No abstract

Tunisia is considered to be one of the dates-producing countries. The mean annual yield of date fruits is about 200,000 tons. From this, around 20,000 tons of date seeds could be collected. This by-product of date processing industries could be regarded as an excellent source of dietary fiber with interesting technological functionality and many beneficial effects on human health. Then, date seeds could present a value addition by extraction and use of date seed fiber concentrate in chocolate spread formulation.

In this study, the chemical composition and functional properties ofAgave americanaL. (AA) leaves were determined. TheAgaveleaves powder had a high amount of total dietary fiber (38.40%), total sugars (45.83%), and protein (35.33%), with a relatively low content in ash (5.94%) and lipid (2.03%). TheAgaveleaves were exhibited with potential food application. TheAgaveinulin showed a significant difference compared with the commercial inulin as for aw (0.275 against 0.282), pH (5.53 against 5.98), ash (2.89% against 1.19%), protein (3.46% against 1.58%), water holding capacity (2.42% against 1.59%), solubility (73 g/L against 113 g/L), and emulsion capacity (14.48% against 21.42%), respectively. The textural properties ofAgaveinulin-pectin mixed gels were examined using instrumental Texture Profile Analysis (TPA). Firmness of the preparedAgaveinulin-pectin mixed gels was lower than the pectin gel (0.3554 N against 5.7238 N, resp.). This reduction of firmness showed a synergetic effect between pectin and inulin. These results suggested a positive interaction betweenAgaveinulin and pectin to decrease the firmness of mixed gels and open a good alternative to obtain value added products from this resource.

This study investigated the direct effect of the insecticides deltamethrin and spinosad on three egg parasitoids species: Trichogramma oleae, T. cacoeciae and T. bourarachae. The parasitoid pupae were exposed to pesticide residues on fresh olive tree leaves at recommended concentrations (RC) at different time intervals: 3, 10, 17, 24 and 31 days after pesticide applications. Parasitism viability (% emergence from parasitized eggs) and adult emergence time (developmental time from pupa to adult emergence) were evaluated. Regarding to the International Organization of Biological Control (IOBC) guidelines, results of toxicity effects of insecticides show that: Deltamethrin was moderately harmful to all Trichogramma species at RC (Decis ® 100 milliliters•ha −1), however, spinosad was harmless to moderately harmful at RC (Tracer ® 20 milliliters•ha −1). Trichogramma species revealed differences with regard to adult emergence time and exhibited significant changes in parasitism viability with increasing time after pesticide treatment. While deltamethrin residues affected parasitism viability 31 days after the product application, spinosad displayed similar viability for almost species 24 days after the application. The usefulness of Trichogramma parasitoids used as biological control agents, in olive tree ecosystem, was discussed in integrated pest management programs for Prays oleae control when parasitoid species were exposed during pupal stage to the insecticide residue.

No abstract

Ulva rigida is a worldwide distributed green alga and is commenly used for human nutrition. Extracts of this seaweed were shown anti-hypercholestierinemic, antioxidant and antihyperglycemic activities. The antioxidant effect was often ascribed to the presence of a huge amount of polyphenols. The aim of this study was to characterise by high-performance liquid chromatography-electrospray ionisation mass spectrometry (HPLC-ESI-MS) the phenolic molecules present in extracts obtained from U. rigida. The antioxidant activities of different extracts were evaluated in vitro by DPPH assay and on HeLa cells culture.

The main objective was to investigate the effect of ultrasound‐assisted osmotic dehydration (UOD) pretreatment on the dehydration kinetics and the physicochemical properties of pomegranate seeds using a response surface methodology, in order to optimize the process. Quality attributes of seeds were estimated through the assessment of physical and thermal characteristics. Results showed a good correlation of experimental values with the model. The optimum conditions used for UOD and osmotic dehydration (OD) were found to be 240 min, 60°Brix, 41°C, and 240 min, 29°Brix, 50°C, respectively. UOD pretreatment led to a higher mass transfer rate than the OD process. UOD‐treated seeds reached the optimal moisture content (10%) and water activity (aw < 0.650) faster than both fresh seeds and OD‐treated seeds. Differential scanning calorimetry revealed that UOD pretreatment induced the loss of an important amount of water. X‐ray diffraction analysis showed that ultrasound pretreatment did not affect the amorphous characteristics of pomegranate seed powder during drying. Practical applications Ultrasound‐assisted osmotic dehydration could be a novel approach for food preservation and processing, due to the combined effect of osmotic pressure gradient and ultrasonic effect on the surface of the food material. Ultrasound pretreatment can be implemented as an alternative pretreatment to reduce drying time and, consequently, processing costs. Ultrasound‐assisted osmotic dehydration is gradually gaining attention as a pretreatment method due to its advantages which include preservation of antioxidant properties and bioactive compounds. This study provides information on the application of response surface methodology for the optimization of ultrasound‐assisted osmotic dehydration of pomegranate seeds.

In order to enhance the quality of a meat product, turkey burgers with a low-fat and a high-fiber level were formulated by the incorporation of insoluble fibers from Tunisian Deglet Nour date seeds as insoluble fiber concentrate (IFC) at 3%, 5%, and 10% (w/w). Compared to Deglet Nour date seeds powder (DSP), physicochemical results revealed that IFC presented higher ( P  < 0.05) levels in carbohydrates at 88.85% and lower values of fat (5.94%), protein (3.81%), and ash (2.35%). For the technofunctional properties, IFC improved the oil-holding capacity (OHC) by 57.14% compared to DSP. IFC addition into turkey burgers was also instrumentally investigated by color (L ∗ , a ∗ , and b ∗ ) and textural parameters (hardness, cohesiveness, adhesiveness, and elasticity) and sensory attributes using a 5-point hedonic scale. Furthermore, IFC changed significantly the color of the formulated products. In addition, hardness and adhesiveness values of all experiments increased significantly ( P  < 0.05) with the increase of the incorporation levels compared to the control sample. Regarding sensory analysis, formulated with 5 % IFC, turkey burger samples were most appreciated by the panel with higher ( P  < 0.05) overall acceptability. Additionally, two multivariate exploratory techniques, namely, Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA), were used to all obtained data describing the main characteristics attributed to refrigerated turkey meat samples. The applied chemometric approaches were useful in discriminating meat samples and therefore offer an approach to rely interrelationships between meat quality traits. Overall, the findings demonstrate the potential functional and economic utility of IFC as a promising ingredient for future healthy meat applications.