Levels Of Aerobic Plate Count Research Articles

The microbiological quality, shelf-life, and multidrug-resistant Salmonella contamination rates assessment in chicken giblets purchased from live poultry shops

The objective of the current study was to assess the shelf-life durations and hygienic standards of chicken giblets purchased from Egyptian live poultry outlets compared to the Egyptian Standardization Organization criteria. Salmonella prevalence and antibiotic-resistance profiles were also described. On the first day, forty-five giblet samples were randomly collected and evaluated for aerobic plate count (APC), coliform, Escherichia coli, Staphylococcus and Staphylococcus aureus, and multidrug-resistant Salmonella contamination rates using culturing methods, matrix-assisted laser desorption ionization-time of flight mass spectrometry, and the VITEK® −2 system. Four- and five-day shelf-life durations were assessed. All chicken giblets had acceptable APC levels below the 6 log cfu/g on the collection day, but 27 % were contaminated with Salmonella Enteritidis, rendering them unfit. More than 2-log CFU/gm of Escherichia coli and Staphylococcus aureus contamination was identified in 64 % and 58 % of the giblets, respectively. All targeted indices surpassed maximum authorized requirements after four and five days of chilling at 4 °C, coupled with the detection of obvious greenish discoloration and off odor. All twelve Salmonella Enteritidis were vulnerable to carbapenems, cefepime, and piperacillin/tazobactam, but 83 % were multidrug-resistant (MDR), with four demonstrating extended-spectrum beta-lactam resistance. This could be the first Egyptian report identifying such a high prevalence rate of Salmonella and MDR to key antibiotics in chicken giblets. The current study encourages Egyptian authorities to reevaluate laws governing live poultry outlets to reduce the risk of disease exposure, including the National Egyptian Food Safety Authority's direct supervision over these outlets to establish a stringent safety program.

Nutritional, Sensory, and Microbial Quality of Cookies Produced by Partial Replacement of Wheat Flour with Plantain (Musa paradisiaca) and Cocoyam (Colocasia esculenta) Flours

Nutritional, sensory, texture, and microbiological load analyses were made of cookies consisting of a partial replacement of wheat flour with plantain (Musa paradisiaca) or cocoyam (Colocasia esculenta) flour. There were slight differences in the amounts of protein, fat, and carbohydrate. Accordingly, the nutritional values per 100 g of the cookies correspond to 10-14% protein and 19-21% energy of the recommended daily allowance. In contrast, cookies containing either cocoyam or plantain flour have 20% and 30% more fiber, respectively, compared to cookies containing wheat flour alone. Similarly, plantain and cocoyam cookies’ iron and zinc contents were, respectively, 1-16% and 2-9% more than ( p < 0.05 ) the control. The levels of aerobic plate count in the cookies were lower than recommended thresholds for such food products. Those cookies containing 20% and 40% of either plantain or cocoyam flour had comparable sensory, texture, and color quality compared to the control. The effect of intake of plantain and cocoyam cookies is likely to eliminate population mineral deficiencies, particularly iron, and zinc. These results underline the potential of enabling food security crops such as plantain and cocoyam in sustaining cookies production, utilization, nutritional value, and the role of such crops in addressing food and nutrition insecurity.

Post-drying decontamination of laver by dielectric barrier discharge plasma, UV radiation, ozonation, and hot air treatments

While dried laver serves as an important raw ingredient for seaweed snacks, the microbial quality and safety risks associated with the preparation and processing of dried laver have not been well studied. In this project, three commercial laver processing plants were sampled from 2020 to 2022. Results indicated that the current washing and two-step drying process increased the microbial loads in dried laver. The total aerobic plate count (APC), coliform, and mold counts in dried laver ranged from 7.34 to 7.91, 2.12 to 3.87, and 1.65 to 3.87 Log CFU/g respectively. The study further explored the decontamination efficacy of four post-drying treatments (three non-thermal and one thermal treatments). Dielectric barrier discharge (DBD) plasma (150 kV, 10 min), UV-C radiation (40 cm, 30 min), ozone (150 ppm, 40 min), and hot air (150 °C, 30 min) reduced the APC and coliform levels by 2.10 and ∼1.12, 0.98 and 1.03, 2.12 and ∼2.87, and 3.00 and 2.24 Log CFU/g respectively. Unfortunately, Ozone and hot air treatments led to significant color change and nutrient losses. Microorganisms become harder to control once dried on food, future study should explore the use of pre-drying treatments to better enhance the microbial quality and safety of dried laver.

