Accelerated Storage Test Research Articles

Effect of Metal Contaminants and Antioxidants on the Oxidation Stability of the Methyl Ester of Pongamia

AbstractAccording to the proposed National Mission on biodiesel in India, we have undertaken studies on the stability of biodiesel from tree‐borne non‐edible oil seeds like Pongamia pinnata. Neat Pongamia methyl ester (PoME) exhibited an oxidation stability (OS) of 2.54 h and research was conducted to investigate the effect of the presence of transition metals likely to be present in the metallurgy of storage tanks and barrels, on the OS of PoME. It was found that the influence of metal was detrimental to OS and was catalytic, as even small concentrations of metal contaminants showed nearly the same influence on OS as large amounts. Copper showed the strongest detrimental and catalytic effect on OS. The OS of metal‐contaminated PoME was found to increase with an increase in the dosage of antioxidant but the dosage required for copper‐contaminated PoME became approximately four times than required for neat PoME. The dependence of the OS on the type of metal showed that long‐term storage tests in different types of metal containers for examining the influence of container material on OS of biodiesel may be replaced by the significantly faster Rancimat test serving as an accelerated storage test.

SELECTION OF A SENSORY MARKER TO PREDICT THE SENSORY SHELF LIFE OF A FLUID HUMAN MILK REPLACEMENT FORMULA

ABSTRACT Human milk replacement formulas (HMRFs) are foods designed for babies in their early months of age. An accelerated storage test showed that dark color increased at a higher rate than oxidized flavor. Additionally, a survey among mothers who were giving HMRFs to their babies showed that mothers rarely tasted the product. Thus, the salient sensory attribute they would pay attention to when preparing their babies' bottles was color. If a portion was rejected by the babies, mothers attributed the rejection to stomach trouble and not to an inappropriate flavor. Thus, as a result of the color having increased at a higher rate than flavor changes and being the salient attribute that mothers would pay attention to, it was chosen as the critical shelf life descriptor. The sensory cutoff point was determined from the correlation between mothers' acceptability scores for samples with increasing color and the dark color of the same samples measured by a trained panel. A high correlation was obtained between dark color measurements from a trained panel and CIE‐LAB values (L*, a* and b*). The cutoff point was used to determine shelf life based on sensory attributes of a commercial HMRF stored at 25, 37 and 45C, resulting in 150, 43 and 21 days, respectively. Activation energy is calculated. PRACTICAL APPLICATIONSSensory shelf life determination in foods for babies is not an easy task. This work offers a methodological practice to develop a decision criterion for when the end user cannot be consulted directly.

Modelling the storage shelf life of dates using experimental design

This article studies different factors affecting the deterioration of date fruits at a fixed storage temperature. Effects of date cultivar, texture and treatment on shelf life were studied using an experimental design approach, and the use and contribution of generalised linear models (GLM) in the analysis of the experimental results are described. A model predicting the storage life of dates is suggested and validated. The specified GLM predicted well the shelf life of dates (R 1⁄4 98%). Accelerated storage tests used to predict shelf life were carried out at three temperatures (20, 30 and 408C) to bring about and expedite the deterioration of the dates and, thus, assess their shelf life. It was found that the shelf life of the semi-dry Aligh date cultivar could reach 66.23 days at 308C by means of drying and addition of preservatives. The described model could be used to find the optimal treatment for a given dates’ cultivar and texture. It also gives practitioners accurate tools to predict dates’ shelf life during shipping and distribution phases. Drawbacks of using standard linear models instead of GLMs are also discussed.

Influence of metal contaminants on oxidation stability of Jatropha biodiesel

Abstract According to proposed National Mission on biodiesel in India, we have undertaken studies on stability of biodiesel from tree borne non-edible oil seeds Jatropha. European biodiesel standard EN-14214 calls for determining oxidation stability at 110 °C with a minimum induction time of 6 h by the Rancimat method (EN-14112). Neat Jatropha biodiesel (JBD) exhibited oxidation stability of 3.95 h and research was conducted to investigate influence of presence of transition metals, likely to be present in the metallurgy of storage tanks and barrels, on oxidation stability of Jatropha methyl ester. It was found that influence of metal was detrimental to oxidation stability and catalytic. Even small concentrations of metal contaminants showed nearly same influence on oxidation stability as large amounts. Copper showed strongest detrimental and catalytic effect. The dependence of the oxidation stability on the type of metal showed that long-term storage tests in different types of metal containers for examining the influence of container material on oxidation stability of biodiesel may be replaced by significantly faster Rancimat test serving as an accelerated storage test.

