Alma Alarcon-Rojo

Power ultrasound in meat processing.

Ultrasound has a wide range of applications in various agricultural sectors. In food processing, it is considered to be an emerging technology with the potential to speed up processes without damaging the quality of foodstuffs. Here we review the reports on the applications of ultrasound specifically with a view to its use in meat processing. Emphasis is placed on the effects on quality and technological properties such as texture, water retention, colour, curing, marinating, cooking yield, freezing, thawing and microbial inhibition. After the literature review it is concluded that ultrasound is a useful tool for the meat industry as it helps in tenderisation, accelerates maturation and mass transfer, reduces cooking energy, increases shelf life of meat without affecting other quality properties, improves functional properties of emulsified products, eases mould cleaning and improves the sterilisation of equipment surfaces.

Ultrasound-enhanced mass transfer in Halal compared with non-Halal chicken

BACKGROUND Halal foods are often perceived as wholesome products that are specially selected and processed to achieve the highest standards of quality. In this study, dye penetration from an aqueous solution of methylene blue (1 mol L(-1)) was used as a model for the marination process of Halal and non-Halal chicken breast. RESULTS The effect of dye penetration was evaluated by three techniques: (1) the mass of methylene blue solution in the samples was quantified by mass gain, (2) the amount of dye absorbed was determined by spectroscopy and (3) the penetration distance of dye inside the samples was measured. For non-Halal meat, ultrasound increased the amount of dye inside the samples by 6 and 13% after 15 and 30 min respectively. The effect on Halal meat was much more pronounced, with an increase in dye uptake of over 60% being observed for both time periods. CONCLUSION Dye penetration is an indication of meat permeability and so can be used as an estimate of marinading of meat. Thus the use of high-power ultrasound has potential in poultry-processing methods, in particular that of Halal chicken marination.

Physicochemical and microbiological characteristics of beef treated with high-intensity ultrasound and stored at 4 °C.

BACKGROUND The application of high-intensity ultrasound causes changes in the physical and chemical properties of biological materials including meat. In this study the physicochemical and microbiological characteristics of beef after the application of high-intensity ultrasound for 60 and 90 min and subsequent storage at 4 °C for 0, 2, 4, 6, 8 and 10 days were evaluated. RESULTS The ultrasound-treated meat showed higher (P < 0.05) pH and luminosity than the control, with no difference (P > 0.05) between sonication times. The redness of ultrasound-treated meat was initially lower than that of control meat, but no difference (P > 0.05) was observed after day 8 of storage. The 90 min ultrasound-treated meat had higher (P < 0.05) yellowness during the entire storage period. Ultrasound decreased (P < 0.05) coliform, mesophilic and psychrophilic bacteria in the meat throughout the storage period; however, the original microbial loads increased constantly during refrigeration. The 90 min ultrasound-treated meat showed the greatest reduction in microbial load during storage. Coliforms and psychrophilic bacteria were the most affected by ultrasound. CONCLUSION The application of high-intensity ultrasound to beef semitendinosus muscle stored at 4 °C decreased bacterial growth without affecting the physicochemical quality of meat.

Short communication: Potential of Fresco-style cheese whey as a source of protein fractions with antioxidant and angiotensin-I-converting enzyme inhibitory activities

Recently, traditional Mexican Fresco-style cheese production has been increasing, and the volume of cheese whey generated represents a problem. In this study, we investigated the chemical composition of Fresco-style cheese wheys and their potential as a source of protein fractions with antioxidant and angiotensin-I-converting enzyme (ACE)-inhibitory activities. Three samples from Fresco, Panela, and Ranchero cheeses whey were physicochemically characterized. Water-soluble extracts were fractionated to obtain whey fractions with different molecular weights: 10-5, 5-3, 3-1 and <1 kDa. The results indicated differences in the lactose, protein, ash, and dry matter contents (% wt/wt) in the different Fresco-style cheese wheys. All whey fractions had antioxidant and ACE-inhibitory activities. The 10-5 kDa whey fraction of Ranchero cheese had the highest Trolox equivalent antioxidant capacity (0.62 ± 0.00 mM), and the 3-1 kDa Panela and Fresco cheese whey fractions showed the highest ACE-inhibitory activity (0.57 ± 0.02 and 0.59 ± 0.04 μg/mL 50%-inhibitory concentration values, respectively). These results suggest that Fresco-style cheese wheys may be a source of protein fractions with bioactivity, and thus could be useful ingredients in the manufacture of functional foods with increased nutritional value.

