CATALATIC ACTIVITY AS AN INDICATOR OF END-POINT TEMPERATURES IN BREADED, HEAT PROCESSED CHICKEN PATTIES

Adequate heat-processing of meat and poultry products to destroy harmful pathogens is important to the consumer's safety. The catalatic activity, defined as the decomposition of H₂O₂ into H₂O and O₂, has been evaluated as a potential indicator of heat treatment adequacy for chicken patties. Commercially prepared breast and leg meat patties were processed through a belt type grill to various end-point temperatures (EPTs) and their catalatic activities monitored for up to 120 min. All breast samples heated to EPTs of ≤ 69C and all leg samples heated to ≥ 68C showed positive reactions after incubation for 10 min. As the EPT increased, fewer samples were positive, indicating a decrease in the catalatic activity. For EPTs of ≥ 73C, three of 12 breasts and one of 17 leg patties showed positive activity after 30 min incubation. The catalatic activity test may offer a simple and rapid procedure for estimating the EPT at 73C with 3-4C variation for commercially processed chicken patties.     

Fate of Aflatoxin M1 during Manufacture and Storage of Feta Cheese

ABSTRACT:  The effect of feta cheese manufacture on aflatoxin M₁ (AFM₁) content was studied using an enzyme immunoassay technique. Feta cheese was made from milk spiked with 1 and 2 μg AFM₁ per kilogram milk. Pasteurization at 63 °C for 30 min caused <10% destruction of AFM₁. During cheese making, the remaining AFM₁ in milk was partitioned between curd and whey with two-thirds retained in the curd and one-third going into the whey. Cheeses were then stored for 2 mo in 8%, 10%, and 12% brine solutions at 6 and 18 °C. There was a 22% to 27% reduction of AFM₁ during the first 10 d of storage, with slightly more loss as salt concentration increased and when the cheese was stored at 18 °C. Further storage caused only slight decrease in AFM₁ and after 30 d of brining there was no difference in AFM₁ content of the cheese based upon salt concentration of the brine. At 18 °C, no further losses of AFM₁ occurred after 30 d, and at 6 °C, there was continued slight decrease in AFM₁ levels until 50 d. After 60 d of brining, there was a total loss of 25% and 29% of the AFM₁ originally present for cheese brined at 6 and 18 °C, respectively. Thus, the combination of pasteurization, conversion of milk into feta cheese, and at least 50 d storage of cheese in brine caused a total loss of about 50% of the AFM₁ originally present in the raw milk.     

Low temperature pasteurization to reduce the risk of vibrio infections from raw shell-stock oysters

Vibrio vulnificus and V. parahaemolyticus are natural inhabitants of estuarine environments and may be transmitted to humans by ingestion of raw oysters. This study focused on the use of low temperature pasteurization, to reduce these Vibrio spp. to nondetectable levels, thus reducing the risk of infection associated with raw oyster consumption. Artificially inoculated V. vulnificus and V. parahaemolyticus and naturally-contaminated V. vulnificus in live oysters were pasteurized at 50%deg;C for up to 15min. Samples of processed and unprocessed oysters were enumerated for V. vulnificus, V. parahaemolyticus, and aerobic spoilage bacteria for 0-14 days. Low temperature pasteurization was effective in reducing these pathogens from > 100000 to non-detectable levels in less than 10min of processing. Spoilage bacteria were reduced by 2-3 logs, thus increasing the shelf-life for up to 7 days beyond live unprocessed oysters. Vibrio vulnificus in control oysters was reduced by 102 during ice storage alone. Following pasteurization and during a temperature storage abuse study (24h at 22°C), V. vulnificus was not recovered. During this storage period spoilage bacteria exceeded 1 million/g oyster meat.     