Evaluating the effect of an emerging microwave-assisted induction heating (MAIH) on the quality and shelf life of prepackaged Pacific white shrimp Litopenaeus vannamei stored at 4°C in Taiwan

Microwave-assisted induction heating (MAIH) is an emerging alternative technology for shrimp cooking over traditional heating technologies. This study evaluated the effect of the MAIH and boiling in salt solution on the quality and shelf life of prepackaged Pacific white shrimp L . vannamei stored at 4 °C in Taiwan. Samples were treated for 80 s at 130 °C or for 100 s at 90 °C with the MAIH technology, and 130 s at 90 °C with boiling in salt solution, respectively. Cooked shrimps were stored 28 days at 4 °C to determine changes in aerobic plate count (APC), psychrotrophic bacteria count (PBC), color, texture, pH, and total volatile basic nitrogen (TVBN). Results showed that the levels of APC and PBC were not detectable (<2.0 log CFU/g) during first 12 days of storage in samples treated with the MAIH technology, but they slowly increased afterward, reaching to 3.0 log CFU/g on the 28th day of storage, compared to the traditional boiling technology, when the levels of APC and PBC were gradually increased throughout 28 days of storage, exceeding 8.7 log CFU/g at the end of the storage. In terms of color and TVBN, all cooked samples showed a decreasing trend in lightness ( L* ), redness ( a* ), and whiteness ( W ) but an increasing trend in yellowness ( b* ), absolute color difference ( ΔE ), and the TVBN during the storage period. However, these decreasing and increasing trends occurred slower in samples treated by the MAIH than by boiling ( p < 0.05). In terms of texture, samples treated by the MAIH demonstrated greater hardness and cohesiveness during the storage than samples boiled in salt solution ( p < 0.05). Compared with traditional boiling method, the treatment of shrimp samples with the MAIH delayed the degradation of color and texture and inhibited the growth of microorganisms during refrigerated storage. Therefore, the MAIH technology offers a potential alternative over boiling method for preventing the deterioration and quality loss of shrimps more effectively and extending the refrigerated shelf life of prepackaged Pacific white shrimps stored at 4 °C. • Effect of MAIH and boiled heating on quality of shrimp stored at 4 °C were evaluated. • The MAIH effectively pasteurized and retarded bacterial growth of shrimp until 12 d. • The boiled samples had higher aerobic plate counts and lower physicochemical values. • MAIH can delay reduction of color ( L* , a* , W ) and hardness in samples during storage. . • Shrimps heated by MAIH maintained lower TVBN and extended shelf life from 8 d to 28 d .

Inactivation of microbial loads and retardation of quality loss in Asian hard clam (Meretrix lusoria) using high-hydrostatic-pressure processing during refrigerated storage

The effects of high pressure processing (HPP) at 200, 300, 400, 500, and 600 MPa for 3 min on physicochemical quality and inactivation of microbial loads of Asian hard clam (Meretrix lusoria) were evaluated. In addition, the retardation effects in microbial growth and quality loss of pressurized hard clams stored at 4 °C were investigated. Results showed that the expanding rate, moisture content, shucking ratio, pH, L* (lightness), and W (whiteness) of clam meat increased significantly with the increase in pressure, but a* (redness) and b* (yellowness) values decreased. With the increase in pressure, the levels of aerobic plate count (APC), psychrotrophic bacteria count (PBC), coliform, and Vibrio parahaemolyticus in clam meat significantly decreased. Furthermore, HPP with a pressure of >400 MPa on clam samples significantly delayed the increase in APC (by 6–9 days within Taiwan's regulation standard limit) and PBC during storage at 4 °C. However, the samples pressurized more than 300 MPa had significantly lower levels of total volatile basic nitrogen (TVBN) than control samples during storage. Overall, the results indicated that pressurization at least 400 MPa for 3 min on Asian hard clam were able to reach the highest expanding rate and moisture content, and 100 % shucking, while it can reduce the coliform, and V. parahaemolyticus to a non-detectable level. In addition, HPP conditions of ≥400 MPa for 3 min significantly extended the shelf-life of hard clam during refrigerated storage. Therefore, HPP is a useful technique to preserve Asian hard clam meats due to its ability to reduce bacterial load and retard TVBN production.

