Electrospun fibers based on porcine plasma: a rheological and morphological study

Iranian Polymer Journal - The present work focuses on the assessment of the ability of porcine plasma protein (PPP) to be electrospun satisfactorily to form fibre mats, and their rheological and...     

Antioxidant potential of single-variety red wines aged in the barrel and in the bottle

Wine constitutes a dynamic system in continuous evolution, in which numerous reactions involving polymerization and condensation take place between its phenolic compounds during the ageing process, which undoubtedly affect its structure and, very probably, its antioxidant effect. This study set out to evaluate the effect of ageing on the antioxidant potential of wine. A group of 162 wines were studied, of varying ages, which had undergone different ageing processes, both in the barrel and in the bottle, and which were prepared from different grape varieties and vintages. Total antioxidant capacity (ABTS, DPPH, DMPD, ORAC and FRAP), scavenger activity (HRSA and SRSA) and the biomarkers of oxidative stress (DNA-damage and ABAP-LP) were all analysed. The assay methods showed different behaviours for the same wines, thus the young wines presented higher indices for ABTS, DPPH and DMPD, whereas those that were aged showed higher indices for ABAP-LP and ORAC. Finally, the antioxidant potential of the wines in the study appeared not to be influenced by other factors, such as microoxygenation or grape variety.     

Geographical origin classification of olive oils by PTR-MS

The volatile compositions of 192 olive oil samples from five different European countries were investigated by PTR-MS sample headspace analysis. The mass spectra of all samples showed many masses with high abundances, indicating the complex VOC composition of olive oil. Three different PLS-DA models were fitted to the data to classify samples into ‘country’, ‘region’ and ‘district’ of origin, respectively. Correct classification rates were assessed by cross-validation. The first fitted model produced an 86% success rate in classifying the samples into their country of origin. The second model, which was fitted to the Italian oils only, also demonstrated satisfactory results, with 74% of samples successfully classified into region of origin. The third model, classifying the Italian samples into district of origin, yielded a success rate of only 52%. This lower success rate might be due to either the small class set, or to genuine similarities between olive oil VOC compositions on this tight scale.     

Changes in the volatile composition of red wines during aging in oak barrels due to microoxygenation treatment applied before malolactic fermentation

Microoxygenation is a wine-making technique consisting in the addition of small and controlled amounts of oxygen. This study has examined the effect of this technique on the volatile composition of two red single variety wines during two successive vintages. The microoxygenation treatment was applied at the end of alcoholic fermentation and before beginning malolactic fermentation. Once the microoxygenation treatment had finished, wines were aged in new American oak barrels for 12 months. The results obtained showed that the microoxygenation treatment did not cause significant changes in the varietal and fermentation volatile compounds, however microoxygenation slowed down the extraction of some of the volatile compounds extracted from wood. A varietal and vintage effect was also observed for some of the compounds studied.     

Field testing passive air samplers for current use pesticides in a tropical environment

Air was sampled for one year in the central valley of Costa Rica using an active high-volume sampler as well as passive samplers (PAS) based on polyurethane foam (PUF) disks and XAD-resin filled mesh cylinders. Extracts were analyzed for pesticides that are either banned or currently used in Costa Rican agriculture. Sampling rates for PUF-based passive air samplers, determined from the loss of depuration compounds spiked on the disks prior to deployment averaged 5.9 +/- 0.9 m3 x d(-1) and were higher during the windier dry season than during the rainy season. Sampling rates for the XAD-based passive sampler were determined from the slopes of linear relationships that were observed between the amount of pesticide sequestered in the resin and the length of deployment, which varied from 4 months to 1 year. Those sampling rates increased with decreasing molecular size of a pesticide, and their average of 2.1 +/- 1.5 m3 x d(-1) is higher than rates previously reported for temperate and polar sampling sites. Even though the trends of the sampling rate with molecular size and temperature are consistent with the hypothesis that molecular diffusion controls uptake in passive samplers, the trends are much more pronounced than a direct proportionality between sampling rate and molecular diffusivity would suggest. Air concentrations derived by the three sampling methods are within a factor of 2 of each other, suggesting that properly calibrated PAS can be effective tools for monitoring levels of pesticides in the tropical atmosphere. In particular, HiVol samplers, PUF-disk samplers, and XAD-based passive samplers are suitable for obtaining information on air concentration variability on the time scale of days, seasons and years, respectively. This study represents the first calibration study for the uptake of current use pesticides by passive air samplers.     

