Efficacy of pulsed light for shelf-life extension and inactivation of Listeria monocytogenes on ready-to-eat cooked meat products

Pulsed light (PL) was tested for its utility to improve the microbial quality and safety of ready-to-eat cooked meat products. Vacuum-packaged ham and bologna slices were superficially inoculated with Listeria monocytogenes and treated with 0.7, 2.1, 4.2 and 8.4 J/cm². PL treatment at 8.4 J/cm² reduced L. monocytogenes by 1.78 cfu/cm² in cooked ham and by 1.11 cfu/cm² in bologna. The effect of PL on lipid oxidation and sensory properties was also investigated. The 2-thiobarbituric acid values were very low and chromaticity parameters were within the normal values reported for cooked meat products. PL at 8.4 J/cm² did not affect the sensory quality of cooked ham, while treatments above 2.1 J/cm² negatively influenced the sensory properties of bologna. The combination of PL and vacuum packaging provided ham with an additional shelf-life extension of 30 days compared with only vacuum packaging. The shelf-life of bologna was not extended by PL.

Industrial relevance

The efficacy of pulsed light for the decontamination of surfaces offers excellent possibilities to ensure food safety and to extend shelf-life of ready-to-eat (RTE) products. The results of this study indicate that Listeria monocytogenes can be reduced by approximately 2 log cfu/cm² in RTE cooked ham and 1 log cfu/cm² in bologna using a fluence of 8.4 J/cm². This dose does not affect the sensory properties of ham and triples its shelf-life when compared with conventional RTE products. On the contrary, fluences above 2.1 J/cm² are not suitable for the treatment of bologna since sensory quality is modified.     

Impact of UV‐C Light on the Fatty Acid Profile and Oxidative Stability of Nile Tilapia (Oreochromis niloticus) Fillets

The influence of different ultraviolet (UV‐C) doses (0.103 and 0.305 J/cm²) was investigated by instrumental color parameters, pH, lipid, and protein oxidations, fatty acids (FA) composition and biogenic amines (BAs) in Nile tilapia fillets during 11 d at 4 ± 1 °C. The UV‐C treatment increased (P < 0.05) a^* values and protein oxidation in a dose‐dependent manner, and delayed (P < 0.05) the formation of BAs over the course of the storage period. L^* values and lipid oxidation were not influenced (P > 0.05) by UV‐C light. Fillets treated with a low UV‐C dose exhibited greater (P < 0.05) total polyunsaturated fatty acid (PUFA) than their untreated counterparts. Therefore, a low UV‐C dose can be recommended in tilapia fillets as an alternative processing method to control pH and BAs, as well as improve the total PUFA amount and overall nutritional quality.     

Inactivation of Escherichia coli O157:H7 and Listeria monocytogenes inoculated on raw salmon fillets by pulsed UV-light treatment

The efficacy of pulsed UV‐light to inactivate of Escherichia coli O157:H7 and Listeria monocytogenes Scott A on salmon fillets was investigated in this study by evaluating the effects of treatment times and distance from the UV strobe. The sterilization system generated 5.6 J cm^?2 per pulse at the lamp surface for an input voltage of 3800 V and three pulses per second. Skin or muscle side inoculated salmon fillet (8 cm × 1.5 cm) in a Petri dish was placed on shelf at three different distances from the UV strobe; 3, 5, and 8 cm. At each distance, the pulsed UV‐light treatment was performed for 15, 30, 45, and 60 s. For E. coli O157:H7, maximum log₁₀ reduction was 1.09 log₁₀ CFU g^?1 on muscle side at 8 cm for 60‐s treatment, whereas 0.86 log₁₀ CFU g^?1 reduction on skin at 5 cm for 30‐s treatment. For L. monocytogenes Scott A, maximum reduction was 1.02 log₁₀ CFU g^?1 at 8 cm for 60‐s treatment on skin side, whereas 0.74 log₁₀ CFU g^?1 reduction on muscle at 8 cm for 60‐s treatment. The fillet's surface temperature increased up to 100degrC within 60‐s treatment time. Therefore, some fish samples were overheated after 30 and 45 s at 3‐ and 5‐cm distances from light source, respectively, which resulted in visual colour and quality changes. Overall, this study demonstrated that about one log reduction (c. 90%) of E. coli O157:H7 or L. monocytogenes could be achieved at 60‐s treatment at 8 cm distance without affecting the quality.     

