QUALITY OF MEAT PRODUCTS DURING REFRIGERATED AND ULTRA-CHILLED STORAGE

Standard domestic refrigerators store food between 1 and 5C (33.8–41F). A manufacturer recently developed a refrigerator capable of storing food in the “ultra‐chilled region” (?3 to ?7C) and claimed that storage of fresh meat in this region better maintains quality. To understand quality in terms of chemical reaction rates, microbial growth and texture and flavor changes, three common consumer meat products – steak, ground beef patty and salmon – were stored for a selected period of time, as determined by microbial testing, in five refrigerator models with different environmental conditions (constant temperature and temperature fluctuation). At the end of the storage period, consumer panelists assessed the quality of the cooked samples by ranking them according to preference. In addition, instruments were used to measure the color and shear cutting force (for steak only) of each sample. Results from the consumer Ranking R‐Index Test indicate that panelists preferred samples stored under or near ultra‐chilled conditions rather than samples stored under standard refrigerated conditions. The ultra‐chilled samples not only had higher panelist rankings and more favorable comments, but also had lower microbial aerobic plate counts. The instrument readings, however, highly varied and did not correlate well with sensory data.     

IMPROVEMENT IN MICROBIOLOGICAL QUALITY AND SHELF-LIFE OF BUFFALO MEAT AT AMBIENT TEMPERATURE BY GAMMA IRRADIATION

The effect of low dose gamma-irradiation (2.5 kGy) on the shelf-life of prepacked fresh buffalo meat at ambient temperature (28–30C) in terms of microbiological, chemical and sensory qualities was studied. Unirradiated samples initially showed the presence of Enterobacteriaceae and Staphylococcus spp. These gradually increased during storage. After 12 h of holding , Clostridium spp. were observed in these samples. On the basis of microbiological, chemical and sensory analyses, the shelf-life was limited to 18 h. In contrast , Clostridium spp. and Enterobacteriaceae were not detected in irradiated samples throughout the storage period and Staphylococcus spp. were detected only after 12 h of holding. Irradiated samples had a shelf-life of 42 h.     

控制图在肉及肉制品微生物监测过程中的应用

介绍控制图的基本概念,并试列举控制图在肉及肉制品微生物监测结果方面的应用示例.结果表明在肉及肉制品微生物监测中应用控制图能够对内及肉制品生产过程进行监控,以达到控制产品质量、提高经济效益的目的.     

MODIFIED ATMOSPHERE AND VACUUM PACKAGING OF MEAT AND POULTRY PRODUCTS

Extension of the shelf-life of meat and poultry products is one of the technology needs to meet the demands of consumers. In this respect, increasing attention is put on packaging techniques. Modified atmosphere packaging (MAP) and vacuum packaging (VP) are recent innovations that have been gaining importance as preservation techniques to improve the shelf-life of meat and poultry. MAP provides alterations of atmospheric gas concentrations in the pack. Controlled atmosphere (CA) packaging is also MAP, wherein the selected atmospheric concentration of gas is actively maintained throughout the storage period. In VP, air is completely removed. The three principal gases used in MAP are carbon dioxide (to inhibit bacteria and moulds), nitrogen (to avoid oxidation of fats and pack collapse), and oxygen (to prevent anaerobic growth). Retention of meat color is better in MAP than in VP. However, color is regained when meat is removed from VP packets and exposed to air. Microbial profiles of MAP- and VP-meat do not differ significantly. MAP offers several unique advantages for retaining the desirable market quality of products. The safety of MAP meat is still a concern under temperature abuse conditions but it can be improved by coupling with hurdle technology and proper preservation systems. Active packaging is a significant area of advancement of MAP technology to further improve the safety of meat and poultry products. This contribution critically reviews the existing knowledge on MAP and VP of meat and poultry in order to broaden our understanding of the subject and to suggest further areas of research to effectively use these technologies for marketing safe meat and poultry products.     

MODIFIED ATMOSPHERE AND VACUUM PACKAGING OF MEAT AND POULTRY PRODUCTS

Extension of the shelf-life of meat and poultry products is one of the technology needs to meet the demands of consumers. In this respect, increasing attention is put on packaging techniques. Modified atmosphere packaging (MAP) and vacuum packaging (VP) are recent innovations that have been gaining importance as preservation techniques to improve the shelf-life of meat and poultry. MAP provides alterations of atmospheric gas concentrations in the pack. Controlled atmosphere (CA) packaging is also MAP, wherein the selected atmospheric concentration of gas is actively maintained throughout the storage period. In VP, air is completely removed. The three principal gases used in MAP are carbon dioxide (to inhibit bacteria and moulds), nitrogen (to avoid oxidation of fats and pack collapse), and oxygen (to prevent anaerobic growth). Retention of meat color is better in MAP than in VP. However, color is regained when meat is removed from VP packets and exposed to air. Microbial profiles of MAP- and VP-meat do not differ significantly. MAP offers several unique advantages for retaining the desirable market quality of products. The safety of MAP meat is still a concern under temperature abuse conditions but it can be improved by coupling with hurdle technology and proper preservation systems. Active packaging is a significant area of advancement of MAP technology to further improve the safety of meat and poultry products. This contribution critically reviews the existing knowledge on MAP and VP of meat and poultry in order to broaden our understanding of the subject and to suggest further areas of research to effectively use these technologies for marketing safe meat and poultry products.     

