Conventional Storage Conditions Research Articles

Microfluidic formulation of food additives-loaded nanoparticles for antioxidation

Browning has many important implications with nutrition and the shelf life of foods. Mitigating browning is of particular interest in food chemistry. The addition of antioxidants has been a common strategy to extend shelf life of drug and food products. In this work, we report a microfluidic technology for encapsulation of three common food additives (potassium metathionite (PMS), curcumin (CCM), and β-carotene (β-Car)) into nano-formulations using low-cost and readily available materials such as shellac. The food additives encapsulated nanoparticles provide a microenvironment that can prevent oxidation during daily storage. The results showed that the produced nanoparticles had a narrow size distribution with an average size of around 100 nm, were stable at conventional storage conditions (4 ºC) for 18 weeks, and had sustained release ability at 37 ºC, pH= 7.8, 160 rpm. In addition, further experiments showed that the formulation of hydrophobic additives, such as CCM and β-Car did not only improve their bioavailability but also allowed for the encapsulation of a combination of ingredients. In addition, the antioxidants loaded nanoparticles demonstrated good biocompatibility, low toxicity to human cells. The longer release time of encapsulated food additives increases shelf life of foods and enhances consumer purchase preferences, which not only saves costs but also reduces waste. In summary, this study shows that such antioxidant-loaded nanoparticles provide a promising strategy in extending the shelf life of food products.

The impact of storage buffer and storage conditions on fecal samples for bacteriophage infectivity and metavirome analyses

BackgroundThere is an increasing interest in investigating the human gut virome for its influence on the gut bacterial community and its putative influence on the trajectory towards health or disease. Most gut virome studies are based on sequencing of stored fecal samples. However, relatively little is known about how conventional storage buffers and storage conditions affect the infectivity of bacteriophages and influence the downstream metavirome sequencing.ResultsWe demonstrate that the infectivity and genome recovery rate of different spiked bacteriophages (T4, c2 and Phi X174) are variable and highly dependent on storage buffers. Regardless of the storage temperature and timespan, all tested phages immediately lost 100% (DNA/RNA Shield) or more than 90% (StayRNA and RNAlater) of their infectivity. Generally, in SM buffer at 4 °C phage infectivity was preserved for up to 30 days and phage DNA integrity was maintained for up to 100 days. While in CANVAX, the most effective buffer, all spiked phage genomes were preserved for at least 100 days. Prolonged storage time (500 days) at – 80 °C impacted viral diversity differently in the different buffers. Samples stored in CANVAX or DNA/RNA Shield buffer had the least shifts in metavirome composition, after prolonged storage, but they yielded more contigs classified as “uncharacterised”. Moreover, in contrast to the SM buffer, these storage buffers yielded a higher fraction of bacterial DNA in metavirome-sequencing libraries. We demonstrated that the latter was due to inactivation of the DNases employed to remove extra-cellular DNA during virome extraction. The latter could be partly avoided by employing additional washing steps prior to virome extraction.ConclusionFecal sample storage buffers and storage conditions (time and temperature) strongly influence bacteriophage infectivity and viral composition as determined by plaque assay and metavirome sequencing. The choice of buffer had a larger effect than storage temperature and storage time on the quality of the viral sequences and analyses. Based on these results, we recommend storage of fecal virome samples at in SM buffer at 4 °C for the isolation of viruses and at – 80 °C for metagenomic applications if practically feasible (i.e., access to cold storage). For fecal samples stored in other buffers, samples should be cleared of these buffers before viral extraction and sequencing.2F_FbCzVMdkP5vWvM-fCtaVideo

Measurement of Heat Transfer and Flow Resistance for a Packed Bed of Horticultural Products with the Implementation of a Single Blow Technique

This paper provides the practical implementation of the single blow technique as an effective approach of average convective heat transfer coefficient measurement for a packed bed of horticultural products. The measurement approach was positively validated for the case of a packed bed of balls. The presented results cover heat transfer coefficient results for carrots stored in packed beds for two various arrangements (regular and irregular) and bed of apples under conditions of various turbulent intensity at the inlet to the bed. The turbulent intensity (defined as the ratio of the root mean square of the turbulent fluctuation of the air velocity to the mean air velocity) varied from 0.02 to 0.14. The applied velocity ranges for the tests refers to the conventional storage conditions. The heat transfer correlations were proposed based on the obtained results for each arrangement. It was demonstrated that due to flow laminarization inside the bed, the turbulence intensity has no significant effect on heat transfer inside the bed. Heat transfer enhancement of up to 25% was demonstrated for the case of the irregular carrot arrangement in the tested bed. The flow resistance correlations were additionally proposed for the tested beds. It was demonstrated that the product arrangement does not produce an important effect on the pressure drop.

