Moment Of Harvest Research Articles

Autofluorescence Spectroscopy in Liver Transplantation: Preliminary Results From a Pilot Clinical Study

The evaluation of graft function at various stages after transplantation is relevant, particularly at the moment of organ harvest, when a decision must be made whether to use the organ. Autofluorescence spectroscopy is noninvasive technique to monitor the metabolic condition of a liver graft throughout its course, from an initial evaluation in the donor, through cold ischemia transportation, to reperfusion and reoxygenation in the recipient. Preliminary results are presented in six liver transplantations spanning the periods from liver harvest to implant. The laser-induced fluorescence spectrum at 532-nm excitation was investigated before cold perfusion (autofluorescence), during cold ischemia, at the back table procedure, as well as 5 and 60 minutes after reperfusion. The results showed that the fluorescence analysis was sensitive to changes during the transplantation procedure. Fluorescence spectroscopy potentially provides a real-time, noninvasive technique to monitor liver graft function. The information could potentially be valuable for surgical decisions and transplant success.

Essential oil variability in Baccharis uncinella DC and Baccharis dracunculifolia DC growing wild in southern Brazil, Bolivia and Uruguay

AbstractEssential oils of Baccharis uncinella DC and B. dracunculifolia DC collected from different wild populations growing in Bolivia, southern Brazil and Uruguay were analysed using gas chromatography and gas chromatography–mass spectrometry techniques, to check for chemical variability. Cluster analysis led to the identification of two chemotypes for B. dracunculifolia, related to aromadendrane‐ or cadinane‐derived components. As the timing of sampling of the plant material may have an influence on the composition of the essential oil isolated, the seasonal influence at the moment of harvesting was studied for two populations of each species. The results suggested that the flowering season was optimal both species and this supported the practice of harvesting at the full bloom stage. Copyright © 2008 John Wiley & Sons, Ltd.

Conservação de uvas "Crimson Seedless" e "Itália", submetidas a diferentes tipos de embalagens e dióxido de enxofre (SO2)

Estudaram-se o efeito de diferentes tipos de embalagens e a ação do dióxido de enxofre (SO2) na conservação pós-colheita de uvas finas de mesa var. "Crimson Seedless" e "Itália". Os frutos, colhidos em propriedade agrícola situada no município de Boa Vista-RR (Lat. 2º 50' 06" N e Long. 60º 40' 28" W), apresentavam, no momento da colheita, sólidos solúveis (SS) médios de 16,50 e 14,80°Brix, para as variedades "Crimson Seedless" e "Itália", respectivamente. Antes da confecção dos tratamentos, os cachos foram higienizados em solução de hipoclorito de sódio (NaOCl) a 100 mg.L-1, previamente acidificada, por dez minutos. Utilizaram-se, para a atmosfera modificada passiva, sacolas de polietileno de baixa densidade (PEBD), sem perfuração, com 0,010; 0,015 e 0,020mm de espessura,e acondicionadas em embalagens secundárias de papelão (4kg) e de madeira (7,5kg). Para a geração do SO2, foram utilizados papéis Kraft de liberação rápida, com 3 e 8g de metabissulfito de sódio (Na2S2O5). Após a confecção dos tratamentos, os frutos foram armazenados em câmara frigorífica a 4 ± 1°C e 95 ± 3% de umidade relativa (U.R.). As avaliações foram realizadas no momento da colheita e, 7; 21; 35; 42 e 56 dias de armazenamento refrigerado, quanto à porcentagem de perda de massa fresca, taxa de desgrana e de bagas deterioradas, qualidade do engaço e teor de SS dos frutos. Após oito semanas, foi realizado teste de preferência para as duas variedades. Verificou-se, em ambas as variedades, que as uvas submetidas à ação do gerador de SO2 , contendo 3g de metabissulfito de sódio e acondicionamento em embalagens de PEBD de 0,020mm de espessura, independentemente do tipo de embalagem secundária, apresentaram a menor perda de massa fresca, menor taxa de desgrana e de bagas deterioradas, e melhor qualidade do engaço. Os resultados da análise sensorial concordaram com os resultados das análises físico-químicas. Não foram detectadas diferenças nos teores de SS entre os tratamentos, em ambas as variedades. (Apoio: Roraima Agrofrutas).

