Function Of Storage Time Research Articles

Stable (18) O-labeling method for stercobilin and other bilins for metabolomics.

Bilin tetrapyrroles including stercobilin are unique to mammalian waste; they have been used as markers of source water contamination and may have important diagnostic value in human health conditions. Unfortunately, commercial isotopomers for bilins are not available. Thus, there is a need for isotopomer standards of stercobilin and other bilins for quantification in environmental and clinical diagnostic applications. A procedure is described here using H2 (18) O to label the carboxylic acid groups of bilin tetrapyrroles. Reaction conditions as a function of temperature and reagent volume were found to produce a mixture of isotopomers, as assessed by electrospray ionization and Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). Stability as a function of storage time and temperature and in conjunction with solid-phase extraction (SPE) was assessed. The highest labeling efficiency was achieved at 70 °C for 8 h, while a stable ratio of the isotopmers could be produced at 60 °C for 4 h. The stability of the isotopic distribution was maintained under storage (room temperature or frozen) for 20 days. It was also stable throughout SPE. The high mass accuracy and resolving power of FTICRMS enables clear distinction between (18) O-labeled bilins from other unlabeled bilins present, avoiding a potential interference in quantitation. A procedure was developed to label bilins with (18) O. The final ratio of the (18) O-labeled bilin isotopomers was reproducible and highly stable for at least 20 days under storage. This ratio was not changed in any statistically significant way even after SPE. Thus a reliable method for producing stable isotopomer ratios for bilins has been achieved. Copyright © 2016 John Wiley & Sons, Ltd.

Staling of white wheat bread crumb and effect of maltogenic α-amylases. Part 1: Spatial distribution and kinetic modeling of hardness and resilience

Bread staling is one of the most costly food deterioration processes. This study presents an in-depth, multivariate, statistical assessment of the differences in the staling process of white wheat bread as a function of storage time, usage of maltogenic α-amylases and spatial position in the loaf by texture measurements and non-linear fitting (Avrami).This study demonstrates the effects of anti-staling enzymes upon bread staling, where significant changes in the spatial staling kinetics occur. While the spatial development of staling is reduced in the outer crumb by anti-staling enzymes, the staling is retarded in the middle. The Avrami model suggests that this happens by two different competing mechanisms: one which increases the initial staling rate, and one which slows the convergence towards the limiting hardness. The two enzyme treated breads differed widely in early and ultimate resilience, despite the fact that they were adjusted to provide the same ultimate hardness.

On the control of interferences in the potentiometric fluoride analysis of table salt samples

The causes for the apparent diminishment of the fluoride content as a function of storage time in table salt samples were studied. Originally, the survey was focused on the evaluation of the ion-selective potentiometric method based in the official Mexican Norm NOM-040-SSA-1993. The analysis of fluoride in 20 table salt samples using this procedure showed lower values of analyte content than those expected according to the manufacturers’ specifications and revealed that the amount of fluoride measured varied significantly in many cases. These results prompted analysis and further optimization of the EUSalt Standard Method to free all the fluoride present in the salts. For the optimization, several pretreatment approaches were analyzed, and the most frequently strong complex-forming metal ions present in the salt samples (calcium, magnesium, iron, silicon and aluminum) were determined via inductively coupled plasma optical emission spectrometry (ICP-OES) to simulate the matrix compositions. The results confirmed that the capability of the potentiometric technique is highly influenced by the matrix components (mainly introduced in the form of additives) and indicated that, depending on the nature and concentration of certain additives present and storage time, a thermal ion-release pretreatment may be necessary to obtain reliable results.

Pig Brain Mitochondria as a Biological Model for Study of Mitochondrial Respiration

Oxidative phosphorylation is a key process of intracellular energy transfer by which mitochondria produce ATP. Isolated mitochondria serve as a biological model for understanding the mitochondrial respiration control, effects of various biologically active substances, and pathophysiology of mitochondrial diseases. The aim of our study was to evaluate pig brain mitochondria as a proper biological model for investigation of activity of the mitochondrial electron transport chain. Oxygen consumption rates of isolated pig brain mitochondria were measured using high-resolution respirometry. Mitochondrial respiration of crude mitochondrial fraction, mitochondria purified in sucrose gradient, and mitochondria purified in Percoll gradient were assayed as a function of storage time. Oxygen flux and various mitochondrial respiratory control ratios were not changed within two days of mitochondria storage on ice. Leak respiration was found higher and Complex I-linked respiration lower in purified mitochondria compared to the crude mitochondrial fraction. Damage to both outer and inner mitochondrial membrane caused by the isolation procedure was the greatest after purification in a sucrose gradient. We confirmed that pig brain mitochondria can serve as a biological model for investigation of mitochondrial respiration. The advantage of this biological model is the stability of respiratory parameters for more than 48 h and the possibility to isolate large amounts of mitochondria from specific brain areas without the need to kill laboratory animals. We suggest the use of high-resolution respirometry of pig brain mitochondria for research of the neuroprotective effects and/or mitochondrial toxicity of new medical drugs.

