Eggplant Peels as a Valuable Source of Anthocyanins: Extraction, Thermal Stability and Biological Activities

Abstract

This study aimed to use eggplant peels as a potential source of anthocyanins with biological activities. Two different extraction methods were tested in order to obtain extracts with a high anthocyanin content. The selected methods were the solid–liquid extraction (SLE) and ultrasound-assisted extraction (UAE) methods. For each method, two concentrations of ethanol (EtOH) were used, while varying the extraction time and temperature. Based on the results, the extracts obtained by SLE using EtOH 96% after 30 min of extraction at 50 °C showed the highest anthocyanin concentration. The UAE allowed the best results with EtOH 96% after 30 min at 25 °C. Both selected extracts showed similar chromatographic profiles, with delphinidin 3-O-rutinoside as the major anthocyanin, but in a higher concentration in UAE. The extracts also presented inhibitory activity against lipoxygenase (LOX), lipase, and α-amylase, thus suggesting a possible involvement in reducing the risk of various disorders. The first order kinetic model was used to predict the changes that can occur in the anthocyanin content and antioxidant activity from the eggplant peel extract. The calculated kinetic and thermodynamic parameters confirm the irreversible degradation of phytochemicals.

SmMYB113 Is a Key Transcription Factor Responsible for Compositional Variation of Anthocyanin and Color Diversity Among Eggplant Peels

“…Studies have reported that anthocyanins can have anti-diabetic, anti-cancer, antiinflammatory, anti-microbial, and anti-obesity effects and prevent cardiovascular diseases (Khoo et al, 2017). Therefore, anthocyanin-rich flowers, fruits, and tubers, such as red rose, blue chicory, Condurache et al, 2021). The anthocyanin composition of purple eggplant peels has been reported, however, eggplant peels can be a variety of colors, including black-purple, reddish-purple, lavender, white, orange, or green (Sadilova et al, 2006;Todaro et al, 2009;Ferarsa et al, 2018;Yong et al, 2019;Condurache et al, 2021).…”

“…Recently, eggplant ( Solanum melongena L.) has received much attention as a functional food. The eggplant extracts have potent antioxidative properties, suggesting their possible involvement in reducing the risk of various disorders ( Noda et al, 2000 ; Sadilova et al, 2006 ; Akhbari et al, 2019 ; Condurache et al, 2021 ). The anthocyanin composition of purple eggplant peels has been reported, however, eggplant peels can be a variety of colors, including black-purple, reddish-purple, lavender, white, orange, or green ( Sadilova et al, 2006 ; Todaro et al, 2009 ; Ferarsa et al, 2018 ; Yong et al, 2019 ; Condurache et al, 2021 ).…”

Anthocyanins Recovered from Agri-Food By-Products Using Innovative Processes: Trends, Challenges, and Perspectives for Their Application in Food Systems

“…Other agri-food by-products have been exploited for anthocyanin extraction, such as black carrot pomace [ 39 ], eggplant by-product [ 40 , 41 ], black soybean seed coat [ 42 ], purple corn cob and corn husk [ 43 ], onion peel [ 44 ], black rice bran [ 45 ], and some berry by-products (e.g., blueberry [ 46 ], red raspberry [ 47 ], sweet cherry [ 48 ], sour cherry [ 49 ], bilberry [ 50 ], blackcurrant [ 51 ], blackberry [ 52 ], jabuticaba [ 53 ], black chokeberry [ 54 ], and mulberry [ 55 ], among others). Nonetheless, they are less explored and less known when compared to grape pomace.…”

Spectral Characteristic, Storage Stability and Antioxidant Properties of Anthocyanin Extracts from Flowers of Butterfly Pea (Clitoria ternatea L.)

“…Due to the health concerns associated with synthetic pigments, the food industry has begun to invest heavily in natural food colorants [1,2]. Common plant pigments, including anthocyanins, betalains, and carotenoids, possess a red hue (from yellow to purple) and have been recommended for use as healthy natural food colorants [3,4]. However, among the above plant pigments, only a small fraction of anthocyanins are blue in color [2,3].…”

“…Anthocyanins are a group of bio-active water-soluble flavonoids widely distributed in the plant kingdom that can render plant tissues with hues of pink, red, purple, and blue [3,7]. They are also beneficial to human health, possessing antioxidant and antiinflammatory properties, as well as the ability to prevent tumors, diabetes, and many other cardiovascular diseases [4,6,8,9]. Anthocyanins, which are safe and highly nutritional, have great value and potential in food coloring.…”