Similar Sugar Concentration Research Articles

Towards a wheat straw biorefinery: Combination of Organosolv and Liquid Hot Water for the improved production of sugars from hemicellulose and lignin hydrolysis

One major challenge of sustainable biorefineries relies on valorizing hemicellulose and lignin simultaneously. However, a single pretreatment will unlikely render high sugar and lignin yields. Liquid-Hot-Water (LHW) and Organosolv (OS) highlight as technologies to solubilize these components (in different proportions). A combined pretreatment may hydrolyze lignin and hemicellulose into different fractions, with higher overall yield and leaving cellulose available for further processing. Hence, it must be determined the stages' order to maximize hemicellulose/lignin hydrolysis. We performed both configurations (OS → LHW and LHW → OS) using wheat straw and determined sugar and lignin concentration and the dissolved lignin's molar-mass distributions. Both configurations reached similar sugar concentrations (~12 g/L), but LHW → OS reached a 1.6-times higher lignin extraction (7 to 11 g/L in the OS-stage). The extracted lignin molar mass in LHW → OS had lower polydispersity and molar-mass averages, favoring colloidal particle production. These results bring us closer to a sustainable biorefinery valorizing the different feedstock fractions.

The kinetics of grape ripening revisited through berry density sorting

Aim: In this study, ripening and heterogeneity in density-sorted berries were investigated, with the aim of more clearly understanding the kinetics of water uptake and sugar, acid and anthocyanin accumulation in the fruit of a new, disease-resistant hybrid.Methods and results: The 3184-1-9N hybrid, grown in a semi-arid climate in the South of France, was used. Its genotype is the result of several backcrosses of a Muscadinia ´ Vitis vinifera F1 hybrid with several V. vinifera varieties. From the end of the green plateau to the over-ripening stage, single berries were sampled weekly and sorted by density, to monitor the advancement of ripening and the heterogeneity of grapevine fruit development at population level. Fruit firmness, density, fresh weight, primary metabolite content (sugars and organic acids), secondary metabolite content (anthocyanins), potassium content and pH were measured in berries from each density class. The data showed that softening and hexose accumulation occurred before fruit pigmentation. Based on malic acid and anthocyanin concentration relative to sugar concentration in density-sorted grapes, malic acid breakdown or dilution was promoted and anthocyanin accumulation reduced in late- or slow-ripening berries. In the different population structures in two experimental plots, berries with similar sugar concentration showed considerable heterogeneity in terms of volume and anthocyanin content, whereas pH, potassium content and acid content showed much more homogeneous kinetics.Conclusions: During ripening, analysis of density-sorted berries provides useful information about sugar concentration heterogeneity and its relation with organic acid and anthocyanin content. The stage at which grapes can be considered ripe may be precisely determined through periodic determination of mean berry volume or weight, to detect the cessation of phloem unloading and the onset of berry shrivelling. However, ripening and shrivelling berries generally coexist in the harvested population. Asynchronous berry development and berry weight heterogeneity greatly complicate determination of the timing of developmental events that are regulated at the single-berry level. Therefore, analysis of individual berries would seem to be an indispensable component of investigations of berry growth and development.Significance and impact of the study: Plotting water uptake and solute accumulation relative to sugar accumulation (as an internal clock) provides an original way to display grapevine fruit development data. Analysis of density-sorted berries has identified the relatively invariant fruit features, such as the minimum concentration of tartaric acid, the stability of potassium accumulation and pH, and conversely, the huge variations in berry size.

Appropriate lignocellulosic biomass processing strategies for efficient 2,3-butanediol production from biomass-derived sugars using Bacillus licheniformis DSM 8785

A nonpathogenic organism, Bacillus licheniformis DSM 8785, was evaluated for efficient 2,3- butanediol (BD) production from different sugar media. Productivities in glucose, xylose, and mixed-sugar (glucose:xylose=1:2) media were 2.23, 1.58, and 0.91gL−1h−1, respectively. These were almost two-fold more than use of a more common BD producer, albeit a pathogenic organism, Klebsiella oxytoca ATCC 8724. Fermentation efficiency in the biomass hydrolyzates with 40g/L of total sugar was as efficient as synthetic sugar with a similar sugar concentration, but not so in the hydrolyzates with 80g/L of total sugar. The optimum fed-batch process in a glucose medium produced 103g/L BD in the final fermentation broth, with yield and productivity of 0.47g/g and 0.81gL−1h−1, respectively. Our study concluded that an efficient BD fermentation is possible using a nonpathogenic culture in a single-sugar medium; however, appropriate biomass processing strategies must be developed to produce separate streams of glucose and xylose from lignocellulosic biomass for efficient BD production. We, therefore, proposed a novel biomass processing strategy using a three-step pretreatment process to obtain separate streams of biomass extractives, cellulose hydrolyzate, and hemicellulose hydrolyzate. This information is pertinent for efficient BD production from biomass-derived sugar.