Influência dos estádios de maturação sobre as características físicas dos frutos de maracujá-amarelo

Este trabalho teve como objetivo avaliar a influência dos estádios de maturação sobre as características físicas dos frutos de maracujazeiro-amarelo para indicação do melhor momento de colheita na região Norte Fluminense. Iniciou-se a colheita aos 52 dias após a antese (DAA), antes das primeiras mudanças de cor da casca serem observadas, prosseguindo-se aos 54, 56, 58, 60, 64, 66, 68, 70, 76, 83 e aos 100 DAA. No último dia de colheita, nos frutos marcados ocorreu abscisão no período da noite. Durante o amadurecimento dos frutos, foi observado aumento progressivo dos parâmetros de Hunter L e b, e na região inferior do fruto ocorreu maior índice de luminosidade e de amarelecimento do que na superior. Houve redução da espessura da casca até o momento do início da mudança de sua cor (64 DAA). Neste período, houve aumento inversamente proporcional de rendimento de suco, atingindo valores superiores a 33%, adequado para a industrialização. Verificou-se tendência de aumento do rendimento de suco para 40% nos frutos com aproximadamente 30% de cor amarela da casca (68 DAA).

El efecto de beneficios de café sobre los insectos acuáticos en tres ríos del Valle Central (Alajuela) de Costa Rica

The effect of coffee processing on aquatic insects in three rivers from the Central Valley (Alajuela) of Costa Rica. In Costa Rica one of the greatest sources of organic pollution in the rivers has been the residual material generated from the processing of coffee beans. In this study, the usefulness of aquatic insects as bioindicators is examined in order to measure the effect of spills of coffee processing plants into two rivers of the Central Valley. The study was conducted at three different coffee processing plants at the three most important moments of the harvest, at the beginning, the peak and at the end. On each of the three dates, biological samples were taken 50m up- and 50m down-stream from the point where the coffee processing plants discharge their liquid wastes. The following physical and chemical factors were also measured: DBO, DQO, pH, temperature, fats and oils, sedimentable solids, dissolved oxygen and the discharge of the river. Systematic samples of aquatic insects were taken in order to obtain relative abundance, taxa richness, diversity (Shannon-Wiener), similarity (Bray-Curtis) and biological index B.M.W.P.’ (Biological Monitoring Working Party) adapted for Costa Rica. Physical-chemical results showed a decrease in the amount of dissolved oxygen and in the discharge of the rivers. In addition, in some cases very high values of DBO and DQO were reached as the season advanced; nevertheless, the majority of the measurements taken were within the limits established by the laws of Costa Rica. Populations of insects increased down stream as the season advanced, due mainly to an increase in the density of Chironomus larvae (Diptera) which became the dominant group. At the same time other pollution sensitive taxa diminished or disappeared. This was reflected by decreasing taxonomic richness and a low diversity index. Similarity between samples taken up and down stream was less than half (0,41), and comparing the three main harvest moments, the highest point was very similar to the end of the harvest (0,81) and both were very different from the beginning of the harvest (0,26). According to the modified biological index BMWP’, water quality diminished to category “strongly contaminated” at the highest point of the harvest. The results indicate that there is an important effect on the populations of aquatic insects caused by the period of harvest, which is not necessarily detected by the standard analysis required by law. Therefore we recommend that the fauna of aquatic macroinvertebrates should be included as a mandatory procedure in water quality testing, the capacity of the treatment plants should be evaluated, and the standard limits established by present laws in Costa Rica, should be critically analyzed. Rev. Biol. Trop. 56 (Suppl. 4): 237-256. Epub 2009 June 30.

Screening of variety- and pre-fermentation-related volatile compounds during ripening of white grapes to define their evolution profile

The variety- and pre-fermentation-related volatile compounds of ‘Fernão-Pires’ (FP) white grape berries were analyzed during ripening by headspace-solid phase microextraction (HS-SPME) coupled to gas chromatography-quadrupole mass spectrometry (GC-qMS). A preliminary step, in which the grapes were crushed and macerated before HS-SPME analyses, was used. The sampling started at véraison (beginning of berry ripening) and was carried on during 5 weeks in two different vineyards. Sixteen terpenoids, two C 13 norisoprenoids, two aromatic alcohols, two C 6 aldehydes, and three C 6 alcohols were identified. The amount of all volatiles increased since véraison towards day 20. A sharp decrease was observed after this day. The maximum amount of varietal volatile compounds was coincident with the harvesting day for white table wine production defined by the ratio sugar/acid content. The varietal volatile evolution observed for FP grapes shows that the maximum amount of volatiles occurs only in a very short period. As a consequence, the establishment of the optimum moment for harvesting of FP white variety, based on its volatile content, deserves higher accuracy than that necessary for all other already studied grapes. This work also evidences that the analysis of the evolution of the terpenoids with higher GC peak area can represent the evolution of all varietal compounds. For FP grapes, this work shows that the screening of linalool, α-terpineol, and geraniol during ripening can be used to define the evolution profile of the varietal volatile compounds.

