Consumer acceptance and sensory profiling of reengineered kitoza products

Kitoza refers to a traditional way of preparing beef and pork in Madagascar. However, in order to improve some drawbacks previous identified, the product was submitted to a reengineering process. The acceptance and sensory profiling of improved Kitoza products among Portuguese consumers was investigated. A local smoked loin sausage was selected as basis for comparison. Firstly, a Focus Group study was performed to identify sensory descriptors for Kitoza products and explore product perception. Subsequently, a Flash Profile and a consumer sensory acceptance study were conducted. Flash Profile’s results showed that beef- and pork-based Kitoza products investigated differed considerably in all sensory dimensions. The Portuguese sausage was characterized as having a more intense and lasting after taste, as well as displaying a higher degree of (meat) doneness. The acceptance study yielded higher overall liking ratings for pork- than for beef-based Kitoza, although the Portuguese sausage remained the most appreciated product

Antimicrobial and antioxidant effects of combined high pressure processingand sage in beef burgers during prolonged chilled storage

The combined effect of sage (0.3 and 0.6%) and high pressure processing (HPP) [300 MPa (10 min, 9.9 °C) and 600 MPa (10 min, 10.2 °C)] on the antimicrobial and antioxidant characteristics of beef burgers during prolonged chilled storage (60 days) was analysed. Sage powder showed antioxidant and antimicrobial activities, but the addition of sage powder to burgers had no apparent effect on antimicrobial activity; however, antioxidant activity was detected as measured by TBARS, hexanal and photochemiluminescence (PCL). In general, lipid oxidation increased in all samples during storage. HPP at 600 MPa had no effect on lipid oxidation but caused mesophilic and psychrotrophic counts to remain close to the detection limit for at least 6 days. Significant correlations were found between lipid oxidation measured by TBARS and PCL and between TBARS with hexanal over the storage period. Sage had no detrimental effects on sensory attributes of burgers. Industrial relevance Sage is an aromatic plant with excellent antimicrobial and antioxidant properties. High pressure processing (HPP) is an efficient non-thermal preservation technology. As far as the authors are aware, very few studies have holistically addressed the question of stability (microbial spoilage and oxidation of lipids) of traditionally-prepared burgers as affected by HPP and addition of a natural plant. This paper examines the possible application of both treatments so as to obtain beef burgers with suitable oxidative and microbiological stability over prolonged chilled storage without this affecting sensory attributes.info:eu-repo/semantics/acceptedVersio

Use of response surface methodology to optimize protease synthesis by a novel strain of Bacillus sp. isolated from Portuguese sheep wool

Aims: To investigate the influence of yeast extract, peptone, temperature and pH upon protease productivity by Bacillus sp. HTS102 – a novel wild strain isolated from wool of a Portuguese sheep breed (Merino). Methods and Results: A 24 full factorial, central composite design together with response surface methodology was used to carry out the experiments and analyse the results, respectively. Among the individual parameters tested, temperature and peptone concentration produced significant effects upon protease productivity. A high correlation coefficient (R2 = 0Æ994, P < 0Æ01) indicated that the empiric second-order polynomial model postulated was adequate to predict said productivity, with the optimum loci characterized by: temperature of 43 C, peptone content of 1Æ4 g l)1, pH of 5Æ1 and yeast extract concentration of 10Æ0 g l)1. Conclusions: Protease synthesis depends chiefly on temperature and peptone level. The maximum protease activity was more than twice that obtained with the basal medium, so the experimental design and analysis undertaken were effective towards process optimization. Significance and Impact of the Study: Rational choice of processing conditions for maximum protease productivity will be relevant if an economically feasible fermentation process based on Bacillus sp. HTS102 is intended.info:eu-repo/semantics/publishedVersio

Antimicrobial activity of wild mushroom extracts against clinical isolates resistant to different antibiotics

Aims: This work aimed to screen the antimicrobial activity of aqueous methanolic extracts of 13 mushroom species, collected in Braganc¸a, against several clinical isolates obtained in Hospital Center of Tra´s-os-Montes and Alto Douro, Portugal. Methods and Results: Microdilution method was used to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). MIC results showed that Russula delica and Fistulina hepatica extracts inhibited the growth of gram-negative (Escherichia coli, Morganella morganni and Pasteurella multocida) and gram-positive (Staphylococcus aureus, MRSA, Enterococcus faecalis, Listeria monocytogenes, Streptococcus agalactiae and Streptococcus pyogenes) bacteria. A bactericide effect of both extracts was observed in Past. multocida, Strep. agalactiae and Strep. pyogenes with MBC of 20, 10 and 5 mg ml 1, respectively. Lepista nuda extract exhibited a bactericide effect upon Past. multocida at 5 mg ml 1 and inhibited Proteus mirabilis at 20 mg ml 1. Ramaria botrytis extract showed activity against Enterococcus faecalis and L. monocytogenes, being bactericide for Past. multocida, Strep. agalactiae (MBCs 20 mg ml 1) and Strep. pyogenes (MBC 10 mg ml 1). Leucopaxillus giganteus extract inhibited the growth of E. coli and Pr. mirabilis, being bactericide for Past. multocida, Strep. pyogenes and Strep. agalactiae. Conclusions: Fistulina hepatica, R. botrytis and R. delica are the most promising species as antimicrobial agents. Significance and Impact of the Study: Mushroom extracts could be an alternative as antimicrobials against pathogenic micro-organisms resistant to conventional treatments.info:eu-repo/semantics/publishedVersio

Prevalence and characterization of Listeria monocytogenes isolated from soft cheese

A survey was made in 1995–1996 for Listeria spp. in 63 soft cheeses, made from raw ewe’s milk using traditional methods, in the Province of Beira Baixa (Portugal). Listeria spp. were isolated from 47 (75%) of the cheeses, L.monocytogenes was isolated from 29 (46%), and L.innocua but not L.monocytogenes from 18 (29%). Of 24 isolates of L.monocytogenes that were serotyped, 20 were serotype 4b, three were serotype 1/2b and one was serotype 1/2a. Phage typing of isolates of L.monocytogenes and L.innocua showed that in some cases a particular phage type was associated with cheese from a particular source. Twenty four strains of L.monocytogenes tested were able to grow at 30 Cin culture medium adjusted with HCl to a pH in the range from 4.4 to 6.0 within 3 days; in the pH range 4.4–6.8 a representative strain grew most rapidly at pH 6.8. The pH range in the cheeses during maturation was between about 5.2–6.4. Whether L.monocytogenes could multiply in the cheeses would depend on factors such as concentration of organic acids and of salt, and storage temperature.info:eu-repo/semantics/publishedVersio

Effects of membrane depolarization and divalent-cations on anaphylactic histamine secretion

The effects of membrane depolariz.ation and divalent cations on histamine release have been studied in sensitized mast cells. Membrane potential of these cells has been measured with intracellular microelectrodes. Our results show that mast cells have a large resting potential (-61512 mV) however they do not generate active membrane electrical responses when are depolarized by passing current through the recording microelectrode. High external K+ does not increase histamine release. Histamine secretion is supported by alkaliearth divalent cations (Ca2+> Sr2+>Ba2+) but strongly inhibited by transition metals. Ca2+ concentrations above 1 mM inhibit histamine release, however, this effect is not mimicked by Sr2+ and Ba2+