Longer Storage Periods Research Articles

Effects of storage conditions and storage period on nutritional and other qualities of stored yam (<i>Dioscorea</i> spp) tubers

Yam is one of the preferred staple foods in West Africa. The annual vegetative cycle of yam necessitates a long period of storage to make it available all year round. The major problems in yam tuber storage are sprouting, respiration and transpiration, which cause weight and quality losses. In this work, the effects of storage conditions and storage period on the nutritional and other qualities of stored yam tubers were investigated. Storage conditions used were two traditional yam barns, one with fan to aid air circulation and the other without. A total of 216 tubers of yam (Dioscorea roundata) “Giwa” variety with 108 tubers in each barn, were stored in the barns. Parameters evaluated were temperature and relative humidity of the storage environment, signs of deterioration of the tuber such as sprouting, weight loss and rotting and some nutritional parameters (carbohydrate, calcium, phosphorus, crude fibre, crude fat, crude protein, ash and moisture contents). Temperature and relative humidity were measured three times a week and four times a day at 0800h, 1200h, 1600h and 2000h. The results showed that average temperature and relative humidity in the barn with fan were slightly lower than that of the barn without fan. These differences were statistically significant for April, May and June at P< 0.1. Tubers stored in the barn with fan had the least sprout weight and least weight loss. At the end of a 3-month period, the tubers in the ventilated barn showed 4.7% less weight loss compared to the barn without fan. The difference in sprout weights and weight loss between the structures was statistically significant at P&#8804; 0.05. Also, tubers stored in the barn with fan had the least percentage of rotten tubers (1.85% of stored tubers) compared to the tubers stored in the barn without fan (12.03%). A reduction of some of the nutritional content was also observed during the six months of storage period. From these results it can be concluded that intermittent air flow on stored yam tubers reduces sprouting, weight loss and rot development, thus reducing the overall loss in stored yam tuber. However, moisture, crude protein, carbohydrates, phosphorus and calcium contents of the tuber reduced significantly in the two barns studied. Keywords: Yam, storage conditions, nutritional, content African Journal of Food, Agriculture, Nutrition and Development Vol. 9 (2) 2009: pp. 678-690

Effects of storage type and time on DNA amplification success in tropical ungulate faeces

The present study compares the effect of three storage media (silica, RNAlater®, ethanol) and time to extraction (1week, 1month and 3 months) on mitochondrial and nuclear marker amplification success in faecal DNA extracts from a sympatric community of small to medium-sized Central African forest ungulates (genera Cephalophus, Tragelaphus, Hyemoschus). The effect of storage type and time on nuclear DNA concentrations, genotyping errors and percentage recovery of consensus genotypes was also examined. Regardless of storage method, mitochondrial and nuclear amplification success was high in DNA extracted within the first week after collection. Over longer storage periods, RNAlater yielded better amplification success rates in the mitochondrial assay. However, samples stored on silica showed (i) highest nuclear DNA concentrations, (ii) best microsatellite genotyping success, (iii) lowest genotyping errors, and (iv) greatest percentage recovery of the consensus genotype. The quantity of nuclear DNA was generally a good predictor of microsatellite performance with 83% amplification success or greater achieved with sample DNA concentrations of ≥50pg/µL. If faecal DNA samples are to be used for nuclear microsatellite analyses, we recommend silica as the best storage method. However, for maximum mitochondrial amplification success, RNAlater appears to be the best storage medium. In contrast, ethanol appeared inferior to the other two methods examined here and should not be used to store tropical ungulate faeces. Regardless of storage method, samples should be extracted as soon as possible after collection to ensure optimal recovery of DNA.