Efficacy of Neutral Electrolyzed Water,Quaternary Ammonium and Lactic Acid‐Based Solutions in Controlling Microbial Contamination of Food Cutting Boards Using a Manual Spraying Technique

Bactericidal activity of neutral electrolyzed water (NEW), quaternary ammonium (QUAT), and lactic acid‐based solutions was investigated using a manual spraying technique against Salmonella Typhimurium, Escherichia coli O157:H7, Campylobacter jejuni, Listeria monocytogenes and Staphylococcus aureus that were inoculated onto the surface of scarred polypropylene and wooden food cutting boards. Antimicrobial activity was also examined when using cutting boards in preparation of raw chopped beef, chicken tenders or salmon fillets. Viable counts of survivors were determined as log₁₀ CFU/100 cm² within 0 (untreated control), 1, 3, and 5 min of treatment at ambient temperature. Within the first minute of treatment, NEW and QUAT solutions caused more than 3 log₁₀ bacterial reductions on polypropylene surfaces whereas less than 3 log₁₀ reductions were achieved on wooden surfaces. After 5 min of treatment, more than 5 log₁₀ reductions were achieved for all bacterial strains inoculated onto polypropylene surfaces. Using NEW and QUAT solutions within 5 min reduced Gram‐negative bacteria by 4.58 to 4.85 log₁₀ compared to more than 5 log₁₀ reductions in Gram‐positive bacteria inoculated onto wooden surfaces. Lactic acid treatment was significantly less effective (P < 0.05) compared to NEW and QUAT treatments. A decline in antimicrobial effectiveness was observed (0.5 to <2 log₁₀ reductions were achieved within the first minute) when both cutting board types were used to prepare raw chopped beef, chicken tenders or salmon fillets.     

Use of Fourier transform-infrared spectroscopy to predict spoilage bacteria on aerobically stored chicken breast fillets

In this research work we explored the potential of mid infrared (MIR) spectroscopy to determine spoilage microorganism on the surface of chicken breast fillets that were kept aerobically at 5 °C for 0, 1, 2, 3, 5 and 8 days, and at 15 °C for 0, 0.5, 1, 2, 3 and 5 days. It is shown that MIR spectroscopy (4000 – 1000 cm⁻¹ range) coupled with attenuated total reflectance (ATR) accessory can be used directly on the surface of meat samples to produce fingerprints. Culture dependent methods were used to determine total viable count (TVC), Pseudomonas, Enterobacteriaceae and Brochothrix thermosphacta on chicken breast fillets at each step of the 2 kinetics. In parallel, MIR spectra were recorded. For each kinetic, partial least square discriminant analysis (PLSDA) results showed 100% of good classifications for the six investigated storage times using 4 PLS factors. PLS regression was carried out to predict the microbial counts from the MIR spectral data. Using PLS model with four factors, good correlation (R² = 0.99) and very small root mean squares error of validation (between 0.01 and 0.97 log cfu/cm²) showed a strong correlation between MIR spectral data sets and the results obtained using traditional methods.     

Gamma irradiation as a means to eliminate Listeria monocytogenes from frozen chicken meat

Cells of Listeria monocytogenes ATCC 35152 were sensitive to gamma irradiation in phosphate buffer, pH 7.00 (D₁₀, dose required for 10% survival—0.15 kGy) at 0–5°C. The cells showed higher radiation survival when irradiated under frozen condition, with a D₁₀ of 0.3 kGy. The protection offered by shrimp/chicken/kheema homogenates (100 g litre^?1) was evidenced by even higher D₁₀ values (0.5 kGy) at both 0–5°C and cryogenic temperature. Boneless chicken meat samples were artificially inoculated with L monocytogenes ATCC 35152 cells at low (5 × 10³) colony-forming unit (cfu) g^?1 and high (5 × 10⁶ cfu g^?1) concentrations and irradiated at 1, 3, 4, 6 kGy doses under cryogenic conditions. The efficacy of the radiation process was evaluated by detecting L monocytogenes during storage at 2–4°C in the irradiated samples. These studies, when repeated with three other serotypes of L monocytogenes, clearly suggested the need for a dose of 3 kGy for elimination of 10³ cfu cells of L monocytogenes g^?1 from air-packed frozen chicken meat.     

