Changes In Water Loss Research Articles

Correlation of non-invasive psycho-physiological and skin-physiological measures.

Psychological stress alters epidermal barrier function. While intensive studies on the underlying mechanism have been performed in mice, human studies are limited. Non-invasive skin-physiology measures have not yet been directly linked to non-invasive psycho-physiological assessments. Standard measures of (I) transepidermal water loss prior to and after experimental barrier perturbation via tape stripping, (II) skin surface pH, (III) electrodermal activity, and (IV) heart rate function were taken over a 24h time period. To document perceived stress, a standardized stress self-assessment questionnaire, namely the Trierer Inventar zum chronischen Stress (TICS), was utilized. Twenty healthy, Caucasian (Fitzpatrick skin phototype I-II), female volunteers (21-32 years, mean age 27, SD=3.67 years) were included in this study (random sample). Significant correlations were shown for 24h delta transepidermal water loss changes, that is, barrier repair kinetics (sympathetic activity) and heart rate variability (parasympathetic activity). Further correlations were noted for electrodermal activity and skin surface pH. Perceived stress, as documented by the TICS questionnaire, did not correlate with psycho- and skin physiological parameters, respectively. The presented approaches may provide a basis for non-invasive objective research on the correlation between psychological stressors and epidermal barrier function.

Physicochemical Properties and Young Adult Consumer Preference of Dry-Aged Beef after High-Intensity Ultrasonication

This study aimed to determine the effect of high-intensity ultrasound (HIU. F = 37 kHz, I = 28W/cm2, bath for 30 min, 5 °C) on physicochemical characteristics and sensorial preference of seven aged (23 d ageing) bovine muscles (L. dorsi lumborum, L. dorsi thoracis, Psoas major, Semimembranosus, Biceps femoris, Rectus femoris, and Gluteus medius). Muscles were randomly distributed in two treatments: with and without ultrasonication. Colour (L*, a*, b* and C*), water-holding capacity (WHC), and shear force (N) were determined before and after simulated retail display (SRD) in modified atmosphere packing (MAP; 75% O2: 25% CO2, 3 °C, 13 h led light exposition) for 5 d. Sensorial toughness was also evaluated at the end of the SRD. Ultrasonication slightly reduces 6–9% WHC of beef. HIU did not affect (p ˃ 0.05) water loss, meat colour, shear force and sensorial toughness of the meat. The Semimembranosus was the toughest muscle. Ultrasonication of 23-day-aged beef did not show improvements on quality characteristics, and despite minor changes in water loss and slight increase in shear force, consumers did not detect differences.

Transcript profiles analysis of citrus aquaporins in response to fruit water loss during storage.

Water loss is an essential factor that affects the maintenance of quality of citrus fruit during postharvest handling and storage. Aquaporins (AQPs) play an important role in the transport of water across membranes. However, the expression profiling of AQPs is incomplete for citrus fruits during storage. In this study, a post-harvest storage experiment was performed using sweet orange fruits to determine changes in water loss and fruit quality. Also, genome-wide expression analysis of CsAQP genes was carried out in fruit of different citrus varieties during storage. Low humidity storage conditions accelerated the postharvest water loss and texture decline and increased the TSS content in the fruit. A total of 39 non-redundant CsAQP genes were identified. A comprehensive analysis of these genes demonstrated that all AQPs had conserved filter motifs in the different citrus varieties examined. Moreover, multiple expression analysis revealed AQPs had complex expression profiles upon water loss in citrus fruit, being time-specific in tight-skin varieties (orange and pomelo varieties), tissue-specific between peel and pulp, and variety-specific between loose-skin (mandarin varieties) and tight-skin varieties (such as sweet orange and pummelo). These results indicated that the relative humidity in storage environment affected the postharvest water loss and quality of citrus fruit. Besides, the alternation in AQPs expression may partially account for the different water loss ratio in citrus varieties and the transfer of water between the peel and the pulp of citrus fruit during storage.

