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.

Relating texture perception of cooked ham to the bolus evolution in the mouth.

The aim of the present study was to characterize the dynamics of the bolus formation that take place during mastication of commercial cooked ham samples. In addition, the relationships between these properties and texture perception were studied. Five commercial samples which presented different mechanical properties and moisture contents were studied. Ten participants were asked to chew the cooked ham samples normally and to expectorate the bolus after different chewing periods. Oral activity measurements (chewing time and number of chewing strokes), moisture content, saliva uptake and particle size distribution in the boluses were obtained. Seventeen participants evaluated the sensory perceptions generated over the sample consumption time, using the Temporal Check-All-That-Apply (TCATA) method. The results revealed that the duration of mastication and number of chewing cycles through to swallowing varied significantly among the cooked ham samples and were mainly related to instrumental texture parameters. The pattern of fragmentation under mastication also varied greatly between samples. Sensations of softness and hardness during ham consumption were again linked to instrumental texture parameters (TPA hardness, TPA chewiness and shear force). The perception of fibrousness was related to the degree of fragmentation of the ham in the mouth, and juiciness seemed to be related to the amount of saliva taken up by the product.

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.

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.

Alteration of post-mortem ageing in beef by the addition of enzyme inhibitors and activators.

Twenty-four hours after stunning, slices of beef M. semitendinosus were soaked in buffers at 10 °C at different pH values containing enzyme inhibitors or calcium and magnesium salts and their enzyme levels and toughness determined up to 9 days. High pH meat was tender but appeared to have the same rate of ageing as meat of normal pH. Calcium chloride accelerated ageing and produced, after completion of conditioning, more tender meat than controls. In tenderising, sodium and potassium chlorides were 43% and MgCl(2) 73% as effective as Ca salts. Cysteine proteinase inhibitors were more effective in preventing ageing than serine or aspartate inhibitors. Cysteine and aspartate inhibitors together were the most effective in preventing ageing. The inhibition of ageing by cysteine inhibitors was overcome in the presence of 30 mM CaCl(2). The results suggest a main, but not exclusive, role for calpains in meat ageing and showed a synergistic non-enzymic tenderisation by the addition of high concentrations of salts.

Effect of frozen storage of minced meats on the quality of sausages prepared from them.

Mutton, pork and beef sausages were prepared from minced meats which had been frozen and stored up to 52 weeks at -18°C. There was a significant decrease in texture (W-B shear force) of all the sausages with increased age of the meat. However, concomitantly there were no significant differences in the colour, juiciness or shrinkage (cooking loss) of the sausages. All sausages were organoleptically acceptable even when made from meats stored for 52 weeks at -18°C.