Tuna Protein Nutritional Quality Changes after Canning

Albacore tuna (Thunnus alalunga) was steamed and canned in soy bean oil and sterilized at 115°C for 55 or 90 min. Proximate composition, total amino acid and available lysine content were determined during different phases of the process. Water and protein were lost in all phases and fat content increased. There was a decrease in available lysine during cooking but no loss in total amino acids. Nutritional evaluation of the protein showed differences in biological value and net protein utilization when the canned tuna was mixed with bread flour.     

A BENCHMARK COMPUTATIONAL STUDY OF FINITE ELEMENT ERROR ESTIMATION

Benchmark solutions are presented for a simple linear elastic boundary value problem, as analysed using a range of finite element mesh configurations. For each configuration, various estimates of local (i.e. element) and global discretization error have been computed. These show that the optimal mesh corresponds not only to minimization of global energy (or L₂) norms of the error, but also to equalization of element errors as well. Hence, this demonstrates why element error equalization proves successful as a criterion for guiding the process of mesh refinement in mesh adaptivity. The results also demonstrate the effectiveness of the stress projection method for smoothing discontinuous stress fields which, for this investigation, are more extreme as a consequence of the assumption of nearly incompressible material behaviour. In this case, lower order smoothing produces a continuous stress field which is in close agreement with the exact solution.     

High passage numbers induce resistance to apoptosis in C2C12 muscle cells

Cell lines with high passage numbers exhibit alterations in cell morphology and functions. In the present work, C2C12 skeletal muscle cells with either low (<20) or high (>60) passage numbers (identified as lC2C12 or h-C2C12, respectively) were used to investigate the apoptotic response to H2 O2 as a function of culture age h-C2C12. We found that older cultures (h-C2C12 group) were depleted of mitochondrial DNA (mtDNA). When we analyzed the behavior of Bad, Bax, caspase-3 and mitochondrial transmembrane potential, we observed that cells in the h-C2C12 group were resistant to H2 O2 induction of apoptosis. We propose serially cultured C2C12 cells as a refractory model to H2 O2 -induced apoptosis. In addition, the data obtained in this work suggest that mtDNA is required for apoptotic cell death in skeletal muscle C2C12 cells.     

A MARANTHUS CRUENTUS LECTIN: PURIFICATION, STABILITY, AND SOME BIOCHEMICAL PROPERTIES

Amaranth lectin from Amaranthus cruentus seeds was isolated, purified and partially characterized. The purification method used was based on its ability to interact with fetuin. Effects of temperature, pH and buffers and concentration were determined by measurement of lectin hemagglutination activity. Amaranth lectin biological activity was best maintained at temperatures between 4 and 30°C and pH's above or below 5. It was possible to store amaranth lectin at 4°C in acetate buffers, pH 4.8, for prolonged periods and to concentrate it 10-fold by ultrafiltration with only 18% loss of activity. A subunit molecular weight of 32,500 daltons was determined by SDS-PAGE for amaranth lectin.     

RHEOLOGY OF SUCROSE-CMC MODEL SOLUTION

The rheological behavior of an aqueous solution composed of 65% sucrose and 0.1% CMC was experimentally determined from -10C to 50C using a rotational viscometer equipped with coaxial cylinders. The model solution behaved as pseudoplastic fluid, represented by the power-law model. Flow behavior and consistency indices determined at -10.1, 0.5, 9.8, 19.0, 30.1 and 50. OC, showed values between 0.79 to 0.86 and 0.15 to 10.22 Pa. sⁿ, respectively. The effect of temperature on the rheological parameters was represented by Arrhenius-type relationships, with R²≥ 0.97. They were compared to the rheological behavior of a concentrated orange juice with 65° Brix and 7% pulp content. The comparison of separate rheograms for both fluids showed that the model solution can be used to represent concentrated orange juice.     

OSMOTIC DEHYDRATION OF KIWIFRUIT (ACTINIDIA CHINENSIS): FLUXES AND MASS TRANSFER KINETICS

Pulsed‐Vacuum‐Osmotic‐Dehydration of kiwifruit (Actinidia chinensis) was studied using two kinds of osmotic solution: sucrose (65 Brix) and concentrated grape juice (63 Brix), three temperatures (25, 35 and 45C) and four vacuum pulse times (0, 5, 10 and 15 min). Experimental results enabled the mass transfer kinetics for water and solutes to be studied (compositional changes of the liquid fraction and changes in the liquid fraction/solid matrix ratio). The impregnation of samples, because of the vacuum pulse, was higher when concentrated grape juice was used as the osmotic solution, probably due to its lower viscosity. The effective diffusivity (D_e) was obtained for each experimental condition and the results show higher diffusivities for vacuum‐pulsed treatments, although differences between treatments with different vacuum‐pulse time could not be observed. D_e values were slightly greater for treatments with concentrated grape juice. The activation energies (E_o) were obtained by fitting the data to the Arrhenius equation.     

Karyological and electrophoretic differences between <i>Pomacea flagellata</i> and <i>P. patula catemacensis</i> (Caenogastropoda: Ampullariidae)

The widespread Mexican apple snail Pomacea flagellata (Say 1827) and the strictly endemic "tegogolo" P. patula catemacensis (Baker 1922) (restricted to Lake Catemaco), are the only known American Ampullariidae that have haploid complements n=13. Pomacea patula catemacensis has suffered a critical reduction in abundance due to immoderate fishing for human consumption. Chromosome slides were obtained from colchicine-injected Pomacea snails collected from nine locations along the coastal zone of the Gulf of Mexico, including Lake Catemaco, for use in principal component analysis (PCA). Total proteins in foot homogenates were analyzed through isoelectric focusing (IEF) and native-PAGE electrophoresis on polyacrylamide gels. The chromosome number 2n=26 was confirmed for snails from all locations, with a uniform 9 m + 4 sm formula. However, P. patula catemacensis showed significantly larger chromosomes (absolute size) than any population of P. flagellata. Pomacea patula catemacensis also differed from all populations of P. flagellata in a PCA with standardized data, i.e., independently of the absolute size difference between species. Proteins with an acid isoelectric point were dominant in the foot of both species. The electrophoresis analysis showed that P. flagellata has 17 protein bands, with an upper bound at IEF=7.6, while P. patula catemacensis has only 15 bands, with an upper bound at IEF=7 and a more evenly spaced band pattern. Molecular weights ranged from 40 to approximately 130 kDa in both species. Proteins with high values (>94 kDa) were the most abundant. Pomacea patula catemacensis showed a band of 93 kDa, which was absent from all specimens of P. flagellata. Samples of P. flagellata did not cluster according to any geographical pattern in the statistical analyses, nor did they show any taxonomically useful differences in their electrophoretic patterns that merit sub-specific discrimination.     

Brief Note : Improved <i>in vitro</i> embryo development of stenospermic grape by putrescine

The goal of this study was to determine the effect of putrescine, added to the culture medium, on the in vitro development of stenospermic grape (Vitis vinifera L) embryos. The cross breedings of Perlón x G.C88552 and Perlón x Argentina were used. 0 (control), 2 and 4 mM of putrescine were added to the immature seed’s culture medium. In Perlón x Argentina, 2mM of putrescine statistically increased the percentage of total embryos, direct germination, polyembryos and normal plants. In Perlón x G.C88552, only 2 mM of putrescine increased all the variables considered, eventually tripling the percentage of normal plants obtained. The results suggest that the endogenous concentration of putrescine may be a growth limiting factor. Adding putrescine to the culture medium of immature grape seeds is a legitimate resource to significantly increase the results of this technique.