Water Relationships, Vase Life and Quality of Solidago Cut Spikes as affected by some Natural Extracts in Holding Solutions

Solidago (Solidago canadensis L.) is an excellent cut spikes commonly used for indoor decoration in vases and bowls and as a dried flower. Microorganisms activities in vases solutions is the main cause of limiting the vase life of all cut flowers and preservative solutions is recommended to maintain quality and reduce losses after harvesting. To achieve this purpose, this research was conducted in vegetable and floriculture Department, Faculty of Agriculture, Mansoura Univ., Egypt during two successive seasons of 2019 and 2020. Three ethanolic leaf extracts (neem, oleander and guava) at concentrations of 0.5, 1.0 and 2.0% individually from each of them, besides AgNo3 (10 ppm) and the control (distilled water) treatments were examined. All holding solutions were fortified by sucrose in a concentration of 2.0%. Data were recorded for vase life (days), change in fresh weight (g/100g F.W./2days), the maximum increase in fresh weight (%), relative fresh weight (%), total water uptake(g/ spike), change in water uptake (g/100g F.W./2days), change in water loss (g/100g F.W./2days) and change in water balance (g/100g F.W./2days) were evaluation. Also, chlorophyll a, b, total chl., carotenoids, total sugar (%), N, P and K (%) and total bacterial counts (cfu/ml) were determined. Results showed that the more effective holding solutions in most of the studied postharvest characteristics especially vase life and water relationships besides minimizing the bacterial counts were 0.5% oleander extract, 2.0% neem extract and 2.0% guava extract plus 2.0% sucrose for all.

Changes in water loss and cell wall metabolism during postharvest withering of tobacco (Nicotiana tabacum L.) leaves using tandem mass tag-based quantitative proteomics approach

Withering is an important biological process accompanied by dehydration and cell wall metabolism in postharvest plant organs during curing/processing and storage. However, dynamics involved in cell wall metabolism and resultant water loss during withering in postharvest tobacco leaves is not well-documented. Here, tandem mass tag (TMT)-based quantitative proteomic analysis in postharvest tobacco leaves (cultivar K326) under different withering conditions was performed. In total, 11,556 proteins were detected, among which 496 differentially abundant proteins (DAPs) were identified. To elucidate the withering mechanism of tobacco leaves, 27 DAPs associated with cell wall metabolism were screened. In particular, pectin acetylesterases, glucan endo-1,3-beta-glucosidases, xyloglucan endotransglucosylase/hydrolase, alpha-xylosidase 1-like, probable galactinol-sucrose galactosyltransferases, endochitinase A, chitotriosidase-1-like and expansin were the key proteins responsible for the withering of postharvest tobacco leaves. These DAPs were mainly involved in pectin metabolism, cellulose, hemicellulose and galactose metabolism, amino sugar and nucleotide sugar metabolism as well as cell wall expansion. Furthermore, relative water content and softness values were significantly and positively correlated. Thus, dehydration and cell wall metabolism were crucial for tobacco leaf withering under different conditions. Nine candidate DAPs were confirmed by parallel reaction monitoring (PRM) technique. These results provide new insights into the withering mechanism underlying postharvest physiological regulatory networks in plants/crops.

Optimization of coconut osmotic drying preceded by microwave treatment by Response Surface Methodology

Abstract Osmotic dehydration is an intermediate stage in drying processes in which water is extracted using a hypertonic solution, but it is a slow process, especially in hard foods such as coconut. Microwaves use an electromagnetic field which can raise the temperature in the depth of samples as a result of friction, which facilitates mass transfer due to molecular expansion and increased porosity. The aim of this study was to investigate the effect of a microwave pre-treatment on the quality of the osmotic drying of coconut and optimize the whole process by response surface methodology (RSM). The independent variables were the microwave power (X1), the sugar solution concentration (X2) and the duration of the process (X3.). The responses (dependent variables) were the moisture content difference (MD), weight reduction (WR), water loss (WL) and solids gain (SG). The results showed that the linear terms of X2and X3 had significant effects on all the dependent variables but the linear term of X1 only significantly affected WL, SG and WR (p< 0.05). The interaction of X1X2 significantly affected WL and WR and the interaction of X2X3 significantly affected all the dependent variables, but the interaction of X1X3 only significantly affected MD (p < 0.05). On the other hand, X22 significantly affected SG and WR (p < 0.05). The two-factor model (2FI) was able to express the changes in MD and WL, but only the quadratic model adequately fitted SG and WR, the determination coefficients being 0.98, 0.99, 0.99 and 0.99 respectively. Finally, the optimized condition was obtained with a power of 900 watts, concentration of 47.80% and duration of 5 hours.