Nutrient Composition and Mycotoxin Residues in the Hay Stored as Stack Forms During the Storage Period, and Aflatoxin M1 in the Milk of the Cows Fed by Them

Summary The objectives of the study were to determine nutrient composition and mycotoxin contamination of the pasture samples at harvesting time and their hay forms which were dried in ground and stored as stacks form during the storage period, and to reveal the aflatoxin M1 (AFM1) residues in the milk samples of the cows fed by these hay samples. Ten pasture grass and their hay samples stored as stack form were obtained from 10 different pasture areas and family farms in Kars district, respectively. Upon taking the hay samples from both the inner and outer parts of the stacks, they were analyzed for dry matter (DM), crude ash (CA), organic matter (OM), crude protein (CP), crude fiber (CF), neutral detergent fiber (NDF), acid detergent fiber (ADF), ether extract (EE), nitrogen free extract (NFE) and total aflatoxin, aflatoxin B1 (AFB1), and zearalanone residues in harvesting time, and then 6 times with 45 days of interval during the storage period. The concentrations of DM, CA, OM, CP, CF, NDF, ADF, EE and NFE of pasture at harvesting time were found to be 307.9, 93.3, 906.7, 118.0, 313.2, 509.7, 351.3, 29.1 and 446.4 g/kg DM basis, respectively. Total aflatoxin, AFB1 and zearalenone residues were determined in all the fresh grass samples examined at average 24.10, 15.21 and 14.97 ppb, but they were within the acceptable limits. During the storage period of the hay; DM content fluctuated, CA, OM and NDF contents unchanged, CF content increased, CP decreased in the inner part, and ADF contents increased in the inner part at the beginning of the storage, as compared with at the end of the storage period. During the storage period, mycotoxin residues were also within the acceptable limit except for the total aflatoxin and AFB1 levels in the 4 th period samples. Except for the one milk sample, AFM1 residues were within the acceptable limit. It is concluded that, depending on the longer storage period, generally nutrient composition of the hay unchanged substantially, mycotoxin residues also unchanged and generally not exceed the acceptable limits.

Changes in biogenic amines during iced and ambient temperature storage of tilapia

AbstractBACKGROUND: Changes in the biogenic amine content of tilapia (Oreochromis mossambicus) with time during iced and ambient temperature (28 °C) storage were quantified by high‐performance liquid chromatography in a gradient elution system using acetonitrile and water as solvents.RESULTS: The levels of amines in tilapia were significantly low even after a long storage period (18 h under ambient temperature storage and 15 days under iced storage). All amines except spermidine and spermine increased with time during both iced and ambient temperature storage. Spermidine and spermine showed a decrease with increasing storage time.CONCLUSION: Being euryhaline (tolerant of a wide range of salinity) in nature, tilapia shows significantly low quantities of biogenic amines even after a long period of ambient temperature or iced storage, unlike most other marine fish. Copyright © 2008 Society of Chemical Industry

Development of functional tofu fortified with garlic and calcium carbonate

The objective of this study was to investigate the effects of calcium lactate as a coagulant and garlic on the quality including color, textural properties and shelf‐life of tofu. Statistical analysis of data was carried out using the SPSS 12.0 program. The yield of garlic tofu was of the order: 0.75% addition of garlic juice〉 1.00% addition of garlic juice〉 0.00% addition of garlic juice〉 0.50% addition of garlic juice〉 0.25% addition of garlic juice. The lightness (L value) was significantly decreased with increasing the concentration of garlic juice addition with increasing the concentration of garlic juice addition (p&lt;0.05). The hardness and cohesiveness were significantly decreased with increasing the concentration of garlic juice addition (p&lt;0.05). However, the hardness of tofu with calcium lactate was significantly lower compared to the other samples using different coagulants (p&lt;0.05). All tofu had initial bacterial concentrations of 9.6×103 CFU/g at 0 day of storage. Tofu prepared with 0.75% and 1.0% addition of garlic juice did not show any changes of viable counts by the second day and the fourth day of storage, respectively. However, viable microbial counts of tofu prepared with 0.0%, 0.25%, 0.50% addition of garlic juice increased more rapidly than those of tofu prepared with 0.75% and 1.0% addition of garlic juice during longer storage periods. These results can further help in process optimization that becomes essential in retaining maximum nutritive value in the tofu especially when the choices of coagulants are plenty.