Synchronous front-face fluorescence spectroscopy as a promising tool for the rapid determination of spoilage bacteria on chicken breast fillet

In this work the potential of synchronous front-face fluorescence spectroscopy along chemometric methods was investigated for the determination of microbial load on chicken breast fillets stored aerobically at 5 °C during 0, 1, 2, 3, 5 and 8 days, and 15 °C for 0, 0.5, 1, 2, 3 and 5 days. Total viable count (TVC), Pseudomonas, Enterobacteriaceae and Brochothrix thermosphacta were determined on chicken breast fillets at each step of the 2 kinetics using culture dependent methods. Initial TVC was 3.4 log cfu/cm² and TVC reached 8.4 log cfu/cm² and 8.3 log cfu/cm² following 8 days at 5 °C and 2 days at 15 °C, respectively. In parallel, synchronous fluorescence spectra were recorded in an excitation wavelength range of 250-500 nm using offsets of 20, 40, 60,…, 180 nm between excitation and emission monochromators. PARAFAC (parallel factor) analysis allowed to capture the changes occurring in the synchronous fluorescence spectral data. The best PARAFAC models showed 3 and 2 components for kinetics recorded at 5 and 15 °C, respectively. PLSDA (partial least square discriminant analysis) was carried out to test the reallocation of the spectra of the individual samples within the six groups corresponding to the six investigated storage times and the results showed that 100% of good classifications were obtained using 4 PLS factors. Finally, N-PLS regression was used to predict the microbial counts for TVC, Pseudomonas, Enterobacteriaceae and B. thermosphacta from the spectral data. Good average recoveries of 100 to 102%, excellent correlations (R² = 0.99) and very small root mean squares errors (between 0.1 and 0.2 log cfu/cm²) of prediction were obtained from the spectral data sets recorded on samples stored at 5 °C and 15 °C for TVC, Pseudomonas, Enterobacteriaceae and B. thermosphacta.     

Bacterial inactivation and quality changes of fresh‐cut avocados as affected by intense light pulses of specific spectra

Intense light pulses (ILP) treatments have good prospects for becoming an alternative to traditional thermal methods for decontamination of food surfaces. The aim of this work was to evaluate which ranges of the light spectrum are responsible for bacterial inactivation and their effect on the quality of fresh‐cut avocado. Results show that the effectiveness of ILP treatment decreases when the ultraviolet (UV) spectral region is blocked (particularly UV‐C). ILP treatments without UV‐C light (305–1100 nm) and an overall fluence of 10.68 J cm^?2 caused reductions of 2.47 and 1.35 log CFU g^?1 in the initial counts of inoculated Escherichia coli and Listeria innocua, respectively, in comparison with those treated using only VIS–NIR light (0.83 and 0.68 log CFU g^?1, respectively). Treatments applying light of a wavelength between 305 and 1100 nm had a more pronounced impact on colour, texture and headspace gas composition than treatments that did not contain UV light (400–1100 nm).     

Effect of dietary supplementation with vitamin E on characteristics of vacuum‐packed lamb

The effect of dietary vitamin E supplementation on lamb during vacuum‐packed storage was studied. Thirty‐six weaned male Manchego breed lambs were offered four dietary treatments (20, 270, 520 and 1020 mg vitamin E kg^?1 feed). Lambs were fed the vitamin E‐supplemented diet from 13 until 26 kg live weight. Pieces of M. longissimus dorsi were stored under vacuum at 2 ± 1 °C in the dark and meat quality was assessed after 5, 14 and 28 days of storage. Dietary supplementation significantly increased the α‐tocopherol concentration in the muscle (P < 0.001). Initially, lipid oxidation, meat colour and bacterial load were similar in all groups. In meat of non‐supplemented lambs the thiobarbituric acid reactive substance value increased throughout storage, whereas in meat of supplemented lambs it did not increase. Meat pigments and discolouration proportion were significantly affected by storage time (P < 0.001). The bacterial load was low initially, but after 28 days of storage it was close to 7 log₁₀ colony‐forming units (cfu) cm^?2 and Enterobacteriaceae surpassed the limit of acceptability of 2.5 log₁₀ cfu cm^?2, making the lamb unsuitable for human consumption. Meat of supplemented lambs displayed less lipid oxidation than that of their non‐supplemented counterparts, while meat colour and bacterial load were not affected by supplementation. Copyright © 2007 Society of Chemical Industry     