Experimental study of the dependences of retrieval efficiencies on time delay between magneto-optical-trap being turned off and optical storage**Project supported by the National Basic Research Program of China (Grant No. 2010CB923103) and the National Natural Science Foundation of China (Grant Nos. 11475109, 11274211, and 60821004).

We report an experimental study of electromagnetically induced transparency (EIT)-based light storage in a cloud of cold atoms loaded into a magneto-optical-trap (MOT). After the MOT is turned off, the retrieval efficiencies of right- and left-circularly polarized signal light fields each as a function of storage time are measured for different time delays between MOT off and the storage event, respectively. The results show that in the delay ranging from 0.015 ms to 3.5 ms, the retrieval efficiency for a zero-storage time (0.2 μs) and the storage lifetime can exceed 15% and 1.4 ms, respectively. The measured results will provide important help for optimizing the storage of the polarized entanglement photons in cold atomic ensembles.

Consumers’ behavior in quantitative microbial risk assessment for pathogens in raw milk: Incorporation of the likelihood of consumption as a function of storage time and temperature

Foodborne disease as a result of raw milk consumption is an increasing concern in Western countries. Quantitative microbial risk assessment models have been used to estimate the risk of illness due to different pathogens in raw milk. In these models, the duration and temperature of storage before consumption have a critical influence in the final outcome of the simulations and are usually described and modeled as independent distributions in the consumer phase module. We hypothesize that this assumption can result in the computation, during simulations, of extreme scenarios that ultimately lead to an overestimation of the risk. In this study, a sensorial analysis was conducted to replicate consumers’ behavior. The results of the analysis were used to establish, by means of a logistic model, the relationship between time–temperature combinations and the probability that a serving of raw milk is actually consumed. To assess our hypothesis, 2 recently published quantitative microbial risk assessment models quantifying the risks of listeriosis and salmonellosis related to the consumption of raw milk were implemented. First, the default settings described in the publications were kept; second, the likelihood of consumption as a function of the length and temperature of storage was included. When results were compared, the density of computed extreme scenarios decreased significantly in the modified model; consequently, the probability of illness and the expected number of cases per year also decreased. Reductions of 11.6 and 12.7% in the proportion of computed scenarios in which a contaminated milk serving was consumed were observed for the first and the second study, respectively. Our results confirm that overlooking the time–temperature dependency may yield to an important overestimation of the risk. Furthermore, we provide estimates of this dependency that could easily be implemented in future quantitative microbial risk assessment models of raw milk pathogens.

Stability of Oil‐in‐Water Emulsions with Sunflower (Helianthus annuus L.) and Chia (Salvia hispanica L.) By‐Products

AbstractEmulsifiers and stabilizers play an important role in emulsion stability. Optical characterization and droplet size distribution of oil‐in‐water emulsions formulated with different types and concentrations of modified sunflower lecithin [phosphatidylcholine (PC) enriched lecithin and deoiled sunflower lecithin], with or without chia mucilage (0.75 % wt/wt), have been evaluated as a function of storage time at 4 ± 1 °C. Emulsions with PC‐enriched lecithin (without chia mucilage) exhibited the highest stability at the different concentrations because of the high PC/phosphatidylethanolamine ratio in comparison to Control lecithin. The addition of 0.75 % wt/wt mucilage contributed to obtain stable emulsions for all type and concentrations of emulsifiers studied, mainly with PC‐enriched lecithin due to the reduction of the mobility of oil particles by the formation of a tridimensional network.

