1,720,974 research outputs found
Development a new active packaging system for fresh food through the studies of chemical and biological markers
No full textPackaging and food should not be considered two separate entities, but as elements that can interact, always with the aim to improve the acceptability of the packaged product. In the last two decades many researchers have placed their attention on the study of new packaging systems that improves food preservation. The most investigated new preservation technologies for fresh meat are new packaging systems such as active packaging (AP) and modified atmosphere packaging (MAP) which use natural antimicrobials for bio preservation. AP is the incorporation of specific compounds into packaging systems that interact with the contents environment to maintain or increase product quality and shelf life. AP functions and technologies include moisture control, O2 scavengers or absorbers, CO2 controllers, odours controllers, antimicrobial and antioxidant agents, either natural or synthetic. By preserving the important nutrients of fresh meat such as proteins, essential amino acids, vitamins of group B and others, AP technology can be useful for enhancing the intake of these nutrients too. Natural extracts and essential oils of plants are extraordinary sources of bioactive molecules mixtures, having important antioxidant and antimicrobial actions. The use of natural extracts categorized as flavourings by the European Union (EU) and generally recognized as safe (GRAS) by the US Food and Drug Administration (FDA), represents an interesting approach in AP technology. Considerable results, especially from a biological point of view, have been carried out on the assessment of the antioxidant activity of many herbs such as rosemary (Rosmarinus officinalis), oregano (Origanum vulgare) and others incorporated in an active packaging film. The Rosemary (Rosmarinus officinalis L.) essential oil (REO) contains bioactive compounds having important antioxidant and antimicrobial activities. In this research work the shelf life of different types of fresh food (chicken and beef meat, raw and cooked ham) was studied by monitoring: biogenic amines (BAs), hexanal, microbial growth (such as psychrotrophics, Brochothrix thermosphacta, Pseudomonas spp., and Enterobacteriaceae), pH, colorimetric measurement (L*, a*, b* values) and sensory analyses. The packaging used were Ideabrill® enriched with REO (called ''AP''), Ideabrill® (NAP) and the common packaging (PP). Fresh food wrapped in different systems, were stored at 4°C in different condition: air, under-vacuum and with high-O2 concentration (50:30:20; O2:CO2:N2 %). First of all, more attention was focused on the studies of BAs, that are basic nitrogenous compounds considered important indicator of freshness and quality of food. The active packaging system (AP) that incorporating essential oil of Rosmarinus officinalis at 4% (w/w), inhibits the increase of BAs and the bacteria involved in to their production was developed. BAs were analyzed by a SPE-HPLC-DAD method during the storage time of meat (0-7 days, 4°C). Results showed that, in each monitored day, Biogenic Amine Index (BAI) expressed in mg kg-1 is lower in meat wrapped in AP with respect to that packed in polycoupled packaging (PP) (from 19% to 62%). A strong correlation was found between the inhibition of increase of putrescine, cadaverine, histamine and their bacteria producers such as Enterobacteriaceae, Pseudomonas spp., Brocothrix thermospacta. By exploiting antimicrobial and antioxidant action of essential oil of Rosmarinus officinalis, the new APs contributes to increase the shelf life of fresh meat and to preserve its important nutrients. Moreover, the antioxidant action of new AP system was tested by monitoring hexanal as marker of lipidic oxidation of fresh meat. Preliminary results showed good results in favour of food wrapped in AP system in comparison with PP. In collaboration with Ghent University, the shelf life of beef meat wrapped in AP and in NAP under different air conditions were studied. Microbial growth, sensory characteristics, color parameters, and pH were measured. The use of REO has proved to be efficacious in every storage conditions, because the counts of psychrotrophics, Brochothrix thermosphacta, Pseudomonas spp., and Enterobacteriaceae were lower in AP meat compared to NAP meat. Sensorial and colorimetric analysis showed that the best packaging conditions were high-O2 atmosphere in combination with REO. Based on microbiological data, shelf life of beef meat was 5 days for air packaged samples (AP and NAP), 6-7 days for NAP under vacuum condition samples, 8-9 days for AP under vacuum condition samples, 9-10 for NAP in high-O2 condition samples, and until 15 days for AP in high-O2 condition samples. During the last part of the work, a new analytical method for analyzing ten underivatized BAs in meat by HPLC-MS/MS has been developed. The comparison between ion trap and triple quadrupole as mass analyzers elected triple quadrupole for its higher sensitivity and selectivity. The correlation coefficients of calibration curves of the analyzed compounds were in a range 0.987-0.999, and the Limits of Detection (LODs) and Limits of Quantification (LOQs) were in the range 0.002-0.1 mg l-1 and 0.008-0.5 mg l-1, respectively. The validated method was applied to the analysis of sixteen commercial meat samples for evaluating the freshness of food through the study of BA indices, i.e. Biogenic Amine Index (BAI) and the ratio spermidine/spermine (SPD/SPE). Results showed that all analyzed samples presented good freshness quality with a BAI lower than 1.49 mg kg-1 and a SPD/SPE ratio lower than 0.41 in each case. This methodology to test the freshness of meat could have a great potentiality of application along the entire production chain of meat products
