Months Storage (month + storage)

Distribution by Scientific Domains

Selected Abstracts

Construction of L -Lysine Sensor by Layer-by-Layer Adsorption of L -Lysine 6-Dehydrogenase and Ferrocene-Labeled High Molecular Weight Coenzyme Derivative on Gold Electrode

Haitao Zheng
Abstract A ferrocene-labeled high molecular weight coenzyme derivative (PEI-Fc-NAD) and a thermostable NAD-dependent L -lysine 6-dehydrogenase (LysDH) from thermophile Geobacillus stearothermophilus were used to fabricate a reagentless L -lysine sensor. Both LysDH and PEI-Fc-NAD were immobilized on the surface of a gold electrode by consecutive layer-by-layer adsorption (LBL) technique. By the simple LBL method, the reagentless L -lysine sensor, with co-immobilization of the mediator, coenzyme, and enzyme was obtained, which exhibited current response to L -lysine without the addition of native coenzyme to the analysis system. The amperometric response of the sensor was dependent on the applied potential, bilayer number of PEI-Fc-NAD/LysDH, and substrate concentration. A linear current response, proportional to L -lysine concentration in the range of 1,120,mM was observed. The response of the sensor to L -lysine was decreased by 30% from the original activity after one month storage. [source]

Enterococcus faecalis with the gelatinase phenotype regulated by the fsr operon and with biofilm-forming capacity are common in the agricultural environment

Lilia Macovei
Summary The prevalence of gelatinase activity and biofilm formation among environmental enterococci was assessed. In total, 396 enterococcal isolates from swine and cattle faeces and house flies from a cattle farm were screened for gelatinase activity. The most prevalent phenotype on Todd,Hewitt agar with 1.5% skim milk was the weak protease (WP) (72.2% of isolates), followed by the strong protease (SP) 18.7%, and no protease (NP) (9.1%). The majority of WP isolates was represented by Enterococcus hirae (56.9%), followed by Enterococcus faecium (25.9%), Enterococcus casseliflavus (10.4%), Enterococcus gallinarum (5.2%) and Enterococcus saccharolyticus (1.7%). All WP isolates were negative for gelE (gelatinase) and sprE (serine protease) as well as the fsrABDC operon that regulates the two proteases, and only four isolates (7.0%) formed biofilms in vitro. All SP isolates were Enterococcus faecalis positive for the fsrABDC, gelE, sprE genes and the majority (91.2%) formed a biofilm. Diversity of NP isolates was relatively evenly distributed among E. hirae, E. faecium, E. casseliflavus, E. gallinarum, Enterococcus durans, E. saccharolyticus and Enterococcus mundtii. All NP isolates were negative for the fsr operon and only four E. hirae (11.1%) formed a biofilm. Of further interest was the loss of the gelatinase phenotype (18.9% of isolates) from SP isolates after 4 month storage at 4,8°C and several passages of subculture. Results of reverse transcription PCR analysis indicated that mRNA was produced for all the genes in the frs operon and sequencing of the gelE gene did not reveal any significant mutations. However, gelatinase was not detectable by Western blot analysis. Our study shows that E. faecalis with the complete fsr operon and the potential to form a biofilm are relatively common in the agricultural environment and may represent a source/reservoir of clinically relevant strains. In addition, many environmental enterococci, especially E. hirae, produce an unknown WP that can hydrolyse casein but does not contribute to biofilm formation. The stability of the gelatinase phenotype in E. faecalis and its regulation will require additional studies. [source]


A combined factors preservation technology involving blanching and vacuum solutes (sucrose, potassium sorbate, ascorbic and citric acids, zinc chloride) impregnation was proposed to minimize color changes in minimally processed kiwifruit slices during one month storage. Atmospheric impregnation was also studied in order to compare both impregnation techniques. A Box-Behnken design was adopted and second order polynomial models were computed for different storage times to relate some process variables (blanching time, zinc content, storage temperature) to a color function (Brown Index). As the storage time increased, the response surfaces for vacuum treated fruits were vertically displaced to greater Brown Index values while the response surface behavior for atmospheric impregnated fruits were less dependent on storage time. For vacuum treated fruits, combinations of blanching and addition of zinc chloride improved the color of the finished product at all storage temperatures assayed, but these treatments were detrimental for atmospheric impregnated fruits, increasing significantly the Brown Index values. After storage, total chlorophyll had been degraded between 70 and 90% depending on the pretreatments. There did not appear to be any consistent relation between the changes which occurred in the total chlorophyll content and color. [source]

Alcohol biosensing by polyamidoamine (PAMAM)/cysteamine/alcohol oxidase-modified gold electrode