Avaliação do óleo de girassol adicionado de antioxidantes sob estocagem

The objective of this work was to evaluate the isolated and synergistic effects of the antioxidants coriander extract and ascorbyl palmitate in sunflower oil, submitted to an accelerated storage test. Thus, sunflower oil (control) and sunflower oil with the addition of 1,600 mg.kg-1 coriander extract, 500 mg.kg-1 ascorbyl palmitate and a mixture of these antioxidants were submitted to an accelerated storage test in an oven at 60 °C for 10 days, where samples were taken at time intervals of 0, 2, 4, 6, 8 and 10 days and analysed for peroxide value and conjugated dienes. The results obtained from the analytical determinations were submitted to analysis of variance and the Tukey test at 5%, in a factorial scheme, following an entirely casualized design. From the results obtained, it was verified that the antioxidants coriander extract, ascorbyl palmitate and the mixture of these antioxidants, when added to sunflower oil, showed the ability to retard the formation of peroxides 16.4, 77.5 and 84.0% and conjugated dienes 11.2, 56.9 and 60.9%, respectively. The antioxidant mixture presented a higher antioxidant potential in sunflower oil than the antioxidants applied alone, which proved the synergistic effect of the antoxidants studied.

Influence of the Addition of Raspberry Seed Extract on Changes in the Volatile Pattern of Stored Model Breakfast Cereal

Laboratory-prepared muesli-type breakfast cereal (mixture of oat flakes, wheat flakes, corn flakes, hazelnuts, raisins, sunflower seeds, and flax seeds) was subjected to accelerated storage test at 60 degrees C with or without the addition of red raspberry seed extract. The oxidative changes in muesli resulting in the formation of secondary oxidation products were evaluated using solid phase microextraction (HS-SPME) and solvent-assisted flavor evaporation (SAFE) to isolate volatiles and GC-MS and chromatography-olfactometry to quantify them and determine the key odorants. During 14 days of storage the total amount of volatile compounds changed from 1.0 mg/kg, in freshly prepared muesli, to 32 mg/kg after storage. The predominant compound was hexanal; its content during storage increased 20-fold, reaching 17 mg/kg. Red raspberry seed extract addition limited the rate of lipid oxidation, and the total amount of volatiles was estimated at 11 mg/kg and that of hexanal at almost 5 mg/kg. An elevated temperature of the storage test also influenced the crucial flavor compounds determined using aroma extract dilution analysis (AEDA). The flavor dilution factor (FD) values for volatile lipid oxidation products were lower in samples with red raspberry seed extract added.

The use of electronic and human nose for monitoring rapeseed oil autoxidation

AbstractThis work was aimed at assessing the effectiveness of the electronic nose to monitor off‐flavor associated with lipid oxidation as a supplementary tool to human sensory panel assessment. Therefore, correlations between electronic nose and sensory analysis were determined. Also GC analyses and chemical analyses of oil samples were run to characterize the analyzed samples with well‐described parameters. Refined rapeseed oil was subjected to an accelerated storage test for 12 days at 60 °C and to an ambient temperature storage test in which it was stored in retail plastic bottles for up to 6 months. PCA of electronic nose data samples stored at an elevated temperature was related to PCA of sensory analysis, and similarities in sample clustering were observed. For samples stored at room temperature, the human panel showed greater sensitivity than the electronic nose. Prediction models based on PLS of electronic nose data were able to predict the sensory quality changes during storage at elevated and room temperature, ranging from 0.721 to 0.989 and from 0.849 to 0.881 (p <0.05), respectively. PV and p‐AV were well predicted on the basis of both electronic nose (0.989, 0.998 for elevated temperature; 0.907, 0.881 for room temperature) and sensory analysis data (0.973, 0.993 for elevated temperature; 0.939, 0.886 for room temperature). Applicability of the electronic nose technology to verify sensory and rancidity changes during storage showed to be promising in quality control of oils.