Anthocyanins from blackberry (Rubus fructicosus L.) impregnated in yam bean (Pachyrhizus erosus (L.) Urb.) by osmotic dehydration

Abstract Yam bean (Pachyrhizus erosus (L.) Urb.) tuber has a low carbohydrate content and contains several aminoacids, but contains few active compounds, such as vitamins and antioxidants. Anthocyanins are antioxidants found in Rubus fructicosus L. The osmotic drying is a technique that can be used to impregnate antioxidants in a matrix, so the objective of this study was to impregnate yam bean tuber slices with anthocyanin. The effect of temperature (40, 50 and 60oC), sucrose content (40, 50 and 60oBrix) and vacuum pulse (0, 300 and 600 mbar) on water loss (WL), solid gain (SG), color changes (ΔE) and anthocyanin concentration (ΔA) during osmotic drying of yam bean slices was determined. Polynomial equations were used to determine changes in WL, SG, ΔE and ΔA of yam bean slices after 6 h of osmotic drying. An osmotic solution at 60oC with a SC of 40oBrix, applying a vacuum pulse of 12 mbar maximized anthocyanin impregnation (6.67 mg anthocyanin per g initial dry matter) in tuber slices. The Page equation predicted optimum WL, SG and ΔA of yam bean tuber slices during osmotic drying. No relation was found between temperature, sucrose content and vacuum pulse with K and n parameters in the Page equation.

Degradation of adenosine triphosphate, water loss and textural changes in frozen common carp (Cyprinus carpio) fillets during storage at different temperatures

The quality of frozen aquatic products is directly affected by the changes in water loss and texture, as well as adenosine triphosphate (ATP) degradation, which affects its flavor. In the current study, the drip, cooking and centrifugal losses and texture, as well as the ATP degradation in common carp fillets were compared among four temperatures during frozen storage. The drip, cooking and centrifugal loss, as well as cohesiveness and chewiness at −60 °C storage, showed almost no change. The changes in water loss and texture were similar at −30 and −40 °C storage but these losses were less than those at −20 °C. In addition, the adenosine monophosphate deaminase (AMPD) and acid phosphatase (ACP) of fish during frozen storage were still active. The rate of ATP degradation at −20 °C, which can also be reflected by the changes in K values, was faster than those at −30 and −40 °C. The hypoxanthine ribonucleoside (HxR) and hypoxanthine (Hx) levels were almost constant at −60 °C, while only little changes in the value of ATP and inosine monophosphate (IMP), as well as AMPD and ACP activity, were observed. Overall, ATP degradation still occurred at −20−40 °C while it was almost inhibited during the −60 °C storage.

Characterization of stomata on floral organs and scapes of cut ‘Real’ gerberas and their involvement in postharvest water loss

Stomata present on leaves are the main channels for water vapor exchange between the plant and atmosphere, and contribute to water loss of cut flowers. Although cut gerberas (Gerbera jamesonii Bolus) are commonly composed of a terminal composite floral head and a scape, and have no leaves, they are also prone to severe water deficits, presumably resulting from water loss exceeding water uptake. We have investigated the distribution and characteristics of stomata of cut ‘Real’ gerberas, and their response to light and abscisic acid (ABA) treatments, to increase understanding of their functionality in postharvest water loss. Stomata were widely distributed on various parts of floral organs and the scape in cut gerberas, including the lower epidermis of the ray floret petals, trans florets, disc florets, lower epidermis of sepals, and the uppermost and middle parts of scape surfaces. The highest stomatal density was observed on the lower epidermis of sepals. Cut gerberas had the largest stomata on the middle scape surface and the smallest on the surface of the uppermost scape. Nonetheless, the lower epidermis of sepals had the highest relative stomatal area, which was higher than that of the other parts. Additionally, the lower sepal epidermis had the highest maximum stomatal conductance of water vapor (gwmax), and which was higher than that of the lower and upper leaf epidermis. The opening of stomata on various parts of cut gerberas differed in their response to light, and the highest percentage of open stomata and largest aperture were found in the stomata on the lower epidermis of sepals. Changes in water loss in cut gerberas exhibited a distinct circadian rhythm over a four-day vase period with an alternating 12-h light/dark cycle. In the lower epidermis of sepals, ABA painting treatment significantly inhibited stomatal opening and reduced water loss in cut gerberas over a 6 h light period. These findings imply the critical involvement of stomata on the lower epidermis of sepals in water loss of cut gerberas, and improve our understanding of the mechanism underlying their water deficit symptoms.