The effects of enological practices in anthocyanins, phenolic compounds and wine colour and their dependence on grape characteristics

The effect of three different techniques in flavonoid and non-flavonoid compounds were tested on a Monastrell wine elaborated in 2003 looking for an improvement of wine colour and its stability. These techniques involved running-off part of the must prior to fermentation, the use of a macerating enzyme or an enological tannin, and they were selected for showing good results on wine chromatic characteristics after a previous two years of study. The wine produced by running-off part of the juice had the highest colour intensity during the first steps of winemaking, but it showed very low stability and, at the moment of bottling, a dramatic decrease in colour was observed. At this moment and during bottle aging, the wine treated with enological tannin showed the best chromatic characteristics and stability. The results are not coincident with those observed the previous years, indicating the important role played by the grape characteristics at the moment of harvest on the effectiveness of an enological practice for improving wine colour.

Calidad de Cardo Mariano (Silybum marianum (L.) Gaertn.) Cosechado en Diferentes Estados Fenológicos

Two milk thistle genotypes (Silybum marianum (L.) Gaertn.), German and Chilean, were cultivated to determine the most suitable moment of harvest. A randomized complete block design with a split plot arrangement and four replicates was used. The main plot was harvested timeliness (2, 4, 6 y 10 mature capitula in 50% of the plants) and the subplot was the genotype. For the harvest, the weight of 1000 seeds, the percentage of mature seeds and the silymarin content were evaluated. Always the German genotype showed higher mature seed proportion and with higher weight than the Chilean one. However, the Chilean genotype seeds showed higher silymarin content. This study concluded that the most adequate moment for harvest is the physiological state of four mature capitula for both genotypes.

RESEARCH CONCERNING THE INFLUENCE OF THE CULTIVAR AND DENSENESS ON THE ONION PRODUCTION

Two of the factors that determine the onion crop are the cultivar and denseness. The researches were done on two forms within the period 2005-007. The forms are: SC Oferta Bob SRL situated in the south of the country and SC Petrosu SA – Braila situated in the south-east of the country. A number of 12 cultivars and three densenesses have been experimental. The best Durch and Romanian cultivars were used: Exacta F1, Columbia F1, Vachera F1, Daytona F1, Manas F1, Talon F1, Helenas F1, Briliant, Ariana, Delicioasa, Leone and Diamant. Three densenesses were used: 450.000 plants/ha, 650.000 plants/ha and 850.000 plants/ha based on six row scheme on the bad. The irrigation was made by aspersion at SC Petrosu SA and the dripping at SC Oferta Bob. The crops were influenced both by cultivar and by the number of the plants/ha. The biggest crop has been obtained at the dripping irrigated variants with the biggest denseness (850.000 plants/ha) at hybrids Daytona F1, Vachera F1 and Columbia F1 (over 80 t/ha) at the Romanian cultivar Delicioasa (over 70 t/ha). Differences between these crops and those obtained at the 450.000 plants/ha denseness (54-58 t/ha) are very significant. The crops are lower with about 10 t/ha at the aspersion irrigated variants. And in this case both the cultivars and the denseness have a decisive influence on the crops as well. At the same time Daytona F1, Vachera F1 and Columbia F1 hybrids behaved the best by using the aspersion irrigation. Making a comparison between the crops obtained 15 years ago by using the same denseness but less performant cultivars and the crops obtained in the recent experiments, there have been observed that in the old experiments the crops didn’t increase over 40 t/ha. Whereas in the recent experiments the crops increased over 80 t/ha. As a result of the experiments that have been done we can conclude that, in order to obtain big and of good quality onion crops. It is compulsory that a part the other technological stages necessary to be used in this culture (soil selection, precursory cultures, soil preparation, setting up optimum period, culture maintenance, optimum harvesting moment) to be used cultivars especially performent hybrids and also densiness of over 850.000 plants/ha.

Optimization problems for general simple population with n-impulsive harvest

In this paper, n-impulsive harvest problems of general simple population are discussed by models with Dirac function. The optimal impulsive harvest policies to protect the renewable resource better are obtained under conditions of fixed quantity per impulsive harvest. Then, a concept of the sequence for Ϝ-optimal harvest moments for general simple population is presented which is beneficial to protect resource better and sustainable development. Finally, we apply the conclusions to some special models.