ACCELERATED STORAGE TESTING OF FREEZE-DRIED IMMOBILIZED LACTOBACILLUS ACIDOPHILUS-FERMENTED BANANA MEDIA

Freeze-drying was applied as a drying method for the production of dehydrated immobilized Lactobacillus acidophilus-fermented banana medium containing high levels of probiotics and appropriate prebiotic (mainly fructooligosaccharides) contents in an attempt to develop dried synbiotic products. Ca-alginate and κ-carrageenan were used for the immobilization of L. acidophilus, and the immobilized bacteria were employed directly in the banana media fermentation. The fermented products were then freeze-dried. Results indicated that cell immobilization could provide effective protection to L. acidophilus, and reduce the damage caused by freezing and freeze-drying. Meanwhile, accelerated storage testing using temperatures of 50, 60 and 70C was applied to the dehydrated products. Gel-entrapped L. acidophilus appeared to have lower decimal reduction, and Ca-alginate immobilized cells had a better survival than κ-carrageenan. Results of accelerated storage test showed that immobilization could effectively increase the thermal resistance of entrapped microorganisms, and Ca-alginate showed a better effect than κ-carrageenan, and the beneficial effects increased with the decrease of the storage temperature. The freeze-dried products exhibited little hygroscopicity because of the consumption of monosaccharides during fermentation. Results revealed that freeze-drying could be used as a proper method for the development of dried product of immobilized L. acidophilus-fermented banana media, and accelerated storage test could be used to evaluate the storage stability of the dried products. PRACTICAL APPLICATIONS This research demonstrates the feasibility of the application of accelerated storage testing to the prediction of shelf life and storage stability of freeze-dried probiotic products manufactured by lactic acid bacteria fermentation. The Arrhenius equation was associated in this study. This will provide an efficient approach for the estimation of shelf life of probiotic products.

A Headspace–SPME–MS Method for Monitoring Rapeseed Oil Autoxidation

AbstractHeadspace SPME–MS was used to analyze volatile compounds from rapeseed oil subjected to an accelerated storage test consisting of 0–12 days of storage at 60 °C. The SPME–MS data was compared with the data obtained by solid phase microextraction–gas chromatography/mass spectrometry (SPME–GC/MS). The SPME–GC/MS method allowed detection of 37 volatile compounds, of which 28 were identified. Predominant ones were hexanal, 2,4‐heptadienal, 2‐heptenal and 1‐pentene‐3‐ol. Volatile compounds were not separated in SPME–MS—a single peak reflecting the total amount of volatiles was obtained. An increase in the abundance of characteristic ions in this peak could be used to detect of compounds characteristic for rapeseed oil autoxidation. These compounds (with their characteristic ions) were hexanal (m/z 56), 1‐pentene‐3‐ol and 1‐octene‐3‐ol (m/z 57), 2‐pentenal and 2‐heptenal (m/z 83 and 84), and 2,4‐heptadienal (ions m/z 81 and 110). The SPME–MS peak area was correlated with peroxide value at 0.9779 and with Totox at 0.9841. Principal component analysis (PCA) of fatty acid volatile oxidation products from a model rapeseed oil indicated that SPME–MS was able to differentiate samples containing hexanal at a concentration of 0.2, 0.4, 0.6, 0.8 and 1.0 mg/L with proportional amounts of other compounds. Further, samples that were subjected to 0, 2, 4, 6, 8, 10 and 12 days of storage at 60 °C were differentiated using SPME–MS–PCA. PCA showed similarities in clustering of the data obtained by SPME–MS and sensory analysis.

