Isolation and identification of angiotensin I-converting enzyme inhibitory peptides derived from thermolysin-injected beef M. longissimus.

OBJECTIVE: This study identified angiotensin I-converting enzyme (ACE) inhibitory peptides in beef M. longissimus injected with thermolysin (80 ppm) and stored for 3 days at 5°C. METHODS: Crude peptides (molecular weight <3 kDa) were obtained from the thermolysin hydrolysate and separated into seven fractions. Fraction V showing the highest ACE inhibitory activity was further fractionated, yielding subfractions V-15, V-m1, and V-m2, and selected for superior ACE inhibitory activity. Finally, twelve peptides were identified from the three peak fractions and the ACE inhibitory activity (IC50) of each peptide was evaluated. RESULTS: The Leu-Ser-Trp, Phe-Gly-Tyr, and Tyr-Arg-Gln peptides exhibited the strongest ACE inhibitory activity (IC50 values of 0.89, 2.69, and 3.09 mM, respectively) and had higher concentrations (6.63, 10.60, and 29.91 pg/g; p<0.05) relative to the other peptides tested. CONCLUSION: These results suggest that the thermolysin injection process is beneficial to the generation of bioactive peptides with strong ACE inhibitory activity.

Cooking, storage, and reheating effect on the formation of cholesterol oxidation products in processed meat products.

BACKGROUND: Cholesterol is an important biological compound; however, its oxidation products have been proven to be harmful to human health. Cooking, storage, and reheating methods significantly affect the safety of meat products, as they contribute to the production of cholesterol oxidation products (COPs). METHODS: Three cooking methods were used to cook sausages, loin ham, bacon, luncheon meat, and pressed ham, in order to investigate the effect of cooking, storage, and reheating on total cholesterol and on the formation of COPs. Cooked samples were stored at 4 °C and reheated after 3 and 6 storage days by the same cooking method or by microwaving. The samples were assessed for total lipids, cholesterol, and cholesterol oxides. RESULTS: The average cholesterol content in the processed meat varied from 76.0 mg/100 g to 201.70 mg/100 g. Microwaved ham showed the lowest cholesterol content compared to that of other processed meat products. Significant differences were found in cholesterol content and cholesterol oxidation products depending on cooking, storage, and reheating methods. Six cholesterol oxides were found in processed meat, of which 7ß-hydroxycholesterol and α-epoxides were detected as the major oxidation products. CONCLUSIONS: Microwaving and oven grilling resulted in higher production of COPs in processed meat as compared with other cooking methods. Refrigerated storage tended to significantly increase the COPs content.

Monitoring the formation of cholesterol oxidation products in model systems using response surface methodology.

BACKGROUND: Cholesterol oxidation products (COPs) are produced during thermal processing of animal origin foods and are considered to have negative health impacts. The model systems are helpful to understand the impact of various factors on oxidation changes in foods during cooking process. METHODS: The study presented herein investigates the effects of pH, presence of unsaturated fatty acids, and heat on the formation of cholesterol oxidation products (COPs). Two model systems were designed to investigate the formation of cholesterol oxidation products in different lipid environments. The cholesterol oxides produced were quantified using gas chromatography. RESULTS: The level of cholesterol oxidation products decreased significantly at higher pH (above 5.8) and shorter heating time (3 h). The presence of unsaturated fatty acids (linoleic and oleic acids) significantly increased the amount of COPs under low-temperature heating conditions (100 °C and 1 h) but did not affect the production of COPs at higher temperature (150 °C). Increasing the temperature to 200 °C significantly increased the amount of COPs during the first hour of heating and this amount decreased upon further heating. The most frequently observed COPs in samples were α-epoxide, 20α-hydroxycholesterol, and 25-hydroxycholesterol. CONCLUSIONS: In conclusion, pH below 5.8, presence of unsaturated fatty acid, and high cooking temperature (>150 °C) leads to increased production of cholesterol oxidation products.

Effects of combined treatments of electron-beam irradiation and addition of leek (Allium tuberosum) extract on reduction of pathogens in pork jerky.

This study investigated the combined effect of electron-beam irradiation and addition of leek (Allium tuberosum R.) extract on pork jerky inoculated with selected foodborne pathogens. Prepared pork jerky samples (control and samples with 1.0% leek extract) were inoculated with pathogens and subsequently irradiated at 0, 0.5, 1, 2, 3, and 4 kGy doses. In comparison with the control, samples with 1.0% leek extract showed significant reduction in the numbers of Escherichia coli, Listeria monocytogenes, and Salmonella Typhimurium. No viable counts were detected for Salmonella Typhimurium in both control and leek-extract samples, and for E. coli and L. monocytogenes in the leek-extract sample exposed to 3 kGy irradiation dose. The D(10) values for E. coli, L. monocytogenes, and Salmonella Typhimurium observed in the irradiated samples with leek extract were 0.39, 0.34, and 0.32 kGy, while the D(10) values in those without leek extract were 0.65, 0.65, and 0.39 kGy, respectively. Therefore, our results clearly showed that irradiation combined with leek extract was effective in reducing pathogens, suggesting that a low dose of irradiation combined with the addition of a natural antimicrobial agent can enhance the microbial safety and shelf-life of pork jerky.

