2,163 research outputs found
Theory and experiment of the ESR of Co in Zn % (OH)PO and Mg(OH)AsO
Experiments of Electron Spin Resonance (ESR) were performed on Co
substituting Zn or Mg in powder samples of Zn(OH)PO and
Mg(OH)AsO. The observed resonances are described with a theoretical
model that considers the departures from the two perfect structures. It is
shown that the resonance in the penta-coordinated complex is allowed, and the
crystal fields that would describe the resonance of the Co in the two
environments are calculated. The small intensity of the resonance in the
penta-coordinated complex is explained assuming that this site is much less
populated than the octahedral one; this assumption was verified by a molecular
calculation of the energies of the two environments, with both Co and Zn as
central ions in Zn(OH)PO.Comment: 43 pages, LaTex file, 6 figures, EPS. submitted to Journal of Physics
Condens
The Effect of starter Cultures on the Portuguese Traditional Sausage "Paio do Alentejo" in Terms of its Sensory and Textural Characteristics and Polycyclic Aromatic Hydrocarbons Profile
“Paio do Alentejo” is a Portuguese dry-cured sausage, made with meat from the Alentejano pig breed. The main aim of this study is to evaluate the benefits of the use of starter cultures on the quality of the sausage, mainly with regard to its sensory properties, rheological characteristics and PAH profile.
Three batches of the product were examined: S1-inoculated with a commercial starter comprising Lactobacillus spp., Micrococcaceae and yeasts; S2-inoculated with a starter comprising Lactobacillus sakei and Staphylococcus xylosus; C-the control batch, was not inoculated.
A sensory panel of 12 experts analysed samples in accordance with a descriptive analysis using a structured scale. A Texture Profile Analysis and 16 EPA priority PAHs for dry fermented sausages were performed.
Both inoculated batches were well received by the judges, no significant differences being noted between them. The use of S2 led to a slight improvement in terms of cohesiveness. However, the use of starter cultures was not found to influence PAH content
LA PROPAGACIÓN MASIVA DE ORQUÍDEAS (Orchidaceae); UNA ALTERNATIVA DE CONSERVACIÓN DE ESPECIES SILVESTRES
this work the use of in vitro cultivation techniques is reviewed as a fundamental component of the propagation and conservation programs of native orchids. Through micropropagation, the massive production of plants has been possible, free of pathogens, at low cost, in reduced space, less time, and under controlled conditions. The banks of in vitro germplasm are sites for the conservation of phytogenetic resources under controlled laboratory conditions and involve diverse cultivation and preservation techniques; in addition, the advantages of this technique as a tool for the study of environmental factors that influence the development and flowering of orchids are analyzed.En el presente trabajo se revisa el uso de las técnicas de cultivo in vitro como componente fundamental de los programas de propagación y conservación de orquídeas nativas. A través de la micropropagación ha sido posible la producción masiva de plantas, libres de patógenos, a bajo costo, en espacio reducido, en menor tiempo y bajo condiciones controladas. Los bancos de germoplasma in vitro son sitios para la conservación de recursos fitogenéticos en condiciones controladas de laboratorio e involucran diversas técnicas de cultivo y preservación, además, se analizan las ventajas de dicha técnica como herramienta para el estudio de los factores ambientales que influyen en el desarrollo y la floración de las orquídeas
The effect of the addition of a commercial bioprotector in characteristics of "alheira" made from Alentejano pig meat
“Alheira” is a traditional fermented sausage usually produced from poultry meat. A new product was developed at a Portuguese traditional meat plant using Alentejano pig breed meat [1]. The aim of this study was to evaluate the use of a commercial bioprotector in the physicochemical, microbiological and instrumental texture parameters, as well as in the sensorial attributes of the “alheiras”.
Two different treatments were compared, namely control and bioprotector and three end product “alheiras” with three days were used per treatment. One-Way ANOVA was used for statistical analyses.
The pH of the “alheiras” with bioprotector (4.29) was lower than the pH of the control treatment (4.48). However, no significant differences were observed between control and bioprotector regarding water activity (aw). The “alheiras” microbiological flora showed no significant differences regarding total mesophiles, total anaerobes, lactic acid bacteria, enterobacteria, Escherichia coli and Listeria spp. The counts of psychrophiles (2×107 cfu/g) and psychrophilic anaerobes (1.7×107 cfu/g) were higher in the control treatment, whereas more yeasts and moulds (7×104 cfu/g) are present in the “alheiras” with bioprotector. No contamination with Salmonella sp. was detected, but some samples showed a minor contamination with Listeria monocytogenes. Further studies are in course to reduce microbial contamination, particularly to eradicate Listeria monocytogenes [2]. Texture Profile Analysis (TPA) results revealed that the adhesiveness of the bioprotector “alheiras” (-0.386 N s) is lower than in the control (-0.2 N s). However, no significant differences were observed for other instrumental texture parameters. Regarding sensorial analysis, although no differences were observed between control and bioprotector “alheiras”, panellists noticed some off tastes in the bioprotector treatment.