Osmotic dehydration of blueberries pretreated with pulsed electric fields: Effects on dehydration kinetics, and microbiological and nutritional qualities

ABSTRACTFresh blueberries were treated by pulsed electric fields (PEF) at 2 kV/cm before osmotic dehydration in 70% cane sugar syrup. The changes in water loss, solids gain, populations of native microorganisms, antioxidant activity, contents of anthocyanins, predominant phenolic acids and flavonols, and total phenolics in blueberries were investigated after PEF pretreatment and during osmotic dehydration at 40°C. Compared with non-PEF-pretreated blueberry samples, PEF pretreatment reduced the osmotic dehydration time of blueberry samples from 120 to 48 h at target moisture content (3.0 g/g initial dry matter). No significant differences (p > 0.05) in total phenolics, antioxidant activity, anthocyanins, and predominant phenolic acids and flavonols were observed between the PEF-pretreated and non-PEF-pretreated blueberry samples. The PEF-pretreated blueberry samples had lower microbial populations than those which were not subjected to PEF pretreatment. Regardless of pretreatment, decreases in anthocyanins, predominant phenolic acids and flavonols, total phenolics, and antioxidant activity in blueberries were observed during the osmotic dehydration process. The results demonstrate that PEF pretreatment significantly reduced the dehydration time and enhanced the microbiological quality of blueberries without affecting their nutritional quality.

Adaptation of the spiders to the environment: the case of some Chilean species.

Spiders are small arthropods that have colonized terrestrial environments. These impose three main problems: (i) terrestrial habitats have large fluctuations in temperature and humidity; (ii) the internal concentration of water is higher than the external environment in spiders, which exposes them continually to water loss; and (iii) their small body size determines a large surface/volume ratio, affecting energy exchange and influencing the life strategy. In this review we focus on body design, energetic, thermal selection, and water balance characteristics of some spider species present in Chile and correlate our results with ecological and behavioral information. Preferred temperatures and critical temperatures of Chilean spiders vary among species and individuals and may be adjusted by phenotypic plasticity. For example in the mygalomorph high-altitude spider Paraphysa parvula the preferred temperature is similar to that of the lowland spider Grammostola rosea; but while P. parvula shows phenotypic plasticity, G. rosea does not. The araneomorph spiders Loxosceles laeta and Scytodes globula have greater daily variations in preferred temperatures at twilight and during the night, which are set to the nocturnal activity rhythms of these species. They also present acclimation of the minimum critical temperatures. Dysdera crocata has a low preferred temperature adjusted to its favorite prey, the woodlouse. Spider metabolic rate is low compared to other arthropods, which may be associated with its sit and wait predatory strategy particularly in primitive hunter and weavers. In mygalomorph spiders the respiratory system is highly optimized with high oxygen conductance, for example G. rosea needs only a difference of 0.12–0.16 kPa in the oxygen partial pressure across the air-hemolymph barrier to satisfy its resting oxygen consumption demands. Water loss is a significant stress for spiders. Paraphysa parvula shows an evaporative water loss 10 times more than usual when the temperature approaches 40°C and the participation of book lungs in this loss is about 60%. This species and others show seasonal changes in water loss accounted for by changes in cuticle permeability. The case of Chilean spiders shows how the ecophysiology in spiders is associated to their design and body size and how is affected by fluctuating Mediterranean environments, suggesting that the adaptive process can be seen as a route of optimizing the use of energy to cope with environmental restrictions imposed by the interaction with the terrestrial environment and lifestyle.

A Comparative Study of the Physico-Chemical Characteristics of the Ready-to Eat Coconut Based Snack

Coconut slices (thickness 0.8 ± 0.1 mm) were osmotically dehydrated (0 min to 720 min) using filtrates of functional ingredients such as beet root, carrot, ginger and mint as impregnating solutions. During the osmotic process, the diffusion of minerals, organic acids, phenolics and vitamins between coconut slices and osmotic medium might have contributed various physico-chemical changes in acidity, TSS (Total soluble solids) of the osmotic medium and rehydration characteristics of the snack. The kinetics of osmotic dehydration process revealed that significant changes in mass transfer parameters WR (Weight reduction), SG (Solid gain) and WL (Water loss) observed during 450th minutes of the process, irrespective of the functional filtrates and dehydration methods used (hot-air oven at temperature 45-60°C for about 6-7 hours and freeze drying at temperature (-40 to 30°C) for a duration of 14-16 hours). Texture analysis revealed that osmotic dehydration induced modifications in cell structure of the coconut based snack with respect to the drying methods and the use of sugar as osmotic infusions.