Combined effects of irrigation regimes and crop load on ‘Tempranillo’ grape composition

The effects of different irrigation regimes, maintained during fruit set to post-harvest (rainfed vines and vines irrigated at 25, 50 and 100% of estimated crop evapotranspiration), were investigated during four consecutive seasons (2005–2008) in a vineyard located in south-western Spain on grapevine cv. Tempranillo berry composition. In addition, two crop level regimes were established for each irrigation treatment by cluster thinning carried out around veraison in a split-plot design with irrigation as the main factor and cluster thinning as second. Considerable vintage-to-vintage variations in many quality parameters were observed despite berry total soluble solids content remaining nearly constant at around 23°Brix each year. Irrigation applications, when compared with rainfed cultivation, increased berry titratable acidity and malic acid but slightly decreased berry total polyphenols and anthocyanins potential. Veraison cluster thinning increased berry malic acid, potassium and total phenolic compounds but reduced titratable acidity. High crop level slightly delayed harvest date around three days, but grapes from both thinned and unthinned vines reached similar sugar concentrations in all seasons except when leaf area-to-yield ratio was lower than 1m2kg−1, where sugar berry concentration was below 21°Brix. It is concluded that irrigation is an interesting technique to increase berry titratable acidity for Tempranillo grapes in semi-arid terroirs where grape acidity is usually too low. Cluster thinning can be used to increase berry phenolic potential. However, in addition to the detrimental effects on performance, cluster thinning may decrease the acidity levels. It is therefore only recommended when very high yield hinders proper ripening.

No spatial patterns for early nectar storage in honey bee colonies

Honey bees, Apis, forage for nectar and pollen, which are subsequently stored in cells of their nests. Despite the importance of honey storage for colony survival, very little is known about decision making by honey bee workers that could optimise the transformation of nectar into honey. Here we test, using diagnostic radioentomology, whether workers use rules based on sugar concentration to optimise the spatial distribution of storage cells during nectar ripening. The data show that after the first 3 days of storing activity, various sugar concentrations were mixed in individual cells. A spatial clustering of cells with content of similar concentration was only occasionally observed. The results, therefore, suggest that at early stages of storage, spatial proximity of cells with similar sugar concentrations does not result in improved efficiency and, therefore, does not seem adaptive. The costs involved in locating particular cells probably outweighs the benefits of clustering. Alternatively, but not mutually exclusive, physiological constraints (e.g. variation in the perception of sugar concentration) might limit such optimisation behaviour. Storing behaviour can serve as a model to better understand food provisioning and complex organisation of insect societies.

Sugar concentration influences decision making in <i>Apis mellifera</i> L. workers during early-stage honey storage behaviour

Decision making in honeybees is based on information which is acquired and processed in order to make choices between two or more alternatives. These choices lead to the expression of optimal behaviour strategies such as floral constancy. Optimal foraging strategies such as floral constancy improve a colony’s chances of survival, however to our knowledge, there has been no research on decision making based on optimal storage strategies. Here we show, using diagnostic radioentomology, that decision making in storer bees is influenced by nectar sugar concentrations and that, within 48 hours of collection, honeybees workers store carbohydrates in groups of cells with similar sugar concentrations in a nonrandom way. This behaviour, as evidenced by patchy spatial cell distributions, would help to hasten the ripening process by reducing the distance between cells of similar sugar concentrations. Thus, colonies which exhibit optimal storage strategies such as these would have an evolutionary advantage and improve colony survival expectations over less efficient colonies and it should be plausible to select colonies that exhibit these preferred traits.

Simulation of production potential of self-defoliating sugarcane cultivars

Cane burning before harvest is increasingly questioned due to environmental concerns. Harvesting of un-burned or green cane, whether by mechanical or manual means, increases trash delivery to the sugar mills with consequent losses in sugar recovery and increased transport costs. The self-defoliating trait, in which the leaves fall naturally as the cane matures, offers the potential to facilitate green cane harvesting. The effects of the self-defoliating character on cane production and sugar concentration had not been determined. Trials were superimposed on commercial cane of two cultivars (CC 85-63 and V 71-51), in which leaves were artificially removed to simulate the self-defoliating character. The two cultivars responded differently to the leaf removal treatments. CC 85-63 with only four leaves per stem produced similar levels of cane with similar sugar concentration to the controls with 10 leaves per stem. In V 71-51, cane production decreased as leaf number per stem decreased from eight leaves per stem found in the controls. Nevertheless, in both cases, high levels of productivity of more than 16 t recoverable sugar/ha in 13 months were obtained with only four leaves per stem in both cultivars. In CC 85-63, net photosynthetic rate of individual leaves increased as leaf number per stem was reduced, whilst in V 71-51 no compensation was observed. Lodging in both cultivars tended to be less as leaf number per stem decreased. The results indicate that breeders can develop self-defoliating cultivars with a minimum of 4 to 6 leaves per stem, which are highly productive in terms of total sugar production and which also maintain acceptable levels of recoverable sugar.

