Isolation, Purification and Physicochemical Characterization of Polyphenoloxidases (PPO) from a Dwarf Variety of Banana (Musa cavendishii, L)

A procedure for isolating and purifying polyphenoloxidase from banana pulp is described. Maximum activity was obtained from the inner portion of the pulp by extraction with 0.2M sodium phosphate buffer, pH 7.0, containing 1% insoluble PVP and 0.25% Triton X-100. The enzyme was purified 38.8-fold after acetone precipitation, re-extraction of the precipitate with phosphate buffer containing Triton X-100, storage in the freezer for 7 days (-40°C), chromatography on Sephadex G-100 and electrophoresis on polyacrylamide gel. The purified enzyme (four isozymes) gave a poly-peptide molecular weight (SDS-gel) of 31,000 ± 1,000 and molecular weight on sucrose gradient ultracentrifugation of 62,000 ± 2,000. The isoelectric point, determined by isoelectric focusing on polyacrylamide gel, was 5.2. The enzyme was stable at 55°C for 30 min; it lost mole than 90% of the activity after 5 min at 85°C and was completely inactivated at 95°C for the same time. The absorption spectrum of the purified enzyme showed a maximum at 278 nm and a shoulder at 340-350 nm. This preparation, when submitted to paper chromatography revealed the presence of a fluorescent compound with R_f= 0.57, which was identical with chlorogenic acid.     

Leaf blade anatomy and ultrastructure of six <i>Simira</i> species (Rubiaceae) from the Atlantic Rain Forest,Brazil

Simira is a predominantly woody Neotropical genus comprising 41 taxa, 16 of which occur in Brazil and eight of them in the southeastern region of Brazil. Leaf blades of Simira eliezeriana Peixoto, S. glaziovii (K. Schum.) Steyerm., S. grazielae Peixoto, S. pikia (K. Schum.) Steyerm., S. rubra (Mart.) Steyerm., S. sampaioana (Standl.) Steyerm. were collected in the southeastern region of Brazil and fixed according to usual methods for light and electron microscopy. The leaf blades show typical characteristics of the Rubiaceae family as dorsiventral mesophyll and paracytic stomata. The presence of two bundle sheaths that extend to the upper epidermal layer, prismatic crystal and crystal-sand, alkaloids in the mesophyll and the organization micromorphological of the outer periclinal wall are considered characteristics representative for the genus. This study also demonstrates some leaf blade characteristics that can be used to Simira species identification (leaf surface, domatia types, epicuticular wax types and patterns of epidermis anticlinal cell walls).     

GREEN COLOR DEGRADATION of BLANCHED BROCCOLI (BRASSICA OLERACEA) DUE to ACID and MICROBIAL GROWTH

Effect of acid and microbial growth on green color degradation of blanched broccoli (Brassica oleracea) during storage at 7C was studied. When broccoli was submerged in McIlvaine's buffer at pH 3–8, color degradation accelerated as pH decreased, as expected. High Performance Liquid Chromatography (HPLC) was used to show that the color degradation was due to the conversion of chlorophyll to pheophytin only. Pheophytinization followed a first order reaction. the logarithm of the reaction rate constants were linearly correlated to the environmental pH, up to pH 7. Acids containing a benzene ring caused a faster color change than acids with a simple carbon chain due to their hydrophobicity. Microbial growth accelerated color change by producing acid and produced what appear to be holes in the surface of the broccoli, as shown by Environmental Scanning Electron Microscopy (ESEM).     

CHEMICAL CHARACTERIZATION AND PREPARATION OF SALTED MINCES FROM BIGEYE GRUNT AND LONGFIN BONEFISH

The proximate chemical composition, amino add and fatty add profile of bigeye grunt (Brachydeuterus auritus) and longfin bonefish (Pterothrissus belloci) minces were determined. Both minces contained a low fat content. Polyunsatu‐rated fatty adds represented more than 50% of the fatty adds in bigeye grunt but in the case of longfin bonefish the percentages of saturated, mono‐, and polyunsaturated were similar. The amino add profile of minces from these species was very similar. The preparation of salted minces using different drying methods is described. The chemical and physical characteristics of raw and dried salted minces as well as cooked products were measured. Dried salted minces from these species had high water uptake and cooked products presented a low salt content (1 %). Cooked rehydrated salted minces from longfin bonefish were lighter in color than those from bigeye grunt and color values were not significantly influenced by the salt level used in the preparation.     