Prediction of the Preservation of Lyophilized Tobamoviruses

ABSTRACTEleven tobamovirus strains were lyophilized in the form of leaves, plant sap with and without protectant, as well as protected purified preparation. Accelerated storage test at 28–81 °C for 30 to 240 days was applied to the freeze-dried samples. The infectivity was tested on a local host. The survival decrease was represented as pseudo-first order reaction and predictions for stability of lyophilizates at real storage conditions (4 °C) were developed by means of Arrhenius equation. The preservation depended on the lyophilic form and was strain specific. Some strains were expected to loose 90% of the survival after 1–3 years while others—after more than 25 years in unprotected variants. The preservation as protected purified preparations will be more than 60–70 years. Among the tested strains of tomato mosaic virus the highest longevity for the strains of group “2” after Pelham was predicted. The accelerated storage test and the prediction facilitate the maintenance of a plant virus collection.

Combined effects of gamma irradiation and rosemary extract on the shelf-life of a ready-to-eat hamburger steak

To evaluate the effects of the combined treatment of gamma irradiation and rosemary extract powder (rosemary) for improving the quality of a ready-to-eat hamburger steak by changing the storage condition from frozen (−20°C) to a chilled temperature (4°C), an accelerated storage test was carried out. The hamburger steak was prepared with 200 or 500 ppm of rosemary, or 200 ppm of butylated hydroxyanisole by a commercially used recipe, gamma irradiated at absorbed doses of 5.0, 10.0 and 20.0 kGy, and stored at 30°C. From the microbiological aspect, irradiation at 20 kGy or a higher dose was needed to inactivate the normal microflora. Little effect of the antioxidant was, if any, observed. Thiobarbituric acid values were not very different during storage regardless of the irradiation dose and the addition of the antioxidant. Textural and sensory results were also not significantly different in all the samples.

Antioxidative properties and enzymatic synthesis of ascorbyl FA esters

AbstractEfficient synthesis of unsaturated FA esters of ascorbic acid is possible with only a small excess of one of the reactants in t‐amyl alcohol using Candida antarctica lipase as biocatalyst. Using free acids, we obtained yields that were comparable to yields reached using vinyl‐activated acyl donors (71, 80, and 86% yields of esters with FA excesses of 1∶1, 1∶1.5, and 1∶2, respectively). As very low water activity is needed to achieve sufficiently high yields of product, molecular sieves were used to improve the ascorbyl ester yields. Ascorbyl oleate is more amorphous and has a much lower m.p. and lower enthalpy of fusion than ascorbyl palmitate. This leads to a higher solubility of ascorbyl oleate in oil, resulting in an increased antioxidant effect compared to that of the palmitate. In an accelerated storage test using deodorized rapeseed oil, samples incubated with ascorbyl palmitate showed noticeable oxidation after 1 wk of storage, whereas samples incubated with ascorbyl oleate displayed negligible oxidation for 9 and 4 wk at 30 and 40°C, respectively.

Study on Improving Oxidation Stability of Catalytically-Cracked Diesel Oil

In this article, oxidation stabilities of catalytically-cracked diesel oil extracted with several solvents were studied respectively. The experimental results showed that double-solvent extraction was the better method than others, in which furfural containing transition metal ion was used as the first extraction solvent and the 95% ethanol solution was the second extraction solvent. During the course of accelerated storage test, the amount of sediment was reduced from 27.56 mg/100 mL to 0.43 mg/100 mL, and met the requirement of premium grade diesel oil. Under the experimental condition: shaking time of 3 min, the volume ratio of solvent to oil of one and operating temperature 30°C, the extraction result is most satisfied. The color and existent gum reached the standard of premium grade diesel oil. The removal rate of sulfur was up to 74.5%, the removal rate of nitrogen 93.8%. The cetane number of catalytically-cracked diesel oil was enhanced from 37.3 to 51.2. The oxidation stability was improved greatly after being treated.