Antimicrobial effect of κ-carrageenan-based edible film containing ovotransferrin in fresh chicken breast stored at 5°C.

The antimicrobial activity of κ-carrageenan-based film (κCF) containing ovotransferrin (OTf) against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Candida albicans was investigated. The effects of packaging with κCF-OTf on fresh chicken breast were also investigated during storage at 5°C. The κCF-OTf showed a slight antimicrobial activity against E. coli (diameter of inhibition zone was <2mm), but the effect was increased synergistically in the presence of 5mM EDTA (diameter of inhibition zone is 2-5mm). However, there were only weak inhibitory effects against S. aureus and S. typhimurium (diameter of inhibition zone was <2mm). The growth of total microbes and E. coli in fresh chicken breast wrapped with κCF showed 1.8 and 2.7 decimal reductions by the addition of 5mM EDTA or 5mM EDTA in combination with 25mg of OTf (P<0.05), respectively, when compared to that of control at day 7. The chicken breast wrapped with κCF-PS-EDTA was also inhibited the growth of total microbes and E. coli during storage period. However, the addition of either 25mg of OTf alone or 10mg of potassium sorbate alone slightly inhibited the growth of microorganisms in chicken breast. Based on the obtained results, the κ-carrageenan-based film containing ovotransferrin combined with EDTA can be used for extending shelf life of fresh chicken breast.

Comparison of hypolipidemic activity of synthetic gallic acid-linoleic acid ester with mixture of gallic acid and linoleic acid, gallic acid, and linoleic acid on high-fat diet induced obesity in C57BL/6 Cr Slc mice.

Hyperlipidemia is the major risk factors of heart disease such as atherosclerosis, stroke, and death. In the present study, we studied the effect of gallic acid (GA), linoleic acid (LA), mixture of GA and LA (MGL), and chemically synthesized gallic acid-linoleic acid ester (octadeca-9,12-dienyl-3,4,5-trihydroxybenzoate, GLE) on the ability to ameliorate hyperlipidemia in C57BL/6 mice fed a high-fat diet (HFD). GLE, GA, LA, and MGL were mixed with HFD and the composition of the test compounds were 1% of the diet for 7 weeks. After 7 weeks, the average body weight of ND and GLE groups was lower than that of HFD group (P<0.05). The liver weight of mice decreased (P<0.05) in all treatment groups relative to HFD fed group. The plasma lipids such as triglyceride and LDL-cholesterol were found to be decreased (P<0.05) in GLE, GA, LA, and MGL fed mice when compared to that of HFD fed mice. But high-density lipoprotein (HDL) cholesterol increased (P<0.05) in HFD and GLE fed mice when compared to that of ND fed mice. The hepatic accumulation of fat droplets of GA, LA, GLE, and MGL group showed considerably lower than that of HFD group. Adipose histology showed that GLE supplementation was found to be more effective in decreasing the size of adipocyte relative to those of other treatment groups. In conclusion, the supplementation of synthetic GLE from gallic acid and linoleic acid ester may have a potential hypolipidemic effect on mice fed high-fat diet. Further studies are required to prove GLE as a hypolipidemic agent.

Comparison of analytical methods for the detection of central nervous system tissue in ground beef.

Bovine spongiform encephalopathy is most likely transmitted by the consumption of central nervous system tissue of infected cows. The objective of this study was to compare the sensitivity or limits of detection of two central nervous system tissue detection assays (glial fibrillary acidic protein enzyme-linked immunosorbent assay [ELISA] and neuron-specific enolase Western blotting assay) in by-products and ground beef. By-products including brain, spinal cord, and ileum were collected from the slaughterhouse and used for analyses with ELISA and Western blotting assays. Beef samples were prepared by mixing ground beef with different amounts of spinal cord tissue (0, 0.03, 0.06, and 0.1%) and were analyzed using the two central nervous system tissue detection methods. Both analytical assays were applicable in detecting central nervous system tissue in ground beef. However, the ELISA method was considered superior because of its ease of use, high sensitivity, and rapidity as compared with the Western blot method.

Quality and Lactic Acid Bacteria Diversity of Pork Salami Containing Kimchi Powder.