Mehriban Akin
Abstract A highly stable and sensitive amperometric alcohol biosensor was developed by immobilizing alcohol oxidase (AOX) through Polyamidoamine (PAMAM) dendrimers on a cysteamine-modified gold electrode surface. Ethanol determination is based on the consumption of dissolved oxygen content due to the enzymatic reaction. The decrease in oxygen level was monitored at ,0.7 V vs. Ag/AgCl and correlated with ethanol concentration. Optimization of variables affecting the system was performed. The optimized ethanol biosensor showed a wide linearity from 0.025 to 1.0 mM with 100 s response time and detection limit of (LOD) 0.016 mM. In the characterization studies, besides linearity some parameters such as operational and storage stability, reproducibility, repeatability, and substrate specificity were studied in detail. Stability studies showed a good preservation of the bioanalytical properties of the sensor, 67% of its initial sensitivity was kept after 1 month storage at 4°C. The analytical characteristics of the system were also evaluated for alcohol determination in flow injection analysis (FIA) mode. Finally, proposed biosensor was applied for ethanol analysis in various alcoholic beverage as well as offline monitoring of alcohol production through the yeast cultivation. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source]

Quality of applesauces processed by pulsed electric fields and HTST pasteurisation,

Z. T. Jin
Summary A pilot plant scale continuous flow pulsed electric field (PEF) and high temperature short time (HTST) processing system was integrated with an aseptic packaging machine. Fuji applesauce and blueberry applesauce were processed with PEF followed by HTST pasteurisation (PEF + HTST). PEF + HTST processed Fuji applesauce from fresh Fuji apples demonstrated high and stable sensory scores during 9 months storage at 27 °C, and had comparative sensory quality with Meal Read-to-Eat (MRE) and commercial applesauce products stored at 4 °C. PEF + HTST processed blueberry applesauce from pre-pasteurised materials had lower sensory scores than PEF + HTST processed Fuji applesauce and was significantly less stable during the storage at 27 °C. PEF + HTST processed applesauces had aerobic count and mould and yeast count of <10 cfu mL,1 during storage. Electrical conductivity, pH and °Brix, were not significantly changed throughout storage time (P > 0.05). [source]

Small-scale production and storage quality of dry-milled degermed maize products for tropical countries

Christian Mestres
Summary A small-scale, single operation, dry degerminator, originating from Brazil was tested on six maize samples (from France and Mali) at two moisture contents (10 and 15% wb). The yield of brewery maize grits (<1% lipids) was higher for extensively dry (10% mc) and hard grains. It ranged from 50 to 70% for four cultivars, which was equivalent or higher than for industrial plants. The rancidity of the products was controlled by the fat acidity level, which was 40,60 mg KOH 100 g,1db, after 4 months storage of degermed flour. This indicates that degermed products can be stored at 35 °C for up to 6 months without developing significant rancid off-flavour. Thus the Brazilian dry degerminator appears suitable for the treatment of maize in the tropical zone of Africa. [source]

Effect of thermal processing on the texture of canned apricots

Constantin G. Mallidis
The effect of thermal processing on the texture of canned apricots was studied by using the main cultivar canned in Greece, Bebecou. The test temperature ranged from 82 to 95 °C. The loss of hardness was tested immediately after processing and after 3 months storage. The z -value was 16.7 °C and the energy of activation 116.5 kJ mol,1. Some restoration in the hardness was found after 3 months storage, which might be attributable to the absorption of sucrose by the fruit. [source]

Cyclodextrin microparticles for drug delivery to the posterior segment of the eye: aqueous dexamethasone eye drops

Thorsteinn Loftsson
Delivery of steroids to the retina is currently undertaken with invasive injections into the vitreous cavity. This paper describes a non-invasive method to deliver steroids in therapeutic levels to the retina in rabbits. Dexamethasone was formulated as somewhat water-soluble dexamethasone/,-cyclodextrin (,CD) microparticles in a low-viscosity aqueous eye drop suspension. The mean (± standard deviation) diameter of the particles was 20.4 ± 10.3 ,m, with no particles larger than 60 ,m. The aqueous suspension formulation was tested in rabbits and compared with an aqueous dexamethasone eye drop solution containing randomly methylated ,-cyclodextrin (RM,CD). The dexamethasone concentration was identical in both formulations (15 mg mL,1). The drug was administered to the left eye but determined in both eyes. The amount reaching different eye tissues via the topical route was determined by subtracting the amount found in the right eye from the amount found in the left eye. Two hours after single application of the dexamethasone/,CD eye drops to rabbits the mean (± s.d.) concentration in vitreous was 29 ± 16 ng g,1, 86% of which reached vitreous via the topical route and in retina the concentration was 57 ± 22 ng g,1 (49% via topical route). For the RM,CD the values were 22.6 ± 9 and 66 ± 49 ng g,1 (73 and 14% via topical route), respectively. These steroid levels are comparable with the dexamethasone concentration achieved 1 month after intravitreal injection. The aqueous dexamethasone/,CD eye drop formulation was chemically stable during 7 months storage and well tolerated with no visible short-term side effects. [source]