Effects of cutting and maturity on antioxidant activity of fresh-cut tomatoes

To investigate the changes in total antioxidant activity of fresh-cut tomato during storage, tomato fruits harvested at three different stages of maturity were cut into 7-mm thick slices and stored at 5 °C. Intact fruits were stored in the same conditions as a control. The antioxidant activity was evaluated as the capacity to scavenge the radical ABTS + in both hydrophilic (HAA) and lipophilic (LAA) extracts. Cutting resulted in a decrease in the HAA compared to the control fruits and did not influence significantly the LAA. Changes in LAA during storage were described by a simple exponential model developing towards an asymptotic end value. The HAA also decreased exponentially in the beginning of the storage time but increased again afterwards. For both hydrophilic and lipophilic antioxidant activity the riper the fruit the higher was the antioxidant activity. Since no relevant interaction was found between time of storage and stage of maturity, the major factor determining the level of antioxidants in tomatoes seems to be the initial level of antioxidant activity at the moment of harvest. The levels of HAA did not differ significantly due to ripening during storage, while the LAA increased with ripening. These results indicate a potential effect of processing to decrease the antioxidant activity in vivo. This would represent a decrease in the value of cut tomatoes as a source of hydrophilic antioxidants in the diet compared with the fruit stored intact. In another experiment, realized at the same conditions, the total antioxidant activity was evaluated using a lipid peroxidation inhibition assay. Antioxidant activity could be measured in methanol extracts, but not in THF extracts. Aqueous extracts showed pro-oxidant activity. No effect of cutting or storage time was observed.

Adenylate patterns of autumn‐sown sugar beet differ from spring‐sown sugar beet. Implications for root quality

Sugar beet (Beta vulgaris L) is generally cultivated using two different planting and harvest patterns. In northern zones, spring sugar beet is sown in spring and harvested in autumn, whereas in subtropical latitudes, autumn sugar beet is sown in autumn and harvested in summer. The industrial quality of the root is frequently higher in spring‐sown sugar beet crops. In order to explore physiological changes associated with this fact, this study has been focused on the seasonal changes of adenosine 5′‐triphosphate and adenosine 5′‐diphosphate levels in the storage roots of sugar beet plants, as an index of its metabolic status. The results obtained correspond to a different metabolic status of spring and autumn sugar beet at the moment of harvest. The adenylate patterns of autumn beets suggested a functional and active respiratory system. On the contrary, the patterns shown by spring beets corresponded to those we would expect to see in plants becoming dormant. The proline and glucose contents, which decrease the industrial quality of the root, and the respiratory rate measured in autumn‐sown sugar beets, were nearly twice those of spring‐sown sugar beets. The combination of an active respiratory system, which allows the carbohydrate catabolism and the synthesis of stress molecules, with the environmental factors at the time of the harvest, could be the underlying physiological mechanism causing some of the differences between spring‐ and autumn‐sown sugar beet crops.

BIOLOGICAL VARIANCE IN AGRICULTURAL PRODUCTS EXPERIMENTAL EXAMPLES

Based on the colour development of tomatoes (theoretical) and apples (measured) as an example the approach to biological variance from a new perspective is made more clear and more explicit. The origin of biological variance is traced back to the stage of maturity at the moment of harvest. By modelling the colour development of individual units in a batch in a generic fashion, and using this model in a non-linear regression analysis on all data from different stages of maturity at harvest, orchards and storage temperatures combined, the effects of biological variance present and its changes in time can be described and predicted. From the analysis it is clear that the most important variable to explain and described variance in colour is the difference between the actual colour and the minimally possible colour for that cultivar. The explained part obtained (well over 95%) is a major indication of the usefulness and applicability of this approach

Resveratrol content of Palomino fino grapes: influence of vintage and fungal infection.

The objective of this study was to determine the influence of certain factors on the resveratrol content of Palomino fino grapes, cultivated in the Jerez-Xérèz-Sherry area, at the moment of harvest. The results show that the resveratrol content is highly influenced by the climatic conditions prior to the period of maturation of the fruit. On the other hand, the gray mold pressure in the vineyard, a fungal infection caused by Botrytis cinerea, increased the resveratrol contents at the early stages of fungal development. When Botrytis development was extensive, the resveratrol content tended to decrease in the juice but tended to increase in the skin. Physiological stress of the plant leads to increases in the resveratrol content, caused as much by the climatic conditions of the vintage as by biotic factors. In this case resveratrol is present mainly in the glycosylated form.

On-Line Harvest Prediction for the Production of Biologicals

To achieve good product quality and consistency the bioreactor has to be harvested in time. A prediction algorithm is developed which aids the operator in determining and scheduling the right moment of harvest. An observer was build for biomass concentration and specific growth rate from oxygen consumption measurements only. With these estimations and a dual-substrate kinetic model the substrate concentrations are calculated. With the estimated biomass and calculated substrateconcentrations the future trajectory of the cultivation is computed by forward simulation to successfully determine the harvest time on-line. Several experiments with a benchscale bioreactor to cultivate B. pertussis were carried out.

