Browsing by Author "Agosin, E"

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    A neural network estimator for total biomass of filamentous fungi growing on two dimensional solid substrate
    (KLUWER ACADEMIC PUBL, 1998) Acuna, G; Giral, R; Agosin, E; Jorquera, H; Perez Correa, R; Ferret, E; Molin, P; Thibault, J
    A neural network dynamic model is proposed for the on-line estimation of total biomass during filamentous fungi cultures on two dimensional solid substrate. The neural network provides an accurate and robust estimation of biomass from macroscopic measurements of the colony radius evolution. Experiments were performed on Gibberella fujikuroi growing on Petri dishes under different conditions of temperature and water activity.
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    Biological and integrated control of Botrytis bunch rot of grape using Trichoderma spp.
    (1996) Harman, GE; Latorre, B; Agosin, E; SanMartin, R; Riegel, DG; Nielsen, PA; Tronsmo, A; Pearson, RC
    Field trials were carried out in upstate New York in 1990, 1992, 1998, and 1994 and in Chile in 1992-1993 and 1993-1994 in order to evaluate the ability of various strains of Trichoderma spp. to control bunch rot of grape, to assess the compatibility and possible additive effects of selected biocontrol fungi and dicarboximide fungicides, and to determine factors affecting biocontrol efficacy. In 1990, three strains of Trichoderma spp. were evaluated for their biocontrol ability, and all provided significant control of Botrytis cinerea. As few as two late applications of the biocontrol fungi were nearly as effective as up to five applications throughout bloom and fruit development. Trials in New York in 1992 and in Chile in 1992-1993 indicated that Trichoderma harzianum could replace some applications of iprodione or vinclozolin with little reduction in efficacy. In New York in 1993, we found that applications of T. harzianum at bloom and early fruit development followed by a tank-mix application of T. harzianum and half rates of iprodione gave extremely effective control of bunch rot. In 1994, less effective control was obtained than in earlier years. Addition of a nutritive adhesive (Pelgel, a mixture of carboxymethyl cellulose and gum arabic) applied with the biocontrol agent tended to improve results. Thus, biological control of bunch rot of grape with T. harzianum can be an effective method of management of this disease. (C) 1996 Academic Press, Inc.
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    Capture of volatile metabolites for tracking the evolution of gibberellic acid in a solid-state culture of Gibberella fujikuroi
    (2000) González-Sepúlveda, M; Agosin, E
    The evolution of volatile compounds produced during solid substrate cultivation (SSC) of Gibberella fujikuroi on wheat bran was tracked looking for volatile metabolites related with GA(3) production. Ethyl acetate and isoamyl acetate gave identical profiles and sharp increases that abated as the production of GA(3) began, while ent-kaurene displayed a profile matching that of the development of GA(3). ent-Kaurene is a precursor in the synthesis of gibberellins and was the most abundant compound found.
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    Chemical markers for tracking the sensory contribution of production stages in muscat wine distillates
    (WILEY, 2005) Lillo, MPY; Agosin, E; Latrille, E
    The main sensory contribution of each post-fermentation production stage of muscat wine distillates can be tracked by following the concentration of just 1 corresponding chemical marker. Matching sample clusters of sensory and chemical data by using principal components analysis (PCA) revealed potential chemical markers. The data used in this study correspond to 12 sensory attributes that showed significant differences among products (P < 0.05) and concentrations of 23 volatile compounds of 14 distillate fractions and 15 finished. Piscos. Artificial fruit attribute, characteristic of the head fraction (FR1) can be tracked with esters. Linalool, main odor attribute of the 1st part of the heart (FR2) can be tracked with linalool molecule. The 2nd part of the heart (FR3) can be tracked with octanoic acid, decanoic acid, furfural and ethyl lactate, accounting for tails attribute. In blended and aged finished products, chemical markers accounting for the effects of distillate fractions were similar but not identical to the markers from samples obtained from the purely distilled samples. Chemical markers for FR1 are ethyl hexanoate, ethyl octanoate, ethyl decanoate. Differentiation between FR1 and FR2 is less evident than in the purely distilled samples due to the linalool and artificial fruit attribute correlation. Chemical markers for FR2, therefore, include linalool and esters ethyl hexanoate, ethyl octanoate, and ethyl decanoate. The blending of the 2nd, part of the heart (FR3) can be tracked with 2-phenylethanol, ethyl lactate, and decanoic acid. Oak aging was tracked with eugenol and whisky lactones, while 5-hydroxy-methyl-2-furfural accounted for added caramel.