A New Approach to Accelerated Drug-Excipient Compatibility Testing

The purpose of this study was to develop a method of qualitatively predicting the most likely degradants in a formulation or probing specific drug-excipient interactions in a significantly shorter time frame than the typical 1 month storage testing. In the example studied, accelerated storage testing of a solid dosage form at 50°C, the drug substance SB-243213-A degraded via the formation of two oxidative impurities. These impurities reached a level of 1% PAR after 3 months. Various stressing methods were examined to try to recreate this degradation and in doing so provide a practical and reliable method capable of predicting drug-excipient interactions. The technique developed was able to mimic the 1-month's accelerated degradation in just 1 hr. The method was suitable for automated analysis, capable of multisample stressing, and ideal for use in drug-excipient compatibility screening.

A model for longevity prediction of freeze-dried tobamoviruses

An accelerated storage test was carried out on freeze-dried samples of five variants of tomato mosaic virus – from leaf material, plant sap and purified preparation with and without protectant, at 28, 37 and 45 °C. A model for longevity prediction of lyophilized tobamoviruses was developed. The preservation of tomato mosaic virus decreased to 10% after 0.7–2.8 years in unprotected variants and after 7.5–11 years in protected samples under real storage conditions. Experimental data have confirmed the predicted values.

Prediction of the preservation of freeze-dried cucumber mosaic virus.

A mathematical model to predict the outcome of preserving plant viruses has been developed. The survival of two cucumber mosaic virus strains lyophilized in leaves and in protected plant sap was evaluated using an accelerated storage test at 28, 37 and 45 °C. The combinations of 5% (w/v) sorbitol and 7% (w/v) glucose with 3.6% (w/v) dextran 40 000 were applied as protecting media. The predicted values to a great extent correspond to the experimental data, achieved after 1, 4 and 7 years of storage.

FUEL SYSTEM ICING INHIBITORS: THE SYNTHESIS OF ESTERS OF OXAACIDS

ABSTRACT Currently ethylene glycol mono methyl ether (EGME) and diethylene glycol mono methyl ether (DiEGME) are used as fuel system icing inhibitor additives in both military and commercial aircraft. These compounds are toxic at the concentrations that required for effective deicing When fuel systems sumps, filters and storage tanks are drained, they contain EGME/DiEGME and create hazards for personnel. Ethyl esters synthesized from oxaacids have been identified as possible fuel system icing inhibitor additive replacements. These compounds were synthesized from oxaacids and ethanol by an acid catalyzed Fischer esterfication method The products were identified by infrared spectrometry, nuclear magnetic resonance spectrometry, and elemental analysis Physical characterization included boiling point determination and refractive index. The tested oxaesters were found to be fuel stable for at least two years by accelerated storage tests. Octanol-water partition coefficients were determined and indicate the compounds have a higher solubility in fuel than in water. These oxaesters are predicted to be non-toxic.

NONENZYMIC BROWNING REACTIONS IN MULTI SUGAR AND AMINO ACID SYSTEMS

Accelerated storage tests were carried out for accumulation of 5-hydroxy methyl furfural (HMF) and brown pigment formation (BPF) in the model systems containing more than one sugar and amino acid. In these tests, the effects of temperature and amino acid type were investigated at pH 3.5. In the model systems with glutamine or arginine, the accumulation of HMF and BPF were higher than the model systems containing proline at 55, 65 and 75C. The presence of more than one amino acid in the model caused an additive increase in HMF accumulation and BPF. The effect of temperature on both HMF accumulation and BPF were significant (P < 0.05). Both HMF accumulation and BPF were affected significantly (P < 0.05) by the addition of amino acid(s) into sugar solution.

Accelerated storage testing of freeze-dried and controlled low-temperature vacuum dehydrated Lactobacillus acidophilus.

Accelerated storage testing of freeze-dried and controlled low-temperature vacuum dehydrated Lactobacillus acidophilus.

Application of accelerated storage test to lyophilized plant viruses

The preservation of nine plant virus strains of tobamovirus and cucumovirus groups after freeze-drying in different lyophilic forms was examined. Quantitative studies on survival were performed. In tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV), accelerated storage test at 70 – 100°C was applied for screening 20 protecting media. A perspective medium, 5% sorbitol, 3.6% dextran, for plant viruses lyophilization with high cryo- and xeroprotective effects was found.