Artichoke by Products as a Source of Antioxidant and Fiber: How It Can Be Affected by Drying Temperature

The reuse of food industry by-products constitutes one of the essential pillars of the change from a linear to a circular economic model. Drying is one of the most affordable techniques with which to stabilize by-products, making their subsequent processing possible. However, it can affect material properties. The objective of this study was to assess the effect of the drying temperature on the drying kinetics and final quality of the main artichoke processing by-products, bracts and stems, which have never been studied as independent materials. For this purpose, air drying experiments at different temperatures (40, 60, 80, 100 and 120 °C) were carried out. The alcohol insoluble residue (AIR) and the total phenolic content (TPC), antioxidant capacity (AC) and vitamin C (VC) of the fresh and dried samples were determined. The bracts dried faster than the stems, increasing drying rate with temperature. The two by-products presented relatively large amounts of AIR, the content being higher in bracts, but better functional properties in stems. The TPC, AC and VC values of the dried samples decreased in relation to the fresh samples, with the temperatures of 40 °C (bracts) and 120 °C (stems) being the most adequate for the purposes of preserving these characteristics.

Profiling the main cell wall polysaccharides of grapevine leaves using high-throughput and fractionation methods

Vitis species include Vitis vinifera, the domesticated grapevine, used for wine and grape agricultural production and considered the world's most important fruit crop. A cell wall preparation, isolated from fully expanded photosynthetically active leaves, was fractionated via chemical and enzymatic reagents; and the various extracts obtained were assayed using high-throughput cell wall profiling tools according to a previously optimized and validated workflow. The bulk of the homogalacturonan-rich pectin present was efficiently extracted using CDTA treatment, whereas over half of the grapevine leaf cell wall consisted of vascular veins, comprised of xylans and cellulose. The main hemicellulose component was found to be xyloglucan and an enzymatic oligosaccharide fingerprinting approach was used to analyze the grapevine leaf xyloglucan fraction. When Paenibacillus sp. xyloglucanase was applied the main subunits released were XXFG and XLFG; whereas the less-specific Trichoderma reesei EGII was also able to release the XXXG motif as well as other oligomers likely of mannan and xylan origin. This latter enzyme would thus be useful to screen for xyloglucan, xylan and mannan-linked cell wall alterations in laboratory and field grapevine populations. This methodology is well-suited for high-throughput cell wall profiling of grapevine mutant and transgenic plants for investigating the range of biological processes, specifically plant disease studies and plant-pathogen interactions, where the cell wall plays a crucial role.