Pressurized Liquid Extraction of Polyphenols and Anthocyanins from Saffron Processing Waste with Aqueous Organic Acid Solutions: Comparison with Stirred-Tank and Ultrasound-Assisted Techniques

• Published in: Sustainability Vol. 13; no. 22; p. 12578
• Main Authors: Pappas, Vasileios M., Athanasiadis, Vassilis, Palaiogiannis, Dimitrios, Poulianiti, Konstantina, Bozinou, Eleni, Lalas, Stavros I., Makris, Dimitris P.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.11.2021
• Subjects: Acids; Anthocyanins; Antioxidants; Aqueous solutions; Buttresses; By products; Cavitation; Food waste; Lactic acid; Liquid chromatography; Mass spectrometry; Mass spectroscopy; Organic acids; Pigments; Polyphenols; Pretreatment; Raw materials; Saffron; Solvent extraction processes; Solvents; Sustainability; Ultrasonic testing; United States > US; Germany
• ISSN: 2071-1050; 2071-1050
• DOI: 10.3390/su132212578

Fοllow up with our previous study on the extraction of saffron processing waste polyphenols using deep eutectic solvents, the objective of this examination was a comparative evaluation of pressurized liquid extraction (PLE), stirred-tank extraction (STE) and stirred-tank extraction with ultrasonication pretreatment (STE/UP) with respect to the recovery of pigments and antioxidant polyphenols from saffron processing waste. Aqueous solutions of citric and lactic acids at two different concentrations were used as green solvents. The extracts obtained under the specified conditions were analyzed for total pigment and total polyphenol yields as well as for their ferric-reducing power and antiradical activity. Furthermore, each produced extract was analyzed with liquid chromatography–mass spectrometry to profile its analytical polyphenolic composition. In all cases, PLE provided inferior results compared to the two other techniques, producing extracts with lower polyphenolic concentration and weaker antioxidant properties. On the other hand, no specific pattern was detected concerning the effect of ultrasonication, acid type and acid concentration. Hierarchical cluster analysis indicated that stirred-tank extraction with 1% (w/v) lactic acid and ultrasonication pretreatment might be the highest-performing combination, providing extracts with increased polyphenol and pigment concentration; however, it also enhanced antioxidant activity. It was also concluded that the significantly shorter extraction time when using PLE might be an important element in further optimizing the process, buttressing the use of this technique for the establishment of innovative and sustainable-by-design extraction methodologies.