Crystallization Risk Assessment of Amorphous Solid Dispersions by Physical Shelf-Life Modeling: A Practical Approach.

Amorphous solid dispersions (ASDs) of a poorly water-soluble active pharmaceutical ingredient (API) in a polymer matrix can enhance the water solubility and therefore generally improve the bioavailability of the API. Although examples of long-term stability are emerging in the literature, many ASD products are kinetically stabilized, and inhibition of crystallization of a drug substance within and beyond shelf life is still a matter of debate, since, in some cases, the formation of crystals may impact bioavailability. In this study, a risk assessment of API crystallization in packaged ASD drug products and a mitigation strategy are outlined. The risk of shelf-life crystallization and the respective mitigation steps are assigned for different drug product development scenarios and the scientific principles of each step are discussed. Ultimately, the physical stability of ASD drug products during shelf-life storage is modeled. The methodology is based on the quantification of crystal growth kinetics by transmission Raman spectroscopy (TRS), modeling the impact of water sorption on the glass-transition temperature of the ASD, and the prediction of moisture uptake by the packaged ASD drug product during storage. This approach is applied to an ASD of fenofibrate that features both fast API crystallization under accelerated storage conditions and long-term stability in a suitable protective packaging under conventional storage conditions.

Long-term stabilization of DNA at room temperature using a one-step microwave assisted process

Long-term stabilization of DNA is needed for forensic, clinical, in-field operations and numerous other applications. Although freezing (<−20 °C) and dry storage are currently the preferential methods for long-term storage, a noticeable pre-analytical degradation of DNA over time, upfront capital investment and recurring costs have demonstrated a need for an alternative long-term room-temperature preservation method. Herein, we report a novel, fast (~5 min) silica sol–gel preparation method using a standard microwave-initiated polymerization reaction amenable to stabilization of DNA. The method involves use of one chemical, tetramethoxy silane (TMOS) and eliminates the use of alcohol as co-solvent and catalysts such as acids. In addition, the process involves minimal technical expertise, thus making it an ideal choice for resource-challenged countries and in-field applications. The sol–gel is capable to store and stabilize Escherichia coli DNA in ambient conditions for 210 days. DNA recovered from the sol–gel showed no significant nucleolytic and/or oxidative degradation, outperforming conventional storage conditions at −20 °C, and reported state-of-the-art technology.Supplementary InformationThe online version contains supplementary material available at 10.1007/s42247-021-00208-3.

The Occurrence of Aflatoxins in Nuts and Dry Nuts Packed in Four Different Plastic Packaging from the Romanian Market.

Mycotoxins are secondary metabolites produced by various fungi. A very important category of mycotoxins are aflatoxins, considered to be the most dangerous in humans. Aflatoxin B1, well known as a favorable factor in the occurrence of hepatocellular carcinoma in humans, is the most controversial of all mycotoxins. Aflatoxins, found in naturally contaminated food, are resistant to degradation by heat. Current food processing practices and conventional storage conditions do not completely eliminate aflatoxin contamination from the food supply chain. Long storage food products—such as peanuts, pistachio, nuts in general, and dried fruits—are susceptible to aflatoxins contamination. The type of plastic material can influence the concentration of aflatoxins during storage due to the permeability to gas and moisture exchange with the external milieu. Nuts in general and dried fruits are consumed in large quantities worldwide. Therefore, herein we investigated the effect of plastic material on the total aflatoxins and aflatoxin B1 content in 64 samples of nuts and dried fruits packed and stored in low-density polyethylene (LDPE), polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET). The method consisted in a cleanup procedure using immunoaffinity columns coupled with RIDASCREEN FAST immunoenzymatic competitive assays based on the ELISA technique. Collected data were subjected to statistical analysis and multiple comparisons tests were applied. From the total analyzed samples, 14.06% exceeded the maximum admitted European levels for total aflatoxins. The highest concentrations of total aflatoxins were obtained from samples packed in LDPE, followed by PP, PE, and PET. Aflatoxin B1 was detected in all samples packed in LDPE, PP, and PE. Most of the samples packed in PET had concentrations <1 µg/kg. These results indicate that nuts in general packed and stored in LDPE are more prone to contamination with aflatoxins, while PET is more suitable for maintaining the quality and safety of these products.

