1/.2:547.29 Original Research Article Introduction Chicken meat is one of the important animal protein sources in human diet. However, if raw chicken meat is not properly handled and preserved, it supports the growth of spoilage bacteria and foodborne pathogens such as Salmonella spp. (1, 2). Guran et al. (3) found that Salmonella spp. prevalence in the skin of chicken drumstick, chicken breast and thighs were 41%, 44.7% and 40.9%, respectively. In Turkey, the data from National Salmonella spp. Control Program, which was conducted between 2014 and THE COMBINED EFFECT OF SODIUM LACTATE, LACTIC ACID AND ACETIC ACID ON THE SURVIVAL OF Salmonella spp. AND THE MICROBIOTA OF CHICKEN DRUMSTICKS Goran Ali Habeeb1, Halil Durmuşoğlu2, Osman İrfan İlhak3* 1Sulaimani Veterinary Directorate, Veterinary Quarantine, International Border Compound of Bashmakh, Sulaimani, Iraq, 2Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Dicle University, Diyarbakır, 3Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Balikesir University, Balikesir, Turkey *Corresponding author, E-mail: irfan.ilhak@balikesir.edu.tr Abstract: The poultry processing industry has been investigating the new decontamination applications to prevent foodborne pathogens and extend the shelf life of poultry products. This study investigates the effects of lactic acid, acetic acid and sodium lactate, alone and in combination, on the survival of Salmonella spp. and the shelf life of chicken drumsticks. The fresh chicken drumsticks were inoculated with Salmonella Typhimurium and Salmonella Enteritidis and they were divided into groups as con- trol (sterile tap water), 1% sodium lactate (SL), 1.5% lactic acid (LA), 1.5% acetic acid (AA), and their combinations. The drumstick samples were immersed into the treatment solutions for 5 minutes and stored at 4˚C for eight days, and they were analyzed for aerobic psychrotrophic bacteria (APB), Pseudomonas spp., lactic acid bacteria (LAB), Salmonella spp. and pH level. On day 5, APB, Pseudomonas spp. and LAB numbers exceeded 7.0 log 10 CFU ml-1 in the control, SL, LA and LA+ SL groups. The reduction levels of Salmonella spp. were 1.2 and 0.9 log 10 CFU ml-1 in the LA and AA+LA groups on day 0, and they were significantly different from the control group (P<0.05). The shelf life of the chicken drumsticks that were treated with the solutions containing 1.5% AA (AA, AA+ SL, AA+ LA and AA+ LA+ SL) was at least two days longer than the control group. It is concluded that the combinations of 1.5% LA, 1.5% AA and 1% SL can be used to reduce the number of Salmonella spp. and to extend the shelf life of chicken drumstick. Key words: chicken drumstick; lactic acid; acetic acid; sodium lactate; Shelf life; Salmonella spp. 2017, revealed that 47% of the carcass samples (n= 691) taken from chicken slaughterhouses were contaminated with Salmonella spp. (4). The investigations to find effective applications to control Salmonella spp. in poultry carcasses and poultry products have still been continuing. On the other hand, there is increasing concern about the use of chemical preservatives in foodstuff by consumers. More and more people prefer minimally processed foods or foods treated with organic preservatives (5). Lactic acid (LA) is one of the organic acids naturally occurring in muscles. Sodium lactate (SL) is the sodium salt of lactic acid. Acetic acid (AA), which is commonly known as vinegar, is one of the organic acids that occurs naturally during G.A. Habeeb, H. Durmuşoğlu, O.