Browsing by Author "Jahncke, Michael L."
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- Acceptability and Shelf-Life of Fresh and Pasteurized Crab Meat Stored Under Different Environmental ConditionsTyler, Carla Gutierrez (Virginia Tech, 2009-02-02)Crab meat is important to the economy of coastal Virginia. The objectives of this study were to complete a shelf-life study on two different packaging styles of fresh crab meat and to test the inhibition capabilities of Carnobacterium piscicola against the pathogen, Listeria monocytogenes. In a shelf-life study, a 12 ounce food grade polyethylene traditional snap-lid container of fresh crab meat was compared to an 8 ounce SimpleStep® trays with Cryovac™ film of equally fresh crab meat sealed with 10,000 cc/m2/24hr oxygen transmission rate (OTR) film. Eleven g samples were used for the microbial shelf-life study conducted at 4°C for 12 days. Aerobic plate counts of crab meat indicated microbial growth from the SimpleStep® trays with Cryovac™ film in 10,000 cc/m2/24hr OTR versus the polyethylene snap-lid was not significant (P>0.05). In objective two, 25 g samples of fresh and pasteurized blue crab (Callinectes sapidus) meat were inoculated with 0.1ml of each, C. piscicola and L. monocytogenes. Three different concentrations of the inoculation levels were studied on select days at both 4°C and 10°C. Microbial spoilage was defined as 107 CFU/g. In fresh crab meat, at both 4°C and 10°C, crab meat spoilage occurred at 7 days or less. In the pasteurized crab meat, at 4°C and 10°C, spoilage did not occur prior to 26 days, and studies were terminated at 28 days of storage. The growth of the two organisms in fresh crab meat was found to be significant for the differing concentration levels and sampling days (P<0.05). The growth of the two organisms in pasteurized crab meat was significant for different concentration levels, sampling days and temperature (P<0.05). In both fresh and pasteurized crab meat, regardless of the inoculation ratios, the L. monocytogenes and C.piscicola followed similar growth trends, but L. monocytogenes was higher in the 2:2 CFU/g concentration and lower at the 6:2 CFU/g concentration level. Although C. piscicola did not completely inhibit L. monocytogenes growth at any concentration ratio, some inhibition was observed.
- Analysis of crab meat volatiles as possible spoilage indicators for blue crab (Callinectes sapidus) meat by gas chromatography-mass spectrometrySarnoski, Paul J.; O'Keefe, Sean F.; Jahncke, Michael L.; Mallikarjunan, Parameswarakumar; Flick, George J. Jr. (Elsevier, 2010-10-01)Traditionally crab meat spoilage has been evaluated using sensory panels. A method was developed using solid-phase microextraction–gas chromatography–mass spectrometry (SPME–GC–MS) to examine the aroma profile of blue crab (Callinectes sapidus) for chemical indicators of spoilage. The chemicals found to correlate best with spoilage were trimethylamine (TMA), ammonia, and indole over a period of 7 days. In addition, chemicals previously not identified in the aroma profile of blue crab were tentatively detected. Scan mode of the mass spectrometer was used to qualitatively determine compounds extracted from the volatile profile of spoiling blue crab by the SPME fiber. Selected ion monitoring (SIM) mode of the mass spectrometer improved resolution, identified compounds at low concentrations, and allowed spoilage related compounds to be detected in one chromatographic run without sample heating. TMA increased linearly. A significant difference in TMA concentrations were found for day 0 and day 4 samples. Indole concentrations corresponded well with sensory and microbial evaluations, in early, mid, and highly spoiled crab meat samples.