Storage of short-lived seeds of Inga vera subsp. affinis in osmotic medium

AbstractInga vera subsp. affinis (Fabaceae) is a tree species native to riparian forests in Southeast Brazil and is key for the restoration of deforested areas. The species produce seeds that are highly recalcitrant. Extreme sensitivity to desiccation as well as vivipary are commonly observed in mature seeds, which also tend towards polyembryony. Past research has shown that typical strategies to store seeds are inapplicable to Inga vera as viability is completely lost when seeds are either dried to around 28% water content (wet basis) or stored at 5°C for a few weeks. Here, we examine the feasibility of storing the seeds under hydrated conditions but at reduced water potential. Freshly collected seeds were kept under conventional storage conditions (plastic bags in cold chamber, 5°C) and in polyethylene glycol (PEG) solutions (−1.6 and −2.4 MPa) at 10°C. Seed germination was assessed after various intervals of time, until all seeds had lost viability. Before storage, seeds attained 100% germination and produced an average of 1.8 normal seedlings per seed (due to polyembryony). Storage in PEG at −1.6 MPa maintained 90% germination (radicle protrusion) and one normal seedling per seed on average for more than 200 d. Osmotic storage likely slowed down metabolism within the seed and hence consumption of food reserves. The storage time achieved has practical applications for in situ restoration, but cannot address ex situ germplasm conservation. Extending shelf life for an additional 6 months allows tree nurseries to optimize the production of seedlings so that they can be planted during the wet season.

Short-term culture under pressurized and hypoxic conditions reduces hematopoietic stem cell apoptosis and improves cellular function of transplant products

Background & Aim Hematopoietic stem cell transplantation (HSCT) is a potential curative therapy for numerous diseases. The success of HSCT is dependent upon the viability, homing, and engraftment capabilities of the hematopoietic stem cells (HSCs). Current clinical approaches allow for storage times up to 48 hours at either room temperature (20-24°C) or refrigerated conditions (2-8°C) prior to transplantation, resulting in high levels of cellular apoptosis and reduced functionality, thus compromising the effectiveness of the transplanted cells. To address this, we substituted the current conditions with short-term culturing methods ( Methods, Results & Conclusion Environmental optimization can selectively enhance the fitness and functionality of specific cell types and increase the stemness or differentiation potential of cells in culture. By varying the temperature (4°C, room temperature, 37°C, 43°C), oxygen (20%, 5%, and 1%), and pressure levels (1.00 to 1.35 atm), we optimized the culture conditions to improve the functionality of HSCs. Cell health was measured using assays measuring apoptosis and metabolic function. Significant decreases in cell populations positive for apoptosis markers, annexin V and DilC1(5), were observed after 24 hours of incubation in optimized conditions compared to current clinical approaches. DUSP4, a stress-related gene that prevents apoptosis, was upregulated under optimized environmental conditions; this, along with higher ATP levels, is indicative of functional and healthy cells. Preconditioned cells exhibit characteristics of a product with improved rates of bone marrow homing and immune reconstitution. They show increased surface expression of the receptor for stromal cell-derived factor (CXCR4), the sialomucin receptor for P-selectin glycoprotein ligand-1 (PSGL-1), the β1 integrin very-late antigen (VLA-4), and the tetraspanin CD82, which are all implicated in the homing capacity of HSCs to the bone marrow. Immune reconstitution, as assessed by measuring proliferation and differentiation via a colony forming units in vitro, predicts robust reconstitution capability of HSCs cultured under optimized conditions. As shown, cells for HSCT maintained under optimized temperature, oxygen, and pressure levels result in improved cell viability and function over conventional storage conditions, suggesting a potential clinical benefit in the transplantation setting.

Active chitosan–chestnut extract films used for packaging and storage of fresh pasta

SummaryA tannins‐rich chestnut extract was used to enhance the antioxidant and antibacterial properties of chitosan‐based film materials. The favourable mechanical properties of the novel material enabled its application in the preparation of the sachets that were used for packing and storage of filled fresh pasta. The fresh pasta ageing progressed in conventional refrigerated storage conditions of 8 °C with 60 ± 2% relative humidity in the absence of light for 60 days. The rapid moisture mobility between a starchy food and sachets during the first 9 days of storage induced retrogradation of the fresh pasta, whereby total phenolic content show dependency on moisture throughout the shelf life. Active components within the sachet prevented microbial growth on the food surface during the entire 60 days.

