Effects of high-energy ultrasound on the functional properties of proteins

In recent years, high-energy ultrasound has been used as an alternative to improve the functional properties of various proteins, such as from milk, eggs, soy and poultry. The benefits of implementing this technology depend on the inherent characteristics of the protein source and the intensity and amplitude of the ultrasound, as well as on the pH, temperature, ionic strength, time, and all of the variables that have an effect on the physicochemical properties of proteins. Therefore, it is necessary to establish the optimal conditions for each type of food. The use of ultrasound is a promising technique in food technology with a low impact on the environment, and it has thus become known as a green technology. Therefore, this review focuses on the application of high-energy ultrasound to food; its effects on the functional properties of proteins; and how different conditions such as the frequency, time, amplitude, temperature, and protein concentration affect the functional properties.

Postmortem biochemical behavior of giant squid (Dosidicus gigas) mantle muscle stored in ice and its relation with quality parameters

Several freshness and spoilage indicators were monitored to characterize the postmortem biochemistry of giant squid (Dosidicus gigas) mantle muscle. Squid samples were obtained directly from the sea and kept at 0 degrees C during a 15-d storage period. Data at zero time were obtained from cryogenically frozen samples at time of capture. The adenosine 5'-triphosphate (ATP) degradation followed a different pattern as compared with that from fish species. ATP was almost completely depleted at 24-h postcatch from 6.54 to <1 micromol/g, while at the same time Hx was the predominant catabolite with a concentration of 4 mumol/g, reaching 6.85 micromol/g at day 15. K-value data followed a logarithmic pattern with time instead of a linear one, with no change after day 3, thus reducing its suitability as a freshness index. The coefficient Hx/AMP seems to be an adequate alternative for this purpose due to its constant increment with time. The high NH4Cl content in mantle muscle (461.3 +/- 24.5 mg of NH4(+)/100 g) derived from its physiological importance for the species compromises the use of the distillation step of the TVB-N analysis commonly used as a spoilage index. This fact explains why the initially high value of TVB-N detected in mantle muscle (243.7 mg N/100 g) did not correlate with the initial low TMA-N content (1.5 +/- 0.1 mg/100 g of muscle). The results suggested that under the experimental conditions the shelf life of squid exceeds 15 d.