MICROBIOLOGICAL STATUS OF BEEF CARCASS MEAT IN INDONESIA

The microbiological status of beef carcass meat was investigated at a traditional and a semi-modern abattoir in Indonesia. Carcasses from the traditional abattoir were generally less contaminated than those from the semi-modern abattoir. The average total aerobic viable bacterial count of carcasses produced at the traditional abattoir, (log₁₀ 3.62/cm²) was found to be significantly lower (p = 0.02) at the semi-modern abattoir (log₁₀ 4.02/cm²). More than 70% of carcasses at both abattoirs were found to be positive for Escherichia coli (> 10 organisms/cm²), while Salmonellae were found on approximately 15% of carcasses at both locations.     

The manufacture and some quality characteristics of kurut, a dried dairy product

This study was designed to investigate the microbiological and chemical characteristics of kurut, a dairy product obtained by drying yogurt under the sun in rural areas of Turkey. For this purpose, 50 randomly collected kurut samples from the Kars Region were analysed for determination of their microbiological and chemical characteristics. Analysis of kurut samples showed that kurut contained on average 4.52 log₁₀ cfu/g of aerobic mesophilic bacteria, 2.78 log₁₀ cfu/g of aerobic mesophyl spores, 3.60 log₁₀ cfu/g of lactic acid bacteria, 3.60 log₁₀ cfu/g of Lactococcus , 3.94 log₁₀ cfu/g of mould and yeast, 2.13 log₁₀ cfu/g of Enterobacteriaceae, l.51 log₁₀ cfu/g of sulphite-reducing clostridia, and 1.81 log₁₀ cfu/g of coagulase-positive s taphylococci . Coliform bacteria and enterococci bacteria were not detected in any of the kurut samples. Furthermore, chemical characteristics of the kurut were as follows: pH 4.2, acidity (lactic acid) 2.9, moisture 12.1%, fat 45.9% protein 25.5%, salt 6.7% and ash 10.0%. The quality characteristics of kurut presented here may help create a different perspective for new products to be produced in the dairy sector.     

INFLUENCE OF WASHING TREATMENT ON NATIVE MICROFLORA AND ESCHERICHIA COLI POPULATION OF INOCULATED CANTALOUPES

The influence of chlorine or hydrogen peroxide treatment on populations of Escherichia coli 25922 on the external surface of inoculated cantaloupe was investigated. Surface treatment with 70% EtOH, followed by immersion in 10⁸ CFU/mL E. coli inoculum deposited an average of 4.4 log₁₀CFU/cm² cell population on the cantaloupe surface. The efficncy of washing inoculated cantaloupe was dependent on storage interval between inoculation and treatment. Dipping the cantaloupes in solutions containing 1000 mg/L chlorine or 5% peroxide for 5 min, within 24 h of inoculation, caused a 2 log₁₀ CFU/cm² reduction of the indigenous surface microflora and a 3–4.0 log₁₀ CFU/cm² reduction in E. coli. The efficacy was less when the interval between inoculation and treatment exceeded 24 h. Chlorine appeared in be a better antimicrobial agent than hydrogen peroxide against F. coli ATCC 25922 inoculated on cantaloupe surfaces while hydrogen peroxide was better in reducing surface microflora of cantaloupe.     

Methods to Detect the Occurrence of Various Indicator Bacteria on the Surface of Retail Poultry in Spain

ABSTRACT: Contamination levels (cfu/g and cfu/cm²) of indicator microorganisms in retail broiler chicken carcasses in León (Spain) were investigated. Counts (log₁₀ cfu/g) were 5.19, 3.04, 2.73, 3.38, and 3.16 for total aerobic counts ( TAC), Enterobacteriaceae , coliforms determined by the standard VRBA method (coliforms-VRBA), coliforms determined by the Hydrophobic Grid Membrane Filter method (coliforms-HGMF), and Escherichia coli (HGMF method), respectively. These values fit into the microbiological criteria for poultry meat consulted. A low correlation coefficient was found between TAC and Enterobacteriaceae counts (r = 0.308; P = 0.053) and between coliforms-VRBA and coliforms-HGMF counts ( r = 0.398; P = 0.048). The determination method had a significant influence on the coliform counts obtained. All broiler chicken carcasses harbored E. coli biotype I. E. coli biotype II was detected in 20% of the samples. The HGMF method was not completely specific for detecting E. coli since 11.25% of false positive colonies were found.     