Reduction ofEscherichia coliandSalmonella senftenbergon pork skin and pork muscle using ultraviolet light

The objective of this study was to evaluate the effect of ultraviolet (UV) light on the reduction ofEscherichia coliandSalmonella senftenberg. Microbial reduction was measured by determining total reduction and inactivation rates of surviving bacteria after exposure to different UV treatments. Surfaces of tryptic soy agar, pork skin and pork muscle were inoculated with eitherE. coliorS. senftenbergand exposed to 20, 50, 80, 100, 500 and 1000 microwatts per square centimeter (μW cm⁻²) of UV light. On the agar surface after 120 s, a >5-log reduction ofE. colion agar was obtained at intensities of 100μW cm⁻²or greater and, after 960 s, a >7-log reduction was observed at intensities of 80μW cm⁻²or greater forS. senftenberg. For fresh pork muscle and after 1920-s exposure, greatest logarithmic reductions (P<0.05) were achieved at intensities of 100μW cm⁻²or greater forE. coliand at intensities of 80μW cm⁻²or greater forS. senftenbergwhere a 1.5- and 2-log reduction was observed, respectively. For pork skin exposed at 1920 s, maximum logarithmic reductions forS. senftenbergwere observed at intensities of 100μW cm⁻². However, greatest logarithmic reduction ofE. colion pork skin was not observed until UV intensity reached 1000μW cm⁻². After exposure to 100μW cm⁻², UV D-values forE. coliwere 1370 s for pork muscle, 1282 s for pork skin, and 242 s for agar. WhenS. senftenbergwas exposed to 100μW cm⁻², UV D-values were 1163 s for pork muscle, 595 s for pork skin, and 15 s for agar. When surfaces were inoculated withE. coliand exposed to 1000μW cm⁻², UV D-values on muscle, pork skin and agar surfaces were 1205 s, 592 s, and 177 s, respectively. When surfaces inoculated withS. seftenbergwere exposed to 1000μW cm⁻², UV D-values were 1064 s, 490 s, and 21 s on muscle, skin and agar, respectively, In all cases,E. coliappeared to be more resistant to UV treatment compared toS. senftenberg. This study demonstrates that UV light can be used to reduce certain pathogens on pork meat surfaces. More research is needed to determine the antimicrobial activity of UV light exposure to meat carcasses or meat cuts in a food-processing environment.     

Inactivation of Escherichia coli K12 by pulsed UV light on goat meat and beef: microbial responses and modelling

The objective of this study was to investigate the efficacy of pulsed UV light (PUVL) in inactivating Escherichia coli K12 on goat meat and beef surfaces. Inactivation studies were conducted for 5 to 60 s at three distances from the light source (4.47, 8.28 and 12.09 cm) in the PUVL chamber. Predictive models using regression and artificial neural networks (ANN) were developed to quantify log reductions. Pulsed UV light was more effective on beef than goat meat. Maximum log reductions of 1.66 and 1.74 CFU mL⁻¹ rinse solution were achieved on goat meat and beef, respectively, at 4.47 cm distance for 60 s. Escherichia coli K12 reduction increased significantly with increasing treatment time and closer distance from the light source. In general, both ANN and regression models effectively described inactivation of E. coli K12. Predictive models describing PUVL inactivation kinetics of E. coli K12 can be used for process optimisation in meat industry.     