İ. İlhak48 the spoilage of fruit and certain other foods by the bacteria of the genus Acetobacter. LA, SL and AA are substances affirmed as Generally Recognized as Safe (GRAS) by the Food and Drug Administration (FDA), and they are allowed to be directly added to various foods to inhibit the microbial growth and to extend the shelf life of products (6). The antimicrobial efficacy of SL, LA and AA has been intensely studied by many researchers (7-10). However, there is limited information related to effect of organic acid blends on the shelf life of chicken meat parts and the survival of Salmonella spp. on chicken meat. Some researchers have studied the effects of various organic acid blends against the pathogenic microorganisms on poultry carcasses (11-15), and they have noted that the combinations of organic acids may improve the microbiological quality of poultry meat. In meat processing environments, the poultry meat microbiota consists mainly of Pseudomonas spp., lactic acid bacteria and many other psychrotrophic bacteria (16). There is limited information regarding the effect of organic acid blends on the microbiota in chicken meat. The aims of this study were (i) to evaluate the antimicrobial efficacy of the combination of so- dium lactate, lactic acid and acetic acid against aerobic psychrotrophic bacteria, Pseudomonas spp., lactic acid bacteria and Salmonella spp. on chicken drumstick, and (ii) to investigate the shelf life of chicken drumstick that are treated with the blends of sodium lactate, lactic acid and acetic acid. Materials and methods Samples and preparation of Salmonella spp. inoculum In each of the three trials, 36 fresh chicken drumsticks with skin (each one weighed 100 - 150 gram) were used. Their production date was one or two days before the purchase date from a local supermarket. Throughout the experiments, a to- tal of 108 chicken drumsticks were used. Because of the differences in bacterial strains against antimicrobials, one salmonella cocktail culture, which was composed of one Salmonella Enteritidis (RSKK 92 (RSKK is a microorganism culture collection center in Turkish Public Health – Turkey)) and two Salmonella Typhimurium (NCTC 12416 and NCTC 74) strains, were used. Each of the Salmonella strains was grown in 10 ml of tryp- tic soy broth (TSB, Acumedia, Maryland) at 37°C for 18 h. Cultures were then centrifuged at 4192 × g for 10 minutes at 5°C, and the supernatant was discarded. The formed pellets were re-suspended in 10 ml of 0.1% sterile peptone water, and then they were centrifuged again to remove the organic residues. The supernatant was removed and the pellets of each strain were re-suspended in 1-2 ml of 0.1% sterile peptone water. These suspensions were combined in a single tube to obtain the sal- monella cocktail, and the salmonella cocktail tube was completed to 10 ml with 0.1% sterile peptone water. Inoculation of chicken drumstick Before the inoculation procedure, two randomly selected drumstick samples were taken, and tested for the existence of indigenous Salmonella spp.. For the inoculation, the Salmonella spp. cocktail of 0.25 ml was spread on each of the drumstick samples using a sterile L-shaped spreader. After inoculation, the drumsticks were kept at room temperature for 10 minutes for bacterial attachment. Then, the two samples were taken and analyzed to detect the initial inoculation numbers of Salmonella spp. Decontamination treatments Sodium lactate solution (60% w/w) (CAS number 72-17-3), L(+) - Lactic acid solution (88-92%) (CAS number: 79-33-4), and Acetic acid (100%) (CAS number: 64-19-7) were used in this study, and they were purchased from Sigma (Sigma-Aldrich, Germany). The chicken samples in each trial were divided into eight groups. Each group of drumstick samples was dipped into a sterile glass beaker containing 500 ml of one of the following sterile decontamination solutions (v/v) at ambient temperature for 5 minutes. Decontamination solutions (treatment groups) and their pH values were as follows: 1- Control (sterile tap water), 2- 1.5% Lactic acid (pH 2.3), 3- 1.5% Acetic acid (pH 2.75), 4- 1% Sodium lactate (pH 6.96), 5- 1.5% Lactic acid + 1% Sodium lactate (pH 3.33), The combined effect of sodium lactate, lactic acid and acetic acid on the survival of Salmonella spp. and the microbiota of chicken drumsticks 49 6- 1.5% Acetic