Portable Electronic Nose for Detection of Spoiling Alaska Pink Salmon (Oncorhynchus gorbuscha)

ABSTRACT:  The ability of a portable hand-held electronic nose (EN) in detecting spoilage of whole Alaska pink salmon ( Oncorhynchus gorbuscha ) stored at 14 °C and in slush ice (1 °C) was investigated. Fish were sampled daily at 14 °C for up to 3 d, while fish stored in slush ice were sampled at various intervals up to 16 d. Sensory evaluations indicated that fish were rejected at day 3 when stored at 14 °C and at day 12 when stored in slush ice. Aerobic bacteria counts for fish skin at 14 °C ranged from 3.4 log₁₀ colony-forming units (CFU)/cm² (day 0) to 4.8 log₁₀ CFU/cm² (day 3) and for fish stored in slush ice ranged from 3.4 log₁₀ CFU/cm² (day 0) to 5.5 log₁₀ CFU/cm² (day 16). The correct classification rate using forward stepwise general discriminate analysis was 85% and 92% for EN analysis of belly cavity volatiles for fish held at 14 °C and in slush ice, respectively. A predictive model may be developed for spoilage of whole Alaska pink salmon by analyzing belly cavity odors using the EN.     

Some insight into the mechanism of inhibition of psychrotrophic bacterial growth in raw milk by lactic acid bacteria

Addition of lactic acid bacteria to refrigerated raw milk inhibited growth of Gram-negative psychrotrophic bacteria. In order to obtain complete inhibition, population levels of lactic acid bacteria approaching 1× 10₈ cfu/ml were required. At this inoculum level a substantial pH change was observed in the milk during storage. The degree of inhibition was related to the final pH of the milk. Inhibition of the psychrotrophs was brought about by adjustment of pH with L(+) lactic acid but not by HCI. Inhibition by the lactic acid bacteria was observed in heat-treated milks seeded with a small volume of raw milk, but no inhibition of Gram-negative psychrotrophic growth was observed when cell-free preparations of lactic acid bacteria were used. A cell-free ultrafiltrate of one lactic acid culture did inhibit a strain of Bacillus circulans.     

不同工艺条件对猪胴体和冷却猪肉微生物去污染效果的影响

调查了冷却猪肉生产企业现有生产工艺下微生物污染的状况 ;研究了对现有生产工序 (冲淋工序、冷却工序 )采用新的处理工艺 ,包括水冲洗、乳酸喷淋、冷分割以及联合处理等对猪胴体和冷却猪肉微生物去污染的效果。结果表明 ,在现有生产工艺下 ,冷却猪肉微生物污染随季节发生显著变化 ,且达不到HACCP体系微生物控制要求 ;水冲淋、乳酸喷淋、冷分割单独处理或联合处理 ,均有显著的微生物去污染效果。如果采用热分割 ,劈半后冲洗 1min ,乳酸喷淋 1min ,则微生物去污染效果显著 ,可基本达到HACCP对微生物控制要求。如果采用冷分割 ,劈半后冲洗 1min ,冷却 2 4h ,再次采用冷分割效果较好 ,冷却猪肉可基本达到HACCP对微生物控制要求 ;若劈半后冲洗 1min ,乳酸喷淋 1min ,冷却 2 4h则可完全达到HACCP对微生物控制要求。     

Efficacy of pulsed UV-light for the decontamination of Escherichia coli O157:H7 and Salmonella spp. on raspberries and strawberries

ABSTRACT:  Small fruits are increasingly being implicated in outbreaks of foodborne illness, and fresh produce is now the 2nd leading cause of foodborne illness in the United States. Conventional methods of decontamination are not effective, and there is a need to evaluate novel technologies. Pulsed ultraviolet (UV)-light is one such technology. In this study, pulsed UV-light was applied to strawberries and raspberries at varying UV doses and times. On raspberries, maximum reductions of Escherichia coli O157:H7 and Salmonella were 3.9 and 3.4 log₁₀ CFU/g at 72 and 59.2 J/cm², respectively. On the surfaces of strawberries, maximum reductions were 2.1 and 2.8 log₁₀ CFU/g at 25.7 and 34.2 J/cm², respectively. There was no observable damage to the fruits at these UV doses. The results obtained in this study indicate that pulsed UV-light has the potential to be used as a decontamination method for raspberries and strawberries.     