Effect of selected mould strains on the sensory properties of dry fermented sausages

The effect of one Mucor and two Penicillium strains (Penicillium-3 and Penicillium-6) on the development of the sensory properties of dry fermented sausages has been studied. These strains were previously isolated from Spanish fermented sausages and selected for their proteolytic and lipolytic activity. Several experimental batches were prepared: one of them was non-inoculated and considered as control batch, three were inoculated with the selected strains, and the last one was inoculated with a commercial starter culture of P. nalgiovense. The pleasantness of the sensory attributes of the different batches were determined using an unstructured line scale of 10 cm. A triangular test was also carried out. Apart from their external appearance, batches inoculated with Mucor and Penicillium-3 had the highest scores for all the sensory attributes studied. The batch inoculated with P. nalgiovense had the lowest scores and similar to the control batch but its external appearance was considered to be the most pleasant. The batch inoculated with Penicillium-6 presented intermediate characteristics. A relation between these results and the enzymic activity of the moulds was established. The three strains selected for this study are proposed to be incorporated in a commercial starter culture because they improve the sensory properties of these meat products.     

Evaluation of freshness decay of minced beef stored in high-oxygen modified atmosphere packaged at different temperatures using NIR and MIR spectroscopy

Meat freshness has been monitored by various microbiological, chemical and sensorial indices. However, these methods are slow and not suited to automation. Infrared spectroscopy is one of the most convenient analytical tools which could be used to monitor the evolution of food quality. The aim of this work was to investigate the ability of both NIR (Near Infrared) and MIR (Mid Infrared) spectroscopy to follow meat freshness decay. The minced beef was packaged in high-oxygen modified atmosphere (30% CO₂ and 70% O₂) and stored at three temperatures. Spectra were collected by Fourier-Transformation (FT)-NIR and FT-IR instruments. PCA, applied to the data, was able to discriminate samples on the basis of storage time and temperature. The modelling of PC scores versus time allowed the setting of the time of initial freshness decay for the samples (6–7 days at 4.3 °C, 2–3 days at 8.1 °C and less than 1 day at 15.5 °C).     

Impact of postharvest methyl jasmonate treatment on the volatile composition and flavonol content of strawberries

BACKGROUND: Although strawberry aroma is very complex, certain compounds have been described as main contributors, i.e. furanones, aldehydes, alcohols, sulfur compounds and particularly methyl and ethyl esters. In addition, strawberries possess potent antioxidant activity because of their high content of phenolic compounds. Among them, flavonols are highlighted as important antioxidant compounds in strawberry. The objective of this study was to assess the effect of methyl jasmonate (MJ) on the composition of the major contributors to aroma and on the content of certain flavonols in strawberry fruits. RESULTS: The levels of all studied volatile compounds were significantly affected by MJ treatment, though the individual effect differed according to the specific compound considered. Most of them increased significantly (P < 0.05), except methyl butanoate, which always showed higher levels in untreated strawberries. In contrast to aroma compounds, the change in the concentration of flavonols (i.e. myricetin, quercetin and kaempferol) was not significant in MJ‐treated strawberries. Considering the health‐promoting activity of these compounds, further investigations on the experimental conditions related to the treatment are required to control flavonol bioformation by means of MJ. CONCLUSION: The exogenous application of MJ vapour to strawberry enhances, in general, the production of the most relevant aroma‐active compounds. On the contrary, MJ treatment does not appear to influence the levels of myricetin, quercetin and kaempferol. Thus postharvest MJ treatment is proposed as an approach to obtain improved strawberry fruits in terms of sensory quality and health‐promoting properties. Copyright © 2010 Society of Chemical Industry     

Effect of selected yeast strains on the sensory properties of dry fermented sausages

This study examines the role of yeasts in the sensorial characteristics of dry fermented sausages. A total of 172 yeast strains were isolated from commercially obtained dry fermented sausages and their enzymatic activities studied. Those most active against meat proteins and pork fat were selected. Experimental sausages were manufactured and the yeasts inoculated onto the surface or into the mince. Control batches were manufactured similarly, but without inoculation. After ripening, the composition of the protein and lipid fractions were studied. The sensory properties of the products were evaluated by trained judges. Despite the enzymatic activity of the yeasts, the organoleptic characteristics of the sausages—irrespective of inoculation site—did not differ significantly from those of the controls. The influence of yeasts on the ripening of dry fermented sausages is, therefore, doubtful.     

Solid phase microextraction (SPME) applied to honey quality control

The assessment of the botanical origin of unifloral honeys is an important application in food control. The current official methods mainly use pollen analysis. The aim of this paper is to present an SPME analytical approach to the study of honey volatiles. Honey samples (40) obtained from hive sites in different regions of Italy were analysed. The samples had six different botanical origins: citrus (five), chestnut (10), eucalyptus (eight), lime tree (11), thyme (two) and dandelion (four). Melissopalynological analysis was also performed. Identification of volatile compounds was carried out by SPME/GC/MS analysis, and quantitative evaluation was done by SPME/GC/FID analysis for compounds with well‐resolved peaks. Using the SPME method, all samples with the same botanical origin gave remarkably similar GC profiles. Some volatile compounds were found only in specific floral source honey samples and thus could be interesting for use as markers. Copyright © 2003 Society of Chemical Industry