acid + 1% Sodium lactate (pH 3.72), 7- 1.5% Lactic acid + 1.5% Acetic acid (pH 2.20), 8- 1.5% Lactic acid + 1.5% Acetic acid + 1% Sodium lactate (pH 3.28) After the decontamination procedures, the chicken drumsticks were allowed to drain at room temperature for 10 minutes. After draining, each drumstick was individually placed in a separate foam plate, and it was wrapped with cling film and stored at 4°C for eight days. Microbiological analysis Microbiological analyses were carried out on days 0 (after the dipping treatment), 3, 5 and 8. Briefly, 100 ml of 0.1% sterile peptone water (PW) was added into a sterile stomacher bag containing a chicken drumstick sample, and the stomacher bag was shaken manually for one minute. Then, 1 ml of the rinse solution was taken from the stomacher bag and serially diluted up to 10-6 in sterile tubes containing 9 ml of 0.1% PW, and they were used for the following microbial analyses. Microbiological analyses were conducted by using the spread plate method and duplicate plates. Since a 1 ml rinse solution was used for microbiological analysis, the numbers of microorganisms were expressed as log10 CFU per ml rinse solution in all the samples. Plate Count Agar (Merck, Germany) was used to enumerate Aerobic Psychrotrophic Bacteria (APB), and the plates were incubated at 6.5°C for 10 days. Pseudomonas Selective Agar (Merck, Germany) supplemented with Pseudomonas CFC Selective Supplement (Merck, Germany) was used to detect Pseudomonas spp., and the plates were incubated at 25°C for 2 days. After the incubation period, three colonies from each plate were randomly selected and subjected to oxidase test (Bactident Oxidase, Merck, Germany). According to the results obtained in the oxidase test (Pseudomonas spp. is oxidase positive), the numbers of Pseudomonas spp. were calculated. Lactic acid bacteria (LAB) were enumerated using de Man Rogosa and Sharpe (MRS) Agar (LAB-M, Merck, Germany), and the plates were incubated at 28°C for 2 days. Salmonella spp. was enumerated using Xylose Lysine Deoxycholate (XLD) agar (HiMedia, India), and the plates were incubated at 35°C for 24-36 h. Determination of pH values of the samples After the microbiological analysis was completed, the pH values of the rinse solution of the samples were measured by using a pH meter (Selecta pH 2001, J.P., Spain). Statistical analysis Analyses of the microbiological data and pH values of three independent trials were carried out using SPSS 22 software (IBM, SPSS Statistics, Version 22, USA). The numbers of bacteria were converted to logarithmic values (log CFU ml-1 rinse solution) before calculating means and performing statistical analysis. The data were subjected to analysis of variance (ANOVA) appropriate to replicate × treatment groups × sampling times to determine fixed effects and interactions between variables. The Bonferroni test was used for multiple comparisons between the groups. Statistical significant level was expressed as P<0.05. Results The decontamination treatment with 1% sodium lactate (SL) did not show bacteriostatic or bacteri- cidal effect on Salmonella spp. or microbiota in the chicken drumsticks; however APB, Pseudomonas spp. and LAB counts in the groups that were treated with 1.5% lactic acid (LA), 1.5% acetic acid (AA) and their combination were lower than those in the con- trol and SL groups (Table 1). On day 0, the number of APB and Pseudomonas spp. counts in the groups that were treated with AA, AA+LA and AA+LA+SL were between 3.9 and 4.4 log10 CFU ml -1 rinse solution, and they were statistically different from the control group (5.4 log10 CFU ml -1) (P<0.05). On day 5, APB, Pseudomonas and LAB counts were below 7.0 log10 CFU ml-1 rinse solution in the groups that were treated with AA, AA+LA and AA+LA+SL, and they were significantly different from the SL and control groups (P<0.05). During the five days storage, the results showed that Pseudomonas numbers of the groups containing AA were numerically lower than the other groups that did not contain AA (Table 1). The drumstick samples in the control, SL and LA+SL groups had a bad odor and a slight slime layer on day 5. Their APB and Pseudomonas counts were above 7.2 log10 CFU ml -1 rinse solution. The control, SL and LA+SL groups were not analyzed on day 8 because of their apparent sensorial defect. G.A. Habeeb, H. Durmuşoğlu, O.