FAT THICKNESS AND LOIN EYE AREA EFFECTS ON PORK CARCASS QUALITY MEASURES

Pork carcasses (n = 133), varying in fatness and muscling, were selected to evaluate the relationship between pork carcass cutability and pork meat quality. Carcasses were selected with three levels of 10^th rib fat (TRBF: < 2.03 cm, n = 60; 2.03 - 2.54 cm, n = 31; and > 2.54 cm, n = 42) and three levels of loin eye area (LEA: < 35.5 cm², n = 33; 35.5 – 41.9 cm², n = 52; and > 41.9 cm², n = 48). Data were collected on the longissimus muscle of ribbed carcasses. Carcasses in the leanest TRBF group had less (P < 0.05) marbling, and softer (P < 0.05) and more watery (P < 0.05) lean than the fatter categories. Carcasses in the leanest category were also redder in color (P < 0.05; higher a* values) than the fattest category. Carcasses in the smallest LEA group had higher (P < 0.05) marbling and firmness scores than the largest LEA group and carcasses in the largest LEA group had more (P < 0.05) exudative loin muscles than the remaining LEA groups. Collectively, these data indicate that selection for reduced carcass fatness and increased carcass muscling, in swine, has significant negative effects on pork meat quality.     

Rapid dye reduction tests for the determination of microbiological quality of meat

Rapid dye reduction tests have been developed to determine the quality of meat. Three chemical indicators, resazurin and two tetrazolium compounds, were used to correlate the microbial numbers and reduction times in meat samples. Twenty-five surface samples from sheep carcasses were subjected to each reduction test. Total viable counts given were obtained at 37°C. Resazurin reduction time was 90–120 min when the bacterial counts ranged from 1.5×10⁶ to 7.7×10⁶/cm². Samples showing bacterial counts between 1.5×10⁶ and 6.0×10⁶/cm² reduced tetrazolium (NBT) in 360–390 min whereas samples containing bacterial counts of 2.1×10⁶/cm² took 420–450 min to reduce iodophenyl nitrophenyl tetrazolium (INT) dye. Regression equations relating the number of organisms per cm² and reduction time were applied to predict the microbiological quality of meat samples from reduction time data. Among the three dyes, resazurin gave the lowest reduction time.     

Effect of irradiation and modified atmosphere packaging on the microbiological safety of minced pork stored under temperature abuse conditions

The safety of irradiated pork packed in 25% CO₂:75% N₂ and stored at abuse temperature (10 or 15°C) was assessed by inoculation studies involving Salmonella typhimurium, Listeria monocytogenes, Escherichia coli, Yersinia enterocolitica and Clostridium perfringens . Irradiation to a dose of 1.75 kGy reduced pathogen numbers to below the detection limit of 10² cells g^-1. When higher inoculum levels were used (10⁶ cells g^-1) irradiation at 1.75 kGy reduced pathogen numbers by 1 –>5 log₁₀ cycles depending on strain. Clostridium perfringens was the most resistant, and Y. enterocolitica the most sensitive of the pathogens studied.
In all cases when high numbers (10⁶ to 10⁷g^-1) of spoilage and/or pathogenic bacteria were present initially on the pork the meat appeared spoiled, and although irradiation reduced the number of microorganisms, the meat was still unacceptable from a sensory viewpoint after treatment.
It was concluded that the microbiological safety of irradiated, modified atmosphere packaged (MAP) pork is better than that of unirradiated MAP pork.     

THE EFFECT OF LACTIC ACID DECONTAMINATION ON THE MICROFLORA ON MEAT

Meat acquires a characteristic microflora after slaughter and butchering. This normal microflora may be beneficial in that it occupies a niche that would otherwise permit unimpeded growth of potential pathogens. Lactic acid decontamination (LAD) is intended to eliminate pathogens but also affects the normal microflora. The immediate effect was studied by means of an in-vitro model. Experiments using this model achieved a reduction in the mesophilic Enterobacteriaceae on meat by 1 to 3 log₁₀ colony forming units and shifted the predominant microflora in the direction of Gram-positive bacteria and yeasts. Colony counts were an unreliable indicator of LAD-induced reductions in Gramnegative foodborne pathogens. Their reduction depended on the ratio of the more lactic acid resistant Gram-positive bacteria to the more sensitive Gram-negative bacteria. The rank order of lactic acid-resistance of nonpathogens present on meat was yeasts = lactobacilli > psychrotrophic Gram-positive bacteria > mesophilic Enterobacteriaceae. Psychrotrophic Gram-negative bacteria were the most sensitive.     