Stability of Cefuroxime Axetil Oral Suspension at Different Temperature Storage Conditions

Stability testing of an active substance or finished product provides information of the variation of drug substance or final product with time influenced by a variety of environmental factors such as temperature, humidity and light. Knowledge gained from stability studies enables understanding of the effects of the environment on the drugs. The aim of our study was to determine the stability of cefuroxime axetil oral suspension at different temperature storage conditions (stored at room /20 degrees C/ and refrigerated /5 degrees C/ conditions). Determination of cefuroxime (as cefuroxime axetil) was performed by dissolution testing. Fractions of the released cefuroxime axetil were compared using f2 value. After interpolating data for dissolution profiles at room and refrigerated conditions the following f2values were obtained: 62,56; 56,32 and 36,18 on 3rd, 6th and 10th day, respectively. These values indicate similarities in drug release from analyzed cefuroxime axetil oral suspension on 3rd, 6th day, and differences on 10th day. Based on our results, we may assume that cefuroxime axetil oral suspension preserves its stability for 10 days after reconstitution under room and refrigerated conditions. It is obvious, according to the f2 value obtained on the 10th day, that there is a difference between the released cefuroxime axetil from oral suspension at room (87,68%) and refrigerated (92,35%) conditions. Concentration changes can be caused by the mechanisms associated with drug release and hydrolytical decomposition of the sample and higher temperatures during longer period of storage.

Dietary Fibre Content and its Fractional Composition in Cabbage as Affected by Cultivar Earliness and Sauerkraut Storage Period

Dietary Fibre Content and its Fractional Composition in Cabbage as Affected by Cultivar Earliness and Sauerkraut Storage Period The aim of the study was to determine the dietary fibre content and its fractional composition in white head cabbage cultivars of different maturity earliness and also in fermented cabbage (sauerkraut) after several months of storage, as well as the level of fibre and its composition in sauerkraut in relation to the method of fermentation. It was found that there were significant differences in fibre content and its fractions composition among the white cabbage cultivars studied. The early cultivar Tekila F1, had a lower total fibre content and smaller cellulose and pectin fractions than the later-maturing cultivars, Tolerator F1 and Agresor F1. The fermented cabbage, as compared with the raw material, contained a significantly larger cellulose fraction, a significantly reduced pectin fraction, slightly reduced amounts of hemicelluloses, and a similar amount of lignin. There was no obvious effect of inoculating cabbage with starter cultures containing strains of Lactobacillus plantarum on the level of fibre and its fractions in the resulting sauerkraut in comparison with the traditionally fermented cabbage. Water-absorbing capacity of cabbage fibre depended on the cultivar, the length of sauerkraut storage period and fermentation method. The fibre of the early cabbage variety had a significantly lower water-binding capacity than the fibre of the later-maturing cultivars. Rehydration capacity of dried sauerkraut increased for up to 30 days from the end of fermentation, with longer storage period having no longer any effect on the levels of water absorption. Water-holding capacity of the fibre in the sauerkraut produced with the addition of a starter culture was lower than that of the fibre of the traditionally fermented cabbage over the entire storage period of the fermented sauerkraut samples.

Effects of cold storage, rearing temperature, parasitoid age and irradiation on the performance of Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae)

In this study, the effects of cold storage, rearing temperature, parasitoid age, and irradiation on the performance of the egg parasitoid Trichogramma evanescens were investigated. Pupae of T. evanescens can be stored at 4 °C for up to 3 weeks without much loss of performance. The longevity and walking speed of adults emerging from chilled pupae significantly decreased after longer storage periods. The F 1 generation of adults which emerged from pupae stored up to 3 weeks was able to parasitize as well as the control. The parasitization rate was similar at 24, 27, and 30 °C, but significantly decreased at 33 and 36 °C. Although T. evanescens developed to the pupal stage at 36 °C, no adult emergence was observed at this temperature. Developmental periods were longer at 24 °C than at higher temperatures. The optimum age for T. evanescens to successfully parasitize host eggs ranged from 24 to 90 h. The parasitization frequency of the 56–78 h aged females was higher than for the other age groups. The daily egg laying pattern of female T. evanescens adults was similar when they were reared on Ephestia kuehniella or Plodia interpunctella eggs. Gamma- or ultraviolet-irradiated and unirradiated host eggs were equally preferred by adult females.