- Application of Alternative Technologies to Eliminate Vibrios spp. in Raw OystersHu, Xiaopei (Virginia Tech, 2004-12-15)High pressure processing (HPP) and gamma irradiation were applied to inactivate Vibrio vulnificus (MO624) and Vibrio parahaemolyticus (O3:K6 TX2103) in pure culture and in inoculated live oysters. Vibrio pure culture and inoculated oysters were exposed to pressures of 207 MPa (30 kpsi) to 552 MPa (80 kpsi) for 0 min to maximum of 20 min. More than 5.4 log reductions of V. vulnificus occurred at 345 MPa for 0 min in oysters; 345 MPa for 2 min can achieve 4 log reductions on V. parahaemolyticus. Dosage of 1 kGy gamma-irradiation was proved to be effective in producing Vibrio free oysters with comparable organoleptic quality to raw oysters. Thermal conductivity of shucked oysters was measured to be 0.58 to 0.68 W/m°C, as temperature increased from 0 to 50 °C, using a line heat source probe. The specific heat was measured by differential scanning calorimeter methods. It increased from 3.80 to 4.05 kJ/kg °C, when temperature rose from 10 to 50 °C. The thermal diffusivity was calculated employing the data of thermal conductivity, specific heat and density of shucked oysters. The results showed that, under the tested temperature range, thermal properties did not change significantly with temperature. The dielectric constant and loss factor of oysters were determined by an open-ended coaxial line probe connected to a network analyzer at frequency of 30 MHz to 3000 MHz from 1 to 55 °C. The penetration depth of dielectric heating was calculated to be 1.1 cm with the dielectric constant of 55 and loss factor of 14. A two-dimensional mathematical model was established to simulate the heat transfer of microwave heating using a fish gel. Finite difference method was utilized to solve partial differential heat transfer equations. The model was able to predict the temperature distribution in heated fish gel with an accuracy of ± 8°C. Applying the developed mathematical model, the lethality of Vibrio spp., artificially inoculated in live oysters, was estimated collectively by integrating the individual localized lethality of designated heating units. The predicted lethality was compared with microwave enumeration data on Vibrios in oysters. The observed maximum log reductions by microbial enumeration were 4.4 and 3.4 for V. vulnificus and V. parahaemolyticus, respectively. The lethality calculated by integrating temperature profiles was acceptable. The discrepancy between the estimated lethality and microbial test was attributed to the simplified model construction. The quality of processed oysters, including color, aroma and texture properties, was evaluated instrumentally by a digital image system, an electronic nose and universal testing machine. The performance of two electronic nose systems on their abilities to detect oyster aroma and classify the aroma data into distinct groups was evaluated using a trained sensory panel and microbial tests. Cyranose 320 system has demonstrated potential as a quality assessment tool due to its sound correlation with microbial quality data and sensory evaluation scores. According to the quality measurement results, high pressure processing conditions were recommended to be at 345 MPa for less than 3 min and 379 MPa for less than 1.5 min. Deterioration of the quality was distinct for oyster meats exposed to 60 °C or above by thermal processing. The critical thermal processing condition was identified to be 55 °C for 2 min. With careful control, microwave processing could be considered as a candidate for seafood processing to reduce potential bacterial hazard but still retain the quality of the product.
- Assessment of Current Guidelines for Culinary Preparation Methods of Fish and ShellfishKostal, Jeri Elizabeth (Virginia Tech, 2012-12-17)Consumers regularly decide to consume fish and shellfish raw or undercooked, which can cause foodborne illness due to product contamination or unsafe handling by the consumer. In order to be considered safe for consumption, intact fish and shellfish should be prepared to an internal temperature of 63"C, according to the 2009 FDA Food Code, with Salmonella spp. as the target organism. Focus groups (5 groups, 32 participants) were conducted to determine consumer beliefs and concerns regarding fish and shellfish safety and preparation. Transcripts of focus groups where coded for themes, which were then grouped into categories. Nine categories emerged including: experience, trust, confidence, quality of product, motivation, concerns, cooking procedures, cooking instructions, and knowledge. Emerging themes were used to help develop educational materials to increase consumer ability to properly prepare fish and shellfish. In a separate experiment, participants (n=6) cooked salmon (baked, broiled), tilapia (baked, broiled), and shrimp (broiled, boiled) according to cookbook-based directions. Internal temperatures of products were recorded, with 33.3% of products cooked to a temperature less than 63"C. A group training session was held, during which participants received additional visual and non-oral cues to determine when products were prepared to 63"C and safe food handling practices. After training, participants prepared the same products. Participants demonstrated improved food safety behaviors and were more successful at cooking products to temperatures "63"C (94.4% of products). Improved cooking instruction and educational materials may reduce the risk of foodborne illness from undercooked fish and shellfish.