Soil fertility self-development under ecological restoration in the Zhuxi watershed in the red soil hilly region of China

Current methods that utilize simple data or models to judge whether soil fertility can self-develop are not sufficiently rigorous. A new framework has been set up using catastrophe theory, laboratory experiment, field work, and 3S (Geographic information system, Global positioning system, and Remote sensing) to explore soil fertility catastrophe under ecological restoration, discriminate whether soil fertility can self-develop, and propose adjustment of ecological restoration measures in the Zhuxi watershed of Changting County, Fujian Province, China, which is a typical representative of the red soil hilly region of China. The results show that: 1) the soil fertility is obviously improved through the four ecological restoration measures, which impels soil fertility catastrophe. Among 89 soil samples, catastrophic soil samples and stable soil samples account for 26 (29.21%) and 63 (70.79%) of the samples, respectively. The four ecological restoration measures are listed in the order low-quality forest improvement > arbor–bush–herb mixed plantation > orchard improvement > closing measures according to the proportions of catastrophic soil samples. A typical soil sample in Bashilihe that can self-develop is selected as the criterion to judge the upper lobe and lower lobe of soil fertility in the process surface of the Cusp catastrophe model. Twenty-six (29.21%) were in the middle lobe, 10 (11.24%) were in the upper lobe, and 53 (70.79%) were in the lower lobe. The catastrophic direction of 26 catastrophic soil samples is to the upper lobe according to soil and water loss change as well as fieldwork. There is a significant positive correlation of Δ with soil and water loss change, and the lower soil and water loss relates to higher catastrophic probability. 2) Soil fertility self-development could be regionalized as “Soil fertility can self-develop” whose area was 12.74 km2 (28.33%) distributed mainly in the leftmost and rightmost parts, “Soil fertility tends to self-develop” whose area was 11.63 km2 (25.89%) distributed mainly in the middle part, and “Soil fertility cannot self-develop” whose area was 20.58 km2 (45.78%) distributed mainly between the above two types. 3) There is no need to take ecological restoration measures and excessive human interference should be avoided in the future in regions of “Soil fertility can self-develop” and “Soil fertility tends to self-develop,” and ecological restoration measures should be taken in region of “Soil fertility cannot self-develop.” 4) We suggest withdrawal and implementation of ecological restoration measures should be incorporated into the evaluation criteria of ecological restoration to avoid misuse of funds.

How does tree density affect water loss of peatlands? A mesocosm experiment.

Raised bogs have accumulated more atmospheric carbon than any other terrestrial ecosystem on Earth. Climate-induced expansion of trees and shrubs may turn these ecosystems from net carbon sinks into sources when associated with reduced water tables. Increasing water loss through tree evapotranspiration could potentially deepen water tables, thus stimulating peat decomposition and carbon release. Bridging the gap between modelling and field studies, we conducted a three-year mesocosm experiment subjecting natural bog vegetation to three birch tree densities, and studied the changes in subsurface temperature, water balance components, leaf area index and vegetation composition. We found the deepest water table in mesocosms with low tree density. Mesocosms with high tree density remained wettest (i.e. highest water tables) whereas the control treatment without trees had intermediate water tables. These differences are attributed mostly to differences in evapotranspiration. Although our mesocosm results cannot be directly scaled up to ecosystem level, the systematic effect of tree density suggests that as bogs become colonized by trees, the effect of trees on ecosystem water loss changes with time, with tree transpiration effects of drying becoming increasingly offset by shading effects during the later phases of tree encroachment. These density-dependent effects of trees on water loss have important implications for the structure and functioning of peatbogs.