EFFECT OF WATER ACTIVITY ON THE GROWTH OF STAPHYLOCOCCUS AUREUS AT MEAT-CHEESE INTERFACES

There is increased marketing of ready-to-eat nonrefrigerated snack foods which consist of meat or sausage products with low or intermediate moisture levels combined with high moisture food products, i.e., cheese products. Packaging the intermediate moisture meat in direct contact with a high moisture food might change the water activity (a_w) of the products sufficiently to support growth of Staphylococcus aureus at contaminated interfaces. To evaluate this possibility, sterile sausage slices (a_w= 0.60 to 0.82) were surface inoculated with log 2-3 CFU/g of S. aureus, interfaced with processed cheese slices (a_w= 0.94), vacuum packaged, and incubated at 19, 28, 37C and at cyclic temperature of 19–37–19C. S. aureus levels and water activities were determined weekly for 0 to 9 weeks. The a_w at the interface changed rapidly and reached an a_w that supported S. aureus growth. Growth of S. aureus occurred under all test conditions when the samples were stored at 28 and 37C. At 19C storage S. aureus remained viable for the length of the study.     

Control of nonproteolytic Clostridium botulinum types B and E in crab analogs by combinations of heat pasteurization and water phase salt.

Water phase sodium chloride (WPS) levels of 1.8 to 3.0% in combination with heat pasteurization for 15 min at temperatures of 75, 80, 85, and 90 degrees C were evaluated as methods for the inactivation or inhibition of nonproteolytic, psychrotrophic Clostridium botulinum types B and E in crab analogs (imitation crab legs) subsequently stored at 10 and 25 degrees C. Samples inoculated with 10(2) type B or E spores per g prior to pasteurization remained nontoxic for 120 days at 10 degrees C and for 15 days at 25 degrees C. With 10(4) type E spores per g and 80 degrees C pasteurization, > or = 2.4 and 2.7% WPS was required for inhibition at 10 and 25 degrees C storage, respectively. Pasteurization at 85 degrees C decreased the inhibitory level of WPS to 2.1% at 10 degrees C and to 2.4% at 25 degrees C. When the inoculum was 10(4) type B spores per g, samples with 2.7% WPS were toxic after 80 days of storage at 10 degrees C. Samples inoculated with 10(3) type B spores per g and processed at 85 degrees C remained nontoxic for 15 days at 25 degrees C with a WPS of > or = 2.4%. When pasteurization was carried out before inoculation and packaging, 1.8% WPS prevented toxin production by 10(2) and 10(4) type E spores per g for 30 days at 10 degrees C, and this time period increased as the WPS concentrations increased. Three percent WPS prevented toxin production by 10(4) type E spores per g in vacuum-packaged analogs stored 110 days at 10 degrees C. Pasteurization processes used in these experiments, however, do not inactivate the heat-resistant proteolytic types of Clostridium botulinum. Therefore, the most important factor controlling the growth of this bacterium is continuous refrigeration below 3.0 degrees C or frozen storage of the finished product.     

中华绒螯蟹雌雄蟹肉中游离氨基酸的提取工艺优化

本文以中华绒螯蟹雌雄蟹肉为原料,探究了超声时间、超声温度、超声功率、提取次数和料液比对其游离氨基酸提取量的影响,以游离氨基酸提取量为衡量指标,进行四因素三水平正交试验,得到最优提取工艺。结果表明:各提取影响因素对雌雄蟹肉中游离氨基酸提取量的影响由大至小依次均为料液比、提取次数、超声时间和超声温度。正交试验得出的雄蟹最佳提取工艺为超声功率200W,超声提取温度40℃,料液比为1:30(g/mL)超声提取7 min,提取次数为3次,在此条件下得到的雄蟹蟹肉游离氨基酸提取量为(26.227±0.244)mg/g;雌蟹最佳提取工艺为超声功率200W,超声提取温度20℃,料液比为1:40(g/mL)超声提取5 min,提取次数为2次,在此条件下得到的雌蟹蟹肉游离氨基酸提取量为(25.101±0.135)mg/g。     

Non-volatile taste active compounds in the meat of Chinese mitten crab (Eriocheir sinensis)