We investigated the quality properties and bacteria diversity of pork salami containing homemade kimchi powder (KP). Pork salamis were manufactured with commercial starter culture (control), and 1% KP (KP1), 3% KP (KP3), and 5% KP (KP5). The salami was fermented and aged for 2 days and 56 days, respectively. The pH and AW values of salamis with KP were significantly lower than that of the control (p<0.05). The 2-thiobarbituric acid reactive substance values of all salamis with KP increased but were below 0.2 mg MDA/kg. Salamis with KP, decreased the L* value, but increased the a* and b* values (p<0.05). The Lactobacillus count was significantly higher in the salamis with KP than in the control by day 14 (p<0.05). The number of Leuconostoc was higher in salamis with KP than in the control and was the highest in salamis in KP1. The KP1 protected lipid oxidation and showed low TBARS value of pork salami compared to the control. This study demonstrates that KP can improve pork salami properties and can serve as a potential natural compounds for fermented meat prodcuts like Metzgerei.

Influence of Cooking, Storage Period, and Re-heating on Production of Cholesterol Oxides in Chicken Meat.

The objective of present study was to investigate the effect of cooking and their combinations with re-heating methods on the formation of cholesterol oxidation products (COPs) in stored chicken thigh meat. Pan roasting, steaming, oven grilling, charcoal grilling, and microwaving were used for cooking. Re-heating of samples was done using the same cooking methods or microwaving after 3 and 6 d of refrigerated storage. Cooking and re-heating resulted in reduction of crude fat and cholesterol contents of chicken thigh meat depending on storage period before re-heating. Cooking and storage period had no influence on the total amount of COPs. The highest total amount of COPs was observed in meat samples cooked by steaming and reheated by microwaving after 6 d of storage, which showed similar value to raw chicken meat stored for 6 days. However, different re-heating methods formed different types of COPs depending on storage period before re-heating. The high amount (p<0.05) of 25-hydroxycholesterol or α-epoxide was detected in meat samples reheated by steaming or microwaving at 3 or 6 d of storage after steamed cooking, respectively. As a result, the combination of steaming and re-heating with microwaving could increase the total amount of COPs in chicken thigh meat and different cooking/re-heating methods could form different types of COPs, even though no significant difference in the total amount of COPs depending on storage period.

Anti-inflammatory effect of dietary pork extract on proliferation and cytokine secretion using mouse primary splenocytes.

The anti-inflammatory effects of boiled pork meat (BPM) and hot water extracts of pork meat (WPM) on splenocyte proliferation and T cell cytokine regulation in BALB/c mice were evaluated. The proliferation of splenocytes in high concentration WPM groups was significantly higher than the control stimulated by LPS and Con A. In the white blood cells, WPM groups had significantly higher counts of lymphocytes and lower counts of neutrophils than the control (p<0.05). The Th1 (IFN-γ, TNF-α, IL-2) and Th2 (IL-4, IL-5, IL-10) cytokine levels in high-concentration WPM groups were higher than those in the control. In addition, TNF-α/IL-10 and IL-2/IL-4 secretions of splenocytes in the high concentration WPM group with LPS or Con A treatment was significantly lower than the control (p<0.05). Therefore, this study suggested that high concentration of WPM had anti-inflammatory effects on the primary splenocyte, which indicating that water extracts of pork meat can enhance the immune system of mice.

Impact of Cooking, Storage, and Reheating Conditions on the Formation of Cholesterol Oxidation Products in Pork Loin.

This study investigates the effect of cooking, storage, and reheating conditions on the formation of cholesterol oxidation products (COPs) in pork loin. Samples of pork loin procured 24 h postmortem were initially processed and assessed for total fat and cholesterol content. The cooking methods evaluated were pan roasting, steaming, oven grilling, and microwaving. Cooked pork loin samples were stored at 4℃ and reheated after 3 and 6 d of storage using the original method of preparation or alternately, microwaving. Fat content increased significantly with cooking as a result of the loss in moisture but cholesterol content remained unchanged. Pan roasting and microwave cooking caused a significantly higher production of COPs, as with the process of reheating using microwave, pan roasting, and oven grilling methods. The major COPs found in pork loin were cholestanetriol, 20-hydroxycholesterol, and 25-hydroxycholesterol, whose concentrations varied according to the different cooking and reheating methods used. Moreover, the aerobic storage of cooked pork loin under a refrigerated condition also increased the formation of cholesterol oxides on reheating.

Combined effect of electron-beam (beta) irradiation and organic acids on shelf life of pork loins during cold storage.

The combined effects of organic acids and irradiation on shelf life of pork loins were examined. Fresh pork loins were sprayed with organic acids (lactic, citric, and acetic) at 2%, packaged aerobically, and irradiated with an electron beam at 1, 2, and 3 kGy. During 14 days of storage, total plate count, coliform number, pH, and thiobarbituric acid-reactive substances were measured. Combinations of organic acid and irradiation were more effective in reducing and maintaining low total plate counts and coliform levels during storage than either treatment alone. Higher lipid oxidations were observed in all combination treatments at 1 day of storage than in the irradiation-only group. However, lower lipid oxidations were the result after 14 days of storage when combination treatments were used with irradiations of 2 and 3 kGy. Combined treatments involving lower irradiation doses than those required for irradiation alone could be used to extend the shelf life of pork loins during postirradiation storage without increasing lipid oxidation.

