Concentrated Sucrose Solutions Research Articles

Optimisation of processing variables affecting the osmotic dehydration of pomegranate arils

SummaryFor the optimisation of osmotic dehydration by response surface methodology, the experiments were conducted according to Central Composite Rotatable Design (CCRD) with three variables at five levels. The low and high levels of the variables were 40 and 50 °C for osmotic solution temperature, 45 and 55°Bx for sucrose solution concentration, 60 and 100 min for duration of dipping in osmotic solution, respectively. The fruit to solution ratio was kept 1:4 (w/w) during all the experiments. Before dipping the arils in sucrose solution, the freezing of the whole pomegranate at −18 °C was carried out to increase the permeability of the outer cellular layer of the arils. The arils were further convectively dehydrated at 60 °C air temperature up to final moisture content of 10% (wb) to make it a shelf stable product. The optimum conditions for osmotic solution concentration, temperature and process duration were 55°Bx, 40 °C and 100 min, respectively.

Kinetics of thermal inactivation of free Aureobasidium pullulans fructosyltransferase

A batch catalytic process of fructooligosaccharide production with the initial sucrose concentration of 700 g dm −3 was carried out in the temperature interval of 67.5–78 °C to investigate the thermal stability of free Aureobasidium pullulans fructosyltransferase. Inactivation experiments were carried out also for a saccharide-free solution in the temperature interval of 53.1–71 °C so that a stabilizing effect of saccharides contained in the reaction mixture could be assessed. A model of enzyme inactivation kinetics based on a two-step sequential mechanism was developed and verified for both media using the multitemperature evaluation of inactivation data. The model was used to predict the operational lifetime and optimal operational temperature of the biocatalyst. It was found that the use of the concentrated sucrose solution increases the operational temperature by about 15 °C compared to a dilute aqueous solution. The value of 47.5 °C was estimated as an optimal temperature at which the enzyme operational lifetime would be 1 year.

A new method to efficiently produce transgenic embryos and mice from low-titer lentiviral vectors

Vector injection into the perivitelline space has emerged as the standard delivery method to transduce lentivirus to mammalian oocytes or one-cell embryos, but its application is limited by the need for high titers of lentivirus. Herein we developed a new method by using a Piezo impact micro-manipulator for injecting low titer of lentivirus into the subzonal space of two-cell embryos or the perivitelline space of one-cell embryos that were shrunk with a highly concentrated sucrose solution. The survival rate of embryos was greater than 98% using this micromanipulation strategy, which was increased compared to the normal one-cell embryo injection method. More than 90% of injected embryos were GFP positive after subzonal injection of a lentivirus vector carrying the GFP gene with titers of 2 × 10⁸ I.U./ml. Even when a low titer of lentivirus (2 × 10⁶ I.U./ml) was used, 53.26% and 40.85% transgenic embryos were obtained after two-cell embryonic injection and one-cell sucrose treated embryonic injection, respectively. The GFP-positive rates were also greater than in the conventional method of injecting one-cell embryos (25.39%). In addition, blastocysts from the two-cell embryo injection group displayed stronger GFP fluorescence than the one-cell embryo injection groups treated with or without the sucrose solution. Increased expression of GFP suggests that the embryos obtained from this injection method have higher exogenous gene expression levels compared to previous methods. Therefore, in contrast with the traditional injection method, we have demonstrated a simplified and efficient lentivirus-mediated gene transfer method based on a low-titer virus preparation.