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    Comparison between odour and aroma profiles of Chilean Pisco spirit
    (ELSEVIER SCI LTD, 2005) Lillo, MPY; Latrille, E; Casaubon, G; Agosin, E; Bordeu, E; Martin, N
    Precise sensory measurements of odour (orthonasal) and aroma (retronasal olfactory perception) are time and resource consuming. The aim of this work was to develop improved olfactory tasting procedures. Odour and aroma profiles of 13 Pisco spirits and 14 distillation fractions were obtained through descriptive analysis by a panel of 12 trained subjects. The samples were discriminated by 12 odour and 11 aroma attributes out of 13, with odour being slightly more discriminant at a panel and individual level. Samples were differentiated according to the type of distillation fraction and maturation process. None of the tasting modes induced significantly higher intensity judgement, with the exception of linalol whose average sample odour intensity was higher. However, there were differences in intensity scores between modes due to subject-mode interactions for all attributes except linalol and, to a lesser extent, to product-mode interactions for tails, ethyl acetate and linalol. Partial least square (PLS) models gave a good prediction of aroma from odour scores, except for oak attribute which exhibited a non-linear behaviour. Overall, Pisco olfactory perception can be limited to odour assessment. (C) 2004 Elsevier Ltd. All rights reserved.
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    Effect of culture conditions on spore shelf life of the biocontrol agent Trichoderma harzianum
    (1997) Agosin, E; Volpe, D; Munoz, G; SanMartin, R; Crawford, A
    The influence of pH, carbon:nitrogen (C:N) ratio, carbon content and harvesting time on spore attributes of the biocontrol agent Trichoderma harzianum was evaluated. The effect of these culture parameters on viability, shelf-life and ultrastucture was also assessed. pH was a key parameter to manipulate for both growth and sporulation, while carbon concentration and C:N ratio strongly affected spore production time. At fixed pH, the C:N ratio had a limited influence on production yield, but was critical for spore shelf-life. The highest spore longevity was found in a medium with a C:N ratio of 14 and a pH of 7.0, when most resulting spores were still alive after 45 d storage. These spores also remained viable during storage under a broad range of relative humidities, indicating that they would be more sustainable in the field.
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    Effect of water activity on gibberellic acid production by Gibberella fujikuroi under solid-state fermentation conditions
    (ELSEVIER SCI LTD, 2005) Corona, A; Saez, D; Agosin, E
    The evolution of water activity during solid-state cultivation of Gibberella fujikuroi was followed. A typical organic substrate, wheat bran and soluble starch, was used. Culture sorption isotherms were determined verifying that, as culture evolves, higher moisture contents were necessary to maintain the same water activity level. Optimal values for Gibberella fujikuroi growth and gibberellic acid production rates and yields were established, around a(w) 0.99. A non-linear model, based on neural networks, is proposed to represent the sorption curves of the substrate during the fermentation process. (c) 2005 Elsevier Ltd. All rights reserved.
