Sierra-Gómez, María del P.

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    Biotransformation of coffee pulp using filamentous fungi
    (2012) Sierra-Gómez, María del P.; Ortiz-Bermúdez, Patricia; College of Engineering; Saliceti Piazza, Lorenzo; Maldonado Ramírez, Sandra L.; Department of Chemical Engineering; Plaza, María L.
    Efforts devoted to the efficient use of agro-industrial residues have increased, especially if the use contributes to solve pollution problems. Coffee pulp/husk is the main byproduct generated during coffee wet processing. To reduce the pollution from this source it is necessary to establish new treatments to bio-transform these wastes, which contain various toxic substances (e.g. caffeine and lignin). The presence of these substances limits their recycling potential and makes their management an environmental challenge. This study focuses on the characterization of fungal strains which might be able to detoxify coffee processing wastes. Among the activities we screened for are decaffeination and delignification. We have identified Alternaria alternata as a potential candidate to degrade caffeine. This isolate was obtained from a ligniculous fungi collection provided by the Forest Products Laboratory in Madison, Wisconsin. A. alternata was evaluated in terms of caffeine degradation as carbon and nitrogen source. Under these conditions we observed a decrease near to 45.33% in the caffeine content. After addition of sucrose the caffeine degradation was 60.92%, in the same period (69 days). Analysis in coffee pulp using Alternaria alternata showed the ability to caffeine degradation during fermentation time (20 days) obtaining a 44.5% of caffeine degradation.
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    Physical - chemical analysis of selected quenepa (Melicoccus bijugatus Jacq) varieties
    (2006) Sierra-Gómez, María del P.; Negrón, Edna; College of Agricultural Sciences; Cedeño-Maldonado, Arturo; Flores-Ortega, Carlos; Department of Food Science and Technology; Zamora-Echavarría, José L
    Tropical fruits are desired by international markets, especially by those markets in which Latin people predominate. In Puerto Rico, there are diverse varieties of quenepa (Melicoccus bijugatus Jacq.), which present different characteristics as to size, shape, flavor, quantity of pulp, time of harvest, and others. The original distribution of this fruit extends from northern South America, to Central America and the Caribbean. The objective of this study was to determine pulp adherence to the seed and the differences in physical- chemical properties of selected varieties of quenepa grown in Puerto Rico. Ten varieties ́Perfa ́, ́Jose Pabón ́, ́Sotomayor ́, ́ Doña Fela ́, ́Sasa ́, ́Martínez ́, ́Las Cuevas ́, ́César Ramos ́, ́Alina ́ and ́Carmen ́, were evaluated for yield of pulp, pulp adherence (pressure), total soluble solids, color, pH, titratable acidity and organic acids. The results showed that the percent of pulp varied from 38 – 53%. The pressure of extraction was an indicator of pulp adherence to the seed. The lowest value was 3.4 PSI and the highest value was 12.0 PSI. In addition, the quantity of soluble solids varied between 18 and 22 °Brix. The predominant acids in the fruit are citric acid, malic acid, succinic acid, acetic acid using HPLC method. The column used was Supecogel C-610 H.