The non-volatile taste active compounds, including soluble sugars, succinic acid, free amino acids and flavour 5′-nucleotides in the meat of Chinese mitten crab (Eriocheir sinensis) were analyzed, and their taste impacts were evaluated by taste active values (TAVs) and equivalent umami concentration (EUC) methods. The total free amino acid content of crab meat was 20.9 mg/g. Arginine, glycine and alanine were the major free amino acids, accounting for more than 70% of the total free amino acids. 5′-Adenosine monophosphate (AMP) was the main flavour 5′-nucleotide (75.3 mg/100 g), followed by 5′-inosine monophosphate (IMP) (34.4 mg/100 g) and 5′-guanosine monophosphate (GMP) (2.3 mg/100 g). Arginine, glycine, alanine, glutamic acid, IMP and AMP were of high TAV (greater than one), and they had strong taste impacts on the crab meat flavour. Glycine and alanine contributed to the major sweet taste, while glutamic acid, IMP and AMP contributed to the strong umami taste. As the TAVs of soluble sugar, succinic acid and bitter free amino acids were lower than one, thus those compounds are likely to have insignificant impact on the taste of the crab meat. The EUC was 4.2 g MSG/100 g crab meat, which meant that the umami taste of the crab meat was very intense.     

我国沿海主要海域雌性三疣梭子蟹呈味成分含量的比较

以我国渤海、黄海、东海和南海4个海域中雌性三疣梭子蟹的肝胰腺、性腺和体肉为研究对象,采用电子舌、氨基酸自动分析法以及高效液相色谱法研究不同海域的生长环境对雌性三疣梭子蟹3个可食部位游离氨基酸含量和呈味核苷酸化合物的变化,并采用滋味强度值和味精当量对呈味成分的强度进行评价。结果表明:电子舌可对4个海域中雌性三疣梭子蟹的肝胰腺、性腺和体肉进行有效区分;在肝胰腺部分,游离氨基酸总量是3个可食部位最高的,3种呈味核苷酸中肌苷酸和腺苷酸的含量较高;在不同海域中,渤海肝胰腺组游离氨基酸总量最高,为3 315.05 mg/100 g,且其味精当量值最高,为15.87 g MSG/100 g;南海肝胰腺组游离氨基酸总量最低,但甜味氨基酸含量所占比例最高,为63.10%,并且呈味核苷酸含量最高,肌苷酸和腺苷酸的滋味强度值大于1。蟹的性腺部分,呈味核苷酸含量与味精当量值是3个可食部位中最高的,其中南海性腺的味精当量值为36.46 g MSG/100 g,是4个海域中最高。蟹的体肉部分中肌苷酸含量较高,黄海体肉肌苷酸组中含量较低,其滋味强度值小于1,对体肉的滋味无直接贡献,但黄海体肉组游离氨基酸总量最高,为2 564.44 mg/100 g;东海体肉组的味精当量值最高,为7.19 g MSG/100 g。     

COLOR IMPROVEMENT OF KOSHER BEEF USING SODIUM ASCORBATE AND ERYTHORBATE

The koshering process involves soaking meat in water followed by massive surface salting and rinsing to remove the salt. This process causes undesirable discoloration during storage at 4C, as compared to nonkosher beef (P<0.01). Beef steaks were dipped into sodium ascorbate (SA) or erythorbate (SE) solutions for various time periods. Untreated steaks, from the same cut, served as controls. All samples were packaged into modified atmospheres of 65% O₂ and 35% CO₂. The color of sample was observed periodically during illuminated storage at 4C. The typical red color was maintained at 4C for up to 21 days when the meat was dipped for 1 min in a 2 or 4% SE solution (pH 6.5), packaged in 65% O₂ and 35% CO₂, while the controls showed severe discoloration after 2 to 3 days. The treatment with SE had also a positive effect in reducing initial total microbial counts by 1.5 log CFU/g.     

Thermal Gelation of Previously Cooked Minced Meat from Jonah Crab (Cancer borealis)