Impacts of high-pressure processing on quality and shelf-life of yellowfin tuna (Thunnus albacares) stored at 4°C and 15°C

ABSTRACT The objective of this work was to study the application of high-pressure processing (HPP) on the quality change and extending the shelf-life of yellowfin tuna (Thunnus albacares) stored at low temperature. The effects of HPP treatments (200, 300, 400, 500, and 600 MPa for 5 min) on microbiological and chemical quality, and histamine content of tuna flesh stored at 4°C and 15°C, respectively, were evaluated. With the increased pressure, the levels of aerobic plate count (APC) and coliform in tuna flesh significantly decreased. It was also found that the L* (lightness), b* (yellowness), W (whiteness), ΔE (color difference), and texture (hardness, cohesiveness and chewiness) of fish flesh increased significantly with the increased pressure; however, a* (redness) value decreased. Furthermore, HPP with a pressure of >300 MPa on tuna samples significantly delayed the increase in APC during storage at 4°C or 15°C, respectively, while the samples pressurized more than 200 MPa had significantly lower levels of total volatile basic nitrogen (TVBN) and histamine compared to the control samples during storage. The results indicated that tuna flesh pressurized at least 300 MPa for 5 min could be a technique employed to extend the shelf-life to 1 d at 15°C and 6 d at 4°C, based on the APC limit standard (6.47 log CFU/g). In this study, HPP can be seen as a potential useful technique to preserve tuna flesh due to its ability to reduce bacterial load and retard TVBN and histamine production.

Preliminary Evaluation of a Novel Microwave-Assisted Induction Heating (MAIH) System on White Shrimp Cooking.

The microwave-assisted induction heating (MAIH) system provides comprehensive heating by combining microwave heating (with 1300 W of power and 2450 MHz of frequency) in the top part and induction heating (with 1800 W of power) in the bottom part. In this study, fresh white shrimps were placed in a sealed crystallized polyethylene terephthalate (CPET) container and heated in the MAIH system at two temperatures (130 and 90 °C) from 60 to 120 s. Afterwards, the shrimp samples were rapidly cooled, and the changes in the shrimp quality, including the appearance, cook loss, aerobic plate count (APC), color values, and texture, during the heating process were analyzed. The results demonstrate that longer heating times decrease the APC levels, but increase the cook loss, color values (lightness, redness, and whiteness), and texture (hardness, cohesiveness and chewiness) of the white shrimp samples. In particular, the white shrimp is fully cooked and gains a completely red appearance, along with no APC detected after heating in the MAIH system at 130 °C for at least 80 s or at 90 °C for at least 100 s. In summary, to achieve a good appearance, no APC detected, and low cook loss, the following heating conditions are recommended for cooking white shrimp in the MAIH system: heating at 130 °C for 80 s or at 90 °C for 100 s. This novel MAIH technology allows food to be heated and sterilized after being packed, thereby eliminating the post-pollution issue. To the best of the authors’ knowledge, this is the first study to evaluate the use of MAIH in the application of food processing.

Identification of Listeria monocytogenes Contamination in a Ready-to-Eat Meat Processing Plant in China.

