Ultrasound-assisted extraction of hemicelluloses from grape pomace using response surface methodology.

An ultrasound-assisted procedure was applied to the extraction of hemicelluloses from grape pomace at a mild temperature (20°C). A Central composite design (CCD) was employed to optimize the ultrasound-assisted extraction (UAE) of hemicelluloses from grape pomace with the aim to maximize their extraction yield, and, also, the obtention of the main polymers forming this fraction: Xyloglucans (XLG), Mannans (MAN) and Xylans (XN). Extraction time (X1), solid:liquid ratio (X2) and KOH concentration (X3) were the variables used to optimize the process. The conditions that maximize (1) the extraction yield of hemicelluloses and the contents of (2) XLG, (3) MAN and (4) XN, were: (1) X1=2.6h; X2=1:48 (w/v); X3=0.4M, (2) X1=2.9h; X2=1:57 (w/v); X3=2.25M, (3) X1=2.7h; X2=1:58(w/v);X3=2.2M, and (4) X1=3h; X2=1:60 (w/v); X3=2.3M, respectively. Under these conditions, the maximum extraction yield of hemicelluloses, XLG, MAN and XN contents were: ∼7.9±0.2%, ∼3.6±0.02%, ∼1.1±0.04% and ∼1.2±0.02%, respectively. Close agreement between experimental and predicted values was found. The results suggest that the ultrasound-assisted extraction could be a good option for the extraction of hemicellulosic polysaccharides from grape pomace at industrial level.

Effect of power ultrasound application on aqueous extraction of phenolic compounds and antioxidant capacity from grape pomace (Vitis vinifera L.): experimental kinetics and modeling.

The kinetics of both conventional (mechanical stirring, 200rpm) and acoustic (55±5kHz, 435±5W/L) aqueous extraction of total phenolic content and antioxidant capacity from grape pomace by-products (Vitis vinifera L.) have been experimentally evaluated and modeled at different extraction temperatures (20, 35 and 50°C). A gradual and significant increase of total phenolic content and antioxidant capacity of the extracts was observed as the temperature increased, the highest values being obtained in the case of the extraction assisted acoustically. According to the results, the acoustic assistance of the extraction process led to aqueous extracts with phenolic and antioxidant characteristics similar to those obtained with mechanical stirring, working under lower temperature conditions and during less operating time. Specifically, the conventional extraction of total phenolics at 35 and 50°C did not differ significantly from extractions assisted with power ultrasound at 20 and 35°C, respectively; and the acoustic process required approximately 3, 4 and 8 times less time, at 20, 35 and 50°C, than the conventional extraction to obtain extracts with similar characteristics. The extraction curves obtained for total phenolic content and antioxidant capacity, measured by the ABTS and FRAP methods, were properly represented by a modified Weibull model for both conventional and acoustic extractions within the temperature range 20-50°C, presenting an average percentage of explained variance⩾97.9%, and an average mean relative error⩽7.0%. A high correlation (r(2)⩾0.992) was observed between the experimental and simulated values for all the quality attributes in study.

Ultrasound-assisted extraction of pectins from grape pomace using citric acid: a response surface methodology approach.

An ultrasound-assisted procedure for the extraction of pectins from grape pomace with citric acid as the extracting agent was established. A Box-Behnken design (BBD) was employed to optimize the extraction temperature (X1: 35-75°C), extraction time (X2: 20-60 min) and pH (X3: 1.0-2.0) to obtain a high yield of pectins with high average molecular weight (MW) and degree of esterification (DE) from grape pomace. Analysis of variance showed that the contribution of a quadratic model was significant for the pectin extraction yield and for pectin MW whereas the DE of pectins was more influenced by a linear model. An optimization study using response surface methodology was performed and 3D response surfaces were plotted from the mathematical model. According to the RSM model, the highest pectin yield (∼32.3%) can be achieved when the UAE process is carried out at 75°C for 60 min using a citric acid solution of pH 2.0. These pectic polysaccharides, composed mainly by galacturonic acid units (<97% of total sugars), have an average MW of 163.9 kDa and a DE of 55.2%. Close agreement between experimental and predicted values was found. These results suggest that ultrasound-assisted extraction could be a good option for the extraction of functional pectins with citric acid from grape pomace at industrial level.

Ginecomastia y tumor testicular en niño afecto de síndrome de Peutz-Jeghers / Gynecomastia and testicular tumor in children with Peutz-Jeghers syndrome

Presentamos un enfermo de tumor testicular y síndrome de Peutz-Jeghers (SPJ). La rareza de ambas patologías y la precocidad de aparición, 4 años, lo hacen interesante para el pediatra y cirujano pediátrico. El carácter autosómicodominante del SPJ obliga a control y seguimiento. La aparición de tumor testicular plantea diferencias de criterio sobre su manejo. (AU)

[Gynecomastia and testicular tumor in children with Peutz-Jeghers syndrome]. / Ginecomastia y tumor testicular en niño afecto de síndrome de Peutz-Jeghers.

The rarity of both conditions and the precocity of its onset (4 years old) make the case of interest for pediatricians and pediatric surgeons. The finding of a testicular tumor poses same differences of criterium about its management.

Effects of supercritical carbon dioxide (SC-CO(2)) oil extraction on the cell wall composition of almond fruits.

