Agro-industrial waste as a source of bioactive compounds: ultrasound-assisted extraction from blueberry (Vaccinium myrtillus) and raspberry (Rubus idaeus) pomace

Abstract

Blueberry and raspberry pomace are a rich source of bioactive compounds that have not been commercially utilized yet, and ultrasound-assisted technology can efficiently extract these compounds. Also, the use of water as a solvent added to the ultrasound-assisted technology improves this eco-friendly process. Therefore, an aqueous eco-friendly extraction, including extraction time and ultrasound presence or absence (conventional extraction) was performed in order to extract bioactive compounds from blueberry and raspberry pomace. Response parameters included levels of anthocyanins, phenolic compounds, and flavonoids, and antioxidant activity determined by DPPH, ABTS, and FRAP methods. Analysis of variance results indicated that ultrasound-assisted extraction for 45 min. was feasible to extract the bioactive compounds. The antioxidant content of the extract obtained by the ultrasound-assisted process was 1.4 times higher on average and the total phenolic concentration was 1.6 times higher (for blueberry 5.02 and for raspberry 2.53 mg gallic acid equivalent/g) compared with those obtained by the conventional process. Thus, the ultrasound-assisted extraction method can be a profitable alternative to extract bioactive compounds from blueberry and raspberry pomace, as it is energy efficient, requires fewer chemicals, and produces less effluent. This eco-friendly technology is therefore viable for food, nutraceutical, and cosmetic industries, and also for reducing food waste.

Bioactivity and Chemical Profile of Rubus idaeus L. Leaves Steam-Distillation Extract

“…The value obtained in the DPPH assay was 6746 ± 555 µM TE 100 mL −1 of RH used, which is not very different from the values found in the literature [5,[86][87][88][89]. Regarding the ABTS assay, the value obtained was 13.57 ± 0.56 µM TE 100 mL −1 of RH, which is slightly lower but still in line with that observed by other researchers [5,[86][87][88][89][90][91][92][93][94]. In the FRAP assay, the value obtained was 307.48 ± 3.08 µM TE 100 mL −1 of RH.…”

“…In the FRAP assay, the value obtained was 307.48 ± 3.08 µM TE 100 mL −1 of RH. In this case, comparing the values with those found in the bibliography showed that the effects of the hydrolate in this assay were, in general, greater than other work [88,[92][93][94][95][96][97][98][99][100]. The content of total phenols in the hydrolate was very scarce (6.25 ± 0.54 mg GAE 100 mL −1 ), consistent with the extraction technique adopted, and much lower than the extracts with the solvent [99][100][101][102][103][104][105].…”

Response Surface Methodology for Optimization of Ultrasound-Assisted Antioxidants Extraction from Blackberry, Chokeberry and Raspberry Pomaces

“…However, some researchers have reported the opposite effect of time. Blueberry and raspberry extracts obtained using UAE over 45 min were characterized by higher TPC values than extracts obtained with a UAE time of 15 min using the same US power [ 17 ]. Silva Junior et al [ 18 ] concluded that applying the longest time (15 min) and the highest value of ultrasound amplitude (100%) resulted in ciriguela peel extracts with the highest TPC results.…”