OSMOTIC DEHYDRATION OF POMEGRANATE SEEDS (PUNICA GRANATUM L.): EFFECT OF FREEZING PRE‐TREATMENT

ABSTRACTThe osmotic dehydration of pomegranate seeds was compared using fresh and frozen seeds. The process was carried out at 50C in a 55°Brix solution of sucrose. Freezing pomegranate seeds before osmotic dehydration involved an increase of effective diffusivity and a reduction in dehydration time. The most significant changes of water loss (WL) (46 g/100 g of fresh seeds [FS]) and solids gain (SG) (7 g/100 g of FS) took place during the first 20 min for frozen seeds. After this period, seeds WL and SG ranged on average close to 43 and 8 g/100 g of FS, respectively. Osmotic dehydration was slower starting from fresh fruits but led to a higher rate of WL (62 g/100 g of FS) at the end of the process. Both scanning electron microscopy and texture analysis showed a destruction of cell structure and seed texture during the pretreatment (freezing). The same techniques also revealed a texture/structure modification induced by the osmotic dehydration process.PRACTICAL APPLICATIONSIn Tunisia, the research of addition value to pomegranate seeds is very limited and presents a traditional feature such as jam preparation or direct consummation of fruit during the crop season (between September and December). However, other perspectives of transformation and exploitation of the pomegranate seeds should be undertaken to give an added value to this typical fruit. Osmotic dehydration can be an alternative process to increase the conservation time of fruit and to give a new osmodehydrated fruit that can be included in some food formulation such as ice cream, cereals, dairy, confectionery and bakery products.

Connectivity of agroecosystems: dispersal costs can vary among crops

Knowledge of how habitat heterogeneity affects dispersal is critical for conserving connectivity in current and changing landscapes. However, we generally lack an understanding of how dispersal costs and animal movements vary among crops characteristic of agroecosystems. We hypothesized that a physiological constraint, desiccation risk, influences movement behavior among crops and other matrix habitats (corn, soybean, forest, prairie) in Ambystoma tigrinum (tiger salamander) in Illinois, USA. In a desiccation experiment, salamanders were added to enclosures in four replicate plots of each matrix habitat, and water loss was measured every 12 h for 48 h. Changes in water loss were examined using a linear mixed model. Water loss varied among treatments, over time, and there was a significant treatment-time interaction. Water loss was greater in corn and prairie than in forest and soybean. To assess whether salamanders move through matrix habitats that minimize desiccation, we tracked movements of individuals released on edges between habitats for two treatment combinations: soybean–corn, and soybean–prairie. As predicted based on our desiccation experiment, movements were oriented towards soybean in both cases. Thus, variation in desiccation risk among matrix habitats likely influenced movement decisions by salamanders, although other factors such as predation risk could have contributed to habitat choice. We argue that conceptualizing dispersal cost as uniformly high in all crop types is too simplistic. Estimating crop-specific dispersal costs and movement patterns may be necessary for constructing effective measures of landscape connectivity in agroecosystems.

Simulation in maize–water relations: a case study for continental climate (Hungary)

AbstractLocal consequences of the global climate change in the Carpathian Basin were followed on the basis of simulated stomatal resistances. The Crop Microclimate Simulation Model of Goudriaan was applied in our study. The expected weather, plant and soil modifications were based on long‐term observations during the time period 1961–1990 in the Keszthely area (Hungary, N 46°44′, E 17°14′; altitude 112 m). Besides application of the A2 and B2 SRES scenarios, the impact of extreme hot days was also included in the study. This was necessary as these events have recently occurred more and more frequently. Demonstration of weather scenarios with relatively high warming rates was made possible by the high resolution of the model, simulating even daily changes. The stomatal resistance significantly increased in all scenarios, as was indeed experienced in the last decade (1997–2006). A twofold increase in CO2 concentration approximately halves stomatal openings even under unchanged weather conditions. This can be considered as an advantageous side effect of the global climate change on the plant's water balance, important in continental climate because of scarce precipitation. In Scenarios A2 and B2, increases in resistance were close to the effect of doubled CO2 concentration. Surprisingly, the effect of an increase in the number of extreme hot days on stomatal resistance was moderate, below than what might have been expected. The common impact of the environmental and biological factors on stomatal resistance was realized using normalized leaf area indices, where the highest increases were predicted by using the hottest and driest scenario. Moderate changes in water loss and photosynthesis indicated a certain amount of available soil moisture reserve even in the extreme weather situations in July, at Keszthely. Decrease in carbon assimilation can occur in days with extreme temperatures. Our scenarios do not include significant precipitation decline because of forecast uncertainties. A significant precipitation decrease would fundamentally reshape our results, so we do not propose to extend our conclusions in the case of significant modification in rainfall amount or distribution. Copyright © 2010 John Wiley & Sons, Ltd.

