Sergio Feijoó

We studied the effect of Microfluidizer technology (sometimes referred to as "microfluidization"), a new ultra-high pressure homogenization process, on spores of Bacillus licheniformis in ice cream mix. Four batches of pasteurized ice cream mix were preheated to 33, 36, 44, or 50 degrees C, and spores of B. licheniformis were added to yield an inoculum of 2.0 x 10(4) spores/ ml of mix. Samples were treated at 50,000, 100,000, 150,000, and 200,000 kPa. Respective percentages of spore destruction ranged from 6 to 68%. As process pressure in the Microfluidizer system increased, the temperature of the product also increased. At the Microfluidizer system outlet, temperatures ranged from 46 to 88 degrees C. Therefore, a combination of forces, including high pressure and temperature, likely had a multiplier effect on spore destruction during Microfluidizer processing of ice cream mix. Data suggest that it might be possible to design a pasteurizer-Microfluidizer system that would inactivate most bacterial spores in dairy foods without the extreme heat treatment currently required in commercial processing operations.

The vocal quality of 64 normal subjects and 57 subjects suffering various degrees of glottal cancer was investigated using acoustic measures of six different aspects of the voice signal: tone period perturbation, amplitude perturbation, waveform perturbation, vocal noise, spectral periodicity and spectral distortion. The measures were estimated taking the glottal cycle as temporal reference unit to make the influence of the differences in tone period from one person to another as low as possible. The measures were evaluated with regard to (a) their ability to discriminate between healthy and sick subjects, and (b) their correlation with the perceptual evaluation of four trained listeners. The results suggest that signal processing techniques are unsatisfactory for clinical diagnoses but useful for monitoring voice quality.