Considering the results of the end product at three days shelf life, no advantage was seen in the bioprotector “alheiras”. These have lower pH, which could justify the off tastes noticed by some panellists and their higher counts of yeasts and moulds.
Acknowledgements
This work was supported by national funds through project PRODER (QREN/PRODER/Medida 4.1) and funded by FEDER Funds through the COMPETE and National Funds through FCT under the Strategic Project PEst-C/AGR/UI0115/2011. The authors thank PALADARES ALENTEJANOS, Lda. for their collaboration and A. Oliveira and G. Pias for their technical assistance.
References:
1-Elias, M. et al. (2013) “Portuguese traditional sausage, “alheira”, made with different meat: sensory evaluation and texture.” ICoMST 2013 E-Book of Proceedings, 59th International Congress of Meat Science and Technology, Izmir, Turkey, 18-23 August 2013.
2-Felício et al. (2011) “Thermal inactivation of Listeria monocytogenes from alheiras, traditional portuguese sausage during cooking.” Food Control 22, 1960-1964
The calibre effect on two traditional dry fermented sausages from Alentejo, Portugal, made from the same dough
Traditional food products are an important part of European gastronomy and it has been long empirically known that traditional fermented foods are vital to a good digestive health. However, and also due to health concerns, an extensive evaluation of food quality and safety parameters is crucial. Two low-salt dry-fermented sausages were manufactured from the same dough with two different casing calibres (small-“Catalão”/large-“Salchichão”) using two pig genotypes (Alentejano/Iberian x Duroc) and two NaCl concentrations (3%/5%). Three independent batches with replicates were prepared. The effects of calibre, genotype and salt concentration on the microbiological, physicochemical and textural parameters, as well as on sensory acceptability were considered. Analyses of variance were performed considering calibre, genotype and salt concentration. Regarding food safety of these traditional products, no Salmonella spp., Campylobacter spp. and Listeria monocytogenes, nor Enterobacteriaceae or in particular E. coli, were detected in the analysed products. Different numbers of lactic acid bacteria (LAB), enterococci and Micrococaceae were observed between the two calibres (p<0.05). Significantly different pH values were observed between genotypes and calibre (p<0.05). On the other hand, aw values differ significantly with salt (p<0.05). The Texture Profile Analysis (TPA) revealed significant differences between the two calibres regarding hardness, cohesiveness, resilience, gumminess and chewiness (p<0.05). Concerning the sensorial analysis, the calibre effect was sensed in the attributes succulence and tenderness (p<0.05). Salt differences were noted by panellists, but have minor impact on other studied parameters. Overall, the calibre effect was the most distinctive one, followed by the effect of genotype.
Acknowledgements
This work was supported by national funds through project PRODER 13.021 (QREN/PRODER/Medida 4.1), Fundação para a Ciência e a Tecnologia (FCT) under the Strategic Project PEst-OE/AGR/UI0115/2014 and co-funded by FEDER Funds through the COMPETE Programme. The authors thank PALADARES ALENTEJANOS Lda., A. Oliveira, G. Pias and R. Bicho for their collaboration
Comment on "Critique of q-entropy for thermal statistics" by M. Nauenberg
It was recently published by M. Nauenberg [1] a quite long list of objections
about the physical validity for thermal statistics of the theory sometimes
referred to in the literature as {\it nonextensive statistical mechanics}. This
generalization of Boltzmann-Gibbs (BG) statistical mechanics is based on the
following expression for the entropy:
S_q= k\frac{1- \sum_{i=1}^Wp_i^q}{q-1} (q \in {\cal R}; S_1=S_{BG} \equiv
-k\sum_{i=1}^W p_i \ln p_i) .
The author of [1] already presented orally the essence of his arguments in
1993 during a scientific meeting in Buenos Aires. I am replying now
simultaneously to the just cited paper, as well as to the 1993 objections
(essentially, the violation of "fundamental thermodynamic concepts", as stated
in the Abstract of [1]).Comment: 7 pages including 2 figures. This is a reply to M. Nauenberg, Phys.
