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Carob molasses is widely consumed in many Mediterranean countries, including Tunisia where it is known as ‘Rub El Kharroub’. The main objective of the present study was to evaluate the physicochemical properties and biological activities of both commercial and homemade Tunisian carob molasses. The physicochemical characterization revealed that the main parameters (color and HMF concentration) were related to non-enzymatic browning reactions occurring during juice concentration. The phytochemical analysis proved that the presence of bioactive compounds (volatile compounds, phenolic substances and products of non-enzymatic browning reactions) in carob molasses samples justify their biological effects (antioxidant and antibacterial activities). Accordingly, such characteristics may qualify Tunisian carob molasses (both homemade and commercial) as nutritious and healthy food that could be directly consumed or used a functional ingredient in food and pharmaceutical industry.

The feather is a valuable protein resource. The feather is the major waste by-product resulting from the poultry processing plants. Therefore, increasing the values of poultry feather waste has a significant effect in the environment. In this study, the physicochemical and functional properties as well as the antioxidant activities of the feather protein hydrolysates (FPHs) obtained by acid hydrolysis after 100 min (FPH100), 200 min (FPH200) and 300 min (FPH300) were investigated. The results showed that FPH100, FPH200 and FPH300 presented high protein content 74.04%, 71.05% and 73.94%, respectively. All FPHs had a good solubility and possessed some interfacial properties, governed by their concentrations. The antioxidant activities of the different FPHs were evaluated using various in vitro antioxidant assays such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity, total antioxidant capacity, reducing power and β-carotene bleaching. FPH100 generally showed a greater antioxidant activity across all the considered methods. The DPPH IC50 of FPH100 values were found to be 0.47 ± 0.011 mg/mL. Moreover, the FPH100 exhibited notable total antioxidant capacity and strong reducing power. Our results suggested that FPHs could be a new potential source for preparing natural antioxidants applied in food, pharmaceutical and cosmetic preparations.

The aim of this work is to establish a comparative investigation of the effect of different drying processes: microwave dehydration (100–600 W), air drying (40–60 °C) and infrared drying (40–60 °C) on drying kinetics and on the main quality attributes (color, total phenols and flavonoids contents, water and oil retention capacities) kinetics’ of lemon (Citrus limon. v. lunari) peels. The experimental drying kinetics’ of lemon peels were fitted to nine thin layer drying models. The Midilli and Kucuk model showed a better fit to experimental drying data for the three drying processes. Microwave drying at 450W preserved the maximum phenols (1.855 ± 0.016 g CAE/100 g DM) and flavonoids (0.802 ± 0.072 g RE/100 g DM) contents respectively. An increase of phenol content was noticed after 9, 13 and 14 min of microwave drying at 600, 450 and 300 W and after 156, 102 and 54 min of infrared drying at 40, 50 and 60 °C. A first-order kinetic model adequately fitted, at the beginning of drying processes, the change of total phenols and flavonoids contents. Total color difference (ΔE) increased progressively with increasing drying time and temperature or microwave power level. ΔE showed a zero-order model whatever the applied drying process. Water retention capacity (WRC) of dried lemon peels decreased during drying processes. However, infrared and microwave drying increased the oil retention capacity (ORC) of lemon peels. The WRC and ORC followed first-order kinetics during air drying and a second order polynomial model during microwave and infrared drying processes.

In this work, the effect of Detente Instantanee Controlee (DIC) (French for instant controlled pressure drop) on the total polyphenol, flavonoids, α-tocopherol contents, and antioxidant activities of olive leaves was studied. Olive leaf extracts were pre-treated at one cycle DIC under 0.1 MPa pressure for 11 s and followed by an extraction with 95% ethanol at 55 °C during 3 h. The phenolic compounds, flavonoids, oleuropein, and α-tocopherol contents were determined, showing 66.63 mg gallic acid equivalent (GAE)/g db, 12 mg catechin equivalent (CE)/g db, 43.9 mg/g db, and 0.15 mg/g db for the untreated leaves against 239.37 mg GAE/g db, 28 mg CE/g db, 70.3 mg/g db, and 0.59 mg/g db for DIC-treated leaves, respectively. Therefore, DIC allows more availability of bioactive compounds contributing to a high antiradical activity (DPPH) compared to a synthetic antioxidant butylated hydroxytoluene (BHT). Both extracts showed a total antioxidant capacity (method of phosphomolybdenum) greater than that of the standard BHT. Likewise, both extracts have a reducing power (FRAP test) significant concentration-dependent. The DIC-treated leaves showed a higher antioxidant capacity compared to that of untreated leaves. Thus, DIC could be an effective treatment to promote the extraction of bioactive molecules of high antioxidant activities from olive leaves.

Tunisian carob pods were used to produce molasses and powders, which were then analyzed for their composional and functional properties. Molasses were made from carob juice by boiling until three different concentrations (60, 70 and 80 °Brix), while powders were prepared by microwave drying of the by-product derived from carob molasses processing at three power levels (100, 300 and 600 W). Results showed that the processed carob products exhibited interesting characteristics. Carob molasses were characterized by important reducing sugars content, dark color and functional properties with high antioxidant activity and emulsifying capacity. On the other hand, carob powders were characterized by high levels of dietary fibers, brown color and water/oil retention capacity. This study provides, for the first time, a potential valorization of the carob by-product into powder and highlights some functional properties of carob products required by food industry.