Extraction of oil from almond fruits using supercritical carbon dioxide (SC-CO(2)) was carried out at 50 degrees C and 330 bar on three sets of almonds: raw almond seeds, raw almond kernels, and toasted almond seeds. Three different oil extraction percentages were applied on each set ranging from approximately 15 to 16%, from approximately 27 to 33%, and from approximately 49 to 64%. Although no major changes were detected in the fatty acid composition between fresh and partially defatted samples, carbohydrate analysis of partially defatted materials revealed important changes in cell wall polysaccharides from almond tissues. Thus, at low extraction percentages (up to approximately 33%), pectic polysaccharides and hemicellulosic xyloglucans were the main type of polymers affected, suggesting the modification of the cell wall matrix, although without breakage of the walls. Then, as supercritical fluid extraction (SCFE) continues and higher extraction rates are achieved (up to approximately 64%), a major disruption of the cell wall occurred as indicated by the losses of all major types of cell wall polysaccharides, including cellulose. These results suggest that, under the conditions used for oil extraction using SC-CO(2), fatty acid chains are able to exit the cells through nonbroken walls; the modification of the pectin-hemicellulose network might have increased the porosity of the wall. However, as high pressure is being applied, there is a progressive breakage of the cell walls allowing the free transfer of the fatty acid chains from inside the cells. These findings might contribute to providing the basis for the optimization of SCFE procedures based on plant food sources.

Effects of heat treatment and dehydration on properties of cauliflower fiber.

The effects of heat treatment and dehydration on fiber structure and hydration properties, using cauliflower floret/curd and stem tissues, have been investigated. No major changes in fiber composition resulted from sample treatments, but the degree of esterification of pectic polysaccharides, approximately 60% in fresh cauliflower, decreased by approximately 12% in samples heated at temperatures >40 degrees C. Enzymic activity was considered to be responsible, through pectin methyl esterase activity. De-esterification was temperature and moisture sensitive. Hydration properties were also affected by processing conditions. The solubility of nonstarch polysaccharides in fresh, freeze-dried, and 40 degrees C dried samples was approximately 6% but increased to 12% in boiled samples and decreased in samples dried at 75 degrees C. Similar behavior occurred for swelling and water retention capacity (WRC), with swelling and WRC highest for boiled samples and lowest for samples dried at 75 degrees C. Hence, a decrease in de-esterification was not directly responsible for changes in hydration properties. The results demonstrate the importance of processing history on functional properties and on the preparation of fiber-rich ingredients for successful incorporation into foods.

Tissue-related changes in methyl-esterification of pectic polysaccharides in cauliflower (Brassica oleracea L. var. botrytis) stems.

Pectic substances are a major component of cell walls in vegetable plants and have an important influence on plant food texture. Cauliflower (Brassica oleracea L. var. botrytis) stem sections at different regions of the mature plant stem have been monitored for tissue-related changes in the native pectic polysaccharides. Chemical analysis detected appreciable differences in the degree of methyl-esterification (ME) of pectic polysaccharides. About 65% of galacturonic acid (GalpA) residues were methyl-esterified in floret tissues. Relative ME showed a basipetal decrease, from 94% in the upper stem to 51% in the lower-stem vascular tissues. The decrease was not related to a basipetal increase in glucuronic acid (GlcpA) residues. The monoclonal antibodies, JIM 5 and JIM 7, produced distinct labelling patterns for the relatively low-methylesterified and high-methyl-esterified pectin epitopes, respectively. Labelling was related to cell type and tissue location in the stem. Floret cell walls contained epitopes for both JIM 5 and JIM 7 throughout the wall. Stem vascular tissues labelled more strongly with JIM 5. Whereas pith parenchyma in the upper stem labelled more strongly with JIM 7, in the lower-stem pith parenchyma, JIM 5 labelling predominated. Localization of pectic polysaccharide epitopes in cell walls provides an insight into how structural modifications might relate to the textural and nutritional properties of cell walls.

Effects of Drying Pretreatments on the Cell Wall Composition of Grape Tissues.

Pretreatments by consecutive dipping in NaOH, citric acid, and K(2)S(2)O(5) solutions help to increase the drying rate of grapes and to reduce the darkening due to enzymic and nonenzymic browning during storage of raisins. However, such pretreatments have also an important effect on the cell wall composition of grape tissues. In both skin and pulp tissues the yield of cell wall material decreased substantially with processing, by 19.7 and 22.5%, respectively. Sodium hydroxide and citric acid solutions solubilized large amounts of pectic substances and xyloglucans, whereas potassium metabisulfite solution caused minor modifications to the composition of cell wall polysaccharides. Moreover, drying pretreatments promoted important changes in the amounts of Ca and Mg associated with cell wall components, which suggested possible structural rearrangements of polymers within the wall. All of these observations were in good agreement with the main results obtained after the application of a nondegradative technique such as FTIR spectroscopy to the cell wall preparations of fresh and processed tissues.

[Esophagogastric resection in patients with esophagogastric varices]. / Resección esofagogástrica en pacientes con várices esofágicas

The authors carried out a revision of the patients in whom esophagogastric resection resection had been practiced as treatment for varices in the extrahepatic portal hypertensive syndrome. They added up to 13 cases out of which, 11 were with exophagogastroanastomosis and 2 with transposition of colon. Out of the 11 patients in whom esophagogastric resection and anastomosis and 2 with transposition of colon. Out of the 11 patients in whom esophagogastric resection and anastomosis of stomach to esophagus was practiced, 8 are well (72%) and 3 died. Out of 2 cases where a segment of colon was interposed, one followed a satisfactory course (50%), but the other one died. All deaths occurred during the immediate postoperative stage. The technique followed, together with its indications, is described and the conclusion is that, although this method is only palliative, it allows to extend the life of the patient and permits the chance to wait for a later stage when a definite operation may be performed.