İ. İlhak50 Table 1: The mean numbers of APB, Pseudomonas spp. and LAB of the drumstick samples immersed into decontamination solutions for 5 min and stored at 4ºC (log10 CFU ml -1 rinse solution ± SD) Storage days Treatment Groups 0 3 5 8 Aerobic Psychrotrophic Bacteria Control 5.4BCv ± 0.2 6.9Cw± 0.2 7.8CDx ± 0.2 NA SL 5.7Cv ± 0.1 6.9Cw ± 0.2 8.1Dx ± 0.2 NA LA 4.9ABv±0.3 6.3BCw ± 0.3 7.2ABCx ±0.1 8.2Ay ± 0.2 AA 4.4Av± 0.2 5.5Aw ± 0.5 6.8ABx ± 0.1 7.9Ay ± 0.3 LA+ SL 4.9ABv±0.1 6.4BCw ± 0.2 7.5BCDx ±0.2 NA AA+ SL 4.7ABv ± 0.1 5.8ABw ± 0.2 7.0ABCx ±0.1 8.3Ay ± 0.4 AA+ LA 4.2Av ± 0.3 5.6ABw ± 0.2 6.5Ax ± 0.1 7.8Ay ± 0.1 AA+LA+ SL 4.2Av ± 0.3 5.6ABw ± 0.1 6.6Ax ± 0.2 7.8Ay ± 0.2 Pseudomonas spp. Control 5.4BCw ± 0.4 6.8Cx ± 0.4 7.9By ± 0.4 NA SL 5.7Cw ± 0.5 6.9Cx ± 0.4 7.9By ± 0.2 NA LA 4.2Aw ± 0.2 5.6ABx ± 0.3 7.0ABy ± 0.2 7.5Ay ± 0.1 AA 3.9Aw ± 0.1 5.4ABx ± 0.4 6.4Ay ± 0.2 7.6Az ± 0.2 LA+ SL 4.7ABw ± 0.1 5.8Bx ± 0.3 7.2ABy ± 0.3 NA AA+ SL 4.0Aw ± 0.3 5.2ABx ± 0.2 6.7Ay ± 0.2 7.5Az ± 0.2 AA+ LA 4.1Av ± 0.4 5.2ABw ± 0.2 6.6Ax ± 0.17 7.3Ax ± 0.2 AA+LA+ SL 3.9Av ± 0.2 4.8Aw ± 0.1 6.2Ax ± 0.2 7.2Ay ± 0.4 Lactic Acid Bacteria Control 5.1Ax ± 0.1 6.8CDy ± 0.3 7.6Cz ± 0.2 NA SL 5.2Ax ± 0.2 7.0Dy± 0.2 7.8Cz ± 0.3 NA LA 4.7Ax ± 0.2 6.0ABCy ±0.1 7.3BCz ± 0.3 7.9Bz ± 0.1 AA 4.9Ax ± 0.1 5.5Ax ± 0.4 6.6ABy ± 0.2 7.7ABz ± 0.4 LA+ SL 5.1Ax± 0.1 6,3BCDy ±0.4 7.1ABCz± 0.4 NA AA+ SL 5.1Ax ± 0.1 5.9ABxy ±0.4 6.3Ay ± 0.1 7.4ABz ± 0.4 AA+ LA 4.9Ax ± 0.3 5.4Ax ± 0.1 6.5ABy ± 0.1 7.1AByz±0.1 AA+LA+ SL 5.0Aw ± 0.1 5.8ABwx±0.4 6.5ABxy ±0.4 7.0Ayz ± 0.5 ABC: Values with different superscripts within the same column are significantly different (P<0.05) wxyz:Values with the different superscript within the same row are significantly different (P<0.05) NA: Not analyzed SL: Sodium Lactate LA: Lactic acid AA: Acetic acid The samples which were analyzed for indigenous Salmonella spp. showed that the indigenous Salmonella spp. in the purchased drumstick samples was below the detection limit (<1 CFU ml- 1). The average inoculation level of Salmonella spp. colonies in the control samples was 5.4 log10 CFU ml -1 rinse solution (Table 2). After the decontamination treatments (on day 0), the counts of Salmonella spp. colonies of the samples reduced up to 1.2 log10 CFU ml-1 depending on the decontamination solutions when compared with the control sample (P<0.05). After day 0, the numbers of Salmonella spp. in the groups were almost stable during the storage time, and no significant differences was observed between the storage days (P>0.05). On day 5, the combination of AA+LA had the best antimicrobial efficacy on Salmonella spp. compared to the control group (P<0.05). The combined effect of sodium lactate, lactic acid and acetic acid on the survival of Salmonella spp. and the microbiota of chicken drumsticks 51 Table 2: The mean numbers of Salmonella spp. of the drumstick samples immersed into decontamination solutions for 5 min and stored at 4ºC (log10 CFU ml -1 rinse solution ± SD) Storage days Treatment Groups 0 3 5 8 Control 5.4Cx ± 0.1 5.3ABx ± 0.2 5.3Bx ± 0.1 NA SL 5.2BCx ± 0.1 5.4Bx ± 0.2 5.3Bx ± 0.1 NA LA 4.2Ax ± 0.2 4.8ABx ± 0.2 4.8ABx ± 0.3 4.6ABx ±0.1 AA 4.7ABCx± 0.2 4.9ABx ± 0.2 4.7ABx ± 0.2 4.8ABx ±0.1 LA+ SL 4.9ABCx± 0.2 4.9ABx ± 0.1 5.1ABx ± 0.1 NA AA+ SL 5.4Cx ± 0.1 5.3ABx ± 0.2 5.4Bx ± 0.1 5.1Bx± 0.2 AA+ LA 4.5ABx ± 0.1 4.6Ax ± 0.1 4.5Ax ± 0.2 4.4Ax ± 0.3 AA+LA+ SL 4.8ABCx± 0.3 4.8ABx ± 0.1 4.9ABx ± 0.2 4.8ABx ±0.1 ABC: Values with different superscripts within the same column are