Studies of levels of biogenic amines in meat samples in relation to the content of additives

ABSTRACTThe impact of meat additives on the concentration of biogenic amines and the quality of meat was studied. Fresh white and red meat samples were fortified with the following food additives: citric and lactic acids, disodium diphosphate, sodium nitrite, sodium metabisulphite, potassium sorbate, sodium chloride, ascorbic acid, α-tocopherol, propyl 3,4,5-trihydroxybenzoate (propyl gallate) and butylated hydroxyanisole. The content of spermine, spermidine, putrescine, cadaverine, histamine, tyramine, tryptamine and 2-phenylethylamine was determined by capillary isotachophoretic methods in meat samples (fresh and fortified) during four days of storage at 4°C. The results were applied to estimate the impact of the tested additives on the formation of biogenic amines in white and red meat. For all tested meats, sodium nitrite, sodium chloride and disodium diphosphate showed the best inhibition. However, cadaverine and putrescine were characterised by the biggest changes in concentration during the storage time of all the additives. Based on the presented data for the content of biogenic amines in meat samples analysed as a function of storage time and additives, we suggest that cadaverine and putrescine have a significant impact on meat quality.

Egg shell treatment methods effect on commercial eggs quality

ABSTRACT: The objective was to evaluate commercial eggs quality after being subjected to a cleaning process and immersion in whey protein concentrate (WPC) as a function of storage time. The experimental design was completely randomized in a factorial 4x7, being four methods of treating shell (not cleaned and not coated with WPC, not cleaned and coated with WPC, cleaned and not coated with WPC, cleaned and coated with WPC and seven periods of storage (1, 7, 14, 21, 28, 35 and 42 days) for a total of 28 treatments, with five replicates of four eggs each. Quality parameters evaluated were weight loss of eggs (%), specific gravity (g/cm3), haugh units (HU), yolk index (YI) and potential hydrogen (pH) albumen. The storage period increase, regardless of the shell treatment method, causing weight loss in eggs, reductions in specific gravity in the Haugh units, yolk index and increase in the albumen pH. The cleaning method makes egg's internal quality worse during storage. Coverage of whey protein concentrate is a viable alternative for commercial eggs conservation stored at room temperature in order to minimize quality loss during storage, including eggs that need to go through the cleaning process.

Production and Inventory Planning with Variable Holding Cost and All-Units Quantity Discounts

A new production-inventory planning model is considered, in which the holding cost is variable and the purchase cost is subject to quantity discounts. The new production-inventory planning model has three important and realistic features. First, the production rate is finite, so the whole order is not received in one instant, but is gradually produced. Second, the unit holding cost of each item per time period is not constant throughout the entire storage duration, but it increases with longer storage times. Third, the unit purchase cost of each item is not constant, but it decreases with larger orders according to an all-units quantity discount structure. Considering these features, mathematical formulations and optimum solution procedures are developed for two types of holding costs functions of storage time: retroactive increase, and incremental increase.

Potential application of laccase from Pycnoporus sanguineus in methanol/O2 biofuel cells

This paper describes the preparation and characterization of biocathodes for a methanol/O2 biofuel cell using the crude extract and a purified laccase from a strain of Pycnoporus sanguineus (PyS). The biocathode assembly with mediated electron transfer was achieved by immobilizing either the enzymes in the crude extract or the purified laccase with polyamidoamine (PAMAM) dendrimers on top of a polypyrrole matrix containing entrapped 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) species as the redox mediator. Carbon nanotubes modified with anthracene moieties were used to orientate the purified laccase and allow for direct bioelectrocatalytic O2 reduction. The kinetic characterization of the biocathodes showed that samples prepared with either the crude extract or the purified laccase retained ABTS oxidation activity after the immobilization procedure. The biofuel cell tests showed that the biocathodes were able to furnish maximum power densities of 51.2 and 99.8μWcm−2 for the samples prepared with the crude extract and the purified enzyme, respectively. Moreover, it was observed that both biocathodes tested displayed a very similar loss in power performance as a function of storage time, reaching 60% of the initial activity after 60days. Overall, the laccase-based biocathodes prepared either with the crude extract or with the purified enzyme are able to provide electrochemically active and stable biomaterials.

