First Week Of Storage Research Articles

Nutritional value of fresh and concentrated algal diets for larval and juvenile Pacific oysters (Crassostrea gigas)

Three species of microalgae commonly used as feed for bivalves, Pavlova lutheri , Isochrysis aff. galbana (clone T-Iso) and Chaetoceros calcitrans forma pumilum , were produced with standard techniques and then harvested by a flocculation procedure. This method was effective for C. calcitrans and P. lutheri though a partial deterioration of cells was observed for the latter, whereas flocculation heavily damaged T-Iso cells (diffuse cellular lysis, majority of cells clumped and/or misshapen, loss in organic matter). Quality of concentrates concentrated at 1 °C was investigated by means of gross composition analysis and pheophytin a /chlorophyll a evolution over 4 weeks of storage. P. lutheri concentrates did not exhibit significant changes in gross composition over the storage period, whereas the value of pheophytin a /chlorophyll a remarkably increased, from 0.05 to 0.35. In T-Iso concentrates, a dramatic decrease in protein and carbohydrate content occurred during the first week of storage. The chemical composition of concentrated C. calcitrans cells did not substantially change during the first 3 weeks of storage; after this period, the organic matter decreased significantly (−18%). The effectiveness of trispecific ( P. lutheri +T-Iso+ C. calcitrans ) and bispecific ( P. lutheri +T-Iso; P. lutheri + C. calcitrans ; T-Iso+ C. calcitrans ), fresh or concentrated (1 °C), diets were evaluated on Pacific oyster ( Crassostrea gigas ) with larval and juvenile feeding trials, lasting 1 and 4 weeks, respectively. For larvae, concentrated diets of P. lutheri +T-Iso and T-Iso+ C. calcitrans stored for 7–14 days gave better growth than the equivalent fresh diets ( P <0.05). In the juvenile trial, the use of the same concentrates for a longer period (4 weeks) gave significantly lower growth compared to the corresponding fresh microalgae. In this case, the longer time of storage (8–36 days) probably prejudiced the quality of the stored concentrates. This fact was confirmed by means of larval consumption assays of fresh and concentrated microalgae using fluorimetry probes. Indeed, for P. lutheri delivered as fresh microalgae, larval grazing was twice that of concentrated cells.

SUPERFICIAL SCALD VERSUS ETHANOL VAPOURS: A DOSE RESPONSE

Early picked Granny Smith apples (Malus domestica Borkh.) were stored under air or CA (controlled atmosphere at 2 kPa O2 and <1 kPa CO2) at 1°C. During the first week of storage, fruit was subjected to ethanol vapours in doses from 0 to 8 g/kg of fruit. Ethanol at 4 g/kg protected fruit against superficial scald in CA storage for at least 5.5 months, plus two weeks in cold air storage, plus a week at ambient temperature. Ethanol at 6 g/kg protected fruit in cold air storage for 3 months, plus a week at ambient temperature. Effects of ethanol vapours and CA on headspace ethylene levels are discussed. Ethanol vapours did not cause significant off-flavours in Granny Smith apples (consumer panel, hedonic scale), or purpling of the skin of Red Delicious apples (visual assessment).

Monitoring Volatile and Nonvolatile Amines in Dried and Salted Roes of Tuna (Thunnus thynnus L.) during Manufacture and Storage

Dried and salted roe, obtained from the reproductive organs of female tuna (Thunnus tynnus L.), is a typical fish-based food in the Mediterranean area of Spain. In the present study, we monitored the formation of volatile amines (trimethyamine nitrogen [TMA-N] and total basic volatile nitrogen [TBVN]) and nonvolatile amines (biogenic amines) in dried and salted tuna roe after processing and storage for 8 weeks at 4, 20, and 30°C. The salting and drying process significantly increased the TBVN, cadaverine, tyramine, phenylethylamine, and tryptamine contents, and bacteria with histamine decarboxylase activity were detected both in raw and in dried and salted tuna roes. During storage of tuna roe, TMA-N and TBVN levels increased significantly after the fourth week of storage at 30°C, whereas biogenic amine contents remained more or less constant. However, samples stored at 30°C showed histamine formation after the first week of storage, with a concentration of <50 ppm. The volatile and nonvolatile amine concentrations in tuna roe were below the consumer safety limit, with the exception of the total biogenic amine level in roe stored at 30°C, which exceeded the European Community's recommended limit (300 ppm). These results indicate that in properly stored tuna roe, histamine formation will not represent a serious health risk to consumers unless the tuna roe has previously been mishandled.