significantly different (P<0.05) x:Values with the same superscript within the same row are not significantly different (P>0.05) NA: Not analyzed SL: Sodium Lactate LA: Lactic acid AA: Acetic acid The initial pH of the control sample was 6.78. The pH of the samples that were treated with AA and LA decreased to 5.35 and 5.72 on day 0, respectively (Table 3), and the combination of AA and LA decreased the pH of the chicken drumstick to 5.02. Those groups were significantly different from the control and SL groups (P<0.05). However, the pH of the samples treated with organic acids, alone and in combination, dramatically increased and approached to the control group on day 3. Table 3: The mean pH values of the rinse solutions of the drumstick samples immersed into decontamination solutions for 5 min and stored at 4ºC (pH ± SD) Storage days Treatment Groups 0 3 5 8 Control 6.78Cxy± 0.1 6.67ABx±0.1 7.15ABy±0.1 NA SL 7.00Cxy± 0.1 6.87Bx± 0.2 7.33By ± 0.2 NA LA 5.72Bx± 0.1 6.53ABy±0.2 7.15ABz±0.1 7.20Az± 0.0 AA 5.35ABx±0.2 6.39ABy±0.2 6.90ABz±0.2 6.91Az± 0.2 LA+ SL 5.76Bx ± 0.3 6.68ABy±0.1 7.07ABy±0.1 NA AA+ SL 5.53ABx±0.2 6.68ABy±0.2 6.90ABy±0.1 7.02Ay± 0.1 AA+ LA 5.02Ax ± 0.1 6.27Ay± 0.2 6.72Ayz± 0.3 6.85Az± 0.1 AA+LA+SL 5.03Ax ± 0.2 6.53ABy±0.1 6.83AByz±0.1 6.79Ayz±0.1 ABC: Values with different superscripts within the same column are significantly different (P<0.05) xyz:Values with the same superscript within the same row are significantly different (P>0.05) NA: Not analyzed SL: Sodium Lactate LA: Lactic acid AA: Acetic acid Discussion Eliminating foodborne pathogens and reducing the number of microorganisms causing spoilage in poultry products are among the main goals of the poultry industry. Many researchers have reported that using solutions containing 1% to 3% organic acids have no negative effects on the sensory characteristics in poultry meat or may cause acceptable sensory changes such as insignificant differences in color and taste (7,15,17). There was no statistical difference between the LA and AA treatments in point of antibacterial effect in the present study; however, the results showed that AA was more effective than LA on the APB and Pseudomonas spp. This may be due to the concentrations of undissociated acid molecules of LA and AA. Different acids have various impacts on bacterial survival because of their different dissociation degrees. Undissociated acid molecules penetrate into the bacterial cell and show antimicrobial properties (18). International G.A. Habeeb, H. Durmuşoğlu, O.İ. İlhak52 Commission on Microbiological Specifications for Foods (ICMSF) reported that un-dissociated proportions of LA and AA at pH 5 were 6.05% and 34.9%, and at pH 6.0 were 0.64% and 5.1%, respectively (19). In this research, the pH of the samples that were treated with AA and LA are 5.35 and 5.72 on day 0, respectively (Table 3). The high efficacy of AA on the APB and Pseudomonas spp. can be attributed to the low pH of the samples, because the concentration of undissociated acid molecules of AA is greater than that of LA at the same pH (18). The drumstick samples in the control, SL and LA+ SL groups had a bad odor and slight slime layer on their skin on day 5 (Table 1). Their APB and Pseudomonas spp. counts were above 7.2 log10 CFU ml-1 rinse solution. Jay et al. (16) reported that a bad odor in chicken meat can be detected when the surface bacterial number (especially Pseudomonas spp.) is between 7.2 and 8.0 log10 CFU cm-2. As it is known, the initial bacterial load of a product has a great effect on the shelf life of the product. In this study, the initial APB counts of the control and 1% SL groups were 5.4 and 5.7 log10 CFU ml -1, respectively. Therefore, the control and 1% SL groups deteriorated before on day 5. There is limited information regarding the microbiota on chicken meat treated with organic acid blends. Zhu et al. (13) reported that the numbers of total viable bacteria and