Effect of harvest maturity stage on the sensory quality of ‘Palsteyn’ apricot (Prunus armeniaca L.) after cold storage

SummaryFresh apricots (Prunus armeniaca L.) are in high demand, but are available for only a short period during the Spring and the beginning of the Summer. There is no information on the correct harvest maturity stage that should be chosen to ensure a long post-harvest life and high sensory quality. The objective of this study was to evaluate the effect of maturity stage at harvest on the sensory quality of ‘Palsteyn’ apricots after 14, 28, or 42 d in cold storage. Sourness, flavour, and acceptability showed major changes during cold storage. Ripe fruit (orange-yellow skin colour) showed the highest acceptability, as assessed by a “mini-consumer test” (i.e., an untrained panel; n = 36). Fruit harvested at an intermediate stage of maturity (light yellow skin colour) reached an average acceptability, while unripe fruit (greenish skin colour) were not acceptable. After 28 d of cold storage, fruits were still acceptable; but, after 42 d, fruits reached the “dislike” zone. On a principal component analysis, acceptability was shown to be positively associated with sweetness, flavour, juiciness, and aroma, and negatively associated with sourness. After 28 d and 42 d of cold storage, unripe fruit appeared to have low acceptability and quality attributes. ‘Palsteyn’ apricot harvested with an orange-yellow skin colour, as the least ripe fruits, showed that they could reach high sensory quality standards and were able to withstand long periods of cold storage.

Droplet size and stability of nano-emulsions produced by the temperature phase inversion method

We studied the formation and stability of n-decane in water nano-emulsions produced by the phase inversion temperature (PIT) emulsification method using polyoxyethylene lauryl ether as surfactant. The results obtained indicate that the droplet size and size distribution are strongly dependent on the methods of heating and cooling, and on the final temperature to which the mixture is cooled after phase inversion. Importantly, there exists an optimum storage temperature, at which the nano-emulsions are most stable, and develop ultra-small droplet sizes, ranging from 35 nm to 54 nm, with low polydispersity indices (∼0.2). This optimum temperature is about 20 °C below the PIT, and dependent on the surfactant concentration. Any departure in temperature from the optimum would result in increases in droplet sizes, polydispersity and instability by Ostwald ripening. Furthermore, nano-emulsions destabilized after a long period of storage at different temperatures can be rejuvenated simply by equilibration for a few minutes at the optimum temperature.

Molecular Proximity of Cystic Fibrosis Transmembrane Conductance Regulator and Epithelial Sodium Channel Assessed by Fluorescence Resonance Energy Transfer

We present the evidence for a direct physical association of cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial sodium channel (ENaC), two major ion channels implicated in the pathophysiology of cystic fibrosis, a devastating inherited disease. We employed fluorescence resonance energy transfer, a distance-dependent imaging technique with capability to detect molecular complexes with near angstrom resolution, to estimate the proximity of CFTR and ENaC, an essential variable for possible physical interaction to occur. Fluorescence resonance energy transfer studies were complemented with a classic biochemical approach: coimmunoprecipitation. Our results place CFTR and ENaC within reach of each other, suggestive of a direct interaction between these two proteins.

