Ripe Banana Flour as a Source of Antioxidants in Layer and Sponge Cakes.

About one-fifth of all bananas harvested become culls that are normally disposed of improperly. However, ripe banana pulp contains significant amounts of fibre and polyphenol compounds as well as a high content of simple sugars (61.06 g/100 g), making it suitable for sucrose replacement in bakery products. This work studied the feasibility of incorporating ripe banana flour (20 and 40% of replacement) in cake formulation. Physical, nutritional and sensory attributes of sponge and layer cakes were evaluated. The inclusion of ripe banana flour generally led to an increased batter consistency that hindered cake expansion, resulting in a slightly lower specific volume and higher hardness. This effect was minimised in layer cakes where differences in volume were only evident with the higher level of replacement. The lower volume and higher hardness contributed to the decline of the acceptability observed in the sensory test. Unlike physical attributes, the banana flour inclusion significantly improved the nutritional properties of the cakes, bringing about an enhancement in dietary fibre, polyphenols and antioxidant capacity (up to a three-fold improvement in antioxidant capacity performance). Therefore, results showed that sugar replacement by ripe banana flour enhanced the nutritional properties of cakes, but attention should be paid to its inclusion level.

Metallothionein expression in chloroplasts enhances mercury accumulation and phytoremediation capability.

Genetic engineering to enhance mercury phytoremediation has been accomplished by expression of the merAB genes that protects the cell by converting Hg[II] into Hg[0] which volatilizes from the cell. A drawback of this approach is that toxic Hg is released back into the environment. A better phytoremediation strategy would be to accumulate mercury inside plants for subsequent retrieval. We report here the development of a transplastomic approach to express the mouse metallothionein gene (mt1) and accumulate mercury in high concentrations within plant cells. Real-time PCR analysis showed that up to 1284 copies of the mt1 gene were found per cell when compared with 1326 copies of the 16S rrn gene, thereby attaining homoplasmy. Past studies in chloroplast transformation used qualitative Southern blots to evaluate indirectly transgene copy number, whereas we used real-time PCR for the first time to establish homoplasmy and estimate transgene copy number and transcript levels. The mt1 transcript levels were very high with 183,000 copies per ng of RNA or 41% the abundance of the 16S rrn transcripts. The transplastomic lines were resistant up to 20 µm mercury and maintained high chlorophyll content and biomass. Although the transgenic plants accumulated high concentrations of mercury in all tissues, leaves accumulated up to 106 ng, indicating active phytoremediation and translocation of mercury. Such accumulation of mercury in plant tissues facilitates proper disposal or recycling. This study reports, for the first time, the use of metallothioneins in plants for mercury phytoremediation. Chloroplast genetic engineering approach is useful to express metal-scavenging proteins for phytoremediation.

Toxicity and mAChRs binding activity of Cassiopea xamachana venom from Puerto Rican coasts.

A separation of toxic components from the upside down jellyfish Cassiopea xamachana (Cx) was carried out to study their cytotoxic effects and examine whether these effects are combined with a binding activity to cell membrane receptors. Nematocysts containing toxins were isolated from the autolysed tentacles, ruptured by sonication, and the crude venom (CxTX) was separated from the pellets by ultracentrifugation. For identifying its bioactive components, CxTX was fractionated by gel filtration chromatography into six fractions (named fraction I-VI). The toxicity of CxTX and fractions was tested on mice; however, the hemolytic activity was tested on saline washed human erythrocytes. The LD50 of CxTX was 0.75 microg/g of mouse body and for fraction III, IV and VI were 0.28, 0.25 and 0.12 microg/g, respectively. Fractions I, II and V were not lethal at doses equivalent to LD50 1 microg/g. The hemolytic and phospholipase A2 (PLA2) activities of most fractions were well correlated with their mice toxicity. However, fraction VI, which contains the low molecular mass protein components (< or =10 kDa), has shown no PLA2 activity but highest toxicity to mice, highest hemolytic activity, and bound significantly to the acetylcholine muscarinic receptors (mAChRs) isolated from rat brain. The results suggested that fraction VI contains proteinaceous components contributing to most of cytolysis as well as membrane binding events. Meanwhile, fraction IV has shown high PLA2 that may contribute to the venom lethality and paralytic effects.