- Clostridium botulinum toxin development in refrigerated reduced oxygen packaged Atlantic croaker (Micropogonias undulatus)Rheinhart, Courtney Elizabeth (Virginia Tech, 2007-04-30)The purpose of this study was to determine the effects of storage temperature and film oxygen transmission rate (OTR) on toxin development by Clostridium botulinum in refrigerated raw vacuum packaged croaker fillets, and to determine if toxin development precedes microbiological and/or organoleptic spoilage. Raw croaker fillets were vacuum packaged in oxygen-permeable films (OTR of 10,000 cc/m2/24hr or 3,000 cc/m2/24hr) and stored at either 4ºC or 10ºC. Type 83F, 17 Type B, Beluga, Minnesota, and Alaska nonproteolytic strains of C. botulinum were used to inoculate fish prior to vacuum packaging. At both temperatures, microbial spoilage preceded toxin production in fillets vacuum packaged in both film types. At 4ºC microbial spoilage occurred after approximately 7 days for fillets vacuum packaged in the 10,000 cc/m2/24hr OTR film and after 8 days for fillets vacuum packaged in the 3,000 cc/m2/24hr OTR film. However, toxin was not detected until day 8. At 10ºC microbial spoilage occurred after approximately 3 days for fillets vacuum packaged in the 10,000 cc/m2/24hr OTR film, while toxin production occurred on day 5. For fillets vacuum packaged in the 3,000 cc/m2/24hr OTR film microbial spoilage occurred after 4 days. However toxin production did not occur until day 6. In contrast, at both temperatures toxin production preceded or coincided with organoleptic spoilage in fillets vacuum packaged in both film types. At 4ºC organoleptic spoilage occurred after 10 days for fillets packaged in the 10,000 cc/m2/24hr OTR film and after 9 days in the 3,000 cc/m2/24hr OTR film, while toxin production occurred on day 8. At 10ºC organoleptic spoilage occurred after 6 days for fillets packaged in the 10,000 cc/m2/24hr OTR film, and toxin was detected on day 5. For fillets packaged in the 3,000 cc/m2/24hr OTR film and stored at 10ºC, organoleptic spoilage occurred after 6 days, while toxin production occurred on day 6. Although toxin production preceded or coincided with organoleptic spoilage in both film types, this may have been because samples were presented on ice, which could have masked potential odors. This study shows that there are not significant differences between these film types when it comes to microbial and organoleptic spoilage. Therefore lower OTR films, such as 3,000 cc/m2/24hr film, may be used to vacuum package Atlantic croaker.
- Determination of quality attributes of blue crab (Callinectes sapidus) meat by electronic nose and Draeger-Tube analysisSarnoski, Paul J.; Jahncke, Michael L.; O'Keefe, Sean F.; Mallikarjunan, Parameswarakumar; Flick, George J. Jr. (Haworth Press, 2008-01-01)In this study, five groups of sequentially spoiled crabmeat were evaluated by a trained sensory panel, and these results were compared with the findings from a Cyranose 320 Electronic Nose and Draeger gas analyzer. Using the electronic nose with filtered compressed breathing air yielded the best results. Although this approach resulted in 100% separation of the known groups, only 30% of the coded unknown samples were correctly identified. All 5 groups of samples analyzed using Draeger-Tubes were found to be significantly different at α=0.05 using a Tukey-Kramer ANOVA statistical procedure. The coded unknown samples were correctly identified at a rate of 83%. The simplicity and precision of this latter procedure may present opportunities for use of Draeger-Tubes by crab processing industries and other food processing industries as an objective method for quality control.
- The Effect of Thermal Processing Schedules and Unit Operations on the Quality of Blue Crab (Callinectes sapidus) MeatSmith, Jennifer Lynn (Virginia Tech, 1998-10-23)The effects of initial thermal processing, plant sanitation, and employee habits on the microbiological quality of blue crab (Callinectes sapidus) meat were determined in a commercial crab processing facility. Thermal processing was evaluated at 5, 7, and 8 minutes at 250ï °F for the destruction of microorganisms, including Listeria monocytogenes. F-values calculated indicated a sufficient reduction of L. monocytogenes at each processing time. Fresh picked crab meat was evaluated for microbial levels when exposed to ambient temperatures over a four hour period. It was found that time and temperature did not influence the microbial populations significantly except in the fourth hour. Plant sanitation was evaluated based on levels of adenosine triphosphate (ATP) and microbial counts. Areas found to have high levels of ATP typically had low microbial counts, thus suggesting that crab meat residual was the problem. The presence of Listeria species in the plant was determined using a commercial polyclonal antibody test. Listeria species were found under picking tables, on cooler doors, employees' aprons, and on several employees' hands. In a laboratory setting, an automated hand wash was compared with a manual hand wash for the removal of Listeria innocua, as a model for Listeria monocytogenes. It was found that a manual hand wash of 15 seconds was superior to an equal time automated wash. The microbial quality of crab meat was found to be affected by daily plant procedures, and could be changed by modifying procedures.