ALPHA-LINOLENIC ACID AND LINOLEIC ACID IN SERUM AND TISSUES AFTER FLAXSEED (Linum usitatissimum) OIL IN VIVO ADMINISTRATION

Essential fatty acids can be helpful in the prevention of several pathologies. The bioavailability of acute supplementation of different doses of flaxseed oil was studied by analyzing the level of alpha-linolenic acid (ALA) and linoleic acid (LA) in serum and tissues (adipose, liver) of rats tested at 2, 4, 8 and 16 h after the administration. The amount of flaxseed oil administered at increasing doses corresponded to 1, 2.5 and 5 g ALA/kg of body weight. The corresponding fatty acid methyl esters obtained via direct methylation were quantified using gas chromatography/mass spectrometry. Serum ALA level increased after 1 or 2.5 g/kg. ALA was increased in both adipose and liver tissue 4 h after the administration of 1 g/kg of flaxseed oil. There was no further increase by using a higher oil dosage. LA did not change in serum at the doses used.

PRACTICAL APPLICATIONS

The bioavailability of acute supplementation of increasing doses of flaxseed oil was examined by analyzing the level of alpha-linolenic acid (ALA) (ω3) and linoleic acid (ω6) in serum and tissues (adipose, liver).These data suggest that there is a limiting step in the absorption of these fatty acids and that there is no advantage to take more than 1 g/kg of ALA supplementation. The daily use of flaxseed oil could be a good alternative in some cases to fish oil in the prevention of several pathologies.     

Effect of Phytic Acid on the In-Vitro Rate of Digestibility of Rapeseed Protein and Amino Acids

Phytic acid in rapeseed flour was reduced by pH adjustment to 5.15 with subsequent dialysis or by phytase treatment at pH 5.15 with subsequent dialysis. The effect of phytate reduction on the rate and extent of protein and amino acid digestibilities was then determined using an in vitro pepsin-pancreatin proteolysis method with simultaneous dialysis of reaction products. A 51% reduction in phytic acid increased the rate of release of many essential amino acids but a further 89% reduction in phytic acid did not enhance that effect. Phytate removal did not improve the protein digestibility.     

Characterization and Distribution of Aerobic, Spore-Forming Bacteria from Cacao Fermentations in Bahia

Aerobic spore forming bacteria isolated from traditional cacao fermentations in Bahia were identified in the genus Bacillus: B. subtilis, B. licheniformis, B. firmus, B. coagulans, B. pumilus, B. macerans, B. polymyxa, B. laterosporus, B. stearothermophilus, B. circulans, B. pasteurii, B. megaterium, B. brevis, and B. cereus. In the first 8 hr of the fermentations, similar percentages of ten species were found in the distribution. During the fermentation process the amount of spore-forming bacteria increased and B. subtilis, B. circulans, and B. licheniformis appeared more frequently.     

Metastability of Tetragonal Zirconia Powders

The formation of metastable t -ZrO₂ by thermal treatment was studied in a systematic way on two different samples: a gel (G) and zirconyl acetate (A). The results show that initially nucle-ation of t -ZrO₂ is favored by creation of anionic vacancies with trapped electrons. At higher temperatures the electronic defects disappear, the crystallites grow, and the m -phase can nucleate. This evolution is observed perfectly on sample A because of its special morphological characteristics.     

FORMAL SEMIOTICS AND MULTIDIMENSIONAL SEMIOTIC SYSTEMS

Concepts of formal semiotics can be combined into one system. The paper discusses how—by illustrating the dynamics of relations between observations and collected knowledge about objects and production of their copies on a given level of representation-the methodological and integrative role of semiotic conceptions of the foundations of cognition is revealed.     

The integration of manipulation and vision for assembly and quality control

The recent, development of industrial robots has produced quite powerful and cost-effective manipulators. Some crucial operations, as managing parts with random orientation or realigning pieces, can now be solved with the aid of vision systems connected with the manipulator. Quality control can be partially done during the assembly itself.

The solutions we may adopt to integrate manipulation and vision can be various. If we want to make it easy to program the system as a whole, with the same programming language, we should study solutions in which manipulation and vision use high-level languages To this end we will discuss how the choice of the programming language for the application programs is crucial.

The hardware and software structures of an operational example of such a system are presented. Examples of programs are given