Finite Element Simulation of Shelf Life Prediction of Moisture-Sensitive Crackers in Permeable Packaging under Different Storage Conditions

A finite element method (FEM) approach using COMSOL Multiphysics software was presented to solve unsteady-state moisture diffusion differential equations and predict the shelf life of crackers based on critical moisture content obtained by sensory evaluation. The crackers' moisture contents were given as a function of storage time, environment conditions (temperature and relative humidity) and the package materials. Classical Oswin model was used to fit the moisture sorption data at four different temperatures. Effective moisture diffusivity of crackers as a function of moisture content and temperature were investigated. In addition, the relationship of moisture permeability coefficient and temperature of two selected packaging films, low-density polyethylene (LDPE) and cast polypropylene (CPP) film, was determined based on Arrhenius equation. The crackers were packaged in LDPE and CPP packaging pouches, and stored at four different conditions to simulate actual storage conditions and determine the shelf life experimentally. There was a good agreement between experimental results and finite element predictions for moisture-sensitive crackers subjected to different storage and packaging conditions. Practical Applications This paper describes the shelf life prediction of crackers using a simulation model based on unsteady-state Fickian diffusion of moisture through the food. The temperature effect on the moisture sorption, moisture diffusivity of foods and the moisture permeability coefficient of packaging films are considered. The food product's moisture content was simulated using COMSOL Multiphysics as a function of storage time under different storage conditions and packaging film. The finite element simulation provides a powerful support tool for shelf life estimation and packaging development.

Rheological study of automotive adhesives: Influence of storage time, temperature and shear rate on viscosity at dispensing

This study addresses the adhesive dispensing characteristics of three one-part epoxy-based adhesives by investigating the experimental viscosity data as measured by a parallel plate rheometer. The viscosity data was evaluated as a function of storage time, storage temperature, test (adhesive line) temperature and shear rate, which are related to the adhesive flow rate and pumping pressure. A power law equation was found to best fit the viscosity data for the shear rates considered. The Cox–Merz rule was found to fit the viscosity data reasonably well. This paper also shows the application of time–temperature superposition to predict viscosity at dispensing.

Quality Index Method (QIM) for ice stored gutted Amazonian Pintado (Pseudoplatystoma fasciatum × Leiarius marmoratus) and estimation of shelf life

This study aimed to develop a Quality Index Method (QIM) for ice stored gutted Amazonian Pintado (Pseudoplatystoma fasciatum × Leiarius marmoratus), and estimate its shelf life of gutted fish samples during 30 days of storage analyzing periodically microbiological (heterotrophic aerobic psychrotrophic bacteria, heterotrophic aerobic mesophilic bacteria), chemical (TVB-N, pH, TBARs) and sensory (Quality Index Method protocol) characteristics. Partial least squares regression was used to correlate the QIM attributes, and linear regression analysis was used to check the variables as a function of storage time. The QIM scheme was developed based on 18 demerit points, in which zero indicates total freshness. From the integration of sensory, microbiological, and physicochemical data, it was possible to estimate that the shelf life of ice stored gutted Amazonian Pintado is 12 days.

Effect of storage time on metabolic function of apheresis platelets

Objective To study the effect of storage time on metabolic function of apheresis platelets. Methods Selected a total of 30 bags of apheresis platelets which were collected from 30 cases of voluntary blood donors as research subjects. The volume of each bag of apheresis platelets was one therapeutic dose, and platelet count was (2.5~3.0)×1011/L. All of 30 bags of apheresis platelets would been stored in storage tank for 5 days at 22 ℃. The 30 bags of apheresis platelets were randomly divided into storage for 1 day group (n=10), storage for 3 days group and storage for 5 days group (n=10) equally by digital table method after being numbered. Content of lactic acid, lactate dehydrogenase (LDH), content of glucose and pH value were detected among 3 groups. Relationship of the metabolic function of apheresis platelets and storage time were analyzed by statistical method. Results The longer the storage duration time of apheresis platelets was, the lower of pH values and content of glucose in apheresis platelets were, and there were significant differences among 3 groups (P<0.05). At the same time, contents of LDH and lactic acid in apheresis platelets were gradually increased, and there also were significant differences among 3 groups (P<0.05). Conclusions There are marked changes for metabolic function of apheresis platelets in storage of 5 days at 22 ℃. The shorter the storage duration time of apheresis platelets is, the better quality of apheresis platelets is. Key words: Blood component transfusion; Platelets transfusion; Apheresis platelets; Metabolism; Platelet function tests; Blood preservation; Clinical blood transfusion

A kinetic study of furan formation during storage of shelf-stable fruit juices

To this day, research for furan mitigation has mostly targeted the levels of food production and handling of prepared foods by the consumer. The present study demonstrated the importance of appropriate (moderate) storage conditions for shelf-stable fruit juices, because the furan concentrations of pasteurized orange and mango juices originated from the storage phase, rather than the thermal preservation step. For both juices, the increase in furan concentration during storage was best described by an empirical, logistic model. The duration of the lag phase decreased as a linear function of the storage temperature, while the maximum reaction rate constant followed the Arrhenius law. Furthermore, the rate of furan formation was clearly matrix-dependent, which could be attributed to the differences in juice composition (sugars, ascorbic acid and carotenoids). Next to furan, the juices were also analyzed for 2- and 3-methylfuran. Like for furan, the methylfuran concentrations were matrix-dependent and seemed to increase as a function of storage time and temperature.