Salted roads and sodium limitation in a northern forest ant community

1. Road salt is a common, anthropogenic source of NaCl in many temperate ecosystems. Sodium is also an essential and potentially limiting element for inland animal populations. This suggests that Na limitation in inland ecosystems, and hence attraction to Na sources, should increase with distance from salted roads.2. In a North Temperate forest, we tested the prediction that Na recruitment would increase, as soil [Na] decreased, with distance from a salted two‐lane highway. We presented ants with three concentrations of NaCl and sucrose solution along four pairs of transects ca 1, 10, 100, and 1000 m from the road.3. Consistent with the Na‐limitation hypothesis, the ratio of NaCl to sucrose use increased with distance from the road from 1:13 vials at 1 m to 1:5 vials at 1 km. Genera characterised by high Na use did not accumulate farther from the road. For the common and widespread Tapinoma sessile (Say), a 10‐fold increase in distance from the road resulted in ants doubling their use of NaCl relative to sucrose.4. Road salt is a well‐known pollutant, especially of freshwater ecosystems. However, by suppressing plants and potentially promoting consumers, road salt may have more complex effects on terrestrial ecosystems, especially those far inland from oceanic aerosols.

THEORETICAL DETERMINATION OF SORPTION ISOTHERMS APPLIED TO PROCESS CHESTNUT WITH OSMOTIC PRE-TREATMENTS BASED ON ITS CHEMICAL COMPOSITION

Sorption isotherms for fresh chestnut and particularly processed chestnut with osmotic treatments using sodium chloride, glucose and sucrose solutions of different concentrations (22.0%, 56.5%, and 60% w/w, respectively) were predicted at 25°C by means of a simplified prediction algorithm of water sorption isotherms. This model is based on the composition of the main compounds of foods (glucose, fructose, sucrose, salt, protein, fibre and starch). The processed chestnut composition changed significantly by the addition of salts and sugars. The processed chestnut sorption isotherm was theoretically predicted with the same accuracy as the chestnut fresh isotherms. Using the prediction model the equilibrium moisture content could be calculated for the assayed systems with a correlation coefficient (R 2 ) of (>0.989), a mean relative error (E) of (<4.40%) and a standard error (E RMS ) of (<0.049 kg (kg d.b.) -1 ).

A Multi-D-Shaped Optical Fiber for Refractive Index Sensing

A novel class of multi-D-shaped optical fiber suited for refractive index measurements is presented. The multi-D-shaped optical fiber was constructed by forming several D-sections in a multimode optical fiber at localized regions with femtosecond laser pulses. The total number of D-shaped zones fabricated could range from three to seven. Each D-shaped zone covered a sensor volume of 100 μm depth, 250 μm width, and 1 mm length. The mean roughness of the core surface obtained by the AFM images was 231.7 nm, which is relatively smooth. Results of the tensile test indicated that the fibers have sufficient mechanical strength to resist damage from further processing. The multi-D-shaped optical fiber as a high sensitive refractive-index sensor to detect changes in the surrounding refractive index was studied. The results for different concentrations of sucrose solution show that a resolution of 1.27 × 10−3–3.13 × 10−4 RIU is achieved for refractive indices in the range of 1.333 to 1.403, suggesting that the multi-D-shaped fibers are attractive for chemical, biological, and biochemical sensing with aqueous solutions.

Sucrose in the Concentrated Solution or the Supercooled “State”: A Review of Caramelisation Reactions and Physical Behaviour

Sucrose is probably one of the most studied molecules by food scientists, since it plays an important role as an ingredient or preserving agent in many formulations and technological processes. When sucrose is present in a product with a concentration near or greater than the saturation point—i.e. in the supercooled state—it possesses high potentialities for the food industry in areas as different as pastry industry, dairy and frozen desserts or films and coatings production. This paper presents a review on critical issues and research on highly concentrated sucrose solutions—mainly, on sucrose thermal degradation and relaxation behaviour in such solutions. The reviewed works allow identifying several issues with great potential for contributing to significant advances in Food Science and Technology.