NITROGEN AND POST-HARVEST YELLOWING OF BRUSSELS SPROUTS

A study was made of the effect of a late nitrogen application on post-harvest yellowing of Brussels sprouts. Application of nitrogen, whether as granular fertilizer or as a lower amount sprayed over the crop in a watery solution, increased the nitrogen concentration in the outer leaves of the sprouts, but this did not result in less post-harvest yellowing. Size of the sprouts and moment of harvest, however, strongly influenced post-harvest yellowing.

Cytological and compositional evaluation of white asparagus spears as a function of variety, thickness, portion and storage conditions

An evaluation was made of the degree of toughening of asparagus during its storage through a study of the morphological and cellular differences of the xylem vascular bundles as a function of the variety, thickness and portion of the asparagus spear. Light microscopic examinations were carried out to determine the thickness of the cell wall to quantify the extent of the toughening. At the same time a study was made of the fractions of dietary fibre of the asparagus spear by means of chemical extraction techniques. Statistically significant differences were observed in both methods between varieties, thicknesses and portions of the asparagus spear. Different factors such as variety, degree of maturing, portion of spear, moment of harvesting, and type and time of storage have an influence on the toughening of white asparagus that should be taken into account in order to standardise its quality. © 2000 Society of Chemical Industry

Role of ethylene and abscisic acid in physicochemical modifications during melon ripening.

Hormonal metabolism associated with fruit ripening in two cantaloupe muskmelon cultivars, Talma and Manta, has been studied. The ethylene crisis began on day 33 after fruit set, reaching the maximum values of internal ethylene concentration and ethylene production rate on day 35 after fruit set. This was the optimum moment for consumption as shown by the higher content in soluble solids, ripening index, sensory analysis, and color parameter values. The b parameter and the b/a quotient values in peel were good indicators of the maturity stage, the optimum moment for harvesting being about day 33 after fruit set (when autocatalytic ethylene synthesis has begun), with values of 20 and 5 for the b parameter and b/a quotient, respectively. In both cultivars, free 1-aminocyclopropane-1-carboxylic acid (ACC) content increased until day 35 after fruit set and conjugated ACC increased in postclimacterium. The increase in both ACC-synthase and ACC-oxidase activities together could be responsible for the climacteric ethylene production. Significant differences in the abscisic acid evolution in Talma and Manta cultivars were reached, and also a possible stimulation of ethylene by this hormone could be established.

MODELLING THE FIRMNESS OF ‘ELSTAR’ APPLES DURING STORAGE AND TRANSPORT

A dynamic model has been developed that describes the decrease in firmness of ‘Elstar’ apples during different types of conditions, based on the general knowledge how firmness is affected by chemical and biochemical reactions, and on the strict and consistent application of fundamental kinetics. The variable part of the firmness of apples is deduced to depend mainly on the pectic compounds in the middle lamellae. These pectic compounds are supposed to decay during storage in two distinct routes, one consuming/needing oxygen and one occurring with or without oxygen. Depending on the gas conditions (oxygen and carbon dioxide) the respiration rate of apples change. This respiration affects the rate of the oxygen consuming pectin degradation. The moment of harvest defines among other, the initial climacteric stage of the apples. Depending on the relative respiration rate, the rate of development of the climacteric stage changes. The climacteric stage in itself affects the rate of pectin decay: preclimacteric apples can be kept longer than climacteric ones. During CA or MA storage, an enzyme, probably polygalacturonase, accumulates depending on the length of the CA/MA period: the longer kept at CA/MA conditions, the faster firmness decays at the end of the storage period. On top of all those interactions, a temperature dependence is applied on all individual reaction rates. This temperature dependence is described by the well know Arrhenius law. The model can be applied to predict the firmness of ‘Elstar’ apples during all kinds of scenarios encountered in practice, to get an impression of the expected final firmness when reaching the consumer.

Valuation sensors of agricultural products

Information about the conditions of some products is very important for determining the suitable moment for harvesting. In addition, the increasing market requirements of quality and yield need a further valuation of these products for classifying and price fixing. Other performances concerning uniformity and aspect may also be taken into account. We show different measurement principles for the most important parameters, describing the following sensory systems that we have used: continuous hygrometer for rice, corn and cereals, by capacitive methods; fat and acidity meter for live and oleaginous products, by densimetry; sugar content meter for grape and citrus fruits, by refractometry.