Impact of salt reduction on biogenic amines, fatty acids, microbiota, texture and sensory profile in traditional blood dry-cured sausages

Meat industry needs to reduce salt in their products due to health issues. The present study evaluated the effect of salt reduction from 6% to 3% in two Portuguese traditional blood dry-cured sausages. Physicochemical and microbiological parameters, biogenic amines, fatty acids and texture profiles and sensory panel evaluations were considered. Differences due to salt reduction were perceptible in a faint decline of water activity, which slightly favoured microbial growth. Total biogenic amines content ranged from 88.86 to 796.68 mg kg 1 fresh matter, with higher amounts, particularly of cadaverine, histamine and tyramine, in low-salt products. Still, histamine and other vasoactive amines remained at low levels, thus not affecting consumers’ health. Regarding fatty acids, no significant differences were observed due to salt. However, texture profile analysis revealed lower resilience and cohesiveness in low-salt products, although no textural changes were observed by the sensory panel. Nevertheless, low-salt sausages were clearly preferred by panellists.

Development of an organocatalytic method for the enantioselective synthesis of rivastigmine

The focus of this thesis was the study of a recently developed class of picolinamide cinchona alkaloid derivatives for the synthesis of Rivastigmine, a biologically active compound used for the treatment of Alzheimer’s disease. Six 9-picolinamide-cinchona alkaloid derivatives were successfully synthesized through simple and effective methods. These catalysts were then applied in the enantioselective reduction of O-protected ketimines (intermediates of Rivastigmine). The hydrosilylation of the N-phenyl ketimines afforded good results with excellent yields and high enantioselectivities, while much lower values, in terms of both enantioselectivity and yield, were obtained in the reduction of N-benzyl ketimines. Preliminary studies on the immobilization of these organocatalysts to different solid supports were conducted, with the purpose of applying them in continuous flow systems, which to date has never been reported; RESUMO: No âmbito deste trabalho, foi estudada a síntese de um composto biologicamente ativo usado para o tratamento da doença de Alzheimer, Rivastigmina, usando uma classe de picolinamidas derivadas de alcaloides de cinchona recentemente desenvolvida. Seis 9-picolinamida derivados de alcaloides de cinchona foram preparados com êxito através de metodologias simples e eficazes. Os organocatalisadores foram posteriormente aplicados na redução enantiosseletiva de cetiminas O-protegidas (intermediários de Rivastigmina). Foram obtidos bons resultados na hidrossililação de N-fenilo cetiminas, com rendimentos excelentes e elevadas enantiosseletividades, enquanto a redução de N-benzilo cetiminas proporcionou valores muito mais baixos, tanto em termos de rendimento como de enantiosseletividade. Com o objetivo de serem aplicados em sistemas de fluxo contínuo, realizaram-se estudos preliminares sobre a imobilização destes organocatalisadores em diferentes suportes sólidos, a qual, ate à data, ainda não foi descrita na literatura.

Characterisation of "Catalão" and "Salsichão" Portuguese traditional sausages with salt reduction

The present study evaluated the effect of salt reduction on traditional dry-cured sausages' safety, quality and product acceptance, comprising physicochemical and microbiological parameters, biogenic amines, fatty acids, texture profile and sensory analysis. According to our results, salt content had a major effect on microbiological counts, although not compromising the products' safety. Marked differences were identified regarding biogenic amines, in particular for histamine, tyramine and cadaverine, which were detected in larger amounts in products with 3%. Moreover, significant differences in the fatty acids profile have also been found, but only in less abundant components such as linoleic, lauric and heneicosanoic acids. Texture profile analysis of low-salt products, revealed a decrease in hardness and chewiness, along with an increase in adhesiveness values. Sensory evaluations revealed that despite the less intense aroma, products with 3% salt, had a more balanced salt perception. Our results suggest that salt content may be reduced to 50% in dry-cured products, with the obvious health-related advantages.

Using Different Co-Adjuvant Activating Agents to Improve Activated Carbon Adsorption Capacities

Activated carbon (AC) has proved to be an effective adsorbent for the removal of an assortment of organic and inorganic pollutants from aqueous or gaseous media. However, the pursuit for more effective and cheaper AC is still very active and a diversity of textural and chemical treatments are described as a way to expand their applications. It is well known that the surface area and surface chemistry of AC strongly affect their adsorption capacity [1-3]. In particular, an increase in the nitrogen content has been related to an increase of the basic character and also to the development of the porous structure. In most published work this was achieved through an AC post treatment, including either a reaction with nitrogen containing reagents, such as ammonia, nitric acid, or a diversity of amines. However, the AC prepared directly from a nitrogen rich precursor through a physical or chemical activation is referred to as presenting the best characteristics, namely high nitrogen content, high basic character, low nitrogen leaching and also a good thermal stability [4]. To improve the AC adsorption capacities for acidic pesticide removal from the aqueous phase, we intend to improve the porous structure and introduce nitrogenated groups directly into the AC matrix, using different co-adjuvant activating agents as a nitrogen source, by chemical activation, with potassium hydroxide, of cork or poly(ethyleneterephthalate) (PET) precursors.

