The effect of low-intensity ultrasound treatment on shear properties, color stability and shelf-life of vacuum-packaged beef semitendinosus and biceps femoris muscles

A series of experiments were conducted to assess the impact of low-intensity ultrasound treatment on shear properties, color and shelflife of packaged beef muscles. For the first experiment, 15 beef semitendinosus muscles were sliced (6.4 × 2.5 × 70.2 cm) weighed, vacuum packaged, subjected to a 1.55 W/cm(2) intensity ultrasonic field for 8, 16 or 24 min then stored at 3 °C for 4 days; controls were not sonicated. Muscles were then removed from vacuum bags, weighed, cooked to 70 °C internal temperature in a convection oven and evaluated for cooking and shearing properties. For the second experiment, 14 beef semitendinosus muscles were sliced (2.5 × 5.1 × 10.2 cm), vacuum packaged and allocated to either a simultaneous ultrasound/water-bath-heating treatment or water-bath-heating treatment only. Muscles were removed from the water-bath when the water temperature reached 70 °C, removed from the vacuum bags, cooked further to an internal temperature of 70 °C in a convection oven and evaluated for instrumental shear. For the third experiment, 30 beef biceps femoris pieces (1.3 × 7.6 × 10.2 cm) were mixed together to more evenly distribute native microflora, vacuum packaged and allocated to either ultrasound (1.55 W/cm(2), 3 °C, 30 min) treatment or control (no ultrasound treatment). Vacuum-packaged muscles were stored in a retail display case (3 °C) and evaluated at 0, 5, 10, 20 and 30 days for microbial count and instrumental color (CIE L (∗)a (∗)b (∗)). Ultrasound had no effect (p > 0.05) on storage purge loss, cooking loss, or textural properties (Experiments 1 and 2). Microbial levels were initially reduced (p < 0.05) by the ultrasound treatment (0 days), but differences in microbial numbers between ultrasound-treated samples and controls disappeared (p > 0.05) during storage (Experiment 3).

Effects of ultrasound and convection cooking to different end point temperatures on cooking characteristics, shear force and sensory properties, composition, and microscopic morphology of beef longissimus and pectoralis muscles

Longissimus and pectoralis muscles were removed from 10 steer carcasses at 4 d postmortem, aged for 14 d at 2 degrees C, then assigned to either ultrasound or convection cooking to either 62 degrees C or 70 degrees C internal end point temperature. During cooking, time-temperature profiles and energy consumption were monitored. Ultrasound cooking resulted in greater (P < .05) cooking speed, greater (P < .05) moisture retention and less (P < .05) cooking loss, greater (P < .05) efficiency of energy consumption, a more uniform cooking environment, and less (P < .05) instrumental peak-force work to shear muscle samples than convection cooking. The ultrasound treatment also resulted in a reduction (P < .05) in soluble collagen content and superior (P < .05) myofibrillar tenderness, as determined by a trained sensory panel, than convection cooking. Electron micrographs indicated that ultrasound-cooked muscles had longer sarcomeres, larger diameter fibers, and more myofibrillar disruption and shattering. Longissimus muscles cooked faster (P < .05) and more (P < .05) energetically efficient, had less (P < .05) total collagen, and were superior (P < .05) in instrumental evaluated texture and sensory tenderness than pectoralis muscles. Cooking to 70 degrees C caused greater (P < .05) moisture and cooking losses, required more (P < .05) time and energy input to cook, and negatively (P < .05) affected instrumental textural and sensory tenderness characteristics. Electron micrographs indicated a shortening of sarcomeres, more deterioration of the banding structure, reduction in fiber diameter, and breakdown of endomysial and perimysial connective tissue at an internal temperature of 70 degrees C vs 62 degrees C. This research identifies ultrasound cooking as a new, rapid, energy-efficient method that may improve some meat textural attributes.

Reduction of Bacterial Populations on Vacuum-Packaged Ground Beef Patties with Fumaric and Lactic Acids

The effects of fumaric and lactic acid on the total numbers of aerobic, psychrotrophic, and coliform bacteria on vacuum-packaged ground beef patties at 0, 1, 3, 5, 7, 10, and 14 days of storage at 4°C were studied. Fumaric acid treatments resulted in greater reductions in microbial growth than lactic acid treatments. When 5.0% fumaric acid was used, the lag phase was prolonged and microbial growth was reduced (P < 0.05), with total aerobic, psychotrotrophic, and coliform populations reaching net maximum growths of only 1.46, 1.44, and 0.98 log units, respectively, after storage at 4°C for 10 days. Increasing the acid concentrations significantly decreased the growth of all microorganisms. The 5.0% lactic acid was the most inhibitory against coliforms, resulting in a 3.88-1og unit reduction after 10 days of storage.

Inhibition of Listeria monocytogenes and Escherichia coli O157:H7 on Beef by Application of Organic Acids †

Lean beef surfaces were inoculated with Escherichia coli O157:H7 and Listeria monocytogenes and then sanitized with fumaric, acetic, or lactic acid alone and in combined solutions of those acids at 55°C for 5 s. The initial inoculum level was 8.62 log CFU/cm² and 5.13 log CFU/cm² for L. monocytogenes and E. coli O157:H7, respectively. Fumaric acid at a concentration of 1% was the most effective acid in reducing the populations of L. monocytogenes by up to 1 log unit and E. coli O157:H7 by up to 1.3 log units when compared with acetic or lactic acids. The rank order of acids tested against the growth of L. monocytogenes and E. coli O157:H7 was fumaric acid followed by lactic and acetic acids. Fumaric acid at concentrations of 1.0% and 1.5% was more effective than any of the combined solutions of acids.

Properties and quality characteristics of crystalline insulin extracted by ultrasound

Crystalline insulin was obtained from the pancreas by the method of ultrasound extraction. Extreme changes of pancreas structure were noticed, including rupture of the cells of pancreatic islands and decomposition of pancreatic tissue with the formation of micro-and macro-canals. These changes facilitate the migration of solvent inside the structure and washing out beta cell content. Structural changes were maximal in the peripheral parts of the pancreas and in frozen pancreas treated by ultrasound. A rapid filming method recorded factors influencing the extraction process-the dispersing effect of ultrasound, the rapid destruction of pancreatic particles, and the swelling and intensive pulsation of small particles in the ultrasound field. Experimental, control, and standard insulin preparations were nearly identical in Physicochemical properties and ether quality characteristics: activity determined by a biological method and electrophoresis; homogeneity and purity determined by circle chromatography; fractions of insulin determined by starch gel electrophoresis; amino acid composition; solubility; and content of moisture, zinc, and nitrogen.