Comparison of indicators of microbial quality of meat during aerobic cold storage.

This study was undertaken to evaluate various indicators for the prediction of the microbial quality of pork and beef loins during cold storage at 0 and 4 degrees C under aerobic conditions. Fresh loins of beef and pork were packaged aerobically and stored at 0 +/- 1 degrees C for 22 days and at 4 +/- 1 degrees C for 12 days or until the total plate counts (TPCs) for these loins exceeded 10(8) CFU/ml. During storage, samples were taken periodically for the measurement of TPCs, psychrotrophic bacterial counts, amine contents, volatile basic nitrogen (VBN) values, thiobarbituric acid values, D-glucose contents, L-lactate contents, pH, and electrical conductivity. Correlation coefficients were ca. 0.90 for all indicators except pH and conductivity. However, VBN and D-glucose contents showed the best correlation with bacterial counts at both temperatures for both beef and pork. Therefore, VBN and D-glucose could potentially be used as indicators in predicting the microbial quality of beef and pork during chilled storage under aerobic conditions.

Meat Consumption Culture in Ethiopia.

The consumption of animal flesh food in Ethiopia has associated with cultural practices. Meat plays pivotal and vital parts in special occasions and its cultural symbolic weight is markedly greater than that accorded to most other food. Processing and cooking of poultry is a gender based duty and has socio-cultural roles. Ethiopians are dependent on limited types of animals for meats due to the taboo associated culturally. Moreover, the consumption of meat and meat products has a very tidy association with religious beliefs, and are influenced by religions. The main religions of Ethiopia have their own peculiar doctrines of setting the feeding habits and customs of their followers. They influence meat products consumption through dictating the source animals that should be used or not be used for food, and scheduling the days of the years in periodical permeation and restriction of consumptions which in turn influences the pattern of meat consumption in the country. In Ethiopia, a cow or an ox is commonly butchered for the sole purpose of selling within the community. In special occasions, people have a cultural ceremony of slaughtering cow or ox and sharing among the group, called Kircha, which is a very common option of the people in rural area where access of meat is challenging frequently.

Meat products and consumption culture in the East.

Food consumption is a basic activity necessary for survival of the human race and evolved as an integral part of mankind's existence. This not only includes food consumption habits and styles but also food preparation methods, tool development for raw materials, harvesting and preservation as well as preparation of food dishes which are influenced by geographical localization, climatic conditions and abundance of the fauna and flora. Food preparation, trade and consumption have become leading factors shaping human behavior and developing a way of doing things that created tradition which has been passed from generation to generation making it unique for almost every human niche in the surface of the globe. Therefore, the success in understanding the culture of other countries or ethnic groups lies in understanding their rituals in food consumption customs. Meat consumption culture in the East has not been well developed by its characteristic environment, religion, history, and main food staples. However, recently, the amount of meat production and consumption of the Eastern countries has grown rapidly by the globalization of food industry and rapid economic growth of the countries. This manuscript introduces meat-based products and consumption culture in Asian countries. However, because the environments and cultures within Asia are too diverse to cover all food cultures, this manuscript focused mainly on three northeast Asian countries including China, Japan, and Korea (Republic of) and some southeast Asian countries including Vietnam and Thailand, which have similar environments and cultural interactions historically but retain their own characteristic food culture.

Irradiation and Packaging of Fresh Meat and Poultry.

Extensive research on the irradiation of fresh meat and poultry has been carried out during the past 40 years; yet there is a need for consideration of combined use with other technologies such as modified atmosphere (MA) packaging. Some of the past work has focused on spoilage microorganisms and pathogens, whereas other reports emphasize the sensory quality of fresh meat and poultry. Reports published indicate that the effects of irradiation in conjunction with packaging vary depending upon the kind of meat and poultry and the atmosphere composition in the package. Irradiation may result in off-flavor and/or odor and discoloration of fresh meat and poultry in packages containing air (oxygen). One concern is that pathogens may grow and/or produce toxins in irradiated meat or poultry packaged using modified atmospheres because of a lack of competing organisms. This is of even greater concern if spoilage is suppressed and does not provide the usual warning signals. On the other hand, even though there is some evidence of the growth of pathogens in temperature-abuse conditions, most reports have indicated that spoilage preceded toxin production. Therefore, considering the sensory quality and concerns for safety, the effects of irradiation in combination with vacuum or MA packaging of fresh meat and poultry should be studied further. More complete information is needed to ensure the appropriate use of vacuum or MA packaging in combination with irradiation for the safety of fresh meat and poultry.