Carmen Casas

Inulin as fat substitute in low fat, dry fermented sausages.

Low fat, dry fermented sausages were prepared with a fat content close to 50% and 25% of the original amount. The batch with the smallest proportion of fat was less tender, less springy and was gummier than the batch with the highest proportion. However, it was still considered acceptable by the panel of judges. The 25% batch was supplemented with different amounts of soluble dietetic fibre (inulin) as both a powder and in aqueous solution. Ripening was followed by physico-chemical and microbiological analysis. Sensory analysis and texture profile analysis were performed to evaluate the effect of the inulin addition. Results obtained indicated an overall improvement in the sensory properties due to a softer texture and tenderness, springiness and adhesiveness similar to the conventional high fat sausage. Thus, with the addition of inulin a low calorie product (30% of the original), enriched with soluble dietetic fibre (10% approximatively) can be obtained.

Utilization of cereal and fruit fibres in low fat dry fermented sausages

The effect of addition of cereal and fruit dietary fibres on the sensory properties of reduced-fat, dry fermented sausages was studied. Dry fermented sausages with 6 and 10% pork backfat were manufactured, with addition of cereal (wheat and oat) and fruit (peach, apple and orange) dietary fibres, at 1.5 and 3% concentrations. The energy value reduction of the final products was close to 35% and their final fibre contents, after ripening, were 2 and 4%, respectively. The ripening process was monitored by physico-chemical and microbiological analysis. Sensory properties were analyzed using triangular and hedonic tests and, a texture profile analysis was carried out. A correlation principal component analysis was performed. The results showed that the sensory and textural properties of batches with 3% dietary fibre were the worst, due to their hardness and cohesiveness. The best results were obtained with sausages containing 10% pork backfat and 1.5% fruit fibre especially those with orange fibre, which gave organoleptic characteristics similar to conventional high fat products. Thus, reduced fat sausages fortified with dietary fibre can be obtained with an acceptable sensory profile.

Cell surface hydrophobicity and attachment of pathogenic and spoilage bacteria to meat surfaces.

Cell surface hydrophobicity of several pathogenic and spoilage bacteria was determined by hydrocarbon adherence, adhesion to nitrocellulose filter, salt aggregation and adherence to phenyl-sepharose beads. Hydrophobicity of each bacterium was dependent on the method of measurement. Hydrophobicity was compared with the strength of attachment (Sr) of the bacteria to beef muscle surfaces. Bacterial cell surface hydrophobicity, as determined by the bacterial adherence to xylene correlated well with attachment strength (r = 0.800, P < 0.05). Staphylococcus aureus, Clostridium perfringens and Yersinia enterocolitica showed the highest values of attachment strength.

Lactic acid bacteria: hydrophobicity and strength of attachment to meat surfaces

The hydrophobicity and strength of a ttachment of several lactic acid bacteria with antimicrobial activity were studied. Hydrophobicity was determined by bacterial adherence to hydrocarbons (BATH; octane or xylene), adhesion to nitrocellulose filters (NCF), salt aggregation test (SAT) and adherence to phenyl–Sepharose beads (PSB). The relative hydrophobicity of lactic acid bacteria depended markedly on the method used. No correlation between either SAT or BATH (octane) and strength of attachment (Sr value) existed. However, a significant relationship between strength of attachment and BATH (xylene), NCF and PSB, respectively, was observed, showing the highest correlation coefficient (r = 0·778) for BATH (xylene).

Attachment of bacteria to meat surfaces: a review

The mechanism of attachment of bacteria to meat surfaces involves two consecutive stages: reversible and irreversible attachment. The dependence of attachment on various factors is discussed: hydrophobicity and cell surface charge, bacterial structures, type of meat surface, pH, temperature, presence of chemical substances, etc. The consequences of these findings for slaughter hygiene, kitchen hygiene, etc., are clear; avoid bacterial contamination.

Proteolytic and lipolytic activities of mould strains isolated from Spanish dry fermented sausages

Proteolytic and lipolytic activities of ninePenicillium strain and oneMucor strain previously isolated from Spanish dry fermented sausages have been studied.P. camemberti STCC 2267 andAspergillus oryzae ATCC 9362 were also used. Myofibrillar and sarcoplasmic proteins as well as fat extracted from pork meat and β-naphthyl acetate, β-naphthyl caprilate and β-naphthyl laurate were used as substrates. Mould strains were grown in an enrichment medium prepared at pH 5.5 and 7.0 and malt extract broth. Strains were incubated at 18°C and 22°C. Myofibrillar proteins and β-naphthyl caprilate were the most hydrolysed substrates. The greater enzymatic activities were observed at a pH 7.0 and 22°C. However, five mould strains showed considerable enzymatic activities under conditions similar to those used for ripening dry fermented sausages. These strains can be assayed as potential starter cultures for industrial sausage production.