ABSTRACT:  Crab processing typically involves picking meat from whole cooked product. Remaining meat can be recovered as mince and potentially processed into value-added products. This study focused on gelation of commercially processed crab mince. Objectives of the research were to determine the effects of cryoprotectants, freezing, and various heat treatments on gel formation of washed mince from previously cooked crab. Previously frozen minced meat from thermally processed Jonah crab was washed to remove soluble components. Four different treatments were applied to the washed mince: (1) freezing with cryoprotectants, (2) freezing with no cryoprotectants, (3) no freezing with cryoprotectants, and (4) no freezing with no cryoprotectants. Unwashed mince was used as a control treatment. Sodium chloride (2.5%) was mixed into the mince prior to stuffing into sausage casings and heating at 35 °C/30 min, 90 °C/30 min, or 35 °C/30 min followed by 90 °C/30 min. Gels were tested for proximate composition, color, water-holding capacity, and gel strength. All mince samples formed gels except for the unwashed control. Gels with no cryoprotectants had 10% to 20% greater water holding capacity, lower L* values, and greater gel strength than those with cryoprotectants. Freezing of washed mince resulted in lower water-holding capacity of gels and higher a* values. A 2-stage heating treatment resulted in gels with the greatest gel strength, whereas gels cooked at 35 °C had the greatest distance to fracture. Results indicate that protein gels can be formed using previously cooked crab meat, which may be useful in the development of value-added products.     

INACTIVATION OF BACTERIAL SPORES BY COMBINED ACTION OF HYDROSTATIC PRESSURE AND BACTERIOCINS IN ROAST BEEF

Foodborne bacterial spores are normally resistant to high hydrostatic pressure; however, at moderate pressure, they can be induced to germinate and outgrow. At this stage, they can be killed by bacteriocin-based biopreservatives (BP-containing pediocin and nisin at 3:7 ratio; BP_X, BP + 100 μg/mL lysozyme; BP_Y, BP_X+ 500 μg/mL Na-EDTA). Based on this principle, spores of the meat spoilage organism, Clostridium laramie (1–2 × 10² spores/bag) alone or a mixture of four clostridial spores (5 × 10³ spores/bag), Clostridium sporogenes, Clostridium perfringens, Clostridium tertium, and Clostridium laramie, were inoculated in roast beef in the presence of 5000 AU/g of bacteriocin-based biopreservatives. The roast beef samples were subjected to hydrostatic pressure (HP) at 345 MPa for 5 min at 60C and stored at 4 or 12C for 84 days or at 25C for 7 days. The HP treatment of roast beef samples inoculated with a mixture of clostridial spores could be stored for 42 days at 4C. The HP in combination with either BP_X or BP_Y extended the shelf-life of roast beef up to 7 days at 25C. The combined treatment of HP and BP controlled the growth of C. laramie spores and extended the shelf-life of roast beef for 84 days when stored at 4C.     

EFFECTS of SHUCKING METHOD ON OPENING, MEAT YIELD and SELECTED QUALITY PARAMETERS of WEST AFRICAN CLAM, GALATEA PARADOXA (BORN)

Samples (n= 100) of freshly harvested clams ( Galatea paradoxa Born) from the Cross River, Nigeria, were subjected after 24 h depurations to heat treatment (steam and water at 60, 70, 80, 90, 100C) for 1–6 min to evaluate the effects of level of heat treatment on opening, meat yield, sensory properties, proximate composition, pH and electrical conductivity (EC). Observations were also made on the effects of some chemical shucking aids (NaOH, NaHCO₃, Na₂CO₃, NaCl) in 60C water on these parameters.
Results showed that boiling water was most effective in opening the clams, with 100% shucking achieved in 1 min. Steam was least effective, requiring 6 min for 100% opening. Temperature significantly and strongly influenced meat yield (p<0.05;r=-0.92). pH (p<0.01; r=0.97), EC (p<0.05; r =0.65) and sensory properties (p<0.05). In general, shucking aids reduced opening time, significantly p<0.05) raised meat pH and EC, and with the exception of NaCl, insignificantly (P>0.05) improved yield. NaHCO₃, and Na₂CO₃, which cut time for 100% opening from 5 min to 2 min were most effective. There were slight but significant (P <0.05) drops in meat moisture, crude protein and ash contents with increase in temperature (T). the model equations, pH = 4.69 + 0.021 T and % yield = 39.95–0.172 T were found to reliably predict meat pH and yield, with insignificant differences (P>0.05) between predicted and experimental values.     

