Tunisian table olive phenolic compounds and their antioxidant capacity.

For the 1st time, 4 olive cultivars, the Meski, Chemlali, Besbessi, and Tounsi, from the Tunisian market were investigated to evaluate the phenolic compounds' contribution in nutritional value of table olives. From the Meski cultivar, we have chosen 4 different samples to evaluate differences within the same cultivar. Basic characteristics and total phenolic content were evaluated in flesh and kernel. The highest value of flesh phenolic content was observed in sample M4 of the Meski cultivar; however, the lowest value was observed in the Besbessi cultivar and they were 1801 and 339 mg GA/100 g dry weight, respectively. The main simple phenolic compounds identified in flesh extracts are hydroxytyrosol, tyrosol, and vanillic acid. Oleuropein was not detected in any samples. The antioxidant activity of Tunisian olive flesh varies between 212 and 462 muM TEAC/g of dry weight. Antioxidant activity of olives was related to their phenolic content but we found a low correlation between phenolic content and TEAC.

Lyophilized preparations of bacteriocinogenic Lactobacillus curvatus and Lactococcus lactis subsp. lactis as potential protective adjuncts to control Listeria monocytogenes in dry-fermented sausages.

AIM: Study of the effectiveness of in situ bacteriocin production by lactic acid bacteria (LAB) to control Listeria monocytogenes in dry-fermented sausages. METHODS AND RESULTS: Two bacteriocin-producing strains: Lactococcus lactis subsp. lactis LMG21206 and Lactobacillus curvatus LBPE were grown in a pilot scale fermentor and lyophilized to be directly used in dry sausage fermentation. A commercial starter culture (Bel'meat SL-25) not inhibitory to L. monocytogenes (Bac- starter) was mixed (1 : 1) with each of the two lyophilized bacteriocin-producing strains to obtain starters active against the pathogen (Bac+ starter). Anti-Listeria effectiveness of the Bac+ starters was studied in dry-fermented sausages. The meat batter was experimentally contaminated with a mixture of four different strains of L. monocytogenes (10(2)-10(3) CFU g(-1)). The results showed that L. monocytogenes did not grow in any of the contaminated batches, but no significant decrease (P > 0.05) was observed either in the positive control (no added starter culture) or in samples fermented with the Bac- starter culture during the fermentation period and up to 15 days of drying. When the Bac+ starter contained Lb. curvatus LBPE, cell counts of L. monocytogenes decreased to below the detectable limit (<10 CFU g(-1)) after 4 h of fermentation and no survivors could be recovered by enrichment beyond day 8 of drying. When the Bac+ starter culture containing Lc. lactis LMG21206 was used, a decrease in Listeria counts to below the detectable limit was achieved after 15 days of drying. CONCLUSIONS: The bacteriocin-producing strains studied may be used as adjunct cultures for sausage fermentations to control the occurrence and survival of L. monocytogenes. SIGNIFICANCE AND IMPACT OF THE STUDY: Addition of the Bac+ strains, especially the Lb. curvatus strain would provide an additional hurdle to enhance the control of L. monocytogenes in fermented meat products.