Impact of varying thickness in the size of meat cuts on volatile compounds and sensory attributes of Tsire, a Nigerian grilled stick meat product

Tsire is a popular Nigerian stick meat commonly produced by grilling of sliced and spiced beef meat that have been hanged on tips of sharpened sticks. In this study, tsire was produced with thickness of meat cuts of 0.5, 0.75, 1.0, 1.25 and 1.5 mm, with the objective of assessing the impact of varying thickness in the size of meat cuts on volatile compounds and sensory attributes of the product. Solid phase mass extraction gas chromatography – mass spectrometry analysis showed identification of 89 volatile compounds belonging to different classes of ketones, acids, alcohols, esters, aromatic/cyclic hydrocarbons, alkanes/alkenes, nitrogeneous compounds, aldehydes and furans. Concentrations of the volatiles increased with increase in thickness of the size of meat cuts. Some of the major volatile compounds in the product were acetone, 2-butanone, 3-methyl-1-butanol and 2,3-butanedione, which had highest concentrations (μg/g) of 4629, 1543, 1200 and 423, respectively in the 0.5 mm tsire sample. Sensory evaluation of the stick meat indicated that consumers had better preference for the 0.5 and 0.75 mm tsire samples than others in the attributes of aroma and appearance. In contrast, the 1.25 and 1.5 mm samples recorded better preference in the attributes of tenderness, taste and acceptability than others. It was concluded that optimal concentrations of the major volatile compounds occurred in the 0.5, 0.75 and 1.0 mm tsire samples; this therefore may give the thickness sizes advantage over the 1.25 and 1.5 mm meat cuts. Variation however occurred in consumers’ preference for sensory attributes of the meat samples. This is the first report on the effect of varying thickness in the size of meat cuts on volatile compounds and sensory attributes of the stick meat product tsire.Keywords: Tsire; grilling, volatile compounds, thickness in sizes, sensory attribute

The regulation of biofilm development by quorum sensing in Aeromonas hydrophila

Aeromonas hydrophila is an opportunistic Gram-negative pathogen that readily attaches to stainless steel to produce a thin biofilm with a complex 3D structure covering 40–50% of the available surface and producing large microcolonies. As A. hydrophila possesses an N-acylhomoserine lactone (AHL)-dependent quorum-sensing system based on the ahyRI locus, the presence of the AhyI protein and C4-HSL within the biofilm phase was first established by Western blot and AHL biosensor analysis respectively. The ability of the A. hydrophila AH-1 N strain to form biofilms in a continuous-flow chamber was compared with isogenic ahyI and ahyR mutants. The ahyI mutant, which cannot produce C4-HSL, failed to form a mature biofilm. In addition, the viable count of biofilm, but not planktonic phase ahyI mutants, was significantly lower that the parent or ahyR mutant. This defect in the differentiation of the ahyI mutant biofilm could be partially restored by the addition of exogenous C4-HSL. A mutation in ahyR increased coverage of the available surface to around 80% with no obvious effect upon biofilm microcolony formation. These data support a role for AHL-dependent quorum sensing in A. hydrophila biofilm development. Exposure of the A. hydrophila AH-1N biofilm to N-(3-oxodecanoyl)homoserine lactone, which inhibits exoprotease production in planktonic cells, however, had no effect on biofilm formation or architecture within the continuous-flow chambe