Relation of biogenic amines to microbial and sensory changes of precooked chicken meat stored aerobically and under modified atmosphere packaging at 4 °C

The formation of biogenic amines and their correlation to microflora and sensory characteristics of a precooked chicken meat product stored aerobically and under modified atmosphere packaging (MAP) (30% CO₂, 70% N₂) was studied. Putrescine was the main amine formed both in aerobically and MA-packaged chicken samples. For the rest of the biogenic amines, including tyramine, histamine, and cadaverine, a stepwise increase was recorded throughout the 23-day storage period under the above packaging conditions. Spermidine was found in higher amounts, as compared to spermine in both aerobically and MA-packaged chicken samples at 4 °C. Formation of these amines in precooked chicken stored either aerobically or under a 30% CO₂, 70% N₂ atmosphere followed an inconsistent trend during the entire storage period at 4 °C. Agmatine, β-phenyl-ethylamine, and tryptamine were not detected in precooked chicken. Of the bacterial groups monitored, lactic acid bacteria (LAB) became the dominant bacteria after day 8 of storage under MAP while LAB were the dominant population of natural microflora of precooked chicken stored both aerobically or under MAP, reaching 7.5 and 8.0 log cfu/g, respectively, on day 23 of refrigerated storage. Enterobacteriaceae populations in chicken meat were below the detection limit (<1 log cfu/g) by pour plating throughout the 23-day storage period, irrespective of packaging conditions. Based on sensory data, after ca. 8 days for the precooked chicken meat stored aerobically and after 12 days under MAP (time to reach initial decomposition stage, score of 2) the putrescine and tyramine content of chicken samples were ca. 14–19 and 1.4 mg/kg, values that may be proposed as the limit for spoilage initiation of precooked chicken meat (respective TVC for both aerobically and MA-packaged chicken meat were ca. 6.5 log cfu/g).     

Effect of Modified Atmosphere Packaging and Soluble Gas Stabilization on the Shelf Life of Skinless Chicken Breast Fillets

The suitability of soluble gas stabilization (SGS) to dissolve CO₂ into skinless chicken breast fillets before modified atmosphere (MA) packaging (MAP) was investigated. Head space gas composition (%), top web deflation (mm), muscle surface color (Minolta L*a*b*), pH, exudates in the packages (%), microbial characteristics, and off‐odor were assessed in the packaged fillets. Increased SGS treatment time (2 versus 12 h) before MA packaging increased the CO₂ content in the packaged fillets and counteracted package collapse. High package filling degree (51.8%) (low gas to product volume ratio) gave significantly (P < 0.001) lower CO₂ content in head space than normal filling degree (29.7%). Color, pH, and package exudates were not affected by SGS treatment. Aerobic plate count (APC), Enterbacteriaceae count (EC), and lactic acid bacteria (LAB) increased significantly (P < 0.001) at each sampling during storage (5, 11, 17, and 24 d). SGS treatment significantly (P < 0.015) decreased APC, EC, and Pseudomonas spp. counts (PC) compared with no SGS treatment. Filling degree did not have a significant effect on the investigated microbiological characteristics. Off‐odor scores correlated highest with EC (r²_(adj)= 0.82). Fillets SGS treated in 12 h were the only one not rejected at off‐odor evaluation on day 24. The samples stored in air spoiled after 5 d. SGS treatment in combination with MAP can be used successfully on chicken breast fillets to improve the microbiological (APC, EC, and PC) and sensorial characteristics, and in addition reduce package collapse and possibly increase the filling degree.     

Impact of voltage and pulse delivery mode on the efficacy of pulsed light for the inactivation of Listeria

Listeria innocua inactivation by pulsed light (PL) was evaluated at different settings and voltages, to establish the best treatment conditions and post-treatment handling for further implementation of PL in the food industry. Fluences up to 0.2 J/cm² were applied to superficially inoculated TSA agar plates (4.5–5 log cfu/cm²). Inactivation was calculated, and log-linear and Weibull models were applied. A fluence of 0.2 J/cm² applied in a single pulse inactivated 3.8 log cfu/cm², while sequential application of this fluence yielded an inactivation between 1.5 and 2.5 log cfu/cm² depending on the delivery mode (consecutive flashing or with 5 min-holding times under ambient light or in the dark). Data from consecutive PL treatment were fitted with the Weibull model. No photoreactivation following PL was observed after 120-min exposure to ambient light in any of the conditions assayed. This study showed that flashing with a single pulse at higher voltage would offer the highest inactivation of Listeria.Industrial relevanceThis study offered information of practical interest to establish pulsed light processing and post-processing conditions for the control of Listeria spp. in the food industry, for instance in ready-to-eat (RTE) products. The use of higher voltages provided higher inactivation and allowed to minimise the number of flashes. If sequential treatments are to be applied, the treatment is more effective if short holding times are kept between pulses. The post-processing illumination conditions do not influence the efficacy of PL treatment.     