EFFICACIES OF ACETIC, LACTIC AND TWO MIXED ACIDS IN REDUCING NUMBER OF BACTERIA ON SURFACE OF LEARN MEAT

This study on sanitizing beef surfaces was designed to evaluate effects of mixtures of acetic, lactic, citric and ascorbic acids with individual solutions of acetic and lactic acids. Acetic acid (3%), lactic acid (3%), MA1 (2% acetic, 1% lactic, 0.25% citric and 0.1% L-ascorbic acids) and MA2 (2% lactic, 1% acetic, 0.25% citric and 0.1% L-ascorbic acids) solutions were applied to beef core samples of muscle inoculated with bacteria. Experimental variables were type, concentration and temperature of acid solutions and type of microorganisms. Overall, an increase in either acid concentration or treatment temperature decreased numbers of residual viable bacteria. Lactic acid solution was the most effective against S. typhimurium with a reduction of 2 log₁₀ at 70°C. For enterobacteria, acetic, lactic and MA2 solutions at 70°C resulted in a 1.5 log₁₀ reduction. MA2 was the most effective acid solution at both 45 and 70°C, whereas, lactic acid and the MA2 mixture did not differ in effectiveness at 20°C.     

Effect of irradiation and modified atmosphere packaging on the microbiological and sensory quality of pork stored at refrigeration temperatures

The effect of combining low-dose irradiation (1.75 kGy) with modified atmosphere packaging (MAP) on the microbiological and sensory quality of pork chops stored at refrigeration temperatures was studied. The microflora of irradiated MAP pork was almost exclusively composed of lactic acid bacteria, predominantly Lactobacillus spp. Modified atmospheres containing either 25 or 50% CO₂, balance N₂, resulted in the best microbial control in irradiated pork held at 4°C, compared to an unirradiated MAP control, and these atmospheres were subsequently used in sensory studies. The atmosphere containing 25% CO₂ 75% N₂ maintained the uncooked colour and odour of irradiated pork chops more effectively than 50% CO₂ 50% N₂. Therefore packaging in a modified atmosphere containing 25% CO₂, balance N₂, followed by irradiation to a dose of 1.75 kGy is recommended to improve the microbiological and sensory quality of pork chops.     

SODIUM LACTATE EFFECTS ON MICROBIAL, SENSORY, AND PHYSICAL CHARACTERISTICS OF VACUUM-PACKAGED PORK SAUSAGE

Vacuum-packaged fresh meat products held at refrigeration temperatures have limited shelf-life expectancies, often due to growth of anaerobic lactic acid-producing bacteria. Agents that can suppress the growth of this group are beneficial. Fresh pork sausage, formulated to contain 0%, 1%, 2%, or 3% sodium lactate (SL), was vacuum packaged and stored at 4C for 0, 10, 17, 24, and 31 days. A trained sensory panel evaluated pork, salty, sour, and bitter flavors. Aerobic total plate counts (APC), anaerobic total plate counts (AnPC), aerobic lactic acid producers (ALC), anaerobic lactic acid producers (AnLC), TBA values, and pH were determined. SL depressed APC, AnPC, and AnLC. Addition of 1% SL extended shelf-life of vacuum-packaged fresh pork sausage by 1 week compared to controls; samples containing 2% and 3% SL had not reached spoilage level (log₁₀ 7.0 CFU/g) at the conclusion of this study. Addition of SL increased salty taste and prevented loss of pork flavor over time, but had no effect on sour or bitter flavors.     