Physicochemical, textural and viscoelastic properties of palm diacylglycerol bakery shortening during storage

Ling-Zhi Cheong
Abstract BACKGROUND: Diacylglycerol (DAG), which has health-enhancing properties, is sometimes added to bakery shortening to produce baked products with enhanced physical functionality. Nevertheless, the quantity present is often too little to exert any positive healthful effects. This research aimed to produce bakery shortenings containing significant amounts of palm diacyglycerol (PDG). Physicochemical, textural and viscoelastic properties of the PDG bakery shortenings during 3 months storage were evaluated and compared with those of commercial bakery shortening (CS). RESULTS: PDG bakery shortenings (DS55, DS64 and DS73) had less significant increments in slip melting point (SMP), solid fat content (SFC) and hardness during storage as compared to CS. Unlike CS, melting behaviour and viscoelastic properties of PDG bakery shortenings remained unchanged during storage. As for polymorphic transformation, CS contained only , crystals after 8 weeks of storage. PDG bakery shortenings managed to retard polymorphic transformation for up to 10 weeks of storage in DS55 and 12 weeks of storage in DS64 and DS73. CONCLUSION: PDG bakery shortenings had similar if not better storage stability as compared to CS. This is mainly due to the ability of DAG to retard polymorphic transformation from ,, to , crystals. Thus, incorporation of DAG improved physical functionality of bakery shortening. Copyright © 2010 Society of Chemical Industry [source]

Influence of PET bottle weight, closure performance and filling Technique on the oxygen content of soya cooking oil

Léa Mariza de Oliveira
Abstract The use of PET bottles for edible oil in Brazil is increasing but there is a trend to reduce bottle weight for economic reasons, which decreases the oxygen barrier of the package. The barrier performance of a 20,g PET bottle for 900,ml soya oil, submitted to gas flushing with gaseous N2 and pressurization with liquid N2, was compared with a 27,g PET conventional bottle. During 8 months storage at 25°C the internal pressure, dissolved oxygen and oxygen in the headspace were evaluated and did not change significantly. Liquid N2 pressurization did not improve the efficiency of reducing O2 in the headspace compared to N2 gas flushing. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Seed moisture content affects afterripening and smoke responsiveness in three sympatric Australian native species from fire-prone environments

Abstract Germination of freshly collected seeds of three sympatric herbaceous species native to fire-prone environments in south-western Australia was significantly improved through the application of novel combinations of dry heat, gibberellic acid, smoke water and dry afterripening. For fresh seeds, combinations of dry heat, gibberellic acid and/or smoke water resulted in >80% germination in Austrostipa elegantissima (Poaceae) and Stylidium affine (Stylidaceae) seeds and >60% germination in Conostylis candicans (Haemodoraceae) seeds, compared with <10% germination of control seeds. For fresh seeds, two broad germination patterns were observed in response to smoke water: nil , low germination for both control and smoke water-treated seeds (A. elegantissima and S. affine); and a significant smoke response (35%) compared with control seeds (1%) (C. candicans). During afterripening, high germination for A. elegantissima seeds was achieved following 3 months storage of seeds at equilibrium relative humidities of 23,75%, but seeds stored at 5,13% equilibrium relative humidities took 6,36 months to achieve similar levels of germination. Germination of C. candicans seeds also increased after 3 months storage, to >60% at each equilibrium relative humidity and further increases over time were slight. For S. affine seeds >60% germination was achieved only after 36 months storage at 50% equilibrium relative humidity. Seeds from all three species were smoke-responsive at some point, but the interaction/effects of afterripening on the smoke response varied significantly between species. This study highlights an apparent effect of seed dormancy status on response to smoke and a surprisingly high level of ecological variation in pre-germination requirements (cues) for these co-occurring species that may relate to variation(s) in microsite selection forces operating on the soil seed bank of the different species. [source]

Effect of various stabilizing agents on Imperata cylindrica grass pollen allergen extract