- The Effects of E-Beam Irradiation, Microwave Energy and High Hydrostatic Pressure on Presence and Health Significance of Cryptosporidium parvum in Eastern Oysters (Crassostrea virginica)Collins, Marina V. (Virginia Tech, 2005-02-09)Foodborne disease outbreaks associated with the protozoan parasite Cryptosporidium spp. are an emerging public health concern. Shellfish, including Eastern oysters (Crassostrea virginica) in Chesapeake Bay and other Atlantic coastal waters, have been identified as a potential source of Cryptosporidium parvum infection for humans. The inactivation of C. parvum and other pathogens in raw molluscan shellfish would provide increased food safety for normal and at-risk consumers. The objectives of this study were to evaluate the efficacy of three alternative food-processing treatments (e-beam irradiation, microwave energy, and high hydrostatic pressure processing) on the viability of C. parvum oocysts in Eastern oysters. Oysters were artificially infected with the Beltsville strain of C. parvum and subjected to the three treatments in separate experiments. The effects of the treatments were evaluated by inoculation of the processed oyster tissues using the neonatal mouse bioassay. E-beam radiation of in-shell and shucked oysters treated with doses of 1.0, 1.5 or 2.0 kGy produced significant reductions (P < 0.05) in C. parvum mouse infectivity. A dose of 2.0 kGy completely terminated the infectivity of C. parvum and did not adversely affect the visual appearance of the oysters. Microwave treatments of shucked oysters at time (temperature) exposures of 1 sec (43.2°C), 2 sec (54.0°C), and 3 sec (62.5°C) produced a reduction in C. parvum mouse infectivity of 26.7%, 33.3%, and 46.7%, respectively. Microwave treatments at 2 sec (54.0°C) and 3 sec (62.5°C) showed extensive changes in oyster meat texture and color. Thus due to lack of efficacy and unacceptable tissue changes, microwave treatment of oysters is not considered a viable food processing method. High pressure processing of shucked oysters at all pressures tested (305 MPa, 370 MPa, 400 MPa, 480 MPa, 550 MPa) significantly (P < 0.05) reduced infectivity of C. parvum oocysts as measured by the neonatal mouse bioassay. A treatment of 550 MPa at 180 sec produced the maximum decrease of C. parvum infectivity (93.3%). The results indicate that HPP (high pressure processing) can produce significant (P < 0.05) reductions in infectivity of C. parvum oocysts. Measurement of tristimulus color values of pressurized raw oysters at extended processing times from 120 sec to 360 sec at 550 MPa showed an increase (P < 0.05) in whiteness. One (e-beam irradiation) of the three food-processing treatments shows promise for commercial applications to reduce public health risks from cryptosporidiosis in Eastern oysters.
- The Effects of Modified Atmosphere Packaging on Toxin Production by Clostridium botulinum in Raw Aquacultured Flounder Fillets and Fully Cooked Breaded and Battered Pollock PortionsArritt, Fletcher M. III (Virginia Tech, 2004-08-02)Fish products under vacuum (VAC) and/or modified atmosphere packaging (MAP) conditions can have a significantly extended shelf life. Prevention of toxin production by Clostridium botulinum is essential for processors of VAC and MAP refrigerated fishery products. The objective of this study was to determine if C. botulinum toxin development precedes microbiological spoilage and sensory rejection in fully cooked breaded and battered Alaskan Pollock or raw aquacultured flounder fillets. Aquacultured summer flounder (Paralichthys dentatus) fillets and fully cooked breaded and battered Alaskan pollock (Theragra chalcogramma) were either aerobically packed (Oxygen Transmission Rate (OTR) of 3,000 cc/m2/24h@70°F for flounder and 6,000 cc/m2/24h@70°F for Pollock), vacuum packed or MAP packaged in a 100% CO₂ atmosphere (OTR of 7.3 cc/m2/24h@70°F). Flounder fillets were stored at either 4 or 10°C while pollock portions were stored at 8 and 12°C. Based on the time to spoilage (counts >107 CFU/g), additional samples were inoculated with five strains of nonproteolytic C. botulinum and analyzed qualitatively for botulinum toxin using a mouse bioassay. For flounder at 4°C, toxin formation did not occur after 35 days in aerobically packed fillets. Vacuum packed and 100% CO2 fillets produced toxin before spoilage at days 20 and 25, respectively. In the aerobic packages at 10°C, toxin production occurred after spoilage at day 8, but before spoilage in the vacuum and 100% CO₂ packages at day 9. Sensory evaluation of toxic vacuum and 100% CO₂ packages at 4°C revealed toxin production proceeded spoilage and absolute sensory rejection. However, at 10°C toxin production was evident only after absolute sensory rejection and microbiological spoilage for aerobically packed fillets. Vacuum packages and 100% CO₂ packages were toxic during spoilage but before absolute sensory rejection. Toxin was not present in the aerobically and 100% CO₂ packed pollock samples at 8°C and the 100% CO2 packed samples at 12°C after 35 days. Aerobically packed portions stored at 12°C first produced toxin at day 25; toxicity occurred after absolute sensory rejection and before spoilage. The vacuum packed portions first formed toxin at day 25 for 8 and 12°C storage before spoilage and absolute sensory rejection.
