Lactic acid bacteria from chicken carcasses with inhibitory activity against Salmonella spp. and Listeria monocytogenes.

This study was conducted to isolate psychrotrophic lactic acid bacteria (LAB) from chicken carcasses with inhibitory activity against strains of Salmonella spp. and Listeria monocytogenes. A total of 100 broiler samples were examined for the presence of LAB. Ninety-two LAB isolates that showed antimicrobial effects against Salmonella spp. and L. monocytogenes were further analysed to examine their LAB (Gram-positive, catalase negative, oxidase negative) and psychrotrophic characteristics (ability to grow at 7 °C). Fifty isolates were further selected and identified initially using standard biochemical tests in miniature (Micro-kits API CH 50) and then by sequencing of the 16s-23s rRNA gene boundary region (Intergenic Spacer Region). By molecular identification, these isolates were classified into 5 different LAB species: Lactobacillus salivarius, Lactobacillus reuteri, Lactobacillus johnsonii, Pediococcus acidilactici, and Lactobacillus paralimentarius. None of the isolates produced tyramine or histamine.

Effect of lupin seed proteins on quality characteristics of fermented sausages.

Lupin seed flours (LSF) and lupin seed protein isolates (LSPI) from a sweet (S) variety of Lupinus albus and a bitter (B) variety of Lupinus albus ssp. Graecus were used in the manufacture of fermented sausages at 2% level, based on the weight of meat and pork back fat, and hydrated to a protein/water ratio 1/4, to replace beef and pork meat on a protein to protein basis. LSF and LSPI had no effect (p>0.05) on the microbial counts, the pH, the moisture content and weight losses, the instrumentally measured colour numbers (L*, a*, b*), the firmness, the appearance and the sensory evaluated colour of fermented sausages. Fermented sausages produced with LSPI from the bitter variety had similar (p>0.05) sensory attributes to the control and lower (p<0.05) TBA values after the 28th day of storage. Fermented sausages produced with LSPI from the sweet variety had acceptable sensory attributes but TBA values higher than 1 mg of malonaldehyde/kg. LSF from both varieties had a high pro-oxidant effect and affected negatively the odour and taste of fermented sausages.

Storage stability of cooked sausages containing vegetable oils.

Comminuted cooked sausages were produced using standard industrial practices, by substituting corn oil, sunflower oil, cotton seed oil, soybean oil and hydrogenated vegetable fat for animal fat. When processed, products were assessed for their stability with respect to autoxidation and change in organoleptic properties during vacuum-packed storage in a domestic refrigerator at 4 degrees C. Data obtained indicated that changes in thiobarbituric acid (TBA) values and organoleptic properties of products produced using corn oil, sunflower oil and hydrogenated vegetable fat were similar to those observed for reference material produced using lard. In the case of samples produced using soybean and cotton seed oil, TBA value changes were more pronounced, but did not exceed acceptable limits. A more rapid deterioration of organoleptic characteristics was also observed for the same samples, which showed flavour problems after 3 months of storage at 4 degrees C. Substitution of plant oils for lard considerably reduced the cholesterol content and increased the ratio of unsaturated to saturated fatty acids of cooked sausages.

The evaluation in the Ames test of the mutagenicity of tetrahydro-beta-carboline-3-carboxylic acids from smoked foods.

This paper reports the evaluation of five tetrahydro-beta-carboline carboxylic acids, formed from the interaction of woodsmoke carbonyls and tryptophan, for mutagenicity in the Ames test. Three of the compounds tested have been detected recently in smoked foods at levels in the micrograms/kg or mg/kg range. None of the compounds induced mutagenicity in TA 97, TA 98 or TA 100 strains of Salmonella typhimurium either with or without prior activation. However, tetrahydro-beta-carboline-3-carboxylic acid, and to a lesser extent 1-methyl-tetrahydro-beta-carboline-3-carboxylic acid were toxic to the strains of Salmonella typhimurium used. The inability of these beta-carbolines to induce mutation contrasts markedly with the mutagenicity of some beta-carbolines found in grilled meat products.

Tetrahydro-beta-carboline carboxylic acids in smoked foods.

This paper reports for the first time in smoked foods the presence of three tetrahydro-beta-carboline carboxylic acids. One of these, 1-hydroxymethyl-tetrahydro-beta-carboline-3-carboxylic acid, which is derived from the interaction of tryptophan and glycolaldehyde, and which has not previously been reported in foods, was observed in 20 samples at levels up to 444 micrograms/kg. The corresponding products which are derived from tryptophan and formaldehyde or tryptophan and acetaldehyde were found respectively in 28 samples at levels up to 22 mg/kg and in 16 samples at levels up to 881 micrograms/kg. Greater concentrations were generally found in those smoked foods having a lower pH value and produced by using a longer fermentation or maturation. Only 1-methyl-tetrahydro-beta-carboline carboxylic acid (156-574 micrograms/kg) was found in the four unsmoked samples analysed.