Valorization of sunflower by-product using microwave-assisted extraction to obtain a rich protein flour: Recovery of chlorogenic acid, phenolic content and antioxidant capacity

Recovery of Chlorogenic Acids from Agri-Food Wastes: Updates on Green Extraction Techniques

“…An orthogonal array design was used, and the yield extraction efficiency reached a plateau using 60% ethanol; for higher concentration values, the yield decreased, slowly up to 80% ethanol, and then drastically. This trend was confirmed by a recent study on the extraction of CGAs from sunflower by-products by Náthia-Neves et al [ 53 ]. A water-ethanol 30:70, v/v mixture was the most effective, and the CGAs concentration decreased by increasing the ethanol concentration from 70% to 100%.…”

“…This trend was analogous to the behavior described by the Soxhlet extraction. In fact, 70% ethanol was more promising both than 50% and 96% ethanol in the recovery of CGAs from sunflower by-products [ 53 ] and tomato peel extract [ 39 ], respectively. Differently from the above reported works, lower percentages of ethanol (15–20%) were used to recover CGAs from spent coffee grounds at 60 °C for 15 min [ 42 ].…”

“…Due to their electromagnetic components, microwaves penetrate the plant matrix and interact with polar molecules, leading to an increase of the pressure inside the plant cells [ 68 , 69 ]. This mechanism induces alteration at the cellular level, promoting the breaking of cell walls and the subsequent release of phytochemicals, as demonstrated by scanning electron microscopy analysis performed after microwave irradiation on sunflower by-products, cocoa bean shell, and pomegranate peel [ 51 , 53 , 70 ] ( Figure 3 ).…”

“…This is the reason why different authors only took into consideration one of the two parameters of temperature and irradiation power. Náthia-Neves et al [ 53 ] investigated the impact of different extraction powers (100, 200 and 300 W) on the CGAs recovery from sunflower by-products. The optimum CGAs extraction yield was achieved at 200 W, probably because the microwave power promoted the rupture of the cell walls; conversely, at 300 W, when the temperature rose up to 105 °C, thermal degradation reduced the extraction capacity, thus confirming the previous findings of Liazid et al [ 78 ].…”

“…In fact, exposure to microwave irradiation for longer times generally reduced the extraction yield of phenolic compounds [ 81 ]. In particular, the recovery of CGAs from blueberry leaves was very similar, applying 71W for 24 min or 142.1 W for 4 min [ 31 ], but irradiation power of 300 W even only for 120 s may lead to overheating with decomposition of the phenolic compounds [ 53 ]. However, using 400–900 W for shorter times allows setting an optimal temperature, avoiding overheating and thus optimizing CGAs extraction [ 35 , 37 , 45 , 51 , 80 ].…”