- Effects of modified atmosphere packaging on toxin production by Clostridium botulinum in raw aquacultured summer flounder fillets (Paralichthys dentatus)Arritt, Fletcher M.; Eifert, Joseph D.; Jahncke, Michael L.; Pierson, Merle D.; Williams, Robert C. (Int Assoc Food Protection, 2007-05-01)Packaging fishery products under vacuum atmosphere packaging (VAC) and modified atmosphere packaging (MAP) conditions can significantly extend the shelf life of raw, refrigerated fish products. There is considerable commercial interest in marketing VAC and MAP refrigerated (never frozen) raw fish fillets. The objective of this study was to determine if Clostridium botulinum toxin development precedes microbiological spoilage in raw, refrigerated flounder fillets. Aquacultured flounder (Paralichthys dentatus) individual fish fillets either were packed with a film having an oxygen transmission rate (OTR) of 3,000 cm3 m-2 24 h-1 at 22.8°C or were vacuum packaged or packaged under 100% CO2 with a film having an OTR of 7.8 cm3 m-2 24 h-1 at 21.1°C and were stored at 4 and 10°C. Samples were analyzed by aerobic plate count (APC) for spoilage and qualitatively for botulinum toxin with a mouse bioassay. The results demonstrate that flounder fillets (4°C) packaged with a film having an OTR of 3,000 were microbiologically spoiled (APC, >107 CFU/g) on day 15, but there was no toxin formation, even after 35 days of storage. However, at 10°C, toxin production occurred (day 8), but it was after microbial spoilage and absolute sensory rejection (day 5). Vacuum-packaged fillets and 100% CO2 fillets (4°C) packaged with a film having an OTR of 7.8 were toxic on days 20 and 25, respectively, with microbial spoilage (APC, >107 CFU/g) not occurring during the tested storage period (i.e., >35 days). At 10°C, in vacuum-packaged flounder, toxin formation coincided with microbiological spoilage (days 8 to 9). In the 100% CO2-packaged fillets, toxin formation occurred on day 9, with microbial spoilage occurring on day 15. This study indicates that films with an OTR of 3,000 can be used for refrigerated fish fillets and still maintain the safety of the product.
- Implementing Targeted Good Manufacturing Practices and Sanitation Procedures to Minimize Listeria Contamination of Smoked Seafood ProductsGall, Ken; Scott, Virginia N.; Collette, Robert; Jahncke, Michael L.; Hicks, Doris; Wiedmann, Martin (2004)The Smoked Seafood Working Group (SSWG), a collaboration of two national industry trade organizations, smoked seafood processors and academia, developed guidelines to minimize Listeria monocytogenes contamination of finished products in smoked seafood operations. The SSWG identified five elements required for a complete Listeria control program: (1) Listeria specific Good Manufacturing Practices (GMPs) and sanitation procedures, (2) employee training, (3) environmental microbiological monitoring and testing, (4) raw material controls, and (5) temperature controls for finished product. This manuscript describes specific GMPs and sanitation procedures to minimize Listeria contamination in smoked seafood operations. Targeted procedures that need to be implemented include GMPs to prevent cross contamination caused by improper design and layout of processing operations, the movement of people and equipment in the plant, and inadequate employee hygiene and food handling practices. In addition, cleaning and sanitation procedures for equipment and the processing plant environment that are designed to target Listeria contamination specifically need to be in place.