Pseudomonas spp. on the chicken drumsticks that were spray- washed with the combination of 0.5% LA+1% citric acid for 30 s were reduced 1.68 and 1.85 log10 CFU/cm2, respectively. Olaimat et al. (15) noted that the count of aerobic mesophilic bacteria on chicken breast meat that were immersed into 0.5% AA+0.5% malic acid (MA) blends for 5 minutes decreased 2 log10 CFU/g. In this study, none of the treatments showed bactericidal or bacteriostatic effects on LAB during the storage (Table 1). It was observed that LAB is more resistant to LA and AA compared to Pseudomonas spp.. In general, the groups treated with AA had a lower number of LAB than the groups treated with LA during the storage. Although there was no significant difference between the groups treated with AA, LA and their combination, it was observed that AA numerically caused more reduction in LAB compared to the LA. Olaimat et al. (15) reported that LAB counts on chicken breast meat treated with 0.5% AA for 5 min remained almost constant (approximately between 5 and 6 log10 CFU/g), and 0.5%AA+0.5% MA blends solution resulted in approximately 2 log10 CFU/g reduction by the end of 10 days of storage at 4oC. Nagel et al. (20) and Lee et al. (21) reported that it was not easy to remove Salmonella spp. from the folded areas and follicles on chicken skin. İlhak et al. (9) observed that there was no significant reduction in the number of Salmonella spp. on chicken drumstick sprayed with 2% LA for 30 sec. Ramirez-Hernandez et al. (14) used the LA+AA blend at the concentration of 2-2.5% (v/v, pH 2.8) and spray method for 15 sec on Salmonella spp. in chicken thigh, and they did not find a significant reduction in Salmonella spp. counts compared to the control group. In this study, the counts of Salmonella spp. in the samples treated with LA and AA+LA combination were reduced 1.2 and 0.9 log10 CFU ml -1 respectively (P<0.05). Mani-López et al. (8) reported that the sensitivity of bacteria to the antimicrobial effect of acetic acid, lactic acid or sodium lactate increases with a decrease in the pH level of food. On the other hand, Tan et al. (22) noted that chicken skin and chicken meat have buffering capacity against changes in pH. This buffering capacity may help the survival of Salmonella spp. in chicken meat treated with organic acids. In this study, the pH of the samples treated with organic acids was above 5 immediately after the treatments. After day 0, the pH of the samples reached above 6.0 (Table 3). The undissociated acid proportions of AA and LA are very few at pH 6.0 and above (19). The physical structure of chicken skin and the high buffering capacity of the chicken meat may have protected Salmonella spp. from the effect of organic acids (22). The reductions in the number of Salmonella spp. in the treated groups after day 0 were low. This may have been because of the protective effect of the physical structure of chicken skin and the high buffering capacity of the chicken meat and skin. However, Olaimat et al. (15) immersed chicken breast into 0.5 AA%+0.5% malic acid (MA) blends for 5 min, and they found that the acid blend resulted in more than 5.5 log10 CFU/g reduction in viable Salmonella spp. at the end of 10 days storage at 4oC. Mikolajczyk (12) noted that immersing breast meat into a solution composed of equal parts of 1% acetic acid, 1% lactic acid, and 1% tartaric acid for 15 min resulted in 2 log Most Probable Number (MPN)/ml reduction in The combined effect of sodium lactate, lactic acid and acetic acid on the survival of Salmonella spp. and the microbiota of chicken drumsticks 53 the number of Salmonella spp. after storage at 4 ºC for 6 days. When the findings of many studies regarding organic acids applications on poultry carcasses and carcass parts are examined (9, 14, 17, 20, 21), it is seen that the reducing effects of organic acids on Salmonella spp. change from insignificant level to about 2.5 log10 