Listeria monocytogenes is the etiologic agent of listeriosis, which remains a significant public health concern in many countries due to its high case-fatality rate. The constant risk of L. monocytogenes transmission to consumers remains a central challenge in the food production industry. At present, there is very little known about L. monocytogenes contamination in ready-to-eat (RTE) processing plants in China. In this study, L. monocytogenes in an RTE meat processing plant in Shanghai municipality was characterized using pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). Furthermore, the biofilm formation ability of the pathogen was also tested. Results revealed that L. monocytogenes isolates were present in 12 samples out of the 48 samples investigated. Most of them (66.7%, 8/12) were identified from the processing facilities irrespective of observed hygiene levels of aerobic plate count (APC) and coliforms. Coliforms were present in only one processing area. ST5 (1/2b) isolates were predominant (83.3%, 10/12) and were identified in two dominant pulsotypes (PTs) (three in PT3 and seven in PT4, respectively). Results of the core-genome multi-locus sequence typing (cgMLST) showed that ST5 in three PTs (PT1, PT3, and PT4) had 0–8 alleles, which confirmed that clonal transmission occurred in the RTE meat processing facilities. In addition, the biofilm formation test confirmed that the isolates from the processing facilities could form biofilms, which helped them colonize and facilitate persistence in the environment. These results indicated that common sanitation procedures regularly applied in the processing environment were efficient but not sufficient to remove L. monocytogenes isolates, especially biofilm of L. monocytogenes. Furthermore, the ST5 isolates in this study exhibited 12 alleles with one ST5 clinical isolate, which contributes to the understanding of the potential pathogenic risk that L. monocytogenes in RTE meat processing equipment posed to consumers. Therefore, strong hygienic measures, especially sanitation procedures for biofilms eradication, should be implemented to ensure the safety of raw materials. Meanwhile, continuous surveillance might be vital for the prevention and control of listeriosis caused by L. monocytogenes.

Effect of Brine Concentrations on the Bacteriological and Chemical Quality and Histamine Content of Brined and Dried Milkfish

In this research, the occurrence of hygienic quality and histamine in commercial brined and dried milkfish products, and the effects of brine concentrations on the quality of brined and dried milkfish, were studied. Brined and dried milkfish products (n = 20) collected from four retail stores in Taiwan were tested to investigate their histamine-related quality. Among them, five tested samples (25%, 5/20) had histamine contents of more than 5 mg/100 g, the United States Food and Drug Administration guidelines for scombroid fish, while two (10%, 2/20) contained 69 and 301 mg/100 g of histamine, exceeding the 50 mg/100 g potential hazard level. In addition, the effects of brine concentrations (0%, 3%, 6%, 9%, and 15%) on the chemical and bacteriological quality of brined and dried milkfish during sun-drying were evaluated. The results showed that the aerobic plate count (APC), coliform, water activity, total volatile basic nitrogen (TVBN), and histamine content values of the brined and dried milkfish samples decreased with increased brine concentrations, whereas those of salt content and thiobarbituric acid (TBA) increased with increasing brine concentrations. The milkfish samples prepared with 6% NaCl brine had better quality with respect to lower APC, TVBN, TBA, and histamine levels.

Sanitizer efficacy in reducing microbial load on commercially grown hydroponic lettuce.

Most hydroponic lettuce growers harvest and package their marketable-size lettuces with an intact root ball. With a high microbial load on the peat moss substrate, there is a risk of microbial transfer onto the edible portion during packaging and throughout the product's shelf life. Since the produce is believed to have no contact with the substrate, no sanitizer wash is performed before packaging and storage. Aerobic plate count (APC) results suggested that reduction in count was influenced by both sanitizer application and storage time. Peroxyacetic acid significantly reduced APC count on leaves, roots, and substrate, with a 1.8 log CFU g-1 initial reduction on the leaf. Fungi and APC levels increased with storage time, with the greatest APC increase in the roots. Leaves had the lowest coliform bacteria (CB), with chlorine slightly reducing CB count. Unlike APC, CB levels decreased during storage on the substrate and root samples. No Listeria positive was confirmed by agglutination test. Further evaluation of different commercial substrates reveals that Com4, a drier-compacted plug, had the least ability to support growth/survival of all microbial populations enumerated relative to the spongy, wet black plugs. The ability of peat moss substrates to host microorganisms is influenced by the physical properties of the product. Sanitizer wash efficacy is dependent on the initial microbial load and the length of storage. Chlorine and peroxyacetic acid are effective in reducing microbial populations on the leaves of hydroponically grown lettuce without affecting visual quality during shelf life. © 2020 Society of Chemical Industry.

Microbiological quality of beef, mutton, and water from different abattoirs in the Eastern Cape Province, South Africa.