- Inhibiting foodborne pathogens Vibrio parahaemolyticus and Listeria monocytogenes using extracts from traditional medicine: Chinese gallnut, pomegranate peel, Baikal skullcap root and forsythia fruitWu, Jian; Goodrich, Katheryn M.; Eifert, Joseph D.; Jahncke, Michael L.; O'Keefe, Sean F.; Welbaum, Gregory E.; Neilson, Andrew P. (De Gruyter, 2018-06-21)Foodborne illnesses have been a heavy burden in the United States and globally. Many medicinal herbs have been cultivated in the US and many of which contain antimicrobial compounds with the potential to be used for food preservation. Methanol/water extracts of pomegranate peel (“PP”, Punica Granatum L.), Chinese gallnut (“CG”, Galla chinensis), Forsythia fruit (“FF”, Forsythia suspensa) and Baikal skullcap root (“BS”, Scutellaria baicalensis) were tested for antimicrobial activity using the agar diffusion assay on tryptic soy agar (TSA) and microdilution assay in tryptic soy broth (TSB). CG and PP extracts showed good to excellent inhibitory effect against Vibrio parahaemolyticus and Listeria monocytogenes in both assays, with a minimum inhibitory concentration (MIC) range from 0.04 to 5 mg/mL. BS had moderate inhibitory effects against V. parahaemolyticus with an MIC of 5 mg/mL in TSB, and against L. monocytogenes with an MIC of 20 mg/mL on TSA. CG was analyzed using LC-MS and fractionated using HPLC. The major components were identified as gallic acid, digallic acid, methyl gallate, and gallotannins (oligo-galloyl-D-glucose, nGG, n = 1~10). Six fractions (I - VI) were collected and their antibacterial activities were tested against L. monocytogenes, and V. parahaemolyticus both on TSA and in TSB. On TSA, fraction III, IV and V inhibited V. parahaemolyticus but no fraction inhibited L. monocytogenes. In TSB, all fractions inhibited V. parahaemolyticus and fractions II - V inhibited L. monocytogenes. Future studies are needed to investigate the effects of medicinal plants on food products.
- Inhibiting Listeria monocytogenes, Vibrio parahaemolyticus and Morganella morganii with Aqueous Methanol Extracts of Punica granatum and Galla chinensisWu, Jian (Virginia Tech, 2014-12-08)Listeria monocytogenes, Vibrio parahaemolyticus and Morganella morganii are closely related to foodborne illnesses caused by the consumption of seafood and ready-to-eat (RTE) food. Traditional Chinese medicines (TCM) have been widely studied as complementary and alternative medicines, and many of them have been verified to have antimicrobial properties. The purpose of this research was to study antimicrobial effects of plant extracts as potential preservatives in seafood products and to identify the primary antimicrobial compounds in plant extracts. Four plants, Pomegranate peel (PP, Punica Granatum L.), Chinese gallnut (CG, Galla chinensis), forsythia fruit (FS, Forsythia suspensa) and Baikal skullcap root (BS, Scutellaria baicalensis) were ground and extracted with 70% methanol, respectively. The extracts were diluted at tested for antimicrobial activities on V. parahaemolyticus, L. monocytogenes and M. morganii both in agar diffusion assay using tryptic soy agar (TSA), and in microdilution assay using tryptic soy broth (TSB). Both CG and PP extracts, with concentrations no lower than 1 mg/ml, significantly inhibited both V. parahaemolyticus and L. monocytogenes (P<0.01) and reduced the bacterial population by up to 4 logs. No significant inhibition was observed with FS and BS extracts, except for BS at 5 mg/ml on V. parahaemolyticus. None of the extracts showed significant inhibition against M. morganii. The antibacterial activities of CG and PP 70% methanol extracts were tested in ground raw tuna and cooked tail-on shrimp. The extracts were mixed in tuna with final concentration at 1.7 mg/ml, and applied as soaking treatments (5 mg/ml) for shrimp. Both CG and PP extracts inhibited V. parahaemolyticus on both food matrices while only CG significantly inhibited L. monocytogenes. The 70% methanol crude extract of CG was analyzed by HPLC and LC-MS. Oligo-galloyl-O-glucose (nGG, n=1-10) are the major compounds in CG. The crude CG extract was fractionated using HPLC and the fractions were collected based on elution time and tested for their antimicrobial activities against V. parahaemolyticus and L. monocytogenes using agar diffusion methods. The fractions containing 3GG-8GG were the most active antimicrobials on both bacteria.