Simultaneous determination of ten underivatized biogenic amines in meat by liquid chromatography-tandem mass spectrometry (HPLC-MS/MS)
Full text linkBiogenic amines (BAs) are considered to be important indicators of freshness and quality in food. In this work, an analytical
method for analyzing ten underivatized BAs in meat by performance liquid chromatography-tandem mass spectrometry
has been developed. Comparison between ion trap and triple quadrupole as mass analyzers indicated that the latter provides
greater sensitivity and selectivity. The range of the correlation coefficients of the calibration curves of the analyzed
compounds was 0.987–0.999, and the limits of detection and limits of quantification were in the range of 0.002–0.1mgl1
and 0.008–0.5mgl1, respectively. Once validated, the method was used to analyze the concentrations of BAs in 16
commercial meat samples, for evaluating the freshness of food through the study of BA indices, i.e. biogenic amine index
(BAI) and the ratio spermidine/spermine (SPD/SPE). The results indicated that all the samples were fresh, with a BAI lower than
1.49mgkg1 and a SPD/SPE ratio lower than 0.41 in each case. This methodology for testing the freshness of meat has potential
for quality control applications along the entire production chain of meat products
Effect of Rosmarinus officinalis L. essential oil combined with different packaging conditions to extend the shelf life of refrigerated beef meat
No full textRosemary essential oil (REO) contains bioactives having antioxidant and antimicrobial properties. This work investigated the effect of REO combined with modified atmosphere packaging conditions (MAP), in our case, aerobic, vacuum or high O-2, to extend the shelf life of beef. Beef slices were wrapped in special three-layer sheets of packaging material, some with a coating of REO (active packaging, AP), and some without REO (non active packaging, NAP), and stored at 4 degrees C for 20 days. The use of REO proved efficacious in every storage condition, as seen in the lower counts of psychrotrophics, Brochothrix thermosphacta, Pseudomonas spp., and Enterobacteriaceae in AP meat compared to NAP meat. Sensory and colourimetric analyses showed that the best packaging conditions were high-O-2 atmosphere in combination with REO. Based on microbiological data, shelf life of beef was 5-6 days for AP samples packaged under aerobic conditions and 14-15 days for AP samples in high-O-2 conditions
Optimization of espresso machine parameters through the analysis of coffee odorants by HS-SPME–GC/MS
No full textThe aroma profile and the final quality of espresso coffee (EC) are influenced by such technical conditions
as the EC machine extraction temperature and the pressure used. The effect of these two parameters on
EC quality were studied in combination by headspace solid phase micro extraction–gas chromatography–
mass spectrometry (SPME-GC–MS) and sensory profile. Moreover, 10 key odorants at the best EC
machine settings were examined to compare the two coffee cultivars (Arabica and Robusta) and two
EC machines [Aurelia Competizione (A) and Leva Arduino (B)]. The data obtained provides important
information about espresso making technique, suggesting that the usual espresso machine temperature
and pressure settings (i.e. 92 C and 9 bar) are very close to those needed to obtain the best quality
espresso. This confirms the traditional wisdom of coffee making, which judges 25 ml, the typical volume
of a certified Italian EC, to be ideal for very strong aroma intensity
Simultaneous Determination of Squalene, α-Tocopherol and β-Carotene in Table Olives by Solid Phase Extraction and High-Performance Liquid Chromatography with Diode Array Detection
Full text linkOlives, the fruit of the Olea europaea tree, are
highly appreciated in olive oil and table olives (20 % of
crops) not only for their flavor but also for their nutritional
properties, especially for antioxidant compounds such as
squalling (SQ), α-tocopherol (TH) and β-carotene (BC).
This paper presents a new analytical method for simultaneously
determining SQ, TH and BC in table olives by
using solid phase extraction (SPE) and high performanceliquid
chromatography with diode array detection (HPLCDAD),
avoiding the classic saponification process. The correlation
coefficients of calibration curves of the analyzed
compounds ranged from 0.998 to 0.999, and the recoveries
were in the range of 89.4–99.6 %. The validated method was
used to analyze 30 table olive samples from Italy for their
content of SQ (537–1,583 mg kg−1), TH (21–90 mg kg−1) and
BC (0.4–2.6 mg kg−1). Finally, experiments with HPLC-MS
were conducted to compare this novel method with the classic
saponification procedure
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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