Background and Aim:Abattoir processes from skinning, evisceration, to chilling usually lead to meat contamination by foodborne pathogens. Hence, continual microbial surveillance of slaughter carcasses by veterinary public health officials is key to preventing contamination and outbreak of meat-related foodborne diseases. This study was conducted to determine the Enterobacteriaceae count and aerobic plate count (APC) and to detect Escherichia coli and Salmonella spp. in meat and water from selected slaughter facilities.Materials and Methods:Retrospective data (n=100) collected in 2017 by the Provincial Veterinary Department of the Eastern Cape Province from abattoirs and prospective survey data of meat (n=50) collected in 2018 from abattoirs in the Eastern Cape Province were utilized in this study. APC and Enterobacteriaceae were enumerated from the samples. In addition, Salmonella and E. coli were isolated from samples using selective media.Results:The APC in both retrospective and prospective studies for all samples ranged between 2 and 4.50 log CFU/cm2; similar counts of 2-4.00 log CFU/cm2 were recorded for Enterobacteriaceae. No significant difference (p>0.05) for APC and Enterobacteriaceae count across all meat types was noted. Salmonella and E. coli were detected in 50% of beef. E. coli was not detected from mutton, but Salmonella was found in 66.7%. Moreover, 91.7% of the water samples had E. coli, but none had Salmonella.Conclusion:The levels of Enterobacteriaceae and APC observed in meat satisfy regulatory conditions outlined by the Department of Agriculture, Forestry and Fisheries, South Africa and show that meat produced from these abattoirs is of acceptable microbial quality. However, the quality of water used in the abattoirs does not meet the requirements set by the government, and contributes to contamination of meat produced in the abattoirs under study. Therefore, we recommend that sources of water be continuously investigated to eliminate or reduce the risk of contamination of meat processed in the abattoirs.

Effect of Vacuum Packaging on Histamine Production in Japanese Spanish Mackerel (Scomberomorus niphonius) Stored at Various Temperatures

The effect of polyethylene packaging (PEP) in air cushion and vacuum packaging (VP) on histamine related to the quality of Japanese Spanish mackerel (JS mackerel) was studied with samples stored at -20, 4, 15, and 25°C. The aerobic plate count (APC), total volatile basic nitrogen (TVBN), and histamine concentrations of the PEP and VP samples stored at 25°C increased as the storage time continued. The PEP and VP samples stored at temperatures below 15°C showed lower levels of APC, TVBN, and histamine, with VP samples having considerably lower levels of APC, TVBN, and histamine than PEP samples. For the frozen JS mackerel stored at -20°C for 2 months and then thawed and stored at 25°C, the VP treatment delayed the increases of TVBN and histamine longer than did the PEP treatment. Thus, the storage of VP JS mackerel at temperatures below 4°C could prevent quality deterioration and extend shelf life.

Microbiological Testing Results of Cooked Diced Chicken and Pasteurized Egg Products Purchased for United States Federal Nutrition Assistance Programs, 2012-2018.

The Agricultural Marketing Service (AMS) purchases cooked diced chicken, pasteurized liquid whole eggs, and pasteurized dried egg mix for federal nutrition assistance programs. Purchases are made from establishments that have met the financial and technical requirements to become AMS-approved vendors. Cooked diced chicken is tested for the presence of Salmonella and Listeria monocytogenes, and for levels of aerobic plate count (APC) organisms, coliforms, and generic Escherichia coli (GEC). Of 3668 samples collected from October 2012 through September 2018, none were positive for Salmonella, 3 (0.8%) were positive for L. monocytogenes, 8 (0.22%) exceeded the APC critical limit (CL) of 1000 colony-forming units (CFUs)/mL, 15 (0.41%) exceeded the coliform CL of 50 CFU/mL, and 5 (0.14%) exceeded the GEC CL of 10 CFU/mL. Pasteurized liquid whole egg and pasteurized dried egg mix are tested for the presence of Salmonella and for levels of APC and CL. Of 984 pasteurized liquid whole egg samples collected from October 2012 through September 2018, 1 (0.10%) was positive for Salmonella, 29 (2.5%) exceeded the APC CL, and 4 (0.41%) exceeded the coliform CL. Of 380 pasteurized dried egg mix samples collected during this period, none was positive for Salmonella, none exceeded the APC CL, and 3 (0.79%) exceeded the coliform CL. All production lots from which samples found to contain pathogens or to exceed indicator organism CLs were identified and rejected for purchase by AMS. These data suggest that cooked diced chicken and pasteurized egg products produced for federal nutrition assistance programs are done so under effective food safety systems.

Monitoring of Microbial Contaminants of Beef, Pork, and Chicken in HACCP Implemented Meat Processing Plants of Korea.

