Antibacterial Activity of Some Lactic Acid Bacteria Isolated from an Algerian Dairy Product

In the present study, the antibacterial effect of 20 lactic acid bacteria isolates from a traditional cheese was investigated. 6 isolates showed antibacterial effect against Gram positive bacteria. Streptococcus thermophilus T2 strain showed the wide inhibitory spectrum against the Gram positive bacteria. Growth and bacteriocin production profiles showed that the maximal bacteriocin production, by S. thermophilus T2 cells, was measured by the end of the late-log phase (90 AU ml−1) with a bacteriocine production rate of 9.3 (AU ml−1) h−1. In addition, our findings showed that the bacteriocin, produced by S. thermophilus T2, was stable over a wide pH range (4–8); this indicates that such bacteriocin may be useful in acidic as well as nonacidic food. This preliminarily work shows the potential application of autochthonous lactic acid bacteria to improve safety of traditional fermented food

Comparative Study on Biochemical Properties and Antioxidative Activity of Cuttlefish (<i>Sepia officinalis</i>) Protein Hydrolysates Produced by Alcalase and<i>Bacillus licheniformis</i>NH1 Proteases

Antioxidative activities and biochemical properties of protein hydrolysates prepared from cuttlefish (Sepia officinalis) using Alcalase 2.4 L andBacillus licheniformisNH1 proteases with different degrees of hydrolysis (DH) were determined. For the biochemical properties, hydrolysis by both enzymes increased protein solubility to above 75% over a wide pH range. The antioxidant activities of cuttlefish protein hydrolysates (CPHs) increase with increasing DH. In addition, all CPHs exhibited antioxidative activity in a concentration-dependent manner. NH1-CPHs generally showed greater antioxidative activity than Alcalase protein hydrolysates (P&lt;0.05) as indicated by the higher 1,1-diphenyl-1-picryhydrazyl (DPPH) radical scavenging activity and ferrous chelating activity. Both Alcalase and NH1 protein hydrolysates were able to retard lipid peroxidation andβ-carotene-linoleic acid oxidation. Alcalase-CPH (DH = 12.5%) and NH1-CPH (DH = 15%) contained 75.36% and 80.11% protein, respectively, with histidine and arginine as the major amino acids, followed by glutamic acid/glutamine, serine, lysine, and leucine. In addition, CPHs have a high percentage of essential amino acids made up 48.85% and 50.04%. Cuttlefish muscle protein hydrolysates had a high nutritional value and could be used as supplement to poorly balanced dietary proteins.</jats:p

Stabilisation de l'hemoglobine par les solvants organiques: etude de l'auto-oxydation et de la denaturation thermique

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 79638 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Solvent effect on kinetics of appearance of haemorphins in the course of peptic hydrolysis of bovine haemoglobin

International audienceThe effect of the composition of the solvent on the peptic hydrolysis of bovine haemoglobin was studied to improve the preparation of two opioid peptides. Peptic hydrolysis was performed for 24 h at 23 mC in 0.1 M sodium acetate buffer, pH 4.5. A HPLC method was reported for isolating LVV-haemorphin-7 and VV-haemorphin-7 in one step. The kinetics of appearance of haemorphins was investigated in the presence of 20 % (v/v) ethanol, a stabilizing solvent of haemoglobin or urea, a denaturant agent. Ethanol improved the yield of VV-haemorphin-7, whereas urea improved the yield of the two haemorphins. Because the amounts of haemorphins observed in urea were greater than in ethanol, the denatured state of haemoglobin is more favourable to obtaining LVV-haemorphin-7 and W-haemorphin-7. The peptide bonds that give rise to haemorphins would be more accessible to the pepsin.Abbreviations used : DHc, corrected degree of hydrolysis ; MALDI-MS, matrix-assisted laser desorption ionization MS.</div