Long-Term Hypoxic/Hypocapnic Storage of Red Blood Cells Results in Amelioration of Lesion Hallmarks and Increased In Vivorecovery at 24 Hours Post-Transfusion

Oxidative damage, dysmetabolism and decreased levels of 2, 3-diphosphoglycerate (2,3-DPG) affect red blood cell (RBC) survival and the affinity of Hemoglobin for oxygen are relevant hallmarks of RBC storage lesion, especially in specific clinical contexts. We hypothesized that oxygen and carbon dioxide reduction followed by hypoxic/hypocapnic storage would result in amelioration of RBC lesion assessed at the end of their shelf-life and at the shelf-life mode (21 days).To determine the relevance of hypoxic/hypocapnic storage in humans, a pivotal, prospective, randomized, two‐arm, crossover, three‐center trial was conducted to evaluate [Hemanext®] hypoxic/hypocapnic processing system and was used to assess whether this process and storage method met standard FDA acceptability criteria for long-term RBC storage. The Test arm consisted of whole blood (WB)‐derived, leukoreduced RBC in AS-3 additive processed at room temperature with the Hemanext system for 3 hours to achieve hypoxic/hypocapnic state within 12 hours of phlebotomy which was maintained hypoxic during storage for up to 43 days at 1‐6°C (Test).Unprocessed units (Control) were stored within 8 hours under conventional storage conditions. Subjects (N=100) donated CP2D WB (500 ± 50 mL) and a minimum of 93 pairs of RBC units per arm were analyzed for in vitroquality parameters. For in vivo analysis at end of storage, RBCs from 19 test subjects and 21 control subjects (14 paired) from two sites were radiolabeled with 51‐Cr/99‐Tc(m), autologously transfused, and analyzed for 24-hour recovery. Differences between the Test and Control groups were analyzed using the paired t-test (Wilcoxon test where necessary). Paired analyses of 24-hour in vivorecoveries on day 43 was 89.3±4.5% and 84.8±6.2% for the test and control, respectively; p&lt;0.01). Significantly higher levels of 2,3-DPG and adenosine 5'-triphosphate (ATP) were maintained for the Test group by days 21 and 42/43 of storage (Table 1). Percentage of hemolysis was similar in both groups. In summary, these data demonstrate that RBCs preserved in a user-friendly, self-contained hypoxic storage system are superior than the conventionally stored RBCs and may provide more viable RBCs for transfusion at 6 weeks of storage. Disclaimer: The51‐Cr/99‐Tc(m)labeling at one of the three sites occurred without prior RDRC approval and did not meet GMP standards. Disclosures Cancelas: Fresenius-Kabi: Research Funding; Cerus Co.: Research Funding; TerumoBCT: Consultancy, Research Funding; Hemanext: Consultancy, Research Funding; Macopharma Inc: Research Funding; Cytosorbents: Research Funding; Cellphire: Research Funding; Velico: Consultancy, Research Funding. Yoshida:New Health Sciences Inc.: Employment, Equity Ownership. Dioguardi:Hemanext: Employment. Iselin:Hemanext: Employment. Dunham:Hemanext: Employment.

Development of vitamin E‐enriched functional foods: stability of tocotrienols in food systems

SummaryTocotrienols are members of the vitamin E family that provide many nutritional benefits. Developing tocotrienol‐fortified functional foods introduces vitamin E into consumers diets without changing their food habits. The purpose of this study was to compare the stability of tocotrienols in bulk form and six food matrices at a fixed dose (40 mg kg−1) under accelerated and conventional storage conditions. The delta‐ and gamma‐tocotrienol content was measured using HPLC, and the sensory attributes were evaluated using triangle and hedonic tests. Tocotrienol in bulk powder was less stable under stressed conditions than in bulk oil, with the powders having approximately 40% and 80% reduction in δ‐ and γ‐ after storage and bulk oil with no significant degradation. HPLC analysis demonstrated that tocotrienol content remained unchanged in dry mix lemonade, yogurt, raw and UHT milk, and margarine over time; however, complete degradation of γ‐ and partial degradation (up to 50%) of δ‐tocotrienol was observed in bread during ambient and stressed storage conditions. A significant decrease in the δ‐tocotrienol relative concentration was also observed in HTST processed milk samples. Tocotrienol addition was not perceived, and no significant difference in the product attributes and overall liking was reported in the discrimination sensory testing.

