Browsing by Author "Jimenez, M"

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    Extraction kinetics of pre-pelletized Jalapeno peppers with supercritical CO2
    (ELSEVIER SCIENCE BV, 2003) del Valle, JM; Jimenez, M; de la Fuente, JC
    The aim of this work was to assess and model supercritical carbon dioxide (ScCO2) extraction kinetics of pre-pelletized Jalapeno peppers (Capsicum annuum L.). Pepper flakes were conditioned to low moisture, ground finely and pelletized at high pressure, and pellets were subsequently ground and size classified. The effects of average sample particle size (D-p = 0.28-3.19 mm) and superficial solvent velocity (U-s = 0.14-2.62 mm s(-1)) were evaluated at 40 degreesC and 120 or 320 bar. Extraction rate increased as a result of a decrease in D-p. It also increased as a result of an increase in US at 120 bar, but the effect was almost negligible at 320 bar. Integral extraction yields of capsicum oleoresin and capsaicinoids were approximate to0.102 g g(-1) and approximate to240 mg kg(-1), respectively, independent of extraction conditions. External mass transfer coefficients (kr) increased with U-s, but this effect was less pronounced than commonly reported in the literature. Values of kr increased as D-p or process pressure decreased, due respectively to increments in specific area and improvements in transport properties. Internal mass transfer coefficients, on the other hand, were 5.3 x 10(-8) m s(-1) at 40 degreesC and 120 bar, and 34.7 x 10(-8) m s(-1) at 40 degreesC and 320 bar. Solutes were effectively liberated from the original matrix with our multistage pretreatment, so that the fraction of free solute did not depend on D-p (alpha = 0.46). Pseudosolubilities for capsicum oleoresin in ScCO2 ( approximate to 2100 mg l(-1) at 40 degreesC and 120 bar; approximate to13,700 mg l(-1) solute/CO2 at 40 C and 320 bar) were of the same order of magnitude as corresponding true solubilities of capsaicin (5600 and 11,800 mg l(-1) respectively). Estimated true solubilities of chlorophyll-a in ScCO2 (2 mg l(-1) at 40 degreesC and 120 bar; 18 mg l(-1) at 40 degreesC and 320 bar), on the other hand, were orders of magnitude smaller, which justifies a much slower extraction rate for green pigments than pungent compounds. Thus, oleoresin obtained after 4 h at 40 degreesC and 120 bar had a very attractive light yellow tinge. (C) 2002 Elsevier Science B.V. All rights reserved.
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    Pathological characteristics of thyroid microcarcinoma. A review of 402 biopsies
    (2005) Fardella, C; Jimenez, M; Gonzalez, H; Leon, A; Goni, I; Cruz, F; Solar, A; Torres, J; Mosso, L; Gonzalez, G; Rodriguez, JA; Campusano, C; Lopez, JM; Arteaga, E
    Background: Thyroid microcarcinoma is a tumor of 10 mm or less. that should have a low risk of mortality. However a subgroup of these carcinomas is as aggressive as bigger tumors. Aim To describe the pathological presentation of these tumors.. and compare them with larger tumors. Material and methods. All Pathological samples of thyroid carcinoma that were obtained between 1992 and 2003, were studied. In all biopsies, the pathological type, tumor size. the focal or multifocal character the presence of lymph node involvement and the presence of lymphocytic thyroiditis or thyroid hyperplasia, were recorded. Results: One hundred eighteen microcarcinomas and 284 larger tumors were studied. The mean age of patients with microcarcinoma and larger tumors was 42.7 +/- 14 and 49.3 +/- 16 years respectively (p < 0,00.1) and 83% were female. without gender differences between tumor types. klean size of microcarcinomas was 8.6 mm and 116 (98%) were papillary carcinomas. Of these. 109 (94% were well differentiated and seven (6%) were moderatly differentiated. Thirty six(31%) were multifocal and in 10 (8,6%), there was lymph node involvement. The mean size of larger tumors was 23.8 mm and 241 (85%) were papillary carcinomas. Of these, 200 (83%) were well differentiated, and 41 (17%) were moderately differentiated.Eighty five (35%) were multifocal and in 44 (18%) there was lymph node involvement. The prevalence of thyroiditis and hyperplasia was significantly higher among microcardinomas than in larger tumors (15 and 2.5%, respectively, p < 0.001, for the former; 32.4 and 1.7%, respectively, p < 0.001, for the latter. Conclusions. In this series. one third of microcarcinomas were multifocal and 10% had lymph node involvement. Therefore, aggresiveness of these tumors is higher than what is reported in the literature and they should be treated with total thyroidectomy.