Correlation study between standard plate count and flow cytometry for determination of raw milk total bacterial count

Milk samples were collected in the dry season ( n =  155) and in the rainy season ( n =  68) to establish a correlation between electronic flow cytometry and standard plate count for the determination of total bacterial count of raw milk. Results were expressed in individual bacterial count (ibc) and colony forming unit (cfu) for electronic flow cytometry (Bactocount) and standard plate count, respectively. The accuracy of Bactocount, denoted by the residual standard deviation ( s ( y,x )), was 0.309 log cfu/mL. The predictive interval of estimated values was broad and it is suggested that total bacterial count should be expressed in ibc without transformation to cfu.     

On the stability of a class of non-linear continuous systems†

A procedure to find the existence and domain of asymptotic stability for a class of systems described by a set of non-linear partial differential equations is presented in the context of semigroup theory.

No a priori bound is imposed on the non-linearity which is assumed to be a quad ratic (bilinear) or multilinear form.

The linearized system can be non-self-adjoint and need not be asymptotically stable equation by equation.

The solution of the stability problem is carried out. in two steps :

(a) the development of an L₂-like norm that bounds above the sup norm, a requirement to obtain a useful estimate of the non-linear term, and

(a)the computation of an estimate of the L₂-likc norm of the semigroup generated by the linearized system in terms of its usual L₂ norm.     

MULTIVARIATE STATISTICAL ANALYSIS OF VOLATILE COMPOUNDS AS A CRITERION FOR SELECTING TECHNOLOGICAL PARAMETERS IN THE OSMOTIC DEHYDRATION OF PINEAPPLE

Principal component analysis and cluster analysis of volatile compounds were used for selecting technological parameters in the osmotic dehydration of pineapple. Assessment of volatile losses permitted differentiation between samples obtained by different osmotic treatments. Treatments at 30C for 1 h at atmospheric pressure or under vacuum and at 30C or 40C for 1 to 3 h with pulsed vacuum (1 cycle) produce the lowest losses of volatile compounds. Apparently, pulsed vacuum allows higher aromatic volatiles retention than two other pressure modes. It also allows increases in both process temperature and time without an important increase in losses.     

2,3-DIHYDROXYBENZOIC ACID AS A SUBSTRATE FOR MUSHROOM TYROSINASE1,2

When 2, 3-dihydroxybenzoic acid (2, 3-DBA) is acted upon by mushroom tyrosinase, a yellow intermediate, 2, 3-DBA-o-quinone, characterized by a peak at 415 nm, is the first product detected. 2, 3-DBA-o-quinone gives rise to a “final blue product” (λmax = 230, 410, 620 nm), and to “soluble oxidation product(s)” (λmax = 275–280, 350–360 nm). Kinetic data (assayed spectrophotometrically and polarographically) obtained when different concentrations of 2, 3-DBA were oxidized by a fixed amount of mushroom tyrosinase, deviated from classic Michaelis-Menten kinetics. Reduction of the “final blue product” with ascorbate resulted in the loss of the blue chromophore at 620 nm and the concomitant appearance of a “yellowish reduced final product.” The “yellowish reduced final product” could be reoxidized with either mushroom tyrosinase or with NaIO4 to the “final blue product,” indicating that the latter has carbonylic quinonoid groups in ortho position to each other.     

Modernism Made Vernacular: The Brazilian Case

From its early acceptance in the 1940s and 1950s, modern architecture in Brazil has become the vernacular, adapted and adopted by the middle class with the help of contractors and unskilled laborers. Even the poorest favelas are constructed using modernist principles on a scale unmatched in developed nations. The Brazilian case highlights a number of issues regarding the relationship between modernism and vernacular architecture, a topic insufficiently explored in architectural scholarship outside Europe and North America.     

PRODUCTION AND CHARACTERIZATION OF THE CASHEW APPLE (ANACARDIUM OCCIDENTALE L.) AND GUAVA (PSIDIUM GUAJAVA L.) FRUIT POWDERS

Cashew apple and guava residues from fruit juice processing industry were prepared as dehydrated fruit powders. Differences in compositional and physicochemical characteristics between both fruit powders were significant at the 5% probability level, with exception to ash content. It is important to point out that despite the dehydration process, both samples can still be considered good sources of vitamin C. In addition, the results show that the guava and cashew apple powders may be useful in the food industry as high dietary "fiber ingredients." Higher lipid (14.05%) content was observed in guava powder. The guava powder could be an alternative source of lipid. The data also indicated that these materials are good sources of ash. The results suggest further utilization of these residues as valuable food ingredients or as a resource for nutraceuticals.

PRACTICAL APPLICATIONS

Large quantity of agro-industrial residues formed by fruit juice extraction represents a major disposal problem. An alternative to recycling the fruit-industrial residue is to submit it to drying processes and transform into value-added products as dehydrated fruit powder. In this way, this process contributes to diminish the problem and to recover valuable biomass and nutrients. The purpose of this study was to develop a technology to obtain guava and cashew apple powders with the objective of finding alternatives to the exploitation of these residues as valuable sources of vitamin C, as ashes and lipid that should also be regarded as potential nutraceutical resources in future or functional ingredients.     

EFFECT OF MALTOL ON THE OXIDATION OF o-DIHYDROXYPHENOLS BY MUSHROOM TYROSINASE AND BY SODIUM PERIODATE1

Maltol (3-hydroxy-2-methyl-4H-pyran-4-one) inhibits the rate of oxidation of different o-dihydroxyphenols by tyrosinase when assayed spectrophotometrically, but not when assayed polarographically. The spectral changes occurring during the oxidation of different o-dihydroxyphenols by tyrosinase (or by sodium periodate) in the absence or presence of maltol were different, suggesting that maltol conjugates with the o-quinones formed. Maltol does not inhibit tyrosinase activity per se but only gives an apparent inhibition probably due to its ability to conjugate with o-quinones.