Sweet taste enhancement through pulsatile stimulation depends on pulsation period not on conscious pulse perception

When aqueous NaCl solutions are tasted at continuously alternating concentrations, overall saltiness ratings exceed those observed for solutions with the same averaged, but non-alternating concentrations. In the present study, this effect is replicated for alternating aqueous sucrose solutions. We tested the hypothesis that enhancement depends on the conscious perception of intensity contrasts. High sucrose pulses were continuously alternated with low sucrose intervals at pulsation periods between 1.5 s and 20 s. Tastant pulsation enhanced sweetness intensity and this enhancement varied between 8 and 14%, peaking for periods from 4.5 s to 6 s (Study 1). This range coincided with the average pulsation period at which perceived taste pulses blended into a continuous stimulus, i.e. the taste fusion period (TFP). When comparing intensity ratings of sucrose solutions at individualized pulse periods of 0.5, 1.0 and 2.0 times TFP to ratings for continuous sucrose solutions of the same net concentration, pulsatile stimuli were perceived as significantly sweeter ( p < 0.01; Study 2). However, sweetness intensity enhancement was the same for all pulsation periods. It was shown that sweet taste enhancement peaks at pulsation periods ranging from 0.5 to 2.0 TFP and that the level of conscious pulsation perception does not affect taste enhancement. The results suggest the introduction of enhancement effects at pre-conscious stages of gustatory processing. Further mechanisms that may account for such pre-conscious effects are discussed.

Sweet preferences and analgesia during childhood: effects of family history of alcoholism and depression

To determine whether depression and family history of alcoholism are associated with heightened sweet preferences in children, before they have experienced alcohol or tobacco and at a time during the life-span when sweets are particularly salient. Design Between- and within-subject experimental study. Children, 5-12 years old (n = 300), formed four groups based on family history of alcohol dependence up to second-degree relatives [positive (FHP) versus negative (FHN)] and depressive symptoms as determined by the Pictorial Depression Scale [depressed (PDEP) versus non-depressed (NDEP)]. Children were tested individually to measure sucrose preferences, sweet food liking and, for a subset of the children, the analgesic properties of sucrose versus water during the cold pressor test. The co-occurrence of having a family history of alcoholism and self-reports of depressive symptomatology was associated significantly with a preference for a more concentrated sucrose solution, while depressive symptomatology alone was associated with greater liking for sweet-tasting foods and candies and increased pain sensitivity. Depression antagonized the analgesic properties of sucrose. While children as a group innately like sweets and feel better after eating them, the present study reveals significant contributions of family history of alcoholism and depression to this effect. Whether the heightened sweet preference and the use of sweets to alleviate depression are markers for developing alcohol-related problems or responses that are protective are important areas for future research.

Ultrasound-Assisted Osmotic Dehydration of Strawberries: Effect of Pretreatment Time and Ultrasonic Frequency

Pretreatment of fruits prior to drying has shown success in reducing drying time and costs. In this work, ultrasound-assisted osmotic dehydration has been implemented as a method to increase water diffusivity and reduce drying time in strawberries. Strawberry halves were immersed in distilled water and in two different concentrations of sucrose solutions while pretreatment time and ultrasonic frequency levels were varied to determine their effect on drying time, water loss, and soluble solids gain. A microscopic analysis was carried out to evaluate the formation of microchannels and other changes to the fruit tissue structure. Greater sucrose concentration used in ultrasound-assisted osmotic dehydration resulted in greater water loss with greatest loss observed for the strawberry halves pretreated for 45 min in a 50% w/w sucrose solution. The pretreatment carried out for 30 min employing an osmotic solution of 50% w/w of sucrose resulted in the highest drying rate among the pretreatments. Osmotic dehydration used alone during pretreatment increased total processing time, whereas osmotic dehydration combined with ultrasonic energy during pretreatment reduced total processing time and increased effective water diffusivity. Cell distortion and breakdown were observed not only in pretreatments employing ultrasound-assisted osmotic dehydration but in conventional osmotic dehydration. Formation of microchannels through ultrasonic application and effects of osmotic pressure differential were considered to be largely responsible for reducing drying time for strawberry halves.