Rev. E 67, 036114 (2003
Queso fresco Alentejano de cabra con aceite esencial de orégano
El consumo de queso ha aumentado en los últimos años debido a la gran cantidad de tipos de quesos que podemos
encontrar en el mercado, gracias a las diferentes clases de leche y de tecnologías existentes (Gouvea et al., 2017). El queso
fresco es muy apreciado por su valor nutricional y su sabor agradable, considerándose un alimento saludable por su bajo
contenido en sal (Gouvea et al. 2017; Lourenço et al., 2017). Este tipo de queso con bajo contenido en sal, pH próximo a la
neutralidad y alta actividad de agua, favorece el crecimiento de microorganismos, acortando la vida útil del producto
(Gadotti et al., 2014).
Una buena alternativa para evitar la proliferación de microorganismos en los alimentos es el uso de aceites esenciales
extraídos de plantas aromáticas y medicinales (Laranjo et al. 2017). En el aceite esencial de orégano uno de sus compuestos
principales es el carvacrol, que es un compuesto fenólico con capacidad antimicrobiana (Burt, 2004; Laranjo et al., 2017).
Existe un gran número de estudios in vitro que han determinado la concentración mínima inhibitoria del aceite esencial de
orégano en torno a 0,28 mg.ml-1 – 1,25 mg.ml-1 (Burt, 2004; Laranjo et al., 2017).
El objetivo de este estudio fue la comparación de queso fresco de cabra, natural, y queso fresco de cabra, con aceite
esencial de orégano
Essential oils of aromatic and medicinal plants play a role in food safety
Essential oils (EOs) are natural substances extracted from aromatic and medicinal plants (AMPs), important in food preservation. Several studies have shown that AMPs, as well as their EOs have antimicrobial (antibacterial and antifungal) activity. Indeed, our in vitro studies have shown that oregano and thyme EOs are effective against foodborne bacteria, isolated from fermented meat products and cheeses, such as Escherichia coli, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus. However, EOs of thyme and oregano seem to control the growth of fungi, namely Botrytis cinerea and Aspergillus spp., affecting the shelf‐life of fruits during postharvest. The EOs of sage and rosemary have shown little or no antimicrobial activity. Shelf‐life extension studies using several EOs (cinnamon, clove, oregano, rosemary, sage, and thyme) and AMPs were performed using pork meat, goat cheese, strawberries, and table grapes. Preliminary results regarding food safety and sensory acceptability are discussed.Practical applicationsConsumers' demands for more traditional and healthier food products led to a search for alternatives to replace synthetic by natural additives. EOs of AMPs contribute to food safety, due to their antimicrobial properties. Consequently, the use of AMPs' EOs may also extend the shelf‐life of food products. In the present study, experi ‐mental shelf‐life trials using EOs with different food products were performed, with promising preliminary results. Cinnamon, sage, and thyme EOs extended the shelf‐life of strawberries and table grapes. Oregano EO prolonged the shelf‐life of soft cheese. Thyme EO controlled the population of enterobacteria present in pork meat. Furthermore, the conditions used in this study can be directly applied in the food in ‐dustry. Moreover, AMPs may be interesting alternatives to replace or reduce artificial food additives
"Cachena" a bovine rustic Portuguese extensively reared autochthonous breed: meat texture analysis
‘Cachena’ is one of the world’s smallest bovine breeds. Extremely rustic and wild, they are extensively reared, and fed with natural pastures. Meat valorisation is essential to preserve this breed, with a limited livestock.
‘Cachena’’s meat is tender, juicy, low-fat, and highly appreciated due to the association of animal, terroir and producer, balanced by the ecosystem’s sustainability.
The aim of this study was to increase the weight of Longissimus dorsi (LD) and Psoas major (PM) muscles, without depreciating their sensory quality.
Two groups of 16 animals were slaughtered: (A) 9-17 months old animals with 140-225 kg slaughter live weight (SLW); (B) 17-20 months old animals with 260-335 kg SLW. LD and PM muscles’ fresh weight was recorded, and microbiological and physicochemical parameters (pH and aW) were evaluated two days, while instrumental texture (Texture Profile Analysis (TPA) and Warner-Bratzler shear force (WBSF)) and sensory analyses by a trained sensory panel were performed four days after slaughter. Microbiological analyses were conducted following international standards to ensure food safety.
LD and PM weights significantly increased with the animals’ age (P<0.01, LD, and P<0.001, PM). pH values were similar for both groups and aW was significantly higher in group A (P<0.001).
Listeria monocytogenes and Salmonella spp. were not detected in any of the analysed samples.
All analysed meat samples were generally tender, with PM tender than LD. Group A meat was tender (P<0.001) and easier to chew (P<0.001), for both muscles. Nevertheless, WBSF was higher (P<0.001).
Regarding sensory analysis, no significant differences were observed in hardness, elasticity, succulence, and global appreciation between the two groups for LD meat. Moreover, fibrousness values were higher in group A (P<0,01).
The higher SLW, from older ‘Cachena’ animals, associated to larger meat cuts, does not decrease meat tenderness
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