Betty K. Ishida

Carotenoid Extraction from Plants Using a Novel, Environmentally Friendly Solvent

Few environmentally friendly solvents are available to extract carotenoids for use in foods. The most effective known solvents are products of the petroleum industry and toxic for human consumption. Yet carotenoid extracts are desirable for use in dietary supplements and as additives to enhance the health benefits of processed foods. Ethyl lactate is an excellent solvent to extract both trans- and cis-lycopene isomers from dried tomato powder, the extraction efficiency of which is enhanced by the addition of the antioxidants alpha-tocopherol and alpha-lipoic acid, both of which are known to benefit human health. It is also useful to extract lutein and beta-carotene from dried powders prepared from white corn and carrots. Because of its low flammability and its origin as a byproduct of the corn and soybean industries, it is more advantageous than ethyl acetate, which is a petroleum product.

The use of in vitro-grown microtuber discs inAgrobacterium-mediated transformation of Russet Burbank and Lemhi Russet potatoes

We have usedin vitro-grown microtuber discs in the transformation of Russet Burbank and Lemhi Russet potato (Solanum tuberosum L.) cultivars byAgrobacterium-mediated gene transfer. Transformed plants were selected by their resistance to kanamycin and identified by β-glucuronidase activity. Northern blot analysis confirmed the presence of the corresponding messenger RNA. The ability to transform these two cultivars promises significant improvements to agronomically important varieties.

Developmental gene regulation during tomato fruit ripening and in-vitro sepal morphogenesis

BackgroundRed ripe tomatoes are the result of numerous physiological changes controlled by hormonal and developmental signals, causing maturation or differentiation of various fruit tissues simultaneously. These physiological changes affect visual, textural, flavor, and aroma characteristics, making the fruit more appealing to potential consumers for seed dispersal. Developmental regulation of tomato fruit ripening has, until recently, been lacking in rigorous investigation. We previously indicated the presence of up-regulated transcription factors in ripening tomato fruit by data mining in TIGR Tomato Gene Index. In our in-vitro system, green tomato sepals cultured at 16 to 22°C turn red and swell like ripening tomato fruit while those at 28°C remain green.ResultsHere, we have further examined regulation of putative developmental genes possibly involved in tomato fruit ripening and development. Using molecular biological methods, we have determined the relative abundance of various transcripts of genes during in vitro sepal ripening and in tomato fruit pericarp at three stages of development. A number of transcripts show similar expression in fruits to RIN and PSY1, ripening-associated genes, and others show quite different expression.ConclusionsOur investigation has resulted in confirmation of some of our previous database mining results and has revealed differences in gene expression that may be important for tomato cultivar variation. We present new and intriguing information on genes that should now be studied in a more focused fashion.

Improved diosgenin production in Dioscorea deltoidea cell cultures by immobilization in polyurethane foam

Dioscorea deltoidea Wall (Dioscoreaceae) cell cultures were entrapped by passive invasion into reticulate polyurethane foam cubes. Immobilization of cells grown in medium containing 3% sucrose reduced the lag phase in growth and thereby reduced the time required to reach maximum diosgenin concentration by 36% compared to cells in suspension culture. Immobilization also increased the total diosgenin produced by 40%. Increased efficiency in diosgenin production was greatest in 3% sucrose; higher concentrations inhibited diosgenin production.

Developmental Regulation Is Altered in the Calyx during in Vitro Ovary Culture of Tomato.

To develop a system with which to study fruit ripening, in vitro ovary cultures were initiated from tomato flowers. As reported previously [Nitsch, J.P. (1951). Am. J. Bot. 38, 566-577], tomato fruit ripened after 6 to 7 weeks, but calyces swelled unexpectedly, lost their green color, and gradually became red and succulent. Investigations were conducted, therefore, to verify the occurrence of the ripening process in the calyx. Ethylene production increased in both ripening fruit and red calyx, as did tissue contents of its immediate precursor, 1-aminocyclopropane-1-carboxylic acid. In addition, an increase in the mRNA of polygalacturonase [poly(1,4-[alpha]-D-galacturonide) glucanohydrolase, EC 3.2.1.15], an enzyme that in tomato is present in large amounts only in ripening fruit, was established in both ripe fruit and red calyx by RNA gel blot analysis. Ultrastructural studies showed that the disruption of cell walls in red calyx was indistinguishable from that occurring in ripe tomato fruit. Thus, the developmental program of the calyx changed in several aspects to resemble that of tomato fruit.

Effects of a hydrodynamic process on extraction of carotenoids from tomato

We evaluated the results of using a proprietary hydrodynamic method, which was introduced with the hope of increasing accessibility of beneficial nutrition-enhancing fruit and vegetable products. Tomato, a major dietary source of carotenoids, notably lycopene, was tested because of its many health benefits to consumers. Samples before and after treatment were compared for lycopene, phytoene, and phytofluene contents. Extractable lycopene and other carotenoids increased significantly. In nature, lycopene exists almost exclusively as the all-trans stereoisomer. Cis-lycopene isomers form during cooking and digestion, resulting in higher percentages in plasma and tissues than ingested. Cis-lycopene isomers are more bioavailable than all-trans lycopene. Extraction using this proprietary method increased extracted cis-lycopene to as high as 43% of the total lycopene, indicating increased isomerisation. This method could therefore contribute significantly to the delivery of health benefits of biologically available lycopene from tomato products for metabolic functions.