Stability after thawing of RBCs frozen with the high- and low-glycerol method.

RBCs can be frozen with either the high-glycerol method (HGM) or the low-glycerol method (LGM). To date, the use of frozen RBCs is hampered by a 24-hour outdating period after thawing. A closed washing system (ACP 215) may solve this problem. We compared the effects of high- (40%) and low-glycerol (19%) concentration, with and without freezing (at -80 degrees C for HGM, -196 degrees C for LGM) on the in vitro quality of RBCs after deglycerolization with the closed washing system and during storage at 4 degrees C in SAGM after thawing. Glycerol treatment by itself induced hemolysis during processing, which was more pronounced in HGM cells. The freeze-thaw-wash process decreased the stability of RBCs, particularly in LGM cells during storage after thawing. In contrast to LGM cells, in HGM cells no additional effect of freeze or thaw on stability of washed cells was seen during the first week of storage after thawing. Changes in osmotic resistance and cellular metabolism could not explain the observed differences in RBC stability. The closed washing system is able to process both high- and low-glycerol-treated RBCs. Stability after washing during cold storage in SAGM, as measured by hemolysis, is better for HGM cells as compared to LGM cells.

Variation of mass (volume) taken with the calibrated syringe and of the results provided by the Bio-Rad Platelia$^{{\rm TM}}$ BSE test upon storage of brainstem samples at -20 °C

The real mass obtained by sampling with the calibrated syringe provided by the supplier, and the degradation through cold storage was evaluated in view of the measured optical density of suspected bovine BSE brainstem material in the quick Platelia TM test from Bio-Rad. For this, 50 nega- tive BSE cases and 2 positive BSE cases were tested. The brainstems were stored at -20 o Ca nd the weight of each sample was taken with a calibrated syringe at an interval of 1 week. Moreover, the final optical density obtained with the quick Platelia TM ELISA test of each case was evaluated. This was done three times for each case (brainstem), including the primary sampling of the fresh brainstem tis- sue taken immediately after slaughter. The results indicate that storage at -20 o C gives a significant decrease in weight of the mass taken with the calibrated syringe (P = 0.0121) and in optical density (P < 0.001) between the fresh and 1 week old sample for the same volume. This decrease did not seem to continue significantly after this first week of storage. Furthermore, no significant correlation could be noted between the decrease in the weight of the mass (volume) taken between the fresh sample and the sample taken after 1-week storage and the decrease in optical density of the respective negative samples. Our results therefore suggest that there is a significant decrease in optical density after 1-week cold storage, but that this could not be associated with the concurrent decrease in weight of the mass (volume) taken by the calibrated syringe. However, this decrease in optical density did not influence the final diagnosis of BSE, using the ELISA (Platelia TM ) test. Additionally, this study also implicated the reliability of the calibrated syringe provided in the test kit.

Bacteriological and sensory properties of smoke-dried fish stored at ambient temperature

The bacterial load and sensory characteristics of four species of fish (viz., Alestes nurse, Labeo pseudocoubie, Synodontis omias and Tilapia zillii) subjected to smoke-drying and stored at ambient temperature for four weeks were evaluated. The moisture content of fresh fish was reduced drastically to the levels ranging from 9 to 17% due to the smoking process. Changes occurred in the moisture content of the product during storage but most significantly during the first week when the samples all attained contents below 10% except for S. omias which had a slightly higher value. Smoke-dying reduced the bacterial counts of all the samples in the order of approximately 2 log units, but counts increased appreciably during the storage period attaining almost a 2-fold increase during the first week of storage and remained high thereafter . Sensory scores for smoke-dried fish were generally good for colour, smell, dryness, and general appearance. All the sensory parameters remained acceptable during the entire storage period although the range of scores for smell and dryness were of a higher magnitude than for colour and general appearance. Based on these observations it is suggested that subjecting the fish to additional smoke drying once every week would significantly increase their keeping quality. Keywords; Temperature, fish, smoke-drying, keeping-quality. [Global Jnl Agric Sci Vol.1(1) 2002: 21-25]