Improving Cull Cow Meat Quality Using Vacuum Impregnation

Boneless strip loins from mature cows (50 to 70 months of age) were vacuum impregnated (VI) with an isotonic solution (IS) of sodium chloride. This study sought to determine the vacuum impregnation and microstructural properties of meat from cull cows. The experiments were conducted by varying the pressure, p1 (20.3, 71.1 kPa), and time, t1 (0.5, 2.0, 4.0 h), of impregnation. After the VI step, the meat was kept for a time, t2 (0.0, 0.5, 2.0, 4.0 h), in the IS under atmospheric pressure. The microstructural changes, impregnation, deformation, and porosity of the meat were measured in all the treatments. Impregnation and deformation levels in terms of volume fractions of the initial sample at the end of the vacuum step and the VI processes were calculated according to the mathematical model for deformation-relaxation and hydrodynamic mechanisms. Scanning electron microscopy (SEM) was used to study the microstructure of the vacuum-impregnated meat samples. Results showed that both the vacuum and atmospheric pressures generated a positive impregnation and deformation. The highest values of impregnation X (10.5%) and deformation γ (9.3%) were obtained at p1 of 71.1 kPa and t1 of 4.0 h. The sample effective porosity (εe) exhibited a significant interaction (p < 0.01) between p1×t1. The highest εe (14.0%) was achieved at p1 of 20.3 kPa and t1 of 4.0 h, whereas the most extended distension of meat fibers (98 μm) was observed at the highest levels of p1, t1, and t2. These results indicate that meat from mature cows can undergo a vacuum-wetting process successfully, with an IS of sodium chloride to improve its quality.

Microbiological properties of poultry breast meat treated with high-intensity ultrasound

Lactic acid, psychrophilic, and mesophilic bacteria, Escherichia coli, Salmonella spp. and Staphylococcus aureus were enumerated on chicken breasts after treatment with different high intensity ultrasound (frequency 40 kHz, intensity 9.6 W/cm-2) application times (0, 30, and 50 min) and packaging atmospheres (aerobic and vacuum) after a 7-day storage. The experiment was performed in commercial 7-week-old chicken breasts. Counts were performed prior to and immediately after ultrasonication, and on the 7th day of chill-storage. After sonication and storage, mesophiles, psychrophiles, LAB and S. aureus increased statistically. Psychrophiles decreased significantly under anaerobic packaging. There were no differences among ultrasonication times in terms of mesophiles, psychrophiles, LAB, E. coli and Salmonella spp. S. aureus numbers had a significant reduction after 50 min sonication. Under these experimental conditions, high-intensity ultrasound for 50 min is a control method of S. aureus and the anaerobic packaging reduces numbers of psychrophiles in chicken breast. The effect of ultrasound is only significant after the storage time.

Oregano Essential Oil in Animal Production

There is an increasing interest in the use of natural additives in food production such as the use of phytogenic feed additives especially for use in swine and poultry. Essential oils are a natural alternative that can be used in animal feed due to their potential health benefits, improved performance and meat production. Oregano essential oil minimises meat downgrading due to transport stress or the modification of the ruminal microor‐ ganisms. This review suggested a promising development of food natural preservative against spoilage microorganisms in food systems by the use of oregano essential oil. The addition of oregano essential oil is a good way of preserving meat and could replace the synthetic antioxidants. Moreover, oregano oil and modified atmosphere packaging exhibit an additive preservation effect in fresh meat. Oregano essential oil is effective for controlling the growth of microorganisms. However, for meat quality, special attention should be put on the optimal oregano essential oil dose and meat handling to control or improve the physical, chemical and sensory properties of meat.