Introduction. The boreal forest and global change

The boreal forest is the second largest biome in the world containing 33% of the Earth's forest cover ([FAO 2001][1]) of which approximately 25% is natural. It is circumpolar and shares similar taxa across its range. It has approximately 20 300 identified species. Along with the tropics, the

Analysis of the Drying Kinetics of Brachiaria brizantha (Hochst. Stapf) Grass Seeds at Different Drying Modes

Forage grass seeds have a high economical importance in the Brazilian bovine cattle breeding and seed drying is a fundamental stage of processing to guarantee their stability and allow their storage for long periods. In this context, the objective of this work was to develop a pilot-scale belt dryer, which operates also as a fixed and fluidized bed. Brachiaria brizantha seeds dehydration was analyzed under different air velocities and temperatures. Experimental data of moisture content variation along the drying time was successfully fit to a one-term exponential model. The experimental drying rate points were calculated by approximating the derivatives to finite differences. Its behavior was accomplished fitting curves of the drying rate versus water content and time. Finally, fissure, germination, and vigor rates were analyzed as a function of the drying conditions so that the experimental conditions combine the best process efficiency with the best physiological quality maintenance.

Use of lambda DNA as a marker to assess DNA stability in olive oil during storage

Filtered olive oil samples spiked with three different concentrations of λDNA were stored at 25 °C under a 12 h photoperiod for up to a year. These samples were used for DNA extraction and PCR amplification of λDNA amplicons of 107, 415 and 691 bp length. The amplification signal was gradually decreased with longer storage periods, while the strength of the signal was related to the initial concentration of spiking λDNA particularly during longer storage periods. The 107 bp amplicon was the only one successfully amplified from all the samples, regardless of both concentration of spiking λDNA and storage period. The amplification of 415 and 691 bp amplicons was not successful for samples stored longer than a threshold period of 20 and 10 days, respectively. These results suggest that detection of polymorphic markers requiring DNA templates shorter than 100 bp might have a wider range of applications in DNA fingerprinting of olive oil. In addition, the DNA extracts were tested for the presence of inhibitors in PCR amplification reactions of yeast DNA amplicons. The inhibitory effect of olive DNA extracts was partial and gradually increased with the storage period of the olive oil samples used for the DNA extraction.

Light-induced fading of the PSL signal from irradiated herbs and spices

Reliability of the photo-stimulated luminescence (PSL) technique, as screening method for irradiated food identification, has been tested with three kinds of herbs and spices (oregano, red pepper and fennel), prepared in two different ways (granular: i.e. seeds and flakes, or powdered), over a long period of storage with different light exposures. The irradiated samples kept in the dark gave always a positive response (the sample is correctly classified as “irradiated”) for the overall examination period. The samples kept under ambient light conditions, in typical commercial glass containers, exhibited a reduction of the PSL signal, more or less pronounced depending on the type of food and packaging. The different PSL response of the irradiated samples is to be related to the quantity and quality of the mineral debris present in the individual food. It was also found that, for the same type of food, the light-induced fading was much stronger for the flaked and seed samples than for the corresponding powder samples, the penetrating capability of light being much more inhibited in powdered than in whole seeds or flaked form samples. The observed light bleaching of the PSL signal in irradiated herbs and spices is of practical relevance since it may lead to false negative classifications.

Decreased amount of reducing sugars in transgenic potato tubers and its influence on yield characteristics

This work focuses on the comparison of field characteristics and amounts of reducing sugars in cold-stored tubers of transgenic plants derived from two potato cultivars. The bacterial gene coding for phosphofructokinase under the tuber-specific promoter was used to support the glycolysis in stored tubers. While the tubers from untransformed control plants steadily accumulated reducing sugars during cold storage, the tubers from transformed plants regardless the genotype were characterized by subsequent decrease in the sugar content. After long period of cold storage the greatest reduction in the reducing sugar content was by more than 60 % compared to control. Before the storage, however, the content of reducing sugars was in 80 % of transgenic lines higher than in control ones. The plants evaluated in field trials for their appearance showed any changes in growth characteristics in about 25 % of the transgenic lines. Despite the introduced modification of sugar metabolism the yield of transgenic plants with normal appearance did not differ significantly from the yield of control plants.