Altered intracellular purine nucleotides in gamma-irradiated red blood cell concentrates.

Gamma irradiation at a dose of 30 Gy induces deterioration of erythrocytes, resulting in storage lesions that significantly shorten the shelf-life of packed red cell concentrates (RCCs). The aim of the present study was to investigate the effect of gamma irradiation on intracellular purine nucleotides of red blood cells during storage. Three-day-old leucocyte-depleted saline-adenine-glucose-mannitol (SAGM)-preserved RCCs, obtained from the Blood Service of the Austrian Red Cross, were gamma irradiated with 30 Gy. Samples were taken on days 1, 2, 3 and 7 after irradiation and subsequently at weekly intervals up to the end the of shelf-life (day 39 after irradiation) and were investigated for the K+ and Na+ content in the supernatant, for intracellular concentrations of ATP, ADP, ITP, IDP, GTP and GDP of erythrocytes, and for haemolysis. Within the first 24 h after gamma irradiation, no metabolic or biochemical changes were detectable in the RCCs. The K+ concentration in the supernatant increased after 24 h, while the Na+ concentration decreased in irradiated units and this ion disequilibrium persisted until the end of the shelf-life. After an initial increase of intracellular ATP, ADP and GTP during the first week of storage, the intracellular concentrations of ATP, ADP, GTP and ITP decreased, while IDP increased. The decrease of ATP and ADP was found to be more pronounced in irradiated units. At the end of the shelf-life, the ATP, GTP and ITP concentrations of irradiated RCCs had decreased to < 10% of the initial level and the critical threshold of 0.8% haemolysis was reached. Gamma irradiation of SAGM-preserved RCCs leads to serious deterioration of the purine nucleotide metabolism of erythrocytes during storage, which can reduce the in vivo recovery of the transfused red cells.

A DSC study on the effects of various maltodextrins and sucrose on protein changes in frozen-stored minced blue whiting muscle

A DSC heat denaturation study on the effects of various maltodextrins and sucrose on protein changes in minced blue whiting muscle during frozen storage at -10 and -20 degrees C was carried out. All maltodextrins slowed down the decreases in the denaturation enthalpies (deltaHd) ascribed to myosin and actin, making evident a noticeable effectiveness against protein denaturation, especially at -20 degrees C. Sucrose was as effective as maltodextrins at -20 degrees C, but was the least effective treatment at -10 degrees C. Significant correlations between both deltaHds and either protein solubility or formaldehyde production were found at each storage temperature. A low protein sensitivity to the small amounts of formaldehyde produced during the first weeks of storage and errors associated with the determination of enthalpies led to poorer correlations at -20 degrees C. Maximum denaturation temperatures (Tmax) correlated with protein solubility only at -20 degrees C. No clear relationship between either Tmax and the effectiveness of cryostabilisation was found, as Tmax also depends on the effectiveness of the treatments against the thermal denaturation of proteins.

