Optimization of oxalate-free starch production from Taro flour by oxalate oxidase assisted process.

Taro (Colocasia esculenta) starch is known to possess unique physical and functional properties such as low amylose content, A-crystalline form, small granules, higher swelling power, etc. Due to the presence of significant amount of calcium oxalate crystals, the food industry is reluctant to explore this unique and cheap starch source for various food applications. Traditional processes utilizing various physical and chemical methods to remove oxalate content of starch inevitably change its physical and functional properties. However, using oxalate oxidase can effectively remove oxalates without altering the unique properties of starch. Hence, an attempt was made to optimize oxalate oxidase assisted starch extraction process from taro flour using response surface methodology. A central composite design comprising 20 experimental trials with 10 cube points augmented with six axial points and four replicates at the center point was applied. A mathematical model was developed to show the effect of taro flour concentration, enzyme load and incubation time on the oxalate removal. Validity of the model was experimentally verified and found that 98.3% of total oxalates can be removed under optimal conditions. This is the first report of optimization of the production of starch from taro flour using microbial oxalate oxidase.

The complete chloroplast genome of Microcycas calocoma (Miq.) A. DC. (Zamiaceae, Cycadales) and evolution in Cycadales.

Cycadales is an extant group of seed plants occurring in subtropical and tropical regions comprising putatively three families and 10 genera. At least one complete plastid genome sequence has been reported for all of the 10 genera except Microcycas, making it an ideal plant group to conduct comprehensive plastome comparisons at the genus level. This article reports for the first time the plastid genome of Microcycas calocoma. The plastid genome has a length of 165,688 bp with 134 annotated genes including 86 protein-coding genes, 47 non-coding RNA genes (39 tRNA and eight rRNA) and one pseudogene. Using global sequence variation analysis, the results showed that all cycad genomes share highly similar genomic profiles indicating significant slow evolution and little variation. However, identity matrices coinciding with the inverted repeat regions showed fewer similarities indicating that higher polymorphic events occur at those sites. Conserved non-coding regions also appear to be more divergent whereas variations in the exons were less discernible indicating that the latter comprises more conserved sequences. Phylogenetic analysis using 81 concatenated protein-coding genes of chloroplast (cp) genomes, obtained using maximum likelihood and Bayesian inference with high support values (>70% ML and = 1.0 BPP), confirms that Microcycas is closest to Zamia and forms a monophyletic clade with Ceratozamia and Stangeria. While Stangeria joined the Neotropical cycads Ceratozamia, Zamia and Microcyas, Bowenia grouped with the Southern Hemisphere cycads Encephalartos, Lepidozamia and Macrozamia. All Cycas species formed a distinct clade separated from the other genera. Dioon, on the other hand, was outlying from the rest of Zamiaceae encompassing two major clades-the Southern Hemisphere cycads and the Neotropical cycads. Analysis of the whole cp genomes in phylogeny also supports that the previously recognized family-Stangeriaceae-which contained Bowenia and Stangeria, is not monophyletic. Thus, the cp genome topology obtained in our study is congruent with other molecular phylogenies recognizing only a two-family classification (Cycadaceae and Zamiaceae) within extant Cycadales.

Chemical constituents of Cinnamomum cebuense.

AIM: To investigate the chemical constituents of Cinnamomum cebuense, an endemic and critically endangered tree found only in Cebu, Philippines. METHODS: The compounds were isolated by silica gel chromatography. The structures of the isolates were elucidated by NMR spectroscopy. RESULTS: The dichloromethane (DCM) extract of the bark of C. cebuense afforded a new monoterpene natural product 1 and a new sesquiterpene 2, along with the known compounds, 4-hydroxy-3-methoxycinnamaldehyde (3), 4-allyl-2-methoxyphenol (4), α-terpineol (5) and humulene (6). The DCM extract of the leaves of C. cebuense yielded 6, ß-caryophyllene (7), squalene (8), and a mixture of α-amyrin (9), ß-amyrin (10) and bauerenol (11). The structures of 1-7 were elucidated by extensive 1D and 2D NMR spectroscopy, while the structures of 8-11 were identified by comparison of their (13)C NMR data with those reported in the literature. CONCLUSION: The bark of C. cebuense afforded monoterpenes, sesquiterpenes and phenolics, while the leaves yielded sesquiterpenes and triterpenes.