A REVIEW of FUNDAMENTAL PROCESS ASPECTS FOR the PRODUCTION of MUSHROOM MYCELIUM

A review of fundamental process aspects to produce mushroom mycelium in submerged culture is presented. With peat hydrolysate as the main nutrient source, the operations of substrate preparation, cultivation and product recovery are explained. Based on the growth of Agaricus spp. mushroom mycelium, the conditions for the production of the desired mycelial pellets are analyzed.     

Sterilization of Conduction-Heated Foods in Oval-Shaped Containers

A finite difference approximation of the differential equation for transient heat conduction in three dimensions was used to evaluate thermal processes for foods in oval-shaped containers. A sensitivity analysis on the basis of thiamin retention was used to select the time increment and the size of the volume elements required by the numerical method. Estimations of the temperature for the center of the oval container were in close agreement with an analytical solution valid for sufficiently long times, constant boundary conditions, and uniform initial temperature. To validate the model, published experimental data for the retention of thiamin, chlorophyll and betanin were compared with values predicted by the numerical method.     

Pulsed Ultra High Pressure Treatments for Pasteurization of Pineapple Juice

Sinusoidal and step-pressure pulses were compared with static pressure treatments for the inactivation of Saccharomyces cerevisiae 2407-1a in pineapple juice. No inactivation was observed after 40–4,000 fast sinusoidal pulses (10 cycles/s) at 4–400 sec in the 235–270 MPa range. Static 270 MPa treatments at 40 and 400 sec resulted in 0.7 and 5.1 decimal reductions, respectively. Slower 0–270 MPa step pulses at 0.1 (10 pulses), 1 (100 pulses), and 2 (200 pulses) cycles/s with 100 sec total on-pressure time resulted in 3.3, 3.5, and 3.3 decimal reductions, respectively. A comparable static pressure treatment resulted in 2.5 decimal reductions. Changing the on-pressure/off-pressure time ratio (3:1, 3:3 and 1:3) showed that treatments with longer on-pressure time, e.g., 0.6 sec on-pressure and 0.2 sec off-pressure were significantly more effective showing nearly a 4 decimal reduction in 100 sec.     

ENTEROBACTERIACEAE IN ICE CREAM SOLD AT RETAIL IN TENERIFE, SPAIN

Ice cream is a dairy product which favors the growth of microorganisms and can be exposed to contamination during handling while being sold at the retail market. The presence of microorganisms belonging to the Enterobacteriaceae family was studied in 67 ice cream samples in the province of Santa Cruz de Tenerife. All the samples showed positive counts, of which 82.1% revealed microbiol counts of > log 3 - < log 5 CFU/g. The isolated species identified (as percent of total) were: Klebsiella pneumoniae, 34.8; Enterobacter aerogenes, 19.3; Enterobacter cloacae, 11.1; Enterobacter aglomerans, 11.6; Escherichia coli and Salmonella arizonae, 2.6; Citrobacter freundii, 1.3; and Serratia marcenscens, 0.7.     

Optimization of a cascaded structure for noise and echo cancellation using a noise filtering preprocessing

This paper deals with speech enhancement in hands-free telecommunication systems. The two major problems encountered in such contexts - noise reduction and acoustic echo cancellation - are addressed. After the presentation of the two basic cascaded structures found in the literature, we propose a new promising technique which takes advantage of the previous ones. The main objective is to get a near-end speech signal with low levels of distortion, echo and noise. The structure is tested in a real mobile environment and compared with the two others. An objective evaluation shows the improvement provided by this structure.     

POSTMORTEM SHORTENING OF LAMB LONGISSIMUS OXIDATIVE AND GLYCOLYTIC FIBERS

Percentages of lamb M. longissimus thoracis et lumborum fiber types were approximately 66 oxidative and 34 nonoxidative, without significant differences among muscle regions. The effects of skeletal restraint and muscle region on sarcomere shortening during rigor development were found to be highly significant; sarcomeres of caudal-ventral location were stretched by skeletal restraint while the rest were all shortened. In excised muscles, both fiber type and postmortem temperature exerted a highly significant effect on sarcomere shortening. Oxidative fibers showed a more intense shortening, already evident at temperatures well above those causing cold shortening. While shortening of glycolytic fibers was gradually more intense as treatment temperature decreased from 20 to 0°C, a maximum contraction of about 40% was reached at 15°C in oxidative fibers and lower temperatures did not cause any further shortening. Average fiber shortening was found to be highly correlated to meat toughening.