Picking from the Past in Preparation for a Pest: Seed Banks Outperform Herbaria as Sources of Preserved 'Ōhi'a Seed.

Seed banks serve the purpose of maintaining germplasm for ex situ species preservation. Herbarium vouchers may be a viable source of unique and/or additional seeds for restoration as they can sometimes be from larger and more representative populations compared with seed banks. Rapid 'ōhi'a death (ROD) has emerged as a serious threat against Hawaii's most iconic and foundational forest tree (Metrosideros spp.), and seed banking has been identified as an important strategy in preserving the genetic diversity of 'ōhi'a. With respect to 'ōhi'a we ask the following: (1) what is the long-term viability of 'ōhi'a seeds stored in herbarium conditions, (2) how do herbarium curation practices affect seed viability, and (3) how long do seeds survive using conventional storage methods? We placed fresh 'ōhi'a seeds in a herbarium dryer (57°C/5% relative humidity) for 5 days, freezer (-18°C/95% RH) for 2 weeks, and dryer then freezer, and compared against fresh control seeds. Seeds were harvested from a chronosequence of herbarium specimens, withdrawn from conventional storage conditions up to 3.75 and 6.5 years before experiments began, and germination assessed. There was no difference in the proportion germinated among treatments and control testing for herbarium entry (p = 0.56). Although no seeds from herbarium specimens germinated, freshly collected dried and frozen seeds germinated at a level equivalent to the control (p = 0.76). For seeds stored using conventional storage methods at 3.75 and 6.5 years, germination was equivalent to freshly harvested seeds. This suggests that seeds can survive the extreme climate conditions necessary to enter herbaria, but lose viability after storage at ambient conditions in 4 years or less. Although 'ōhi'a seeds may be plentiful in herbaria, we recommend using seeds deposited into seed banks using conventional storage methods for orthodox seeds for postdisturbance restoration, and to combat ROD.

Simultaneous determination of plasma nicotine and cotinine by UHPLC-MS/MS in C57BL/6 mice and its application in a pharmacokinetic study.

Plasma concentrations of nicotine and its active metabolite cotinine are highly correlated with its biological effects. A UHPLC-MS/MS method was developed, validated and applied for nicotine and cotinine analysis in mice plasma. Chromatographic separation was achieved on a BEH HILIC column using acetonitrile (0.1% formic acid) and 10 mm ammonium formate as mobile phase. The gradient elution was performed at 0.4 mL/min with a run time of 3.6 min. The quantitative ion transition was m/z 163.1 > 130.0 for nicotine, m/z 177.1 > 80.0 for cotinine and m/z 167.1 > 134.0 for nicotine-D4 (internal standard, IS). For both nicotine and cotinine, the calibration range was 5-500 ng/mL with 5 ng/mL as the lower limit of quantitation, and the intra- and inter-day bias and imprecision were -4.61-12.00% and <11.12%. The IS normalized recovery was 90.62-98.95% for nicotine and 89.18-101.53% for cotinine, and the IS normalized matrix factor was 106.00-116.44% for nicotine and 100.34-109.85% for cotinine. Both nicotine and cotinine were stable under conventional storage conditions. The validated method has been applied to a pharmacokinetic study in mice to calculate the pharmacokinetic parameters for both analytes.

Hypoxic storage of erythrocytes slows down storage lesions and prolongs shelf-life.

Conventional storage conditions of erythrocytes cause storage lesions. We propose that hypoxic storage conditions, involving removal of oxygen and replacement with helium, the changes in stored erythrocytes under hypoxic condition were observed and assessed. Erythrocytes were divided into two equal parts, then stored in conventional and hypoxic conditions, separately. Blood gas analysis, hemorheology, and hemolysis were performed once a week. Energy metabolism and membrane damage were monitored by enzyme-linked immunosorbent assay. Phosphatidylserine exposure was measured by flow cytometry. P50 was measured and the oxygen dissociation curve(ODC) plotted accordingly. Erythrocyte morphology was observed microscopically. In the 9th week of storage, the hemolysis of the hypoxia group was 0.7%; lower (p < .05) than that of the control group and still below the threshold of quality requirements. The dissolved oxygen and pO2 were only 1/4 of that in the control group (p < .01); the adenosine triphosphate, glucose, and lactic acid levels were decreased (p < .05), while the 2,3-diphosphoglycerate levels were increased relative to that in the control group (p < .01). There were no statistically significant differences in membrane damage, deformability, and aggregation between the two groups. In addition, the ODC of the two groups was shifted to the left but this difference was not statistically different. Basically similar to the effect of completely anaerobic conditions. Erythrocytes stored under hypoxic conditions could maintain a relatively stable state with a significant decrease in hemolysis, reduction of storage lesions, and an increase in shelf-life.