电子束辐照对细点圆趾蟹肉营养及滋味成分的影响

以细点圆趾蟹蟹肉为材料,研究电子束辐照对蟹肉营养和滋味成分的影响,为电子束辐照技术在水产品加工中的应用提供依据。结果表明：辐照处理后7 kGy及以上剂量组蟹肉总氨基酸和非必需氨基酸含量下降比较明显;辐照没有改变蟹肉的第1和第2限制性氨基酸种类,各组蟹肉必需氨基酸与总氨基酸之比和必需氨基酸与非必需氨基酸之比均分别超过40%和60%,为质量较好的蛋白质;脂肪酸分析结果显示,电子束辐照对蟹肉饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸总量均无显著影响;随着辐照剂量增加,蟹肉中的游离氨基酸总量呈下降趋势,但呈鲜、甜鲜味的游离氨基酸含量有所增加,说明适当的辐照剂量对蟹肉氨基酸的呈味有改善作用;蟹肉中的主要呈味核苷酸是5’-肌苷酸二钠,辐照后蟹肉5’-腺苷酸和5’-肌苷酸二钠含量有所上升,而5’-鸟苷酸二钠含量有所下降,辐照对蟹肉鲜味有提升作用;结合鲜味氨基酸和呈味核苷酸的鲜味协同效应,各辐照组味精当量值均高于对照组,其中1 kGy组蟹肉的味精当量值最高,达到17.92%。综合蟹肉氨基酸、脂肪酸组成和滋味成分的变化规律分析,认为1～9 kGy剂量电子束辐照对蟹肉营养和滋味没有明显的负面影响,可用于对蟹肉进行前处理。     

Compositional characteristics and nutritional quality of Chinese mitten crab (Eriocheir sinensis)

Chinese mitten crab (Eriocheir sinensis) was analyzed for proximate composition, minerals, amino acids and fatty acid composition, and also evaluated for nutritional quality. The yields of crab meat and edible viscera were 24.2% and 9.2%, respectively. The crab meat contained 18.9% crude protein. About 80% of the protein resided in the crab meat portion, while about 90% of the fat was in the viscera. Chinese mitten crab was an excellent source of minerals, particularly zinc, iron, copper and phosphorus. The crab protein contained high amounts of glutamic acid (151 mg/g), aspartic acid (99 mg/g), arginine (99 mg/g), lysine (81 mg/g) and leucine (77 mg/g), and it was a high quality protein with well-balanced essential amino acid compositions. Twenty six fatty acids were found in the crab oil. The monounsaturated fatty acids were predominant with a percentage of 49.8. Oleic acid (18:1) was the dominant fatty acid, followed by palmitoleic acid (16:1), palmitic acid (16:0) and linoleic acid (18:2n − 6); and the percentages were 31.0, 14.3, 14.2 and 11.9, respectively. The ratio of n − 6/n − 3 polyunsaturated fatty acids (PUFAs) was 2.2, and this is a n − 3 PUFA-rich food. In short, the results showed that Chinese mitten crab is a nutritious food.     

PASTEURIZATION OF VACUUM-SEALED PACKAGES OF SUMMER SAUSAGE INOCULATED WITH LISTERIA MONOCYTOGENES

Packages containing chubs of summer sausage were inoculated with about 10⁸ cfu/mL of a three-strain mixture of Listeria monocytogenes and vacuum sealed. The fate of the pathogen was then monitored after pasteurization at 150F (66C), 170F (77C), 190F (88C) and 21 OF (99C) for 0 to 240 s. Pathogen numbers were reduced by about 3 log₁₀ cfu per gram within 30, 60, or 90s at 21 OF (99C), 190F (88C), or 170F (77C), respectively, whereas numbers were reduced by <2.0 log₁₀ cfu per gram after 240 s of heating at 150F (66C). The calculated D values were 2.08 min at 150F (66C), 0.84 min at 170F (77C), 0.37 min at 190F (88C), and 0.28 min at 21 OF (99C). These results establish the feasibility of using pasteurization to control L. monocytogenes in packaged summer sausage.     