Dioecy in the endemic genusDendrocacalia (Compositae) on the Bonin (Ogasawara) Islands

Dendrocacalia crepidifolia Nakai (Compositae, Senecioneae), the only species of this arboreal genus endemic to Haha Island in the Bonin Islands, was found to be dioecious. Male flowers differ from female ones in having a stunted style (style in female exserted from corolla and deeply bifurcating) and anthers filled with fertile pollen (anthers in the female lacking pollen). The size of the corolla and number of florets per head were similar between male and female flowers. The crown area of this arboreal species was also similar in male and female plants. The sex ratio was 0.55 male, not significantly different from 0.5. Both sexes produced nectar of similar sugar concentration (ca. 50%). The flowers are pollinated by feral honeybees (Apis mellifera), but they are thought to have been pollinated by small, lesshairy, endemic solitary bees before honeybees were introduced and subsequently became the dominant bee species on the island. The evolution of dioecy ofDendrocacalia on the island is thought to stem from the deleterious effects of inbreeding that are inherent in plants with geitonogamy. The increased geitonogamy on the island has resulted from increased woodiness (i.e., increased number of flowers per plant) and the original dependence on endemic bee pollinators, which are now endangered.

Improvements in ethanol tolerance of Kluyveromyces fragilis in jerusalem artichoke juice

Alcoholic fermentation of Jerusalem artichoke juice, a natural complex medium, allowed the production of 13% (v/v) ethanol utilizing an inulin-fermenting strain of Kluyveromyces fragilis, strongly sensitive to ethanol. However, the fermentation of a simple medium with a similar concentration of fermentable sugars (235 g/L) as saccharose stopped prematurely when only 7% (v/v) ethanol had been produced. Differences in the two fermentation profiles were attributed to the significantly lower ethanol tolerance of K. fragilis IGC 2671 in the simple medium with 2% saccharose as compared with diluted J.a. juice with a similar sugar concentration, in fact, (1) in diluted J. a. juice, growth was possible up to 8% (v/v) added ethanol compared with 6% (v/v) in simple medium and (2) ethanol-induced inhibition of the specific growth and fermentation rate as well as ethanol-induced stimulation of the specific death rate were much more drastic in simple medium. Present results show that (1) the complex composition of the medium used for alcoholic fermentation plays a marked role in the ability of the yeast to tolerate and produce ethanol; (2) J. a. juice proved a very appropriate medium for a productive alcoholic fermentation, namely, in processes based on strains with a low ethanol resistance; and (3) to characterize and compare the ethanol tolerance of fermenting yeasts, the standardization of the medium composition must be taken in consideration.

Effects of Growing Wheat in Hypoxic Nutrient Solutions and of Subsequent Transfer to Aerated Solutions. I. Growth and Carbohydrate Status of Shoots and Roots

This paper evaluates the effects of hypoxia (imposed by flushing N2 gas through the nutrient solution) on the growth and carbohydrate status of wheat (Triticum aestivum L.), and the reversibility of these effects once aeration is resumed. Plants were transferred to hypoxic nutrient solutions (containing 0.003 mol O2 m-3) at the early tillering stage, when they had 3-4 leaves, well developed seminal roots, and a few crown roots. Hypoxia for 10-14 days had little adverse effect on shoot growth, whereas the seminal roots stopped growing, i.e. elongating and increasing in dry weight; in contrast, the crown roots elongated to a maximum of 9 cm and continued to increase in dry weight. Hypoxia increased the porosity of crown roots 2-3-fold compared with those grown under aerated conditions; in contrast, the porosity of seminal roots was unaffected. Oxygen concentrations in the gas filled pores of hypoxic crown roots (65 mm or longer) were estimated from measurements of radial oxygen loss using cylindrical platinum electrodes. Oxygen concentrations in the root tips were substantially lower than the critical oxygen pressures required for maximum respiration. Further, both oxygen concentrations in root tips and rates of root elongation were higher in shorter than in longer roots. Plants grown in hypoxic nutrient solutions had substantially higher sugar concentrations in shoots and roots than plants grown in aerated solutions. Sugars were not deficient in hypoxic roots since concentrations over a diurnal cycle remained higher than in aerated roots in both the bulk of the seminal and crown roots, and in the tips of the crown roots. Furthermore, tips of seminal roots had similar sugar concentrations when exposed to either aerated or hypoxic solutions. Hypoxia presumably killed seminal root apices, since the seminal axes did not resume elongation once aeration was restored. In contrast, crown roots resumed elongation when aeration was resumed. Although seminal root tips were moribund, the bulk of the seminal root was still alive. Following the transfer to aerated solutions, there was a rapid increase in the dry weight of both crown and seminal roots, in the latter case due to the proliferation of laterals.