Efficacy of Sanitized Ice in Reducing Bacterial Load on Fish Fillet and in the Water Collected from the Melted Ice

ABSTRACT: This study investigated the efficacy of sanitized ice for the reduction of bacteria in the water collected from the ice that melted during storage of whole and filleted Tilapia fish. Also, bacterial reductions on the fish fillets were investigated. The sanitized ice was prepared by freezing solutions of PRO-SAN^® (an organic acid formulation) and neutral electrolyzed water (NEW). For the whole fish study, the survival of the natural microflora was determined from the water of the melted ice prepared with PRO-SAN^® and tap water. These water samples were collected during an 8 h storage period. For the fish fillet study, samples were inoculated with Escherichia coli K12, Listeria innocua, and Pseudomonas putida then stored on crushed sanitized ice. The efficacies of these were tested by enumerating each bacterial species on the fish fillet and in the water samples at 12 and 24 h intervals for 72 h, respectively. Results showed that each bacterial population was reduced during the test. However, a bacterial reduction of < 1 log CFU was obtained for the fillet samples. A maximum of approximately 2 log CFU and > 3 log CFU reductions were obtained in the waters sampled after the storage of whole fish and the fillets, respectively. These reductions were significantly (P < 0.05) higher in the water from sanitized ice when compared with the water from the unsanitized melted ice. These results showed that the organic acid formulation and NEW considerably reduced the bacterial numbers in the melted ice and thus reduced the potential for cross-contamination.     

The quality of frozen African sharptooth catfish (Clarias gariepinus) fillets under long‐term storage conditions

The quality of frozen catfish fillets was monitored over a period of 11 months at ?20 °C, in two types of packaging materials, namely vacuum packaging (VP) and oxygen‐permeable packaging (OPP). Representative samples (n = 5) from both types of packaging materials were drawn at random, monthly for the full period of the trial. Samples were pooled and analysed microbiologically using standard methods. Fatty acid analyses of total lipids, neutral lipid, glycolipid and phospholipid fractions as well as sensory evaluation were also conducted every 3 months on the pooled samples. These tests were conducted to determine whether OPP (cheaper option) could be used instead of VP for long‐term superchilling of catfish without detracting from its quality. Low microbiological counts were maintained throughout the trial, ie 4.1 × 10⁴ cfu g^?1 (VP) and 8.9 × 10⁴ cfu g^?1 (OPP) in the 11th month for aerobic plate count. No significant human pathogens were isolated, with the exception of Aeromonas hydrophila (Stanier). Lipid oxidation, irrespective of packaging, showed no fixed trends during the 11 months of investigation. Also, no significant deviation from sensory characteristics was noted. These results indicate that storing catfish fillets in OPP is a feasible and cheaper option for long‐term freezing. © 2001 Society of Chemical Industry     

Raw-meat packaging and storage affect the color and odor of irradiated broiler breast fillets after cooking

Raw breast fillets were divided into two groups and either vacuum or aerobically packaged. The fillets in each group were subdivided equally into two groups and then irradiated at 0 or 3 kGy using a Linear Accelerator. After 0, 3 and 7 days of storage at 4?°C, fillets were cooked in an 85?°C water bath (cook-in-bag) to an internal temperature of 74?°C. Oxidation-reduction potential (ORP) of raw fillets was measured before cooking, and color and sensory characteristics were analyzed after cooking. Irradiation decreased the ORP of meat, but the potential in aerobically packaged fillets increased during storage. After cooking, color a*-value of irradiated fillets was higher than that of the non-irradiated. Irradiation of raw meat also changed color L* and b* values after cooking. Aerobic storage reduced the redness of cooked meat induced by irradiation. Irradiated raw broiler fillets stored for 0 day and 3 day under aerobic conditions before cooking produced a oxidized chicken-like odor. The odor, however, disappeared after 7 days of storage under aerobic conditions before cooking. For raw broiler samples stored under vacuum conditions, significant differences in color and odor between irradiated and non-irradiated fillets remained throughout the 7-day storage period after cooking. Irradiation had only a minor influence on lipid oxidation of raw breast fillets as indicated by low TBARS values. This study indicates that the effect of irradiation on color and odor of broiler breast fillets after cooking can be reduced significantly through shelf-display of raw fillets under aerobic conditions. Storage under vacuum conditions before cooking is not effective in reducing irradiation-induced changes in the color and odor of breast fillet after cooking.     