Delaying establishment of controlled atmosphere or CO2 exposure reduces ‘Fuji’ apple CO2 injury without excessive fruit quality loss

Abstract Storage of ‘Fuji’ apple fruit in a high CO 2 (3 kPa) and low O 2 (1.5 kPa) controlled atmosphere (CA) reduced firmness and titratable acidity (TA) loss during long term storage. This CA environment also induced development of internal CO 2 -injury (brown-heart) and slowed the disappearance of watercore. The symptoms of internal CO 2 -injury were first detected 15 days after CA establishment and the severity increased during the first 4 months of CA-storage. Delaying establishment of CA conditions for 2–12 weeks significantly reduced the severity of CO 2 -injury. Delaying CO 2 accumulation to 3 kPa for 1–4 months during CA (1.5 kPa O 2 +0.05 kPa CO 2 ) storage also reduced development of CO 2 -injury symptoms. Delaying CA or CO 2 accumulation resulted in lower firmness and TA compared to establishment of CA within 72 h of harvest. However, the delay treatments did result in firmness and TA that were significantly higher compared to values for fruit stored in air. The incidence and severity of senescent injuries (flesh browning and core flush) detected during the late period of storage were greater in air- than CA-stored fruit. The results indicate the susceptibility of ‘Fuji’ apples to CO 2 -injury is highest during the first weeks of storage after harvest. Delaying establishment of CA or exposure to elevated CO 2 after harvest may be a practical strategy to reduce CO 2 -injury while maintaining other important quality attributes at acceptable levels.

Survival of Salmonella typhimurium and Escherichia coli O157:H7 in cheese brines

Survival of Salmonella typhimurium and Escherichia coli O157:H7 was studied in model brines and brine from three cheese plants. Three strain mixtures of S. typhimurium and E. coli O157:H7 (10 6 CFU/ml) were inoculated separately into 23% model brine with or without added pasteurized whey (2%) and as a combined inoculum into the commercial brines. The model brines were incubated at 8 and 15°C for 28 days, and the commercial brines at 4 and 13°C for 35 days. Populations of both pathogens in the model brine+whey decreased slowly over 28 days (1.0–2.0 log CFU/ml) with greater survival at 8°C than at 15°C. Corresponding decreases in model brine without whey were 1.9–3.0 log CFU/ml, with greater survival at 8°C than at 15°C. Both S. typhimurium and E. coli O157:H7 survived significantly better ( P<0.05) at 4°C than at 13°C in two of the commercial brines. The survival of each pathogen in the commercial brines at 13°C was significantly influenced by brine pH. Both pathogen populations decreased most rapidly in commercial brines during the first week of storage (2.5–4.0 and 2.3–2.8 log CFU/ml for S. typhimurium and E. coli O157:H7, respectively) with significant recovery (ca. 0.5 log CFU/ml increase) often occurring in the second week of storage. Counts changed little thereafter. Overall, E. coli O157:H7 survived better than S. typhimurium, with differences of 0.1–1.2 log CFU/ml between the two pathogens. Results of this study show that cheese brine could support the survival of contaminating S. typhimurium and E. coli O157:H7 for several weeks under typical brining conditions.

Development of bioactive food packaging materials using immobilised bacteriocins Lacticin 3147 and Nisaplin ®

Immobilisation of the bacteriocins nisin and lacticin 3147 to packaging materials was investigated. Stability of both cellulose-based bioactive inserts and anti-microbial polyethylene/polyamide pouches was examined over time. Anti-microbial activity against the indicator strain Lactococcus lactis subsp. lactis HP, in addition to Listeria innocua DPC 1770 and Staphylococcus aureus MMPR3 was observed for all bacteriocin-adsorbed materials. Activity retention of the inserts showed an initial decrease in the first week of storage but remained stable for the remaining 3 months of the trial. However, adsorption of lacticin 3147 to plastic film was unsuccessful, nisin bound well and the resulting film maintained its activity for 3-month period, both at room temperature and under refrigeration. When applied to food systems, the anti-microbial packaging reduced the population of lactic acid bacteria in sliced cheese and ham stored in modified atmosphere packaging (MAP) at refrigeration temperatures, thus extending the shelf life. Nisin-adsorbed bioactive inserts reduced levels of Listeria innocua by ≥2 log units in both products, and Staphylococcus aureus by ∼1.5 log units in cheese, and ∼2.8 log units in ham. Similar reductions were observed in cheese vacuum-packaged in nisin-adsorbed pouches.