Sandwich ELISA for Detection of Pig Meat in Raw Beef Using Antisera to Muscle Soluble Proteins

A double-antibody sandwich ELISA (enzyme-linked immunosorbent assay) has been successfully developed for the detection of defined amounts of pig meat (1-50%) in raw beef. Antibodies against pig sarcoplasmic extracts were produced in rabbits. Pig-specific antibodies were affinity purified by removing antibodies which crossreacted with horse, chicken or beef extracts followed by immunoadsorption and elution from a pig-extract column. The ELISA involved capturing antigens in sarcoplasmic extracts with pig specific antibodies immobilized on 96-well plates, detecting bound antigen with pig specific, horseradish peroxidase-labeling antibody, and measuring peroxidase activity by the conversion of a clear substrate to a colored product.

Virulence Factors-Pathogenicity Relationships for Aeromonas Species from Clinical and Food Isolates

The presence of virulence factors in 96Aeromonas strains isolated from food and clinical samples was studied. Neither cytotoxic activity and hydrophobicity, not the presence of pili or an extra surface layer made it possible to establish differences between food and clinical strains. Statistical studies showed that cytotoxin production was associated with a positive Voges—Proskauer reaction, inability to ferment arabinose and a positive lysine decarboxylation. Therefore, when comparing cytotoxic clinical and food strains with lysine decarboxylation phenotype, there was a significant difference (p<0.05) between the two groups. The association of a cytotoxin production and lysine decarboxylation character should thus be considered as a possible virulence marker.

Mutagenicity and cytotoxicity of fruits and vegetables evaluated by the Ames test and 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay / Mutagenicidad y citotoxicidad de frutas y vegetales evaluadas por el test de Ames y el ensayo del bromuro de 3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetrazolio (MTT)

The mutagenic and cytotoxic activity of the aqueous (H2O) and ethanolic (EtOH) extracts of fruits and vegetables were studied by the Ames test and the MTT assay. A significant mutagenic activity was found for three H2O extracts of broccoli (Brassica oleracea), carrot (Dacus carota) and licorice (Glycyrrhiza glabra) and for one EtOH extract of kiwi (Ananas sativus ) of the nine species analyzed. The frameshift tester strain TA98 was reverted by broccoli (2.4, 4.8 and 9.6 mg/mL; p < 0.01) and carrot (9.6 mg/mL; p < 0.001) aqueous extracts and by kiwi (9.6 mg/mL; p < 0.0001) EtOH extract, whereas strain TA100 was only sensitive to the mutagens of licorice H,O extract, within the nine fruits and vegetables tested. The mutagenic response of the extracts was not altered by the presence of S9 mix. Cytotoxicity was only found for three of the nine species tested. Percentage cytotoxic ac tivities at 4.8 mg/mL in pineapple (Actinidin diasinensis) and garlic (Allium sativum) H,O extracts were 77 and 91 %, respectively. Licorice EtOH extract was the only one that showed a cytotoxic activity at all of the concentrations used. The percentage of cytotoxic activity of licorice extract was 63% at 0.24 mg/mL and increased with increasing concentration of licorice up to 4.8 mg/mL. Thus, licorice (EtOH) extract was the most cytotoxic of the species tested.

Potential technological interest of a Mucor strain to be used in dry fermented sausage production

Abstract The effect of several parameters on the proteolytic activity of a non-toxigenic Mucor strain previously isolated from Spanish dry fermented sausages was studied. For this, pH and NaCl concentration of a culture medium and temperature and incubation time were modified to reach values near to those used for ripening of dry fermented sausages. The optimum conditions for the development of proteolytic activity were a NaCl concentration of 30 g litre −1 , pH of 5.5 and a temperature of 18 °C. The results, however, obtained at 14 °C (temperature of the final phase of ripening), indicated that the strain studied would be able to produce proteases at this temperature and, therefore, contribute to the proteolytic phenomena occurring during ripening of dry fermented sausages and to the development of the flavour and the odour characteristics of these products.