K. M. Bijli
Summary Background Allergen extracts are unstable, heat labile or susceptible to proteases. Stability of allergen extracts is important for proper diagnosis and therapy of allergic disorders. Objective The present study was undertaken to determine the preservation and stabilization conditions of Imperata cylindrica (Ic) grass pollen extract. Methods The Ic extract was kept with 0.1 m,-aminocaproic acid (EACA), 0.75 m sucrose, 5% glycerol, 0.03% human serum albumin (HSA) or 0.4% phenol for different time periods. The extracts were stored for 3, 6 and 12 months each at 4 °C, 4 °C with daily exposure to room temperature (RT) for 1 h, and RT. The quality of extracts was analysed by SDS-PAGE, Western blot, ELISA, ELISA inhibition and skin test. Results Extracts kept with EACA and sucrose retained most of the protein bands followed by glycerol as determined by SDS-PAGE and Western blot during all storage periods and conditions in comparison with standard extracts. The extracts kept with HSA, phenol and without preservative (WP) showed protein degradation below 33 kDa after 3 months storage at all conditions. However, a 67-kDa allergen was stable in these extracts. EACA extract required 75 to 120 ng of protein for 50% inhibition in IgE binding under different conditions, whereas standard extract required 70 ng for the same. ELISA also demonstrated high allergenic reactivity of EACA extract. ID test on allergy patients with EACA extract demonstrated same allergenic potency as that of standard extract. Conclusion EACA is the best preservative/stabilizing agent of Ic pollen extract, followed by sucrose and glycerol. Ic extract kept with phenol, HSA and without preservative showed degradation within 3 months. EACA preserved extract is equally potent as that of standard extract up to 1 year's storage. [source]

Effect of drying and storage on the degradation of total carotenoids in orange-fleshed sweetpotato cultivars

Aurélie Bechoff
Abstract BACKGROUND: Orange-fleshed sweetpotato (OFSP) can be used to tackle vitamin A deficiency, a major public health problem in most developing countries. In East Africa, common ways of using sweetpotato include drying and subsequent storage. The aim of the study was to investigate the impact of drying and storage on the total carotenoid retention (as an estimate of provitamin A retention) from OFSP. RESULTS: Losses of total carotenoid during drying were generally low (15% or less). Total carotenoid retention in OFSP was not dependent on the type of dryer (solar or sun). Sweetpotato cultivar (Ejumula, Kakamega, SPK004/1, SPK004/1/1, SPK004/6 or SPK004/6/6) had a significant effect on retention in drying (P < 0.05). High percentage losses of total carotenoids were, however, correlated with high moisture content and high carotenoid content in fresh sweetpotato roots. After 4 months' storage at room temperature in Uganda, losses of total carotenoid in dried sweetpotato chips were high (about 70%) and this was not dependent on the use of opaque or transparent packaging. CONCLUSION: Losses of carotenoids during storage were considered to be more of a nutritional constraint to the utilisation of dried sweetpotato than losses occurring during drying. The relationship between characteristics of the cultivars and losses of carotenoids during drying should be taken into account in selection of cultivars for processing. Copyright © 2009 Society of Chemical Industry [source]

Browning reactions during storage of low-moisture Australian sultanas: Further evidence for arginine-mediated Maillard reactions during storage, and some effects of vine-shading and harvest date

Abstract Sultana grapevines (Vitis Vinifera L. cv. Sultana syn. Thompson Seedless) were subjected to four shading regimes: 50% shading (1), 25% shading (2), fully exposed-top of canopy (3) and beneath canopy (4) and harvested early (21 February) and late (13 March) in the 1996/1997 sultana season. Grapes from each of the eight field-treatment combinations represented a range of maturities (14.4 to 23.50oBrix). Grape samples from each of the treatments were dipped and dried to 18% moisture, with half of each of the sultana samples further reduced in moisture by sunfinishing on plastic sheets in direct sun. These field treatments resulted in sixteen unique dried sultana bulk samples with a range of initial chemico-physical properties; aw (0.481,0.691), skin-polyphenoloxidase (PPO) activity (4.40,9.05 ,mol O2/g.minute) free arginine in skin tissues (1.0,5.10 mg/g) and protein (16.40,27.18 mg/g). Sultanas were stored at 10oC and 30oC in either the presence or absence of oxygen for 10 months, and changes in CIE L*a*b* tristimulus values, hue-angle (hab*) and chroma (Cab*) were monitored. Significant changes in sultana colour occurred in samples stored at 30oC, especially in higher aw non-sunfinished sultanas. Although browning was more intense in the presence of oxygen, significant browning also occurred in the absence of oxygen. Lower concentrations of 5-hydroxy methylfurfural, a key marker of Maillard browning in samples stored at 30oC in the presence of oxygen, indicated that the non-enzymatic reactions were sensitive to oxygen. Changes in the concentration of trans -caftaric acid, the main substrate of grape PPO, were also measured during sultana drying. Storage browning (changes in L*, b*, hab*, Cab*)in dried sultanas could be predicted by regression models using pre-storage aw, free-skin arginine or Kjeldahl protein after 10 months' storage between 10oC and 30oC. Non-enzymatic and Maillard-type reactions (sensitive to both oxygen and aw), made an important contribution to sultana storage browning. We provide only weak evidence that either shaded (immature) or green fruit was more susceptible to storage browning. [source]