Pasteurization Effect on Fatty Acid Stability in a Sous Vide Product Containing Seal Meat (Phoca groenlandica)

The stability of selected fatty acids in a sous vide product containing seal meat (Phoca groenlandica) plus vegetables was examined. The product was processed at five time/temperature combinations. In addition to pasteurized and nonpasteurized products, a conventionally heated (about 100°C) product was prepared for comparison. Unsaturated fatty acids constituted 81.3% of the total fatty acids in the nonpasteurized product. Eicosapentaenoic acid (EPA, 20:5n-3) was 0.9 mg/g and docosahexaenoic acid (DHA, 22:6n-3) was 1.2 mg/g in the nonpasteurized product. EPA was 19% higher and DHA 68% higher in the sample pasteurized at 65°C vs the conventional. Furthermore, pasteurization at lower temperatures retained 22% more EPA and 57% more DHA than pasteurization at higher temperatures.     

北海沙蟹特征滋味成分的分析

为研究沙蟹中的非挥发性滋味物质,采用氨基酸自动分析仪、高效液相色谱仪和电感耦合等离子体发射光谱仪检测沙蟹的游离氨基酸、5’-呈味核苷酸、有机酸以及无机离子等呈味物质的含量,并采用味道强度值（taste activity value,TAV）确定其中主要的呈味物质及贡献,最后通过味精当量（equivalent umami concentration,EUC）分析鲜味氨基酸和呈味核苷酸之间的协同作用,并对其鲜味进行评价。结果表明,精氨酸、组氨酸、甘氨酸、丙氨酸、谷氨酸、5’-单磷酸肌苷二钠、5’-单磷酸鸟苷二钠和Na＋的TAV大于1,是沙蟹滋味的主要贡献者。EUC值以谷氨酸钠质量计,结果表明沙蟹样品的EUC值为6.4?g/100?g,说明沙蟹具有强烈的鲜味特点。     

Amino Acid Composition of Breast and Thigh Meat from Broilers Produced in Four Locations of the United States

Broiler breast and thigh meat samples from birds grown and processed in four locations of the United States were analyzed for amino acid composition. On a percent protein basis amounts of valine, leucine, isoleucine, and histidine were significantly greater (p < 0.01) in breast meat and glycine, hydroxyproline, hydroxylysine, threonine, and serine were greater in thigh meat. Area of production and/or related management practices appeared to influence the concentrations of about half the amino acids. Meat from male broilers had more hydroxyproline than did meat from females.     

Carotenoids in crabs from marine and fresh waters of India

Quantitative and qualitative distribution of carotenoids in meat and shell of major marine crab (Charybdis cruciata) and fresh water crab (Potamon potamon) from Indian waters was assessed. The total carotenoid content was low in both species of crabs analysed, highest being 11.0 μg/g in shell of marine crab. Thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) of carotenoid extracts indicated that the marine crab contained astaxanthin and its esters as major carotenoids and zeaxanthin was major carotenoid in fresh water crab extract. Astaxanthin and its esters contributed 67.6 and 65.5 g/100 g of total carotenoids in meat and shell of marine crab. The zeaxanthin content (g/100 g) in the carotenoid extract of meat and shell of fresh water crab was 42.0 and 74.8 of total carotenoids. The carotenoid extracts from both the crabs had higher level of unsaturated fatty acids. Oleic acid (C18:1) and palmitoleic acid (C16:1) were the predominant unsaturated fatty acid in carotenoid extract from meat of marine and fresh water crab, respectively. In the carotenoid extract from shell, eicosenoic acid (C20:1) in marine crab and linolenic acid (C18:3) in fresh water crab were the major unsaturated fatty acids.     

CALCIUM CHLORIDE EFFECTS ON TBA VALUES OF COOKED MEAT

Ground chicken breast and beef top round (semimembranosus) muscles were treated with CaCl₂ (0.05, 0.10, 0.15, and 0.20% on final sample weight basis) and cooked to an internal temperature of 80C. Cooked samples were aerobically stored at 4C for 0 or 4 days and analyzed for 2-thiobarbituric acid (TBA)-reactive substances. Results indicated that CaCl₂ can either inhibit or accelerate lipid oxidation in cooked meat depending on its concentration/meat animal species. TBA values of chicken samples were decreased by CaCl₂ used at ≥ 0.1% of final weight. However, only beef samples treated with the highest CaCl₂ level (0.20%) tended to have lower TBA values when compared to control samples (treated with deionized water only). CaCl₂ used at low levels (0.05% for chicken and ≤0.15% for beef) tended to elevate cooked meat TBA values.