CFU ml-1 depending on acid concentration (1-5%), treatment time (15 sec to 20 min) and application methods (spraying, dipping). In our study, the reduction levels in the number of Salmonella spp. in the groups treated with organic acids, alone and in combined form, changed between 0 and 1.2 log10 CFU ml -1. In each experiment, two drumsticks from the chicken drumstick samples, which were purchased from a supermarket, were randomly selected and analyzed for the presence of indigenous Salmonella spp.. It is expected that chicken meats purchased from supermarkets should not contain Salmonella spp. or should contain at very low concentrations (may be less than 1 log10 CFU/g, at most 2 log10 CFU/g). In this study, the initial inoculation level of Salmonella spp. was about 5.4 log10 CFU/ ml, which was at least 2000 times higher than the numbers likely to be found on the samples. Because of that, no significant interference was expected from indigenous Salmonella spp. Conclusion Decontamination of chicken drumstick with 1% SL showed no advantage in extending the shelf life of the samples or in reduction of the number of Salmonella spp. The combination of 1% SL with 1.5% LA or 1.5% AA did not have a synergistic or additive antibacterial effect on the spoilage bacteria and Salmonella spp. when compared to LA and AA used alone. In conclusion, the shelf life of chicken drumsticks that were treated with the decontamination solutions containing AA (alone or in combination) was extended at least 2 days when compared to the control group. Salmonella spp. was relatively resistant to 1.5% AA and 1.5% LA. This was probably because of the buffering capacity of chicken skin and meat. The buffering capacity of the product should not be neglected when organic acids are used as a decontamination agent. 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Fat contributes to the buffering capacity of chicken skin and meat but enhances the vulnerability of attached Salmo- nella cells to acetic acid treatment. Food Res Int 2014; 66: 417–23. KOMBINIRANI UČINEK NATRIJEVEGA LAKTATA, MLEČNE KISLINE IN OCETNE KISLINE NA PREŽIVETJE Salmonelle spp. IN OSTALIH MIKROORGANIZMOV NA PIŠČANJIH BEDRIH G. A. Habeeb, H. Durmuşoğlu, O. İ. İlhak Izvleček: Perutninsko predelovalna industrija raziskuje nove prilagoditve za dekontaminacijo mesa, da bi preprečila prenašanje patogenih mikroorganizmov s hrano in podaljšala rok uporabnosti perutninskih izdelkov. V opisani raziskavi so avtorji proučevali učinke mlečne kisline, ocetne kisline in natrijevega laktata, samostojno ali v kombinaciji, na preživetje Salmonelle spp. in na rok uporabnosti piščančjih beder. Sveža piščančja bedra so inokulirali s Salmonello typhimurium in Salmonella enteritidis ter jih razdelili v skupine: kontrolna skupina (z dodano sterilno vodo iz vodovoda), skupina z 1% natrijevim laktatom (SL), skupina z 1,5% mlečne kisline (LA), skupina z 1,5% ocetne kisline (AA) in njihovih kombinacij. Bedra so za 5 minut potopili v raztopine za obdelavo in jih osem dni hranili pri 4° C ter jih analizirali za prisotnost aerobne psihrotrofne bakterije (APB), Pseudomonas spp., mlečnokis- linske bakterije (LAB), Salmonella spp. in pH-vrednosti. Peti dan so koncentracije APB, Pseudomonas spp. in LAB presegale 7,0 log10 CFU ml -1 v kontrolni skupini, skupini SL, LA in LA + SL. Znižanje ravni Salmonella spp. so bile 0, 1 in log10 CFU ml-1 v skupinah LA in AA + LA na dan 0 in so se bistveno razlikovale od kontrolne skupine (P <0,05). Rok uporabnosti piščančjih beder, obdelanih z raztopinami, ki vsebujejo 1,5% AA (AA, AA + SL, AA + LA in AA + LA + SL), je bil vsaj dva dni daljši od kontrolne skupine. Ugotovljeno je bilo, da lahko kombinacije 1,5% LA, 1,5% AA in 1% SL uporabimo za zmanjšanje števila Salmonella spp. in podaljšajo rok upo- rabnosti piščančjih beder. Ključne besede: piščančja bedra; mlečna kislina; ocetna kislina; natrijev laktat; rok uporabnosti; Salmonella spp.