Irradiated herbs and spices detection: light‐induced fading of the photo‐stimulated luminescence response

SummaryReliability of the photo‐stimulated luminescence (PSL) technique, both as screening and identification methods, has been tested with several kinds of irradiated herbs and spices over a long period of storage. To check the influence of storage modality on the PSL response, the samples were divided into groups kept in environments with different light exposure. The results clearly indicate a marked light‐induced bleaching of the PSL signal, which may lead to a false negative classification, in a significant percentage, for spices stored in typical market conditions. To limit the occurrence of wrong classifications, the suggestion reported in the European Committee of Normalization Standard 13751 to draw the necessary amount of product from a light‐protected position becomes mandatory. Thermoluminescence measurements, performed for comparison purposes, gave correct results for all the samples tested.

Determination of carcinoembryonic antigen using a novel amperometric enzyme-electrode based on layer-by-layer assembly of gold nanoparticles and thionine

Electrochemical sensing of carcinoembryonic antigen (CEA) on a gold electrode modified by the se-quential incorporation of the mediator, thionine (Thi), and gold nanoparticles (nano-Au), through co-valent linkage and electrostatic interactions onto a self-assembled monolayer configuration is de-scribed in this paper. The enzyme, horseradish peroxidase (HRP), was employed to block the possible remaining active sites of the nano-Au monolayer, avoid the non-specific adsorption, instead of bovine serum albumin (BSA), and amplify the response of the antigen-antibody reaction. Electrochemical ex-periments indicated highly efficient electron transfer by the imbedded Thi mediator and adsorbed nano-Au. The HRP kept its activity after immobilization, and the studied electrode showed sensitive response to CEA and high stability during a long period of storage. The working range for the system was 2.5 to 80.0 ng/mL with a detection limit of 0.90 ng/mL. The model membrane system in this work is a potential biosensor for mimicking the other immunosensor and enzyme sensor.

Property changes and cholesterol‐lowering effects in evening primrose oil‐enriched and cholesterol‐reduced yogurt

The present study was carried out to investigate the changes in chemical and sensory properties and the cholesterol‐lowering effect of evening primrose oil (EPO) addition to cholesterol‐reduced yogurt. The rate of cholesterol removal reached 93.5% by β‐cyclodextrin in yogurt before EPO addition. pH, viscosity and microbial counts decreased with amounts of EPO added. The thiobarbituric acid value of cholesterol‐reduced and EPO‐enriched yogurt increased proportionally to length of storage period and amount of EPO addition, and it was significantly different between the EPO‐enriched groups than in unenriched groups in all storage periods. The production of short‐chain free fatty acids (FFA) increased with longer periods of storage. From 6 days’ storage, the amounts of short‐chain FFA in 6 and 10% EPO‐enriched groups were significantly different from other groups. Most sensory scores of 2% EPO‐enriched group were not significantly different from those of the control, whereas 6 and 10% EPO addition showed an adverse effect on sensory analysis. In blood analysis, the total cholesterol increase after 8 weeks’ feeding was dramatically lowered to 39.2% in the 10% EPO‐enriched group from 57.7% in the control. In addition, the concentration of blood triglyceride increased in the control, whereas it decreased in the 10% EPO‐enriched group. The above results indicated that EPO addition resulted in a profound lowering effect in blood lipids, although it adversely affected some sensory properties.

Optimized Automatic Recovery of Nozzle Health in Inkjet Systems

During the new print head installation process, an inkjet printer carries out several servicing actions to set the print head in the optimum printing conditions. In inkjet systems using pigmented inks there are known issues such as pigment settling after long periods of storage that can clog nozzles and cause bad drop ejection. This paper summarizes a system that initializes print heads after long periods of storage and inactivity. The system measures the level of nozzle health degradation and adjusts the servicing routines correspondingly, thus minimizing the ink waste and time required to guarantee an optimum nozzle health status for printing.