Application of cold oxygen plasma for the reduction of Cladosporium cladosporioides and Penicillium citrinum on the surface of dried filefish (Stephanolepis cirrhifer) fillets

This study was conducted to investigate the effects of cold oxygen plasma (COP) on the reductions of Penicillium citrinum and Cladosporium cladosporioides on the surface of dried filefish fillets (Stephanolepis cirrhifer). The counts were significantly (P < 0.05) reduced with the increase in the treatment time (3–20 min) of COP on the fillets. However, no significant (P > 0.05) differences were observed in the counts between 3 and 5 min of COP. The average decrease in the counts of C. cladosporioides and P. citrinum caused by 3–20 min of COP was 0.91 and 1.04 log₁₀ CFU g^?1, respectively. A reduction of >1‐log₁₀ CFU g^?1 was observed on the fillets treated with COP for >10 min. Decimal reduction time (d_R) by Weibull model was 9.32 and 7.42 min of COP for C. cladosporioides and P. citrinum, respectively. The fillets exposed to 20 min of COP displayed increased thiobarbituric acid reactive substance (TBARS) and decreased overall sensory acceptance. However, the fillets treated with 10 min of COP received satisfactory TBARS and consumer acceptance. Therefore, a 10‐min COP could be effective in reducing >90% and inactivating of the mould without causing any deleterious changes to the physicochemical and sensory qualities of the fillet.     

Evaluation of the Spoilage of Raw Chicken Breast Fillets Using Fourier Transform Infrared Spectroscopy in Tandem with Chemometrics

The aim of this work was to evaluate the potential of Fourier transform infrared (FTIR) spectroscopy as a rapid and accurate technique to detect and predict the onset of spoilage in fresh chicken breast fillets stored at 3, 8, and 30 °C. Chicken breasts were excised from carcasses at 6 h post-mortem; cut in fillets; packed in air; stored at 3, 8, and 30?ºC; and periodically examined for FTIR, pH, microbiological analysis, and sensory assessment of freshness. Partial least squares regression allowed estimations of total viable counts (TVC), lactic acid bacteria (LAB), Pseudomonas spp., Brochothrix thermosphacta, Enterobacteriaceae counts and pH, based on FTIR spectral data. Analysis of an external set of samples allowed the evaluation of the predictability of the method. The correlation coefficients (R²) for prediction were 0.798, 0.832, 0.789, 0.810, 0.857, and 0.880, and the room mean square error of prediction were 0.789, 0.658, 0.715, 0.701, 0.756 log cfu g^?1 and 0.479 for TVC, LAB, Pseudomonas spp., B. thermosphacta, Enterobacteriaceae, and pH, respectively. The spectroscopic variables that can be linked and used by the models to predict the spoilage/freshness of the samples, pH, and microbial counts were the absorbency values of 375 wave numbers from 1,700 to 950 cm^?1. A principal component analysis led to the conclusion that the wave numbers that ranges from 1,408 to 1,370 cm^?1 and from 1,320 to 1,305 cm^?1 are strongly connected to changes during spoilage. These wave numbers are linked to amides and amines and may be considered potential wave numbers associated with the biochemical changes during spoilage. Discriminant analysis of spectral data was successfully applied to support sensory data and to accurately bound samples freshness. According to the results presented, it is possible to conclude that FTIR spectroscopy can be used as a reliable, accurate, and fast method for real time freshness evaluation of chicken breast fillets during storage.