Impact of Plastic Packaging Materials and Storage Time on the Quality Parameters of Lebanese Extra Virgin Olive Oil under Real-Time Storage Conditions

Scarce information is currently available relative to the use of polymeric materials as storage containers for extra virgin olive oil. This paper was devoted to study and compare the impact of glass and 3 types of packaging materials—polyethylene terephthalate (PET), high density polyethylene (HDPE), and polylactic acid (PLA) on Lebanese extra virgin olive oil (EVOO) up to 9 months under non-accelerated storage conditions. The acidity, peroxide value (PV), K232, K270, fatty acid profile, overall migration, and oil sorption into the packaging material were determined. Conventional titration, gas chromatography-mass spectrometry, and spectrophotometry were used to quantify the outcome measures at baseline, 3, 5, 7, and 9 months. Mixed model ANOVA was applied to assess differences according to polymer type and storage period at P 232 and K270), migration, and sorption significantly increased with increasing storage time for oil in contact with glass and plastic materials, especially between the 7th and 9th month of storage. Overall, PLA showed the least deterioration and interaction phenomena compared with PET and HDPE. While glass remains the best container for EVOO, PLA could potentially replace PET and HDPE for short-time storage under conventional storage conditions in Lebanese households.

Phenotypic changes and DNA methylation status in cryopreserved seeds of rye (Secale cereale L.)

Conserving genetic diversity is a major priority of the National Laboratory for Genetic Resources Preservation (NLGRP), operated by the U.S. Department of Agriculture, Agricultural Research Service. There are two long-term preservation methods employed in the NLGRP: storage in a −18 °C freezer (conventional storage) and storage in liquid nitrogen vapor phase at −135 to −180 °C (cryopreservation). To test the phenotypic and epigenetic effects of long-term cryopreservation of orthodox seeds, we evaluated 40 cereal rye accessions (20 spring habit and 20 winter habit) stored for 25 years under both conventional storage and cryogenic conditions. In laboratory evaluations of winter habit rye, seeds from cryopreserved samples had significantly higher normal germination percentage (P < 0.05) and lower abnormal germination percentage (P < 0.05) than those stored under conventional conditions. Cryopreserved spring habit rye also had higher normal germination percentage (P < 0.01) than conventionally stored samples. In addition, winter rye seedlings from cryopreserved seeds had longer roots and smaller root diameter (P < 0.05) than seedlings from conventionally stored seeds. In field evaluations conducted in Fort Collins, Colorado in 2014-15, spikes of plants grown from conventionally stored seeds of the winter accessions were slightly longer than those from cryopreserved seeds (P = 0.045). To detect DNA methylation changes, a methylation-sensitive amplified fragment length polymorphism (metAFLP) technique was applied to two accessions. After false discovery rate adjustment, no differences in methylation were detected between storage treatments on an individual locus basis. Our study indicated that cryopreservation slowed seed deterioration as evidenced by higher germination rates compared to conventional storage, had only minimal effects on other phenotypic traits, and had no significant effects on DNA methylation status.

Microfluidic paper-based device for colorimetric determination of glucose based on a metal-organic framework acting as peroxidase mimetic.