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    Effectiveness of conidia of Trichoderma harzianum produced by liquid fermentation against Botrytis bunch rot of table grape in Chile
    (ELSEVIER SCI LTD, 1997) Latorre, BA; Agosin, E; SanMartin, R; Vasquez, GS
    Over 100 isolates of Trichoderma harzianum Rifai were obtained from soil samples and from the phylloplane of kiwifruit (Actinidia chinensis Planchon), grape (Vitis vinifera), orange (Citrus sinensis (L.) Osbeck), eucalyptus (Eucalyptus globulus Labill.), and apricot (Prunus armeniaca L.) in Chile. A subsample of 48 isolates were tested and found to be antagonistic to Botrytis cinerea Pers. ex Fr. on apple fruits. Isolate S10B from soil in Chile provided similar control of Botrytis bunch rot under field conditions to reference isolate P1 (ATCC 74058) and T39 (Trichodex 25 WP). However, field trials conducted during four growing seasons (1992-1995) with preparations of conidia of formulated or non-formulated T. harzianum P1 provided only partial control of Botrytis bunch rot of 'Thomson Seedless' table grape. Disease incidence was significantly different (p < 0.05) from untreated controls, but equal to or less than the control achieved with vinclozolin (Ronilan 50 WP, 1.5 kg ha(-1)) and similar to captan (Captan 80 WP, 4 kg ha(-1)). This level of control is insufficient considering that tolerance for B. cinerea is very low (< 0.5%) on table grapes. Nevertheless, the antagonistic activity of T. harzianum may be effective if it is integrated with other control practices, and may result in acceptable levels of disease control with reduced levels of pesticide use. (C) 1997 Elsevier Science Ltd.
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    Induction of trehalose in spores of the biocontrol agent Trichoderma harazianum
    (1997) Pedreschi, F; Aguilera, JM; Agosin, E; SanMartin, R
    Spores of the biocontrol agent Trichoderma harzianum P1 produced in liquid media and harvested in the stationary sporulation stage SSS (after 60 h), had higher viability after slow (>4x) and fast drying (>12x) than their counterparts harvested in the exponential sporulation stage, ESS (after 30 h). The trehalose content of SSS spores was almost 20x higher than that of ESS spores (0.16 vs. 3.4 mg/100 mg, respectively). Heat shock (40 degrees C x 90 min) effectively increased the trehalose content 2.5x with respect to untreated SSS spores. The trehalose content achieved in heat-treated SSS spores was almost 60% higher than the maximum reached by holding the spores under water-stress at 97% relative humidity prior to drying.
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    Monitoring large scale wine fermentations with infrared spectroscopy
    (ELSEVIER, 2004) Urtubia, A; Perez Correa, JR; Meurens, M; Agosin, E
    Negative effects on wine quality and productivity caused by stuck and sluggish fermentations can be reduced significantly, if such problems are detected early through periodic chemical analysis. Infrared spectroscopy (IR) has been used successfully for monitoring fermentations, since many compounds can be measured quickly from a single sample without prior treatment. Nevertheless, few applications of this technology in large scale winemaking have been reported, and these do not cover the entire fermentation from must to finished wine. In this work, we developed IR calibrations for analyzing the fermenting must at any stage of fermentation. The calibration model was obtained with multivariable partial least squares and proved effective for analyzing Cabernet Sauvignon fermentations for glucose, fructose, glycerol, ethanol, and the organic acids; malic, tartaric, succinic, lactic, acetic, and citric. Upon external validation we found an average relative predictive error of 4.8%. Malic acid showed the largest relative predictive error (8.7%). In addition, external validation found that insufficient data for these calibrations made the analysis of fermenting musts using other grape varieties less reliable. (C) 2004 Elsevier B.V. All rights reserved.
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    Proposal for a standardized set of sensory terms for pisco, a young muscat wine distillate
    (AMER SOC ENOLOGY VITICULTURE, 2004) Bordeu, E; Formas, G; Agosin, E
    The predominantly muscat aroma of pisco, a young distillate produced in northern Chile and Peru, distinguishes it from other young spirits. Standardized terminology is necessary, however, to describe differences among the wide range of piscos. This is the first proposal for a standardized set of descriptive terminology for this type of product. A panel of trained specialists established the proposed terminology, which is displayed in a wheel format and in a list of corresponding standards.