A Possible Freshness Marker for Royal Jelly: Formation of 5-Hydroxymethyl-2-furaldehyde as a Function of Storage Temperature and Time.

In this article we present a study of the variability of the concentration of 5-hydroxymethyl-2-furaldehyde (HMF) in natural royal jelly (RJ) as a function of its storage temperature (-18, 4, and 25 °C) and time (up to 9 months after harvesting). For this work HMF is evaluated using an RP-HPLC method we previously assessed. While all RJ samples stored at 4 and -18 °C always showed levels of HMF under the limit of detection (0.13 mg kg(-1)), samples kept at 25 °C showed an exponential increase in the concentration of HMF as a function of the storage time. This behavior and a number of desirable features of the analytical method used (ease of use in routine laboratories, availability of a complete validation protocol specifically developed for RJ, based on consolidated chemical knowledge) allow us to hypothesize the use of HMF as a possible, reliable freshness marker for RJ.

Growth of Red Abalone, Haliotis rufescens, Fed Cold‐stored Benthic Diatoms

AbstractWe measured the proximal composition of four benthic diatoms that were stored for 24 mo in the dark at low temperature (4 C by refrigeration) and examined their potential as feed for abalone, Haliotis rufescens, postlarvae. The proximal composition of the four diatoms was modified by species‐specific responses as a function of time in storage. The cultures of all stored diatoms contained low or undetectable concentrations of Vibrio‐like bacteria (&lt;0.01 VLB/mL). As feed for abalone postlarvae, the four diatoms promoted growth under all experimental conditions. Greater shell lengths were measured on Day 14 when Navicula sp. and Navicula incerta were used as feed. Postlarvae that were fed N. incerta and Navicula sp. had higher growth rates. In contrast, lower growth rates were observed on Day 7 with fresh and stored Nitzschia thermalis as food. Survival was high in postlarvae that were fed the four stored diatoms (100%). This report demonstrates that cultures of benthic diatoms that have been stored by refrigeration for 24 mo can be used to feed abalone postlarvae and have an effect on improving growth and survival.

Thermal and storage characteristics of tomato seed oil

The objectives of this research were to determine the changes in quality and oxidative stability of tomato seed oil, including color, antioxidant activity, peroxide value, saponification value, iodine value and acid value, during heating for 50 h at a common frying temperature (180 °C) and under different storage conditions of temperature (25 °C and 35 °C), light, and headspace volume (10 mL and 25 mL in 50 mL container) as a function of storage time (up to 210 days at 25 °C and 105 days at 35 °C). Results showed that tomato seed oil had high thermal stability with excellent physicochemical profile after heating. The antioxidants such as tocopherol and polyphenol were likely the most significant contributor to the high thermal stability. High temperature, exposure to light, and large headspace volume significantly accelerated the deterioration of tomato seed oil during storage, among which the temperature had the most pronounced effect followed by light and headspace volume. It is suggested that tomato seed oil is packaged with minimal light exposure and stored at a low temperature. The study provided important information for the quality evaluation and control of tomato seed oil and has a great significance for value-added utilization of the by-product from tomato processing industry.

A Novel Method for Determination of Histamine in Tuna Fish by Ion Mobility Spectrometry

Ion mobility spectrometry (IMS) was used for determination of the histamine content in samples of tuna stomach, and the results were compared with measurements by high-pressure liquid chromatography (HPLC) that is considered the “gold standard” method. The production of histamine as a function of storage time at ambient temperature (25–29 °C) was followed by both methods and a good correlation was found between them. The results were validated by IMS and HPLC measurements of samples of fresh tuna fillets in which the initial histamine level was below 10 mg histamine per kg (10 ppm). The level gradually increased to thousands of milligrams per kilogram after about 30 h at ambient temperature. In the IMS measurements, the intensity ratio between the fragment ion of histamine (K0 = 2.73 cm2 V−1 s−1) and the sum of all the ions in the mobility spectrum served to quantify the histamine level in the fish samples. Thus, a rapid, simple, and inexpensive method was developed for determination of histamine in tuna.