This work presents a microfluidic paper-based analytical device (μPAD) for glucose determination using a supported metal-organic framework (MOF) acting as a peroxidase mimic. The catalytic action of glucose oxidase (GOx) on glucose causes the formation of H2O2, and the MOF causes the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to form a blue-green product with an absorption peak at 650nm in the detection zone. A digital camera and the iOS feature of a smartphone are used for the quantitation of glucose with the S coordinate of the HSV color space as the analytical parameter. Different factors such as the concentration of TMB, GOx and MOF, pH and buffer, sample volume, reaction time and reagent position in the μPAD were optimized. Under optimal conditions, the value for the S coordinate increases linearly up to 150μmol·L-1 glucose concentrations, with a 2.5μmol·L-1 detection limit. The μPAD remains stable for 21days under conventional storage conditions. Such an enzyme mimetic-based assay to glucose determination using Fe-MIL-101 MOF implemented in a microfluidic paper-based device possesses advantages over enzyme-based assays in terms of costs, durability and stability compared to other existing glucose determination methods. The procedure was applied to the determination of glucose in (spiked) serum and urine. Graphical abstract Schematic representation of microfluidic paper-based analytical device using metal-organic framework as a peroxidase mimic for colorimetric glucose detection with digital camera or smartphone and iOS appreadout.

High Functional Stability of a Low-cost HBV DNA qPCR Primer Pair and Plasmid Standard.

ABSTRACTAimWe studied the functional stability of a primer pair and the standard curve based on a plasmid carrying full-length HBV genome, from a novel low-cost real-time quantitative polymerase chain reaction (qPCR) assay. The assay was developed at the Center for Genetic Engineering and Biotechnology (CIGB) in Havana, to quantify the serum hepatitis B virus (HBV) DNA from chronic HBV-infected (CHB) patients.Materials and methodsIn-house generated oligonucleotides and plasmids were incubated at 37°C during 1 month and compared with the same materials incubated at –20, 4, and 25°C during the same time in qPCR experiments.ResultsThis work shows that the oligonucleotide pair and the plasmid for the quantitative standard curve are functionally stable in severe temperature conditions during 1 month. Polymerase chain reaction amplification with both materials after its incubation 30 days at 37°C produced similar cycle threshold (CT) values and similar degree of sample quantifications compared with the same materials preserved using the conventional storage conditions at –20°C.ConclusionThese results are indicative of the robustness of this low-cost qPCR system for HBV DNA quantification. These results also support that this qPCR assay can be used as a low-cost technology in clinical studies to monitor the viral load changes of serum HBV DNA of CHB patients, which could be used by poor people of third world countries, where there are frequent blackouts and temperature changes that can hinder the primer and plasmid stability.How to cite this articleAguiar J, García G, León Y, Canales E, Silva JA, Gell O, Estrada R, Morán I, Muzio V, Guillén G, Pentón E, Aguilar JC. High Functional Stability of a Low-cost HBV DNA qPCR Primer Pair and Plasmid Standard. Euroasian J Hepato-Gastroenterol 2016;6(1):19-24.

A 3D µPAD based on a multi-enzyme organic-inorganic hybrid nanoflower reactor.

This work reports on the development of a 3D microfluidic paper-based device (3D µPAD) for glucose detection using organic-inorganic hybrid nanoflower technology to immobilize the bi-enzymatic system (glucose oxidase and horseradish peroxidase). The system is based on nanoflowerssupported on cellulose paper (the microreactor zone) coupled to 3,3',5,5'-tetramethylbenzidine (TMB) as the colorimetric probe in the detection zone. We used a digital camera for the quantitative analysis of glucose with the S coordinate of the HSV color space as the analytical parameter. Under optimal operational conditions, linearity was observed for glucose concentrations up to 300 μM, with a detection limit of 15.6 µM. The biosensor is reusable and remains stable for 75 days in conventional storage conditions.

Migration of Chemical Compounds from Packaging Polymers during Microwave, Conventional Heat Treatment, and Storage.

Polymeric packaging protects food during storage and transportation, and withstands mechanical and thermal stresses from high-temperature conventional retort or microwave-assisted food processing treatments. Chemical compounds that are incorporated within polymeric packaging materials to improve functionality, may interact with food components during processing or storage and migrate into the food. Once these compounds reach a specified limit, food quality and safety may be jeopardized. Possible chemical migrants include plasticizers, antioxidants, thermal stabilizers, slip compounds, and monomers. Chemical migration from food packaging is affected by a number of parameters including the nature and complexity of food, the contact time and temperature of the system, the type of packaging contact layer, and the properties of the migrants. Researchers study the migration of food-packaging compounds by exposing food or food-simulating liquids to conventional and microwave heating and storage conditions, primarily through chromatographic or spectroscopic methods; from these data, they develop kinetic and risk assessment models. This review provides a comprehensive overview of the migration of chemical compounds into food or food simulants exposed to various heat treatments and storage conditions, as well as a discussion of regulatory issues.