Evaluation of Mass Exchange During Osmotic Dehydration of Plum Using Response Surface Methodology

Water loss (WL), solid gain (SG), weight reduction (WR) and shrinkage were quantitatively investigated during osmotic dehydration of plum using response surface methodology with the sucrose concentration (30–60g/100 g sample), temperature of sucrose solution (40–60°C) and immersion time (60–240 min). Experiments were designed according to Central Composite Rotatable Design with these three factors. For each response, second order polynomial models were developed using multiple linear regression analysis. With respect to water loss, solid gain, weight reduction and shrinkage, both linear and quadratic effects of four variables were found to be significant. In most cases, an increase of sucrose concentration, temperature and immersion time increased WL, SG, WR and shrinkage, except the increasing of immersion time for osmotic treatment has no effect on shrinkage. It was found that immersion time and temperature were the most significant factors affecting the WL during osmotic dehydration of plum followed by concentration of sucrose solution. This was also true for WR. Effect of temperature and time were more pronounced for SG than the concentration of sucrose solution.

Role of Olfaction in the Conditioned Sucrose Preference of Sweet-Ageusic T1R3 Knockout Mice

Prior work has shown that sweet taste-deficient T1R3 knockout (KO) mice developed significant sucrose preferences when given long-term sugar versus water tests. The current study investigated the role of olfaction in this experience-conditioned sucrose preference. T1R3 KO and C57BL/6 wild-type (WT) mice were given 24-h sugar versus water tests with ascending concentrations of sucrose (0.5-32%), after which the mice received olfactory bulbectomy (OBx) or sham surgery. When retested with sucrose, the Sham-KO mice preferred all sugar solutions to water, although their intake and preference were less than those of the Sham-WT mice. The OBx-KO mice, in contrast, showed no or weak preferences for dilute sucrose solutions (0.5-8%) although they strongly preferred concentrated sugar solutions (16-32%). OBx-WT mice displayed only a partial reduction in their sucrose preference. Although the OBx mice of both genotypes underconsumed dilute sucrose solutions relative to Sham mice, they overconsumed concentrated sucrose. These results indicate that olfaction plays a critical role in the conditioned preference of T1R3 KO mice for dilute sugar solutions. Further, the fact that OBx-KO mice preferred concentrated sucrose solutions in the absence of normal sweet taste and olfactory sensations underscores the potency of postoral nutritive signals in promoting ingestion.

Exogenous sucrose utilization and starch biosynthesis among sweetpotato cultivars

Three sweetpotato cultivars were investigated for their starch content and amylose/amylopectin ratio. Ym starch contains 87.2% amylopectin and 12.8% amylose, when total starch was calculated as 100%. The Zm cultivar contains 33.6% amylopectin and 18.2% amylose, and its total starch was calculated as 51.8% of that of Ym. The Hm cultivar contains 39.1% amylopectin and 30.5% amylose, and its total starch was 69.6%. We analyzed the expression levels of starch and sucrose biosynthesis-related genes including AGPases a, b, and c; sucrose synthases I and II; starch synthase I; GBSS I; and SBEs I and II. All genes tested in this experiment were detected only in Ym, while several genes showed very faint or no expression in Zm and Hm. We also measured tissue-specific expression of these genes in whole plants of Ym. Most of the genes are expressed in the stem and roots of the plants. Expression profiles of starch synthesis-related genes of the sweetpotato leaves were investigated after supplementing the different concentrations of sucrose solution. All genes in Ym were clearly induced by sucrose, but the expression levels of some of these genes did not change in Zm and Hm. The total starch content of Ym, Zm, and Hm gradually increased over time on addition of 3%, 6%, and 9% sucrose concentrations. The greatest accumulation was observed in Ym at 48 h, and it was almost 2.24 times higher than that of the (0%) control, while Zm and Hm showed 1.76 and 1.91 times higher levels of starch, respectively. These results indicate that cooperative expression of all related genes is essential for starch biosynthesis from sucrose. This is the first report on different sucrose contents and the efficiency with which exogenous sucrose switches on gene expression of starch biosynthesis-related genes among cultivars.

The effects of foraging role and genotype on light and sucrose responsiveness in honey bees ( Apis mellifera L.)