Structural effects of sample ageing in hydrocracked coal liquefaction extracts

A sample of Point of Ayr coal extract has been hydrocracked in a microbomb reactor with NiMo on alumina catalyst in tetralin as solvent and hydrogen donor and under hydrogen pressure. The product was separated from solvent and catalyst and then split into equal parts and stored either under nitrogen atmosphere in a freezer or in air at room temperature. Samples of the products were examined at 2 h frequencies for a day, then daily for a week, then at less frequent intervals for a year. Methods used for examination were size exclusion chromatography (SEC) and UV-fluorescence spectroscopy (UV-F), both using 1-methyl-2-pyrrolidinone as solvent. Ageing was assessed in terms of shifts to shorter elution times in SEC and parallel changes in UV-F spectra. Both stored products showed significant structural evidence of ageing over the first week of storage. After that time, changes observed were within the range of variability of the chromatography method based on polystyrene standards. The ageing was attributed to the presence of low-reactivity free radical species, which underwent recombination reactions during storage. These changes are likely to affect the viscosity and combustion characteristics of the hydrocracked product.

Changes in potential denitrification and respiration during the cold storage of soils.

The denitrification potential in moderately fertilized soil sampled four times during 1995 decreased significantly after cold storage, at 4 +/- 2 degrees C for 1 week. Prolonged storage (up to 24 weeks) resulted in a further decrease of denitrification potential which dropped to 38-54% of the original values. Similarly, denitrification potential decreased substantially during the first week of storage in differently fertilized soils. After 24 weeks of storage, denitrification potential dropped to 29-55% of that in fresh soils. The effects of storage at 4 +/- 2 degrees C on denitrification potential and respiration (determined as carbon dioxide evolution) were in general the same in moderately fertilized soils from four different sites: in all soils, depression of both the denitrification potential and potential respiration was found after 8 weeks. However, the extent to which the parameters were decreased differed from case to case. Not only the duration and storage conditions but also unidentified soil parameters are important for the persistence of biological activity in stored soils.

Controlled-release liquid suspensions based on ion-exchange particles entrapped within acrylic microcapsules

Eudragit® RS/RL polymers were used to prepare microcapsules containing terbutaline-loaded ion-exchange resins, with the final aim of formulating this anti-asthmatic drug in a controlled-release liquid form. Oil-in-oil (o/o) and oil-in-water (o/w) solvent evaporation procedures were conveniently modified in order to encapsulate the resin cores. The microcapsules were then suspended in a hydroxypropylmethylcellulose solution of adequate viscosity and palatability, and stored at 20°C and ambient humidity conditions for a 6-month period. Stability studies of the dispersed microparticles were performed in order to evaluate the changes occurred in the diffusion of the drug to the suspending medium and in the dissolution behaviour during storage. The morphological alterations of the stored microcapsules were followed throughout the duration of the study by scanning electron microscopy. The polymer coatings of microcapsules prepared by the o/o method broke up on the first day of storage, while those made by the aqueous procedure remained intact during all the storage period. This agreed with the modification observed in the controlled-release profiles of terbutaline in the case of microcapsules prepared by the o/o method, which completely changed after the first week of storage. On the contrary, the microcapsules prepared by the aqueous method showed identical controlled-release profiles for all the stability study. The different behaviour of both types of microcapsules was attributed to the swelling suffered by the resin particles in contact with the aqueous suspending medium, which was higher in the microcapsules prepared by the o/o technique. In fact, in the anhydrous procedure, the microencapsulation was carried out on the shrunken resin particles, whereas in the o/w method, the presence of water during the microencapsulation process allowed the coating of the swollen particles, thus avoiding the further problem of rupture of the polymer coating.