Some effects of modified-atmosphere packaging and vacuum packaging in combination with antioxidants on quality and storage life of chilled potato strips

A modified-atmosphere packaging system for chilled fresh potato strips, which rapidly produced oxygen levels < 3%, was identified. This system enclosed the strips within 25 μ low density polyethylene film heat sealed to a fibre tray lined with Surlyn-PVdC-Surlyn, and the package flushed with an initial atmosphere of 5% O₂, 10% CO₂. An equilibrium-modified atmosphere of 3–4% CO₂, 1–2% O₂ was established after 3 days' storage at 5°C. This modified-atmosphere package, used in combination with dipping of potato strips in a 10% ascorbic acid solution, inhibited enzymatic discoloration for 1 week at 5°C. Vacuum packaging within a Surlyn/PVdC-coated polyester film, with or without dipping in ascorbic acid solution, inhibited discoloration of chilled potato strips stored at 5°C for at least 2 weeks.     

Microbiological and chemical characterization of Fiore Sardo, a traditional Sardinian cheese made from ewe's milk

The purpose of this study was to assess the chemical and microbial characteristics of 12 batches of artisanal Fiore Sardo, a protected designation of origin (PDO) hard cheese made from raw ewe's milk without addition of starters, during maturation. High standard deviations were observed for moisture percentage, total solids percentage and NaCl percentage content, possibly owing to differences in manufacturing processes and/or milk composition. Total mesophilic bacteria varied between 10 log₁₀ cfu/g in 48-h-old cheese samples and 3 log₁₀ cfu/g in 9-month-old samples. Total coliforms and staphylococci showed the highest counts at 48 h of ripening then decreased significantly, dropping to levels below 2 log₁₀ cfu/g at 3 months of maturation. Lactic acid bacteria and enterococci were the dominant micro-organisms throughout maturation. They were mainly represented by the species Lactococcus lactis ssp. lactis, Enterococcus faecium, Lactobacillus plantarum and Lactobacillus casei group. Low levels of yeasts were detected throughout the maturation period of the cheese. Debaryomyces hansenii and Kluyveromyces lactis var. lactis were the prevalent yeast species isolated.     

Combining Antimicrobial and Steam Treatments in a Vacuum-packaging System to Control Listeria monocytogenes on Ready-to-eat Franks

ABSTRACT: This study was to evaluate the effectiveness of steam or steam in combination with an antimicrobial agent to control Listeria monocytogenes on ready-to-eat (RTE) franks. The franks were surface-inoculated to contain 6 or 3 log₁₀(colony-forming units [CFU])/cm² of L. monocytogenes and treated with steam or steam in combination with an antimicrobial agent, immediately followed by vacuum-sealing the top films of frank packages (6 franks per package in a single layer). Three log (CFU) /cm² of reductions were achieved at the both inoculation levels for L. monocytogenes on franks. At an inoculation level of 3 logs, no outgrowth of L. monocytogenes was obtained on the treated franks after storing at 4.4°C or 16°C for a combined 47 d. This study provided an alternative approach for controlling L. monocytogenes in packaged franks.     

Influence of post-mortem treatments on turkey and chicken meat texture

Toughness of poultry breast muscle was influenced by the rate of rigor onset, the rate of cooling and chilled storage time. The pH of the breast muscle at 20 min after stunning (pH₂₀) in 52-day-old chickens varied from 5.9 to 6.9, and in 70-day-old turkeys from 6.2 to 6.8. In turkey meat with pH₂₀ > 6.4, toughening was induced by immersion chilling to 7°C within 65 min post mortem and subsequent 'tanking' in iced water. Unaged, thawed meat from chicken carcasses, in which freezing commenced about 2 h after stunning was tougher than that from carcasses chilled for 16 h before freezing. Both were tender after 7 days chilled storage. Electrical stimulation of carcasses using 94 V decreased pH₂₀ by an average of 0.3 unit in turkey, with no overall increase in tenderness. In chicken, it decreased the pH₂₀ by 0.5 unit, but caused an overall toughening due to increased rigor shortening in carcasses with pH₂₀ < 5.8.     

肉牛屠宰工序微生物污染状况分析和喷淋减菌技术

以减少冷却后牛胴体表面的微生物数量为目标,在企业实际生产条件下,以菌落总数为指标分析屠宰过程中各工序胴体表面的微生物变化状况,探讨不同喷淋方式的减菌效果。结果表明,屠宰工序中初始剥皮操作对胴体造成的污染最严重,其次为去脏工序。高压清水清洗对全胴体的减菌量为0.62(log10CFU/cm2);2%的乳酸喷淋对胸口部位菌落总数的减少量为1.06(log10CFU/cm2)。采用2%的乳酸喷淋可以有效减少肉牛屠宰过程中的胴体污染。