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    Reassessment of the estimation of dissolved oxygen concentration profile and K(L)a in solid-state fermentation
    (ELSEVIER SCI LTD, 2000) Thibault, J; Pouliot, K; Agosin, E; Perez Correa, R
    Oxygen mass transfer in aerobic microbial growth systems is often a limiting factor for optimal growth and productivity. Oxygen mass transfer has been widely studied in submerged fermentations but has attracted as yet little attention for solid state fermentations. The parallel to submerged fermentation has led to the incorrect interpretation and use of the overall oxygen mass transfer coefficient (K(L)a) to assess the ability of a particular fermentation system to supply the oxygen to microorganisms. The use of K(L)a, as traditionally defined, should be used with caution in solid substrate fermentation systems because there is no convection on the liquid side of the medium, and oxygen is consumed in the biofilm. Hence, K(L)a must be redefined for solid state fermentation. In this payer, the use of oxygen mass transfer coefficients in solid state fermentations is clarified. Published literature data were analysed with a simple pseudo-steady-state model and used to discuss the influence of the biofilm thickness, the dissolved oxygen diffusion coefficient, the convective gas mass transfer coefficient, and the gas flow rate on the oxygen mass transfer coefficient in solid state fermentations. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.
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    Rigorous dynamic modeling and simulation of wine distillations
    (ELSEVIER SCI LTD, 2004) Osorio, D; Perez Correa, R; Belancic, A; Agosin, E
    A novel simulation strategy for dynamic distillation of complex mixtures, such as wine, is proposed and evaluated in terms of computing efficiency and accuracy. The model developed describes wine distillation as a multicomponent reactive batch distillation process. The simulation approach transforms the system of differential algebraic equations (DAE) into a set of ordinary differential equations, by pre-solving the algebraic equations and replacing them with artificial neural networks.
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    Solid substrate cultivation of Gibberella fujikuroi on an inert support
    (ELSEVIER SCI LTD, 2000) Gelmi, C; Perez Correa, R; Gonzalez, M; Agosin, E
    Growth of Gibberella fujikuroi on Amberlite, an inert support, and gibberellic acid (GA,) production was studied in glass columns under different conditions of temperature and water activity (a(w)). Maximum biomass concentration and GA(3) production were respectively 40 (mg/g inert support) and 0.73 (mg/g inert support). While high specific growth rates were obtained, low initial nitrogen resulted in low biomass concentrations. Maximum GA(3) (31 degrees C, a(w)=0.985) was not produced by the maximum concentration of biomass (25 degrees C, a(w)=0.992). Peaks in the rate curves of either outlet gas, CO2 or O-2 occurred on exhaustion of urea indicating, for future works, just when to feed the culture additional nitrogen. (C) 2000 Elsevier Science Ltd. All rights reserved.
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    Solid substrate fermentation of Monascus purpureus: Growth, carbon balance, and consistency analysis
    (WILEY, 2000) Rosenblitt, A; Agosin, E; Delgado, J; Perez Correa, R
    Solid substrate fermentation (SSF) of Monascus purpureus on rice is a promising new technology for obtaining natural pigments. However, before attempts can be made at maximizing pigment yield, all significant macroscopic compounds should be assayed. Here, Monascus purpureus has been grown on rice in batch mode, and the evolution of the main components, biomass, residual rice, O-2, CO2, ethanol, acetic acid, and pigments, have been followed. This set of data, never previously studied for Monascus SSF, allowed both the performance of a macroscopic elemental balance, which accounted for 83-94% of the initial substrate carbon, and a check of data consistency. Standard consistency analysis showed a significant underestimation of the nitrogen fraction of biomass, but it was unable to discriminate the errors in the carbon balance as a result of the simultaneous presence of two gross errors in the system. A simple stoichiometric model in tandem with consistency analysis explained unaccounted carbon as an underestimation of CO2 and ethanol. Using the simplified method to estimate ethanol, the macroscopic balance accounted for 87-99% of the initial carbon.