Phenylalanine Ammonia-lyase, Peroxidase, Pyruvic Acid and Total Phenolics Variations in Onion Bulbs During Long-term Storage

Phenylalanine ammonia-lyase (PAL) and peroxidase (POD) enzyme activities, total phenolics and pyruvic acid (PA) (as pungency indicator) were measured in onion bulb tissues (c.v. Rouge Amposta) during storage at 4 and 20 °C. After 2 wk, PAL activity increased at 4 °C, but decreased at 20 °C, and after 4 wk, PAL activity at 20 °C was higher than activity observed at 4 °C. Peroxidase activity was high during the first weeks of storage, but at 4 °C this high activity lasted longer and a decrease was noted at both temperatures, coinciding with sprouting appearance. Total phenolics, which rose during the first 12 wk but fell during last weeks of storage, appeared to be linked to PAL activity. An inverse relationship was observed between phenolic content and the amount of sprouting development of bulbs. Pyruvic acid production appeared to be influenced by temperature, but in the last period of storage, the effect of temperature on PA production was less. The data demonstrate that PAL activity, which is linked to phenolic metabolism, and POD are highly involved in the sprouting of onion bulbs and these two enzymatic activities are much influenced by low temperature.

Effects of cold storage on anion, ammonium, and total nitrogen concentrations in soil water

Researchers frequently must store water samples >24 h after collection until chemical analyses can be accomplished. Samples are commonly stored in darkness at near‐freezing temperatures until analysis, but effects of this storage method on soil water chemistry are not well‐documented. Soil water samples were collected from eastern hemlock [Tsuga canadensis (L.) Carriere] stands and analyzed initially and over time to determine if nitrate (NC3 ‐), chloride (Cl‐), sulfate (SO4 2‐), ammonium (NH4 +), and/or total nitrogen (TN) concentrations changed when samples were stored in darkness at 2–4°C. Subsamples were analyzed <24 h after collection and reanalyzed five times in a 12 to 24 wk period following sample collection. Nitrate concentrations remained stable for at least one wk and were only slightly lower than initial concentrations after 3–16 wk of storage. Chloride and SO4 2‐ remained stable for 16 wk, while TN remained stable for 8 wk and decreased slightly after 24 wk. Most NH4 + concentrations were below the limit of quantification, but concentrations of samples with quantifiable NH4 + decreased in the first week of storage. Overall, cold storage in darkness was effective for preserving NO3 ‐, Cl‐, SO4 2‐, and TN concentrations in soil water, but NH4 + analyses should probably be performed as soon as possible after sample collection.

99/00208 Changes in sample reactivity and catalyst deactivation during early stages of the hydrocracking of a coal extract

A sample of Point of Ayr coal extract has been hydrocracked in a microbomb reactor with NiMo on alumina catalyst in tetralin as solvent and hydrogen donor and under hydrogen pressure. The product was separated from solvent and catalyst and then split into equal parts and stored either under nitrogen atmosphere in a freezer or in air at room temperature. Samples of the products were examined at 2 h frequencies for a day, then daily for a week, then at less frequent intervals for a year. Methods used for examination were size exclusion chromatography (SEC) and UV-fluorescence spectroscopy (UV-F), both using 1-methyl-2-pyrrolidinone as solvent. Ageing was assessed in terms of shifts to shorter elution times in SEC and parallel changes in UV-F spectra. Both stored products showed significant structural evidence of ageing over the first week of storage. After that time, changes observed were within the range of variability of the chromatography method based on polystyrene standards. The ageing was attributed to the presence of low-reactivity free radical species, which underwent recombination reactions during storage. These changes are likely to affect the viscosity and combustion characteristics of the hydrocracked product.

Storage of partially deacetylated chitosan films.

Chitosan has wide-ranging applications as a biomaterial, but its stability in storage is not widely known. The objective of this study was to evaluate the storage stability of films prepared from chitosan of 77% deacetylation. Both the neutralized and acetate films were evaluated, as chitosan salts offer the advantage of being soluble in water at the neutral-to-basic pH range. Aqueous solutions containing 0.5-5% acetic acid were used as solvents. The X-ray diffraction pattern, the IR spectrum, water uptake, and solubility of the films were influenced by the presence of the N-acetyl functionality, the acetate ions, and storage of the films. The anhydrous chitosan crystal in the neutralized films was unstable to storage at 4 degrees C and 28 degrees C. Its formation, as well as that of the hydrated crystal, were further hindered by the presence of even small quantities of the acetate ions. The resultant amorphous nature of the acetate films, coupled with the acidifying action of the acetic acid, led to greater water uptake and solubility compared to the neutralized films. Storage reduced the differences between the neutralized and acetate films. It also minimized the influence of the initial acetic acid content on the IR absorption and water uptake of the acetate films, exerting its leveling effects mainly within the first week of storage. Using a lower storage temperature of 4 degrees C or heating the films for 2 h at 120 degrees C prior to storage did not significantly modify the results. A pertinent factor appears to be the degree of deacetylation of the chitosan that was used to prepare the films.

