Amal Ben Amira

Phenolic Profiles, Phytchemicals and Mineral Content of Decoction and Infusion of Opuntia ficus-indica Flowers

Opuntia flowers are a natural source of biologically active compounds and they have been used as medicinal plant for a long time. Despite the various uses reported for the decoction and infusion of these flowers, their characterization has been discarded. In this study, the decoction and infusion prepared from Opuntia ficus-indica were analyzed with respect to their content in minerals and phytochemicals in order to evaluate its nutritional characteristics. The obtained data proved that these preparations are a rich source of minerals mainly K and Ca. Moreover, the phytochemical analysis revealed that they have important polyphenols, flavonoids and tannins contents with the infusion that presented the highest polyphenol levels. LC-MS analyses of decoction and infusion allowed the characterization of 20 phenolic compounds. It is mainly identified by the presence of flavonols glycosides.

Combinatorial effect of Bacillus thuringiensis kurstaki and Photorhabdus luminescens against Spodoptera littoralis (Lepidoptera: Noctuidae)

Spodoptera littoralis, one of the major pests of many important crop plants, is more susceptible to Bacillus thuringiensis aizawai delta‐endotoxins than to those of Bacillus thuringiensis kurstaki. Within the framework of the development of efficient bioinsecticides and the prevention against insect resistance, we tested the effect of mixing B. thuringiensis kurstaki delta‐endotoxins and Photorhabdus luminescens cells on S. littoralis growth. The obtained results showed that the growth inhibition of this insect was more effective when B. thuringiensis kurstaki spore‐crystal mixture and Photorhabdus luminescens cells were used in combination. Furthermore, this synergism is mainly due to the presence of Cry1Ac, which is one of the three delta‐endotoxins that form the crystal of B. thuringiensis kurstaki strain BNS3 in addition to Cry1Aa and Cry2Aa. This work shows a possibility to use B. thuringiensis as a delivery means for Photorhabdus bacteria in order to infect the insect hemocoel and to reduce the risk of developing resistance in the target organism.

Influence of the ripening stage and the lyophilization of wild cardoon flowers on their chemical composition, enzymatic activities of extracts and technological properties of cheese curds

The selection of an appropriate Cynara cardunculus flowers batch is a preliminary step to produce rennet with better clotting properties. For this reason, we proposed to study the influence of the ripening stage and the lyophilization of cardoon flowers on their chemical composition, enzymatic activities of extracts, and technological properties of cheese curds. Results of flowers composition have shown that lyophilized flowers harvested at the middle of ripening stage (A) could be employed to produce mainly proteins or milk-clotting proteases. To confirm this, enzymatic activities of extracts and technological properties of curds were assessed. The experimental findings revealed that flowers lyophilization seems to be an efficient way to produce rennet with better clotting properties, leading to higher yield, moisture, and texture parameters of curd. These findings allowed us to select lyophilized flowers (A) for further cheese making process.

Technological properties of milk gels produced by chymosin and wild cardoon rennet optimized by response surface methodology

The aim of this paper was to optimize extraction conditions of C. cardunculus rennet by response surface methodology, in order to maximize its milk-clotting activity (MCA). The second objective was to examine the effect of different amounts of the optimized extract and the type of milk, on technological characteristics of the obtained gels. Results of the central composite design showed that the optimum extraction conditions, corresponding to maximum MCA (9.550CAU/mL), were selected as follows: Grinding time 30s, pH 3, extraction time 50min and solid to liquid ratio 15g/100mL. According to technological properties, it can be concluded that C. cardunculus extract exhibited an excellent efficiency on raw milk, in term of dynamic moduli and gel firmness, as compared to chymosin. A good gelation time and WHC were also obtained. Consequently, the optimized C. cardunculus rennet has the potential to be employed as an efficient milk-clotting agent.