This research was to evaluate microbial contamination levels in meat samples at hazard analysis critical control point (HACCP)-implemented processing plants that produce beef, pork, and chicken. During a period of about a year, a total of 178 samples (76 from beef, 89 from pork, and 13 from chicken) were obtained from raw materials (21.3%) and final products (78.7%). All samples were determined for each 25 g homogenized one. Samples were analyzed to determine the total aerobic plate count (APC), coliform count (CC), and E. coli count (ECC). By month, APC levels were the highest in September and the lowest in February (p<0.001). In comparison among season, APC levels in meat samples were the highest in the summer and the lowest in winter (p<0.001). By month, the highest CC prevalence was found in August, followed by October and then July (p<0.001). By season, the highest CC was obtained in summer, followed by autumn and then spring (p<0.001). All samples were negative for ECC. There was a direct correlation between the product form and coliform presence (p<0.001). In addition, there was a positive correlation between the APC and CC (r=0.261). The APCs in analyzed samples ranged from below <101 CFU/g to <107 CFU/g. In conclusion, the month and season had significant effects on microbial contamination levels at HACCP implemented processing plants. Interrelationships between (i) the product form and coliform, (ii) the APC and CC were revealed.

Evaluation of the microbiological status of raw pork meat in Korea: modification of the microbial guideline levels for meat.

This study aimed to evaluate the suitability of total aerobic plate count (APC) guidelines for raw pork (< 1 × 107CFU/g) distributed in Korea. The APC values for raw pork collected from meat packing centers and meat shops in three provinces (Seoul/Gyeonggi, Gangwon, and Chungcheong) were reported to be ≤ 1.5 × 106CFU/g. To evaluate practical APC guidelines for pork and meat quality, APC levels and quality traits were determined for pork under cold storage. On day 12, APC for pork was 4.3 × 106CFU/g, which was below the guideline level, while overall acceptability scores were < 3.0, indicating that the pork was rated as not acceptable by sensory panels. Therefore, to satisfy both the microbiological safety of pork and organoleptic quality for consumer palatability, we suggest that the current APC guideline levels for pork should be lowered to 1 × 106CFU/g.

Detection of Multi Drug Resistant Bacteria in Retail Fish Market Water Samples of Vashi, Navi Mumbai

Occurrence of faecal indicator bacteria (FIB) is being reported regularly by various researchers. But there is no information about the microbiological quality of the water used in the retail fish markets. Hence to understand the hygienic status of the water used in retail outlets, about 51 water samples were collected from the retail outlets of Navi Mumbai region and microbiological parameters such as aerobic plate count (APC), faecal indicator bacteria viz., Escherichia coli, faecal streptococci (FS) and sulphite reducing clostridia (SRC) were enumerated. Antibiogram was also carried out for 57 isolates against 20 antibiotics. Results indicated that all water samples harboured higher levels of APC, E. coli, FS and SRC with an average value of 558, 41, 51 cfu/mL and 2.42/20 mL respectively. Ratio between the FS and E. coli i.e., 1:1.25 indicates the multiplication of E. coli in the water used in the retail market. Higher level of resistance was observed for Augmentin and Colistin. Four multi drug resistant (MDR) E. coli were observed in the water samples. Checking of water in the retail fish market is the most neglected area where high level of contamination and MDR bacteria have been detected. So, it was inferred that the repeated use of same water without replacement is a major cause of higher levels of FIB and MRD bacteria in the retail fish market water samples that further leads to their transfer from water to fish. Hence, running water facility should be used to clean the fish.

Evaluation of the Microbiological Status of Raw Beef in Korea: Considering the Suitability of Aerobic Plate Count Guidelines.

