THERMAL RESISTANCE OF BACILLUS CEREUS SPORES AS AFFECTED BY ADDITIVES IN THE RECOVERY MEDIUM

The effects of the addition of starch, glucose, sodium chloride, sodium citrate, monopotassium phosphate and disodium phosphate to the recovery medium on apparent heat resistance of Bacillus cereus spores (ATCC 4342, 7004 and 9818) were investigated. Sodium citrate, monopotassium and disodium phosphate at concentrations of 0.1% were effective inhibitory agents for heat injured B. cereus spores especially for strain 9818, although only monopotassium and disodium phosphate caused a significant reduction (p < 0.05) in D-values obtained for strain 9818. Sodium chloride also had a marked effect on the recovery of heat injured spores. Concentration as low as 0.5% caused a significant reduction in the recovery rates for strains 9818 and 7004. In all cases, increasing the salt levels from 0.5 to 4% resulted in a progressive decrease in spore recovery. D-values gradually decreased as the salt content increased, although the concentrations which produced statistically significant differences (p < 0.05) varied among strains. The addition of starch at 0.1% resulted in a significant increase in the counts for strains 9818 and 7004. In contrast, glucose (0.1%), did not significantly modify the counts obtained Neither of these compounds affected decimal reduction times. No statistical significance (p>0.05) differences were detected among z-values for the spores of the three strains recovered in the presence of different additives assayed. z-Values ranged from 6.67 to 8.32, with a mean value of 7.56 ± 0.46C .     

EFFECT OF SEASONAL VARIATIONS ON PROTEIN FUNCTIONAL PROPERTIES OF FISH DURING FROZEN STORAGE

Influence of seasonal variation (February, July and October), time elapsed before freezing, and type of processing of the muscle on several functional properties (protein solubility, emulsifying capacity, and viscosity) in two species of fish with differing seasonal behavior (hake and sardine) were studied. Correlations between the changes in these functional properties during frozen storage were established. Although proximate analyses of the hake muscle were similar throughout the year, significant differences were observed in viscosity and protein solubility during storage between lots of fish caught in different seasons. Changes in the functional properties were less evident in sardine, which undergoes wide seasonal variations. The larger differences in the functional proprities of hake muscle, depending on season, were related to differences in the dimethylamine content after the fifth month of frozen storage. High correlations were established between functional properties in fish caught in the same or different seasons. Any of the three functional properties studied can be used as a suitable index of the quality of frozen fish, irrespective of the different conditions studied.     

Effects of sporulation media and strain on thermal resistance of Bacillus cereus spores

Spores of Bacillus cereus strains ATCC 7004, ATCC 4342 and ATCC 9818 were produced in four sporulation media (Nutrient Agar supplemented with 1 ppm Mn²⁺, Fortified Nutrient Agar, Angelotti Medium and Milk Agar) and their percentages of sporulation and heat resistance parameters obtained in a wide temperature range were compared. In all conditions studied, high rates of sporulation were obtained. Clear differences among D-values for spores produced in the four media were observed. the medium which yielded the most resistant spores and the magnitude with which the sporulation medium affected D-values was different for each strain. z-Values of the three strains were not influenced by the medium used to obtain spores.     

INFLUENCE of REACTION CONDITIONS ON the FORMATION of NONDIALYZABLE MELANOIDINES FROM D-FRUCTOSE and GLYCINE

The influence of the water content, molar ratio of reagents, time and temperature on the formation of nondialyzable melanoidines of the model system D-fructose-glycine has been studied.
The rate constants of the reaction for molar ratios 2.5:1, 1:1, 1:2.5 have been calculated to be (2.38 ± 0.17) x 10⁻⁵ S⁻¹, (3.94 ± 0.28) x 10⁻⁵ S⁻¹ and (5.11 ± 0.36) x 10⁻⁵ S⁻¹, respectively.
The activation energy has been determined (105.0 ± 3.6) kJ/mol and (74.6 ± 7.1) kJ/mol for molar ratios 2.5:1 and 1:2.5, respectively.     

APPLICATION OF MULTIVARIATE STATISTICAL METHODS TO DIFFERENTIATION OF RUM AGED IN TWO TYPES OF OAK BARRELS

Multivariate statistical methods have been applied to analytical data for 14 major volatile compounds collected from various rum samples, in order to differentiate rums aged in two types of oak vessels, hogshead and pipe.     

ISOLATION AND CHARACTERIZATION OF MELANOIDINES FROM MALT AND MALT ROOTS

Preparative isolation of alcohol-soluble and water-soluble melanoidines from pale malt, caramel malt, coffee malt and malt roots was done. The distribution of melanoidines according to molecular weight and the spectral characterization of the separate fractions was studied by gel chromatography on Sephadex G-50. The melanoidines isolated from coffee malt have the largest molecular weights and those from pale malt the smallest. The alcohol-soluble melanoidines of malt are characterized by a greater diversity in spectra and absorbance maxima from 240 to 285 nm. The water-soluble melanoidines absorb in the region 265 to 283 nm.