- Instrumental Methods for Determining Quality of Blue Crab (Callinectes sapidus) MeatSarnoski, Paul J. (Virginia Tech, 2007-05-03)The purpose of this study was to find an alternative instrumental method to sensory analysis and to further investigate the aroma properties of spoiling blue crab meat. This was accomplished by use of a Cyranose 320™ Electronic Nose, Draeger-Tubes®, and solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). These techniques were compared to the more established techniques for determining quality of blue crab meat of sensory and microbiological analysis. Three different electronic nose methods were used to evaluate five sequentially spoiled groups of crab meat. The manufacturer's recommended setup only resulted in a 30 % correct separation of the known groups, and only 10 % of the samples were correctly identified when coded unknown samples were used to validate the electronic nose training results. The compressed air method which utilized compressed tank breathing air, filtered through activated carbon and moisture traps resulted in 100 % separation of the known groups, but only correctly identified 20 % of the coded unknown samples. Draeger-Tubes® were found to be more accurate and precise compared with the electronic nose. All 5 groups of samples analyzed using Draeger-Tubes® were found to be significantly different at α = 0.05 using a Tukey-Kramer ANOVA statistical procedure. The coded unknown samples were correctly identified at a rate of 83 %. The simplicity and rapidness of this procedure allows it to possibly be an alternative for the crab industry as an alternative to sensory analysis. SPME-GC-MS found trimethylamine (TMA), ammonia, and indole to best correlate with spoilage of blue crab meat. TMA was found to be sensitive to the minor changes in the early stages (0 - 4 days of refrigerated storage) of spoilage for blue crab meat. Indole corresponded well with sensory results, which suggests that indole may be a promising indicator for detecting early, mid, and highly spoiled samples. It is feasible that these methods can be applied to other crustaceans to determine spoilage level.
- Optimization of the Quality and Safety of Cooked Seafood ProductsBrookmire, Lauren (Virginia Tech, 2010-09-10)Seafood products are a common consumer choice and a variety of cooking methods are used in seafood preparation. Although often cooked, products such as shrimp and salmon remain some of the most common carriers of foodborne disease. Cooking these products at elevated temperatures efficiently reduces foodborne disease causing pathogens to a safe level, but applying too much heat to seafood products can produce an overcooked, low quality food. It is necessary to investigate the cooking processes used in seafood preparation and establish appropriate consumer cooking parameters that optimize both the quality and microbial safety of the products. To achieve these goals, this study develops mathematical models for the inactivation of Salmonella sp., change in quality attributes, and the product heating profiles during the cooking process for shrimp and Atlantic salmon. Studies were performed to monitor the product heating profile during the baking and boiling of shrimp and the baking and pan-frying of salmon. Product color, texture, moisture content, mass loss, and pressed juice were evaluated during the cooking processes as the products reached the internal temperature recommended by the FDA. Studies were also performed on the inactivation of Salmonella cocktails in homogenized and non-homogenized shrimp and salmon. To effectively predict inactivation during cooking, the Bigelow, Fermi distribution, and Weibull distribution models were applied to the homogenized data. Minimum cooking temperatures necessary to destroy Salmonella sp. in shrimp and salmon were also determined. The heating profiles of the two products were modeled using the finite difference method. Temperature data directly from the modeled heating profiles was then used in the kinetic modeling of quality change and Salmonella inactivation during cooking. It was concluded that consumers need to judge the doneness of both shrimp and Atlantic salmon by the lightness factor (CIE L*) of the core region of both products. The core region's lightness factor, which a consumer may consider as opaqueness, more accurately represented the thermal doneness than the external qualities. The FDA's current recommendations for a 3 log reduction for intact seafood products and homogenized seafood products were each analyzed. Results were in agreement with the recommended 68°C plus 15 seconds for homogenized products. For intact products, shrimp inactivation results were in agreement with the recommended 63°C plus 15 seconds, but intact salmon achieved only a 2 log reduction by the temperature-time combination. It was also found that predictive models can effectively describe the survival data for two Salmonella cocktails. The Weibull distribution model, which takes into account any tailing effect in survival data, fit the survival data of Salmonella in shrimp acceptably. The Fermi distribution model, which incorporates any shouldering effect in data, was an acceptable fit for the inactivation data for salmon. Using three-dimensional slab geometry for salmon fillets and two-dimensional frustum cone geometry for shrimp resulted in acceptable model predictions of thermal distributions for the cooking methods studied. The temperature data attained directly from the modeled heating profiles was effectively used in the predictive quality and inactivation models. Agreeable first-order kinetic models were formulated for Î L and Î C color parameters in shrimp and salmon. Other kinetic models formulated were for texture change in salmon and pressed juice in both salmon and shrimp. Using a fixed inactivation level of 3 logs and a fixed quality of 95% best quality, optimal cooking conditions were determined that both provide a high quality product and assure microbial safety. Based on the specific cooking methods in this study, the optimal boiling times for extra jumbo and colossal sized shrimp were 100 seconds and 159 seconds, respectfully. The optimal oven baking times were 233 seconds for extra jumbo shrimp and 378 seconds for colossal shrimp. For Atlantic salmon, the optimal oven baking time was 1132 seconds and the optimal pan frying time was 399 seconds.