Quality improvement of traditional dry fermented sausages based on innovative technological strategies

Dry fermented sausages are highly appreciated food specialties, mainly in Portugal and other southern European countries. Therefore, all research efforts aiming at improving the food quality and safety of traditional dry sausages are of interest, since they are likely to result in products with higher added value and quality standards most suited to the requirements and concerns of the modern consumers. Among those efforts, it may be highlighted the studies involving innovative processing parameters and technologies to overcome practical problems gathered in the meat industry, which are mostly associated with food quality and safety. Additionally, characterization of traditional dry sausages and rationalization of their processing are essential for further achievement of any official certification. Thus, this article attempts to point out some research lines of highest interest in meat science (and particularly to the broad variety of regional dry fermented sausages), towards to the valorisation of technological, nutritional and commercial features. In addition, it is here emphasized the importance for the continuous improvement of the quality and safety of meat products as a way to respond to the current concerns regarding its consumption and the general advices in reducing its daily intake.

ADDITION OF VINEGAR TO EXTEND THE SHELF-LIFE OF CABEÇA DE XARA

Cabeça de xara is a ready-to-eat meat product, whose production is very characteristic in Alentejo, a particular region of Portugal. It is a galantine usually moulded into parallelepiped shape made with various meats obtained from the Alentejano pig breed reared in the same region, namely deboned pork heads, tongue and connective tissue to which a number of condiments like salt, parsley, wine and pepper, are added. This work intended to test the feasibility of adding vinegar in order to increase the shelf-life of cabeça de xara, by reducing the contaminating microbiota responsible for spoilage, as well as controlling the pathogen Listeria monocytogenes. Three independent batches were produced and proximate composition, pH, aw, microbiological parameters and biogenic amines content evaluated. A sensory analysis was also performed throughout the storage period. No significant differences between control and vinegar samples was found regarding the proximate composition of cabeça de xara. As expected, pH is lower in the vinegar samples, however no differences in aw were observed between the two treatments. L. monocytogenes was present from the first month on only in one batch in the control treatment. However, it is inhibited by the addition of vinegar until the third month of storage, where L. monocytogenes is present but below the limit established in the 2073/2005 regulation. The presence of vinegar significantly decreased the content in biogenic amines, particularly cadaverine, putrescine and tyramine, throughout the storage period. Concerning sensory evaluation, no vinegar taste was reported by the panellists in a depreciating way.

Effect of autochthonous starter cultures in the production of "Paio", a traditional Portuguese dry- cured sausage

Traditional dry-cured sausages are highly appreciated in Mediterranean countries. The aim of the present study was to evaluate the effect of different starter cultures in the sausages Alentejano pig meat was used to prepare drycured sausages in a local factory. Staphylococcus xylosus, Lactobacillus sakei and a yeast strain were inoculated at a concentration of 106 cfu/g meat batter both in separate and in mixed culture. Three independent batches with two replicates per treatment were produced. Samples were collected throughout the ripening process. pH and aw were determined according to the ISO standards. Microbiological counts of total mesophiles, total psycrotrophs, anaerobes, coagulase-negative staphylococci (CNS), lactic acid bacteria (LAB), enterobacteria, yeasts and moulds and Listeria monocytogenes were done according to the respective ISO standards, as well as detection of Salmonella spp. Biogenic amines quantification was performed by HPLC as described by Roseiro et al. (1). The treatment with L. sakei alone was the most effective in reducing the contamination level both with Salmonella spp. and L. monocytogenes, however this effect seems to be lost in the mixed cultures. The presence of the yeast strain seems to increase the levels of phenylethylamine and histamine. The contents in cadaverine, putrescine and tyramine were generally lower in the inoculated sausages. Regarding tyramine, the treatments with L. sakei showed significantly lower values. No significant differences between treatments were observed for both spermine and spermidine.

EFFECT OF SALT REDUCTION ON THE SAFETY AND STABILITY OF TRADITIONAL BLOOD DRY-CURED SAUSAGES

Health issues such as cardiovascular disease are often due to dietary habits. Thus, meat industry needs to reduce salt in their products. However, production of low-salt content dry-cured not affected. The current study evaluated the effect of salt reduction from 6% to 3% in two Portuguese traditional blood dry-cured sausages. Physicochemical and microbiological parameters, biogenic amines content, fatty acids profile, texture profile analyses and sensory panel evaluations were considered. Differences due to salt reduction were noticeable in a faint increase in water activity, which slightly favoured microbial growth, with the highest yeasts numbers found in 6% salt sausages. Total biogenic amines content ranged from 224.72 to 1302.81 mg kg-1 dry matter, with higher amounts, particularly of cadaverine, histamine and tyramine, in low-salt products. Still, histamine significant differences were observed due to salt content. However, texture profile analysis revealed that low-salt products showed lower resilience and cohesiveness, even though no textural changes were observed by the panellists. Nevertheless, low-salt sausages were clearly preferred. Still, taking the safety of these traditional meat products into account, the results obtained for pH, aw and biogenic amines, have shown that a reduction in salt content should be accompanied by complementary safety measures, such as the use of starter cultures to minimise microbiological and chemical risks.