Impact of Agronomic Treatments on the Enzymatic Browning of Eggplants (Solanum melongena L.).

Enzymatic browning could negatively affect the sensory and nutritional properties of eggplants post-harvest. Polyphenols, polyphenol oxidase (PPO), and reactive oxygen species (ROS) are three material conditions involved in enzymatic browning. This paper seeks to evaluate the effect of fertilization techniques and grafting on the activity of PPO and colorimetric parameters in cultivated eggplants. Fertilization alone significantly increased the PPO activity in all eggplant fleshes (p ≤ 0.05), whereas the grafting technique combined with fertilization decreased the PPO activity in most of the samples significantly (p ≤ 0.05). Moreover, there was a significant positive correlation between the PPO activity and the a* values of the eggplants. The a* values in grafted eggplants were significantly different from each other (p ≤ 0.05), showing that grafting the fertilized eggplants could be effective in controlling the enzymatic browning. The eggplant slices exposed to air for 60 min at room temperature showed a significant increase (p ≤ 0.05) in PPO activity, browning index (BI), total color difference (ΔE), and a*, b*, and c* values. Thus, it is necessary to minimize the exposure time of the slices to air at room temperature, even if combining fertilization techniques with grafting could delay the enzymatic browning in fresh-cut eggplants.

Biochemical and functional properties of wheat middlings bioprocessed by lactic acid bacteria.

The present study aimed to investigate the bioprocessing of wheat middlings with different lactic acid bacteria (LAB) in order to improve biological activities of this by-product of wheat flour production. The concentration of lactic acid, reducing sugars, and total phenolics, as well as antioxidant, antibrowning, antibacterial and prebiotic activities of fermented samples were analyzed. All LAB strains were capable to growth on wheat middlings, and pH decreased in the medium associated with lactic acid production during cultivation. Samples inoculated with Lactobacillus plantarum DSM20174 presented the maximum growth, lactic acid concentration above 2 mg/ml, and pH values around 3.8. The amount or reducing sugars decreased after 24 hr growth, except for maltose. Bioprocessed wheat middlings exhibited antioxidant, antibrowning, antibacterial, and prebiotic properties, related with the increase of total phenolic content. Highest values for antioxidant activities were obtained for L. plantarum and Streptococcus thermophilus strains, reaching values around 400 and 640 µM Trolox equivalents (TE) ml-1 for 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric ion reducing antioxidant power (FRAP) assays, respectively. Bioprocessing techniques using LAB can be an interesting approach to improve the availability of compounds with health-promoting properties from lignocellulosic waste material. PRACTICAL APPLICATIONS: The processing of secondary products from wheat milling can represent an important benefit to the industry. Wheat middlings bioprocessed with LAB showed improved biological activities and may represent an interesting ingredient to be incorporated in food and feed formulations.

Valorisation of Ginger and Turmeric Peels as Source of Natural Antioxidants.

The antioxidant activity of ginger and turmeric powders derived from freeze-dried rhizomes and peels as well as commercial spices has been evaluated by two spectrophotometric assays based on electron transfer such as DPPH and FRAP. The phenolic characterization has been also carried out by detecting total polyphenols through Folin-Ciocalteu method and HPLC analysing 6-gingerol and curcumin. Ginger and turmeric peels showed greater antioxidant activity than commercial powders because of their higher phenolic yields. Hence, ginger and turmeric peels can be considered a rich source of phytochemicals which contribute to the antioxidant effects of these agro-food wastes.

Study on the antioxidant and antimicrobial activities of Allium ursinum L. pressurised-liquid extract.

Allium ursinum L. is widely used as a spice as well as a traditional medicine. The aim of this work was to evaluate the antioxidant and antimicrobial activities (AMAs) of A. ursinum extract, obtained by pressurised-liquid extraction. Several reliable procedures such as 2,2-diphenyl-1-picrylhydrazyl, 2,2-azinobis-3ethyl benxothiazoline-6-sulphonic acid, ferric-reducing antioxidant power assay and oxygen radical absorbance capacity assays were carried out. Vegetable oil stability was evaluated by using Rancimat test. Moreover, AMA was performed on different microorganisms. On the basis of the results obtained, it is confirmed that the A. ursinum extract could be used as a natural ingredient in food and/or pharmaceutical industries.