- Overview of Good Aquaculture PracticesSchwarz, Michael H.; van Senten, Jonathan; Jahncke, Michael L.; Lazur, Andrew M. (Virginia Cooperative Extension, 2019-02-22)Provides an overview and general framework for good aquaculture practices, oriented to Virginia's growing pond and recirculating aquaculture production systems.
- Overview of Good Aquaculture PracticesSchwarz, Michael H.; Jahncke, Michael L.; Lazur, Andrew M. (Virginia Cooperative Extension, 2010-05-14)Provides an overview and general framework for good aquaculture practices, oriented to Virginia's growing pond and recirculating aquaculture systems aquaculture production sectors.
- Pescados y Mariscos en Virginia: Inocuos y NutritivosVillalba, Abigail; Serrano, Elena L.; Sarjahani, Andy; Schwarz, Michael H.; Jahncke, Michael L. (Virginia Cooperative Extension, 2010-01-12)Proporciona la informaciòn necesaria para ayudar a garantizar que los productos del mar que se compra y consume es segura y nutritiva.
- Public, animal, and environmental health implications of aquacultureGarrett, E. Spencer; dos Santos, Carlos Lima; Jahncke, Michael L. (1997-10)Aquaculture is important to the United States and the world's fishery system. Both import and export markets for aquaculture products will expand and increase as research begins to remove physiologic and other animal husbandry barriers. Overfishing of wild stock will necessitate supplementation and replenishment through aquaculture. The aquaculture industry must have a better understanding of the impact of the ''shrouded'' public and animal health issues: technology ignorance, abuse, and neglect. Cross-pollination and cross-training of public health and aquaculture personnel in the effect of public health, animal health, and environmental health on aquaculture are also needed. Future aquaculture development programs require an integrated Gestalt public health approach to ensure that aquaculture does not cause unacceptable risks to public or environmental health and negate the potential economic and nutritional benefits of aquaculture.
- Role of package type on shelf-life of fresh crab meatTyler, Carla Gutierrez; Jahncke, Michael L.; Sumner, Susan S.; Boyer, Renee R.; Hackney, Cameron Raj; Rippen, Thomas E. (Food Protection Trends, 2010)Microbiological quality of fresh (not pasteurized) crab meat stored at 4°C in a 340 g (12 oz) food grade polyethylene traditional snap-lid container and equally fresh crab meat stored at 4°C in a 227 g (8 oz) SimpleStep® tray sealed with Cryovac™ film (oxygen transmission rate of 10,000 cc/m2/24 h) was evaluated over a 12-day period. Aerobic plate counts were conducted on storage days 0, 4, 6, 8, 10 and 12. Anaerobic plate counts were conducted on storage days 0, 5 and 12. Aerobic plate counts of crab meat from the two containers did not differ (P > 0.05). Analysis of anaerobic microbial growth indicates that sampling days were significant (P < 0.05), but container type or style was not significant (P > 0.05). Oxygen and CO2 in the package headspace was significantly different between container types (P < 0.05). Gas concentration between sampling days was not significant (P > 0.05). Results of this study demonstrate that there were no significant differences in refrigerated shelf life of crab meat packaged in SimpleStep® trays with Cryovac™ film versus the traditional polyethylene snap-lid container packaging (P > 0.05).