EFFECTS OF SODIUM LACTATE, SODIUM ACETATE AND SODIUM DIACETATE ON MICROBIOLOGICAL QUALITY OF VACUUM-PACKED BEEF DURING REFRIGERATED STORAGE

Beef samples were cut into the pieces and treated with solutions of 1.8 and 2.5% sodium lactate (SL), 0.1% sodium acetate (SA), 0.1 and 0.2% sodium diacetate (SDA) and their combinations, packed under vacuum and stored in a refrigerator at 4C. Microbiological quality of the samples was investigated during their storage for 21 days. Sodium salts and their combinations significantly (P < 0.05) affected the aerobic plate count (APC). Although growth of lactic acid bacteria (LAB), psychrotrophs and coliforms was delayed in treated samples, they were not completely inhibited. The most effective treatment to delay the growth of microorganisms was the combination of 2.5% SL + 0.2% SDA. The count of bacteria of the samples reached and exceeded the spoilage limit (10⁷?10⁸log cfu/g) after 14 days at 4C.     

COMPOSITION AND PROPERTIES OF EXTRUDED, TEXTURIZED POULTRY MEAT

Hand deboned leg and thigh tissues from broilers and mechanically de-boned broiler neck meats were extruded and texturized using a dry heat process. During heat processing of all meat tissues, there was a significant (P< 0.05) reduction of moisture content and significant increases in fat and protein levels as heating time increased. Meat strands from the texturization process became firm, possessing structural integrity as determined by the binding strength among meat tissue particles and strand resistance to shearing. Significant (P < 0.05) increases were observed in tissue water-holding capacity and emulsion stabilizing capacity although salt-soluble protein extractability was significantly (P < 0.01) reduced by the heating during texturization     

COMPARATIVE MICROSTRUCTURE OF RED MEAT, POULTRY AND FISH MUSCLE

Since muscle food researchers tend to focus on disciplines such as red meats, poultry or fish; there is little shared information across commodity lines. Comparisons among these three groups of muscle foods are discussed.     

MICROBIOLOGICAL QUALITY OF BROILER CHICKEN CARCASSES PROCESSED HYGIENICALLY IN A SMALL SCALE POULTRY PROCESSING UNIT

Though large‐scale enterprises in highly‐developed countries often produce millions of items in a single day, world‐wide the volume of food produced in small‐scale enterprises or at home in countries still developing is of great economic importance and hygienic concern. Trials were conducted to determine the degree to which the sanitary state of broilers processed on a small scale could be improved through the application of simple hygienic practices. Dressed broiler chickens were examined for microbiological quality. Live birds carried high microbial load (log cfu/cm²): TPC 5.34; S. aureus 3.08 and fecal streptococci 3.02. The evisceration process resulted in a significant (P > 0.05) increase in microbial fecal contamination. Statistically significant lower microbial counts were observed in hygienically processed carcasses as compared with market carcasses. E. coli and fecal streptococci were completely absent in hygienically processed carcasses. Modest changes inprocessing methods resulted in broilers more hygienic with a gain in shelf‐life compared with those regularly available on the market.     

MICROBIOLOGICAL AND SENSORY ANALYSES OF REFRIGERATED CATFISH FILLETS TREATED WITH ACETIC AND LACTIC ACIDS

The influence of acetic acid (AA) and/or lactic acid (LA) dips on microbial numbers, pH, and sensory scores of catfish fillets was assessed during storage at 4C. Fillets were treated by dipping in 4C AA and/or LA solutions for 0–60s. Fillets treated with either 3–4% AA or 2% AA and 2% LA for 30–60s suppressed growth of aerobic microorganisms for 4 days and extended shelf-life to 16 days. Treatment with either 3–4% LA or 1% AA and 1% LA for 5–60s prolonged microbiological shelf life to 12 days. AA had greater antimicrobial activity than LA. Fillets treated with AA alone or combinations of AA and LA were liked less by sensory panels than controls due to acidic odor and flesh discoloration. Thus, concentrations of AA or LA greater than 2% or exposure times greater than 30s are not recommended for catfish fillets.     

ATTACHMENT AND REMOVAL OF SALMONELLA SPP. ON MEAT AND POULTRY TISSUES

Muscle pieces from beef, pork, and chicken were exposed to Salmonella strains in various aqueous solutions to determine mechanisms of microbial attachment and release. Binding was measured by scanning electron microscopy and by bacteriological methods. Bacteria appear to attach preferentially to connective tissue fibers, rather than to myofibrils. Muscle fiber swelling and shrinkage during processing permits some microbial entrapment between muscle bundles. Mannose and salt solutions were examined as potential inhibitors of attachment or as removal agents. Mannose inhibited attachment slightly and isotonic saline rinses removed some attached cells, but either method effected only about a one log reduction (90%). Application of 41 rinsings only effected a 4 log reduction. The apparent variety of attachment mechanisms by Salmonella hinders complete removal from meat tissues by simple rinsing procedures.