Osmotic dehydration of pomegranate seeds: mass transfer kinetics and differential scanning calorimetry characterization

SummaryOsmotic dehydration of pomegranate seeds was carried out at different temperatures (30, 40, 50 °C) in a 55°Brix solution of sucrose, glucose, and mixture sucrose & glucose (50:50, w/w). The most significant changes of water loss and solids gain took place during the first 20 min of dewatering. During this period, seeds water loss was estimated to 46% in sucrose, 37% in glucose and 41% in mix glucose/sucrose solution. The increase of temperature favoured the increase of water loss, weight reduction, solids gain and effective diffusivity. Differential scanning calorimetry data provided complementary information on the mobility changes of water and solute in osmodehydrated pomegranate seeds. The ratio between % frozen water and % unfreezable water decreased from 5 to 0.5 during the process. That involving the presence of very tightly bound water to the sample, which is very difficult to eliminate with this process. It also appeared that glass transition temperature depends on the types of sugar.

Changes in eggshell conductance, water loss and hatchability of layer hens with flock age and moulting

1. Changes in water loss, eggshell conductance and hatchability with flock age were monitored in layer hens in a commercial hatchery. 2. Optimal water loss for maximal hatchability of layer eggs was found to be 12 to 13% of initial egg mass at d 18 of incubation. 3. Mass specific water vapour conductance (GH2Osp) increased linearly with flock age from 0·31 mg/(d·g·Torr) at the beginning of the first breeding season to 0·40 mg/(d·g·Torr) at its end after 77 weeks (=4·21 and 5·44 mg/(d·100 g·kPa), respectively). 4. After forced moulting GH2Osp increased from 0·35 to 0·41 mg/(d·g·Torr) (=4·76 and 5·58 mg/(d·100 g·kPa), respectively). 5. The coefficients of variation of GH2Osp increased with flock age from 14% at the beginning of the breeding season to 31% at the end of the second breeding season. 6. In order to preserve normal incubation water loss for maximising hatchability, the humidity setting of an incubator should increase gradually, with flock age, from 53% RH to 66% RH in the first laying season and from 61% RH to 67% RH after forced moulting. 7. A 3·5-fold increase (from 2 to 7%) in the difference between mean and median GH2Osp of egg batches with flock age was found, indicating increasing frequency of microscopic cracks in eggshells with flock age. This has to be taken into account when setting the humidity regime in the incubator.

Effects of pulsed-vacuum and ultrasound on the osmodehydration kinetics and microstructure of apples (Fuji)

The influence of pulsed-vacuum (PV) and ultrasound on the osmodehydration kinetics and microstructure of apples (Fuji) was investigated. Apple cylinders (15 mm height × 15 mm diameter) immersed in a 60% (w/w) high-fructose corn syrup solution were subjected to shaking (55 rpm), PV (13 MPa vacuum for 5 min + atmospheric pressure for 5 min + same vacuum for 5 min, then atmospheric pressure), or ultrasound treatment (50/60 Hz and 185 W) for 3 h. Changes in water loss, solid gain, and firmness of apples were measured, and the data were fitted using Weibull and Peleg models. In addition, microstructure was observed using scanning electronic microscopy (SEM). The high regression coefficients ( R 2 > 0.96) and low percent mean relative deviations ( E < 6.37%) indicated the acceptability of Weibull model for predicting both water loss and solid gain under all treatments. The Peleg model well described the sample firmness changes with a R 2 ∼ 0.98 and E ∼ 3.24–6.14%. PV resulted in the lowest shape parameter α value (0.74) for solid gain and the greatest rate constant k 1 (40.98 s) for firmness loss, indicating the largest amount of solid gain (3.02%) and the least firmness loss of samples, while ultrasound led to the lowest α value (0.45) for water loss and k 1 value (33.42 s) for firmness loss: the highest water and firmness losses (56.3% and 22.3%, respectively) in samples among three treatments. SEM showed that cell deformation and cell structure collapse were the most severe in ultrasound treated samples, but moderate in PV samples. SEM also revealed a larger amount of solute uptake in the cells of PV and ultrasound treated samples.