In honey bees, the sensory system can be measured by touching sugar water to the antennae, eliciting the extension of the proboscis. The proboscis extension response (PER) [6,13] is closely associated with complex behavioral traits involving foraging and learning [30–32,34–36,43–49]. Bees specializing in pollen foraging are more responsive to low concentrations of sucrose solution and, as a consequence, perform better in associative learning assays [4,43,46–48]. An important unanswered question is whether sensory-motor differences between pollen and nectar specialists are restricted to the gustatory modality or whether pollen foragers are in general more sensitive to sensory stimuli associated with foraging. We used an assay designed to test responsiveness to varying intensities of light [11] and tested responsiveness to varying concentrations of sucrose in wild-type pollen and non-pollen foragers and bees artificially-selected for differences in pollen-hoarding behavior [27]. Workers of the high pollen-hoarding strain are more likely to specialize on collecting pollen. In wild-type bees, pollen foragers were more responsive to sucrose and light than non-pollen foragers. In the selected strains, high pollen-hoarding pre-foragers were more responsive to sucrose and light than low pollen-hoarding pre-foragers. These PER and light assays demonstrate a positive relationship between the gustatory and visual sensory modalities with respect to foraging behavior and genotype. We propose that light responsiveness, in addition to sucrose responsiveness, is a component of a pollen-hoarding behavioral syndrome – a suite of traits that covary with hoarding behavior [51,52] – previously described for honey bees [14,37,41]. We suggest that the modulation of the sensory system may be partially constrained by the interdependent modulation of multiple sensory modalities associated with hoarding and foraging.

The effect of foraging specialization on various learning tasks in the honey bee (Apis mellifera)

Honey bee foragers may collect nectar, pollen, water, or propolis, and their foraging specialization has been associated with several behavioral traits. By conditioning of the proboscis extension response (PER), we compared the performance of foragers that collected nectar, pollen, both nectar and pollen, or water in several learning and choice assays. Foragers were first tested in a three-trial olfactory associative learning assay. For further tests, we selected only good learners that responded in two out of three conditioning trials. One group was tested in an additional olfactory associative learning assay involving different reward volumes and concentrations. Another group was tested for risk sensitivity in a two-alternative forced-choice PER procedure and then in a latent inhibition (LI) assay. Levels of acquisition in olfactory associative learning were highest in pollen and water foragers, and better acquisition was associated with collection of heavier pollen loads and smaller and lighter nectar loads of lower sugar concentration. Among the good learners, pollen foragers still showed better acquisition than nectar foragers when rewarded with several volumes and concentrations of sucrose solution. Pollen and nectar foragers were equally risk averse, preferring a constant reward to a variable one, and choice was not affected by pollen load weight. Contrary to a previous study, pollen and nectar foragers were similarly affected by LI. We discuss possible explanations for the discrepancy between the two studies. Overall, our results suggest that differences between foraging groups in sensitivity to various stimuli may not correspond to differences in choice behavior.

Interplay between Solvent Effects of Different Nature in Interfacial Bond Breaking Electron Transfer

Solvent dynamics effects on electroreduction of peroxodisulphate anion on mercury electrode (a typical bond breaking electron transfer reaction) are explored in the framework of the Sumi-Marcus model. The reaction three-dimensional free energy surface is constructed using the Anderson model Hamiltonian. A new interpretation of short- and long-time survival times is presented as well. Since the reduction is assumed to proceed from aqueous sucrose and glucose solutions of different concentrations (which are used to vary the solution viscosity), unavoidable changes in the Pekar factor (static effect) are also taken into account. The results of model calculations are employed to interpret challenging experimental data on nonmonotonous constant rate vs solution viscosity dependence reported earlier (in part, appearance of an ascent plot). The influence of mixed solvent composition on the reaction rate and transfer coefficient is explained in terms of the saddle point avoidance in the vicinity of activationless discharge. Splitting of the reaction coordinates into slow (solvent) and fast (intramolecular) ones is argued to be crucial, as the most important reaction features cannot be described by means of more simplified models, even if both static and dynamic effects are addressed.

