Sensory traits, color, and shelf life of low-dose irradiated, raw, ground beef patties

Irradiation of raw ground beef patties had minimal effects on flavor and aroma of patties after cooking. Oxidative rancidity increased when patties were irradiated in aerobic but not in vacuum packages. Irradiation of vacuum-packaged ground beef patties produced a more stable color. In both packaging types, irradiation significantly reduced microbial growth during storage

Sensory traits, color, and shelf life of low-dose irradiated, precooked, ground beef patties

Irradiation did not influence bitter, bloody, burnt, chemical, fat-like, juiciness, liver-like, beef identity, metallic, rancid, sour, sweet, and toughness flavor/textural attributes, beef aroma, or off-odor in precooked ground beef patties. Irradiation slightly increased the animal hair flavor note, but intensity levels were <1 on the 15-point sensory scale. Except for 10% fat non-irradiated controls, reheated precooked patties had a slight sour, ammonia-like, top note. Irradiation at 3.5 kilograys (kGy) increased external redness in vacuum-packaged patties, but not in aerobic packages. Aerobic packaging with or without irradiation decreased external precooked redness. Oxidative rancidity increased when patties were irradiated in aerobic but not in vacuum packages. Reduction of oxygen in vacuum bags extended the shelf life of the precooked ground beef patties, at least in terms of oxidative rancidity. Precooking ground beef patties, irrespective of irradiation or packaging type, posed sensory disadvantages, and improvements to the precooking process are needed before irradiating at low-dose levels is appropriate

Motor-Driven Bacterial Flagella and Buckling Instabilities

Many types of bacteria swim by rotating a bundle of helical filaments also called flagella. Each filament is driven by a rotary motor and a very flexible hook transmits the motor torque to the filament. We model it by discretizing Kirchhoff's elastic-rod theory and develop a coarse-grained approach for driving the helical filament by a motor torque. A rotating flagellum generates a thrust force, which pushes the cell body forward and which increases with the motor torque. We fix the rotating flagellum in space and show that it buckles under the thrust force at a critical motor torque. Buckling becomes visible as a supercritical Hopf bifurcation in the thrust force. A second buckling transition occurs at an even higher motor torque. We attach the flagellum to a spherical cell body and also observe the first buckling transition during locomotion. By changing the size of the cell body, we vary the necessary thrust force and thereby obtain a characteristic relation between the critical thrust force and motor torque. We present a sophisticated analytical model for the buckling transition based on a helical rod which quantitatively reproduces the critical force-torque relation. Real values for motor torque, cell body size, and the geometry of the helical filament suggest that buckling should occur in single bacterial flagella. We also find that the orientation of pulling flagella along the driving torque is not stable and comment on the biological relevance for marine bacteria.Comment: 15 pages, 11 figure

High carbon dioxide, modified-atmosphere packaging (MAP) for beef steaks

To determine the effects of storage in a high-carbon dioxide, modified-atmosphere package (MAP) on shelf life, beef strip steaks were packaged under 30% CO2-70% N2 and stored for up to 42 days at 30 or 38 ̊F. Aerobic plate counts (APC) and lactic acid bacteria (LAB) counts in these ExtendPak™ packages were well below the threshold of spoilage even after 42 days of MAP storage. After 28 days of storage, steaks stored in vacuum packages had APC counts 1.0 log 10 greater than steaks in MAP. APCs increased during a 5-day display period in steaks store d in vacuum packages, but no increases occurred with MAP. Repackaged steaks from vacuum packages bloomed to a brighter red color than steaks stored in MAP, but MAP steaks were more color stable through display. Microbial data indicate d that steaks can be stored for up to 42 days using this promising MAP system. The long storage life of MAP steaks allows packers and retailers more flexibility to respond to variable consumer demand, without the threat of product spoilage

Sensory traits, color, and shelf life of low-dose irradiated beef steaks

Irradiation had minimal effects on flavor and texture of frozen or chilled vacuum-packaged boneless beef steaks. A dose level of 3.5 kilograys (kGy) reduced beef aroma in chilled steaks. Irradiation did not influence internal or external cooked color, most raw color traits, cooking loss, pH, oxidative rancidity, or Warner-Bratzler shear force in chilled or frozen boneless steaks. PVC-wrapped controls were less red than irradiated steaks after 5 days of display. Exposure to oxygen by repackaging into oxygen-permeable film increased oxidative rancidity after display. Vacuum-packaging, in combination with irradiation, enables boneless beef steaks to be stored and/or displayed up to 28 days with minimal effects on color, oxidative rancidity, and bacterial counts

Consumer acceptance of low-dose irradiated, boneless, pork chops

Acceptance of irradiated, chilled, boneless, pork chops and nonirradiated controls by consumers was not different. Coupled with consumer concerns about food safety and well-documented improvement in consumer attitudes about irradiated foods, the potential for market acceptance is very promising

Display life and related traits of low-dose irradiated, boneless, pork chops

Irradiation and vacuum-packaging caused a more intense and stable red color in boneless pork chops. Irradiation up to 2.5 kGy increased cooked internal redness in chilled chops. Oxidative rancidity was greater in aerobic packaging than vacuum-packaging and in irradiated aerobic packaged chops than controls. Irradiation of vacuum-packaged boneless pork chops has promising potential for market acceptance

Flavor and aroma of low-dose irradiated, boneless, pork chops

Irradiation and irradiation source had little to no effect on flavor and aroma of boneless pork chops, either frozen or chilled. Coupled with consumer concerns about food safety and well-documented improvement in consumer attitudes about irradiated foods, irradiation of boneless pork chops has promising potential for market acceptance