Résumé:
The aim of this study was to evaluate the effects of adding phenolic compounds from fennel seeds (Foeniculum vulgare) as a natural food additive on the physicochemical, microbiological, organoleptic quality and stability of a traditional cheese much appreciated by the Algerian population, namely J'ben. The cheese was made from cow's milk in a semi-industrial process using mixed coagulation. The phenolic extract of fennel seeds was obtained by alcoholic maceration (80%). After processing, the J'ben was divided into four batches, each containing three 100 g portions. Each experimental batch was then supplemented with the extract obtained previously at successive rates of 0, 1, 2 and 3%. Physico-chemical, microbiological and organoleptic analyses were carried out in triplicate on the fennel seed phenolic extract and on the experimental cheeses throughout their 15-day storage at 4°C.
DPPH and FRAP test results revealed that the hydroethanolic extract of Foeniculum vulgare has a very high antioxidant activity (43.239 vs. 48.033 mg/ml), due to its high phenolic (1528.27mgEAG/100g MB ) and flavonoid (112.96 mg EQ/100g MB) content.
An inverse trend between cheese acidity and pH values (P<0.01) was observed as a function of storage periods; 14.94 to 17.24°D vs. 4.59 to 4.38°D, respectively. This trend seems to be maintained with increasing plant extract levels from 0 to 3% in cheeses (P<0.05); 17.22 to 15.49 °D vs 4.45 to 4.49°D, successively. The increase in extract levels added as an additive also led to significant changes in dry matter levels (P<0.01), which fell significantly from 42.18 to 36.15%MB, moisture values (P<0.001), which in turn rose from 57.82 to 63.85%MB, and organic matter values (P<0.001), which also fell from 39.91 to 33.71%MB, respectively, in cheeses. Fat content increased significantly with storage time, from 31.58 to 51.5%MB and from 35.44 to 41.97%MB, depending on the rate of addition of Foeniculum vulgare extract (P<0.05). A clear decrease in Malondialdehydes was recorded in cheese treated with 3% extract compared with the control (0.24 vs. 0.29 mg/100 g), due to the high antioxidant activity revealed in the respective products with the DPPH test (197.21 mg/ml vs. 266.53 mg/ml).
The microbiological results clearly showed that the hydroethanol extract of Foeniculum vulgare exhibited remarkable antimicrobial properties and prebiotic power, which enabled J'ben to be preserved for 15 days from contamination by certain pathogenic germs, to reduce the development of other undesirable spoilage bacteria and to promote the growth of beneficial lactic acid bacteria in the products.
Furthermore, cheeses with added fennel phenolic extract were very well accepted by panelists, as well as, if not better than, the control for certain criteria during tasting tests.