Experimental determination of the amount of ice instantaneously formed in high-pressure shift freezing

The main aim of this paper was to experimentally determine the amount of ice instantaneously formed after expansion during high-pressure shift freezing (HPSF). To do that, an easy, quick and cheap procedure was developed able to obtain accurate ice ratio estimations from temperature data of the sample after the pressure release. Very different pressure and temperature conditions, both near and far from the melting curve liquid–ice I, were chosen to produce different amounts of ice after expansion in HPSF experiments. Sucrose solutions of several concentrations (10%, 20%, 30% and 40% w/w) were also employed to study the influence of the water content of the sample. Good agreement was found between experimental estimations and theoretical predictions from the heat balance model for all the pressure and temperature conditions tested. The results showed that increasing pressure at a given temperature before expansion is an effective and fast way to increase the amount of ice produced.

Ice-Structuring Peptides Derived from Bovine Collagen

Antifreeze proteins belonging to structurally diverse families of genetically coded proteins from several living organisms have been isolated and characterized in the past. This paper reports that collagen peptides of a certain molecular size range derived from Alcalase hydrolysis of bovine gelatin are able to inhibit recrystallization of ice in frozen ice cream mix as well as in frozen sucrose solutions in a manner similar to natural antifreeze proteins. The optimum conditions for producing such ice-structuring peptides (ISP) were hydrolysis at pH 9.0 for 30 min at 45 degrees C and an Alcalase-to-gelatin ratio of 0.176 unit per gram of gelatin. The collagen peptides were fractionated on size exclusion (Sephadex G-50) and ion exchange (sulfopropyl-Sephadex C-25) columns, and the molecular mass distribution of the ice-structuring peptide fractions was determined by matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry. The collagen peptide fractions in the molecular mass range of 600-2700 Da inhibited ice recrystallization in a supercooled ice cream mix and in concentrated sucrose solutions. The cationic collagen peptides within this fraction with molecular mass in the range of 1600-2400 Da were more effective than the anionic peptides in inhibiting ice crystal growth.

Microchamber Device Equipped with Complementary Metal Oxide Semiconductor Optical Polarization Analyzer Chip for Micro Total Analysis System

We fabricated a device equipped with a microchannel on a complementary metal oxide semiconductor (CMOS) sensor to observe the optical polarization rotation angle during in situ monitoring. The sensor is based on the integrated wire-grid polarization detection method. The microchannel is fabricated on a Si layer by deep reactive ion etching (DRIE). Using this device, we measured the optical rotation of chiral molecules in a microfluid. This showed that the device is applicable to in situ chiral measurement. Optical rotation angles of the linearly polarized light corresponded to different concentrations of sucrose solution. Sensor output reflecting the temporal concentration change of chiral molecules was also observed. These results clearly demonstrate that the CMOS sensor has the capability of measuring chiral molecules in situ.

Identification of the state of a wet spouted bed through time‐frequency analysis of pressure fluctuation time series

AbstractThe feasibility of detecting instability in wet spouted beds via pressure fluctuation (PF) time‐series analyses was investigated. Experiments were carried out in a cylindrical Plexiglas column of diameter 150 mm with a conical base of internal angle 60°, an inlet orifice diameter of 25 mm and glass beads of diameter 2.4 mm. Transducers at several axial positions measured PF time series with incremental addition of aqueous sucrose solutions of different concentrations. Liquid addition affected the spouted bed dynamics, causing irregular spouting, increased voidage in the annulus, increased fountain height, irregular annulus height, channelling, agglomeration, and adhesion of particles to the column walls. Autocorrelations indicated the appearance of periodicities in the PF signals with increasing sucrose addition. Dominant peaks in power‐spectral density developed at low frequencies with changing system dynamics. The results indicate that PF signals furnish relevant information on system dynamics, useful for monitoring and control of spouted bed operations such as particle coating and drying of paste‐like materials.