This study was conducted to analyze the microbiological contamination status of raw beef distributed in Korea, and evaluate the suitability of current aerobic plate count (APC) guidelines. We analyzed five years (2010-2014) of microbiological monitoring data obtained from the Ministry of Food and Drug Safety and investigated the microbiological status of raw beef collected from meat packing centers and meat shops in the Seoul/Gyeonggi, Gangwon, and Chungcheong regions in August 2015. From 2010-2014, most raw beef (>94%) displayed APC levels of < 1.0 × 106 CFU/g. However, raw beef samples collected from all three regions in August 2015 had comparatively higher APC levels than those reported in previous years. To evaluate the relationship between the APC level and quality, changes in beef loin were evaluated during cold storage for 15 days at 4°C. On day 11, the mean APC level (4.7 × 106 CFU/g) conformed to current guidelines in Korea (1.0 × 107 CFU/g) and the pH value was 5.82. However, the sensory evaluation score for color and overall acceptability was under 3.0, meaning that the beef loin was not acceptable for eating. These results suggest that current APC guideline for raw beef should be lowered to 1.0 × 106 CFU/g to improve both the microbiological safety and palatability of raw beef.

The effect of vacuum packaging on histamine changes of milkfish sticks at various storage temperatures

The effects of polyethylene packaging (PEP) (in air) and vacuum packaging (VP) on the histamine related quality of milkfish sticks stored at different temperatures (−20°C, 4°C, 15°C, and 25°C) were studied. The results showed that the aerobic plate count (APC), pH, total volatile basic nitrogen (TVBN), and histamine contents increased as storage time increased when the PEP and VP samples were stored at 25°C. At below 15°C, the APC, TVBN, pH, and histamine levels in PEP and VP samples were retarded, but the VP samples had considerably lower levels of APC, TVBN, and histamine than PEP samples. Once the frozen fish samples stored at −20°C for 2 months were thawed and stored at 25°C, VP retarded the increase of histamine in milkfish sticks as compared to PEP. In summary, this result suggested the milkfish sticks packed with VP and stored below 4°C could prevent deterioration of product quality and extend shelf-life.

Microbiological Analysis of Rice Cake Processing in Korea

This study was conducted to evaluate the microbial contamination in rice cake materials and products during processing and in the operation environment in nonhazard analysis [and] critical control point factories. Furthermore, the environmental health of the processing facilities and the bacterial and fungal contamination on the workers' hands were investigated. Pour plate methods were used for enumeration of aerobic plate count (APC), yeast and molds (YM), Bacillus cereus, Staphylococcus aureus, and Clostridium perfringens, whereas Petrifilm count plates were used for enumeration of coliforms and Escherichia coli. The respective microbial levels of APC, coliforms, YM, and B. cereus were in the range of 2.6 to 4.7, 1.0 to 3.8, not detected (ND) to 2.9, and ND to 2.8 log CFU/g in the raw materials and in the range of 2.3 to 6.2, ND to 3.6, ND to 2.7, and ND to 3.7 log CFU/g during processing of the rice cake products. During the processing of rice cakes, APC, coliforms, YM, and B. cereus increased during soaking and smashing treatments and decreased after steaming treatment. E. coli, S. aureus, and C. perfringens were not detected in any of the raw materials and operating areas or during processing. B. cereus was detected on the operators' hands at microbial contamination levels of 1.9 ± 0.19 to 2.0 ± 0.19 log CFU/g. The results showed that B. cereus in the end product is presumably the main concern for rice cakes. In addition, the high contamination level of B. cereus during manufacturing processes, including soaking, smashing, and molding, and the absence of B. cereus from the air sampling plates indicated that the contaminated equipment showed the potential risk to cause cross-contamination.

Physical, chemical and microbiological characteristics of fermented surimi with Actinomucor elegans

The physical, chemical and microbiological changes of surimi during surimi pehtze preparation stage, with Actinomucor elegans XH-22 (A. elegans XH-22) as fermentation starter, were investigated. Enzyme assay showed that A. elegans XH-22 could continuously produce protease and α-amylase on surimi surface. Texture profile analysis (TPA) indicated that fermentation for 48 h decreased pH and moisture content and modified the texture properties of surimi. Increases in amino nitrogen and trichloroacetic acid-soluble nitrogen (TCA-N) contents revealed obvious surimi protein degradation, which was further confirmed by size-exclusion HPLC analysis of surimi water soluble protein. Fermentation significantly increased the content of free amino acids and enriched special amino acids such as histidine, phenylalanine and glutamic acid, which could influence the nutritional and sensory properties of fermented surimi product. Considerable levels of aerobic plate count, spores and LAB were detected during the fermentation process. It is thus, from a public health point of view, advisable that the fermentation time in the first stage be controlled to be within 36 h. This research gives a new clue for improving the utilization of low-value fish.