Influence of 30 Gy Gamma Irradiation on the Quality of Red Blood Cell Concentrates in Several Storage Media

Background: The transfusion-associated graft versus host disease (t-GvHD) occurring in immunosuppressed patients can be prevented by irradiation of red blood cell concentrates (RCCs) with gamma irradiation at a dose of 30 Gy prior to transfusion. The aim of this study was to investigate, whether the irradiation of leukocyte-depleted RCCs in different storage media (SAG-M, PAGGS-M, or Adsol) may cause deterioration of red blood cells (RBC), resulting in a shortened shelf life of the RCC. Material and Methods:According to manufacturing (manually, apheresis), storage medium used (SAG-M, PAGGS-M, Adsol) and processing of leukocyte depletion (filtered, nonfiltered), 192 RCCs were separated into 8 groups with 24 RCCs each. Each group was divided into two subgroups. One was irradiated (30 Gy), the other one was used as control. Until the end of shelf life, pH, the concentrations of Na⁺ , K⁺ , lactate, glucose, 2,3-diphosphoglycerate (2,3-DPG) and adenosine triphosphate (ATP), parameters of blood cell count, and external hemoglobin were measured every week. Results:The metabolic parameters did not show significant differences between nonirradiated and irradiated RCCs. K⁺ efflux and hemolysis were significantly higher in the irradiated RCCs after the first week of storage. The values of hemolysis remained below the recommended limit of 0.8% of the hemoglobin content of RCCs until the 28th day of storage. After 28 days of storage the mean values of K⁺ increased by 25% compared to the control samples at the end of shelf life. The mean corpuscular volume (MCV) was significantly higher in the irradiated RCCs with significant differences between the various storage media. Leukocyte-depleted RCCs showed partly smaller rates of hemolysis than unfiltered RCCs. Conclusions:The determined in vitro parameters of irradiated and leukocyte-depleted RCCs stored in SAG-M, PAGGS-M or Adsol revealed no significant quantitative changes until 28th day of storage compared to those of nonirradiated RCCs.

Storage of partially deacetylated chitosan films

Chitosan has wide-ranging applications as a biomaterial, but its stability in storage is not widely known. The objective of this study was to evaluate the storage stability of films prepared from chitosan of 77% deacetylation. Both the neutralized and acetate films were evaluated, as chitosan salts offer the advantage of being soluble in water at the neutral-to-basic pH range. Aqueous solutions containing 0.5–5% acetic acid were used as solvents. The X-ray diffraction pattern, the IR spectrum, water uptake, and solubility of the films were influenced by the presence of the N-acetyl functionality, the acetate ions, and storage of the films. The anhydrous chitosan crystal in the neutralized films was unstable to storage at 4°C and 28°C. Its formation, as well as that of the hydrated crystal, were further hindered by the presence of even small quantities of the acetate ions. The resultant amorphous nature of the acetate films, coupled with the acidifying action of the acetic acid, led to greater water uptake and solubility compared to the neutralized films. Storage reduced the differences between the neutralized and acetate films. It also minimized the influence of the initial acetic acid content on the IR absorption and water uptake of the acetate films, exerting its leveling effects mainly within the first week of storage. Using a lower storage temperature of 4°C or heating the films for 2 h at 120°C prior to storage did not significantly modify the results. A pertinent factor appears to be the degree of deacetylation of the chitosan that was used to prepare the films. © 1999 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 48: 881–888, 1999