The valorization of food organic waste epitomizes sustainability and a green circular economy.
FINNOVER (Innovative strategies for the development of cross border green supply chains) is a project dedicated specifically to the management and valorization of agricultural and food processing waste; more specifically, they use industry byproducts to “sustainably exploit the agrobiodiversity widespread in the ALCOTRA territory.”  The ALCOTRA territory refers to the Alpine area between France and Italy.
Bud-preparations (“herbal preparations from buds and sprouts”) are a novel category of plant-derived food supplements marketed in the European Union and the main focus of the FINNOVER project. The buds in question were derived from Castanea spp., sweet chestnut, which grows spontaneously in Italian valleys during spring. Chestnut buds are used for herbal formulations, but the processing generates significant waste.
The valorization of the processing waste was done via pulsed ultrasound-assisted extraction (PUAE), as ultrasound extraction is one of the greenest methods in terms of cost and sustainability. Pulsation increases efficiency through “diffusion across the plant cell wall and the flushing of the cell contents after the wall breaking.”
Initially, the researchers prepared chestnut bud-preparations using traditional maceration with glycerol and ethanol:water (95:5 v/v). They proceeded to PUAE with the waste from these conventional preparations and used the same solvent.
Reprinted from: Donno D, et al. Sustainable extraction and use of natural bioactive compounds from the waste management process of Castanea spp. bud-derivatives: The FINNOVER project. Sustainability. 2020;12(24):10640. License: CC BY 4.0
The optimal conditions for extraction were a “duty cycle of 80%, extraction time of 15 min, amplitude level of 50%, and a [sample/solvent ratio] of 1/10.” Amplitude is proportional to intensification — as it increases, so do the compression and rarefaction cycles of ultrasonic waves, resulting in a higher recovery rate of plant compounds.
PUAE proved to capture a wide spectrum of molecules, isolating tannins, phenolic acids, and flavonols, and recovered these compounds in quantities of approximately 15% compared to the original maceration extract. The researchers note that the recovered compounds possess “antihepatotoxic, anti-atherosclerotic, antioxidant, anticancer, anti-HIV replication, and anti-inflammatory activities.”
Moreover, PUAE proved to be an effective and green alternative for extracting phenolics, which have so far been usually extracted via traditional methods that consume a lot of energy, solvent, and time, while providing limited yields.
Overall, the researchers conclude that PUAE achieved very satisfactory extraction rates of bioactive compounds, especially when you consider that these compounds were derived from processing waste that would otherwise literally go to waste and be eliminated un-ecologically. PUAE is also much more time-effective than maceration (which, in this case, traditionally requires 21 days).
“For this reason, this ecological extraction technique (PUAE) may also be favorably considered as an excellent and sustainable alternative to processing waste management based on the traditional systems, such as composting or incineration.” 
- Donno D, et al. Sustainable extraction and use of natural bioactive compounds from the waste management process of Castanea bud-derivatives: The FINNOVER project. Sustainability. 2020;12(24):10640. Journal Impact Factor = 3.251; Times Cited = n/a