Betalains, total polyphenols, and antioxidant contents in red beetroot peel (Cylindra type)

Abstract

Since significant percentage of fruits and vegetables go to waste during processing, investigation of how to improve the valuable products of extraction from the wastes is an undeniably effective way to save the planet. Beetroot (root, peel, and stalk) is a chief source of natural betalain color compounds and phenolic compounds with copious radical scavenging activity. The major emphasis of this work is to optimize process variables which are extraction time (10–60 min), operating temperature (20–50 °C), and aqueous ethanol solvent with the concentration of (25–75%) for effective extraction of valuable compounds such as betalains, total polyphenols, and antioxidant activity from beetroot peel. Spectrophotometric analysis was applied for quantification of those compounds. Amongst which, lowest solvent concentration (25% v/v) together with the highest temperature (50 °C) and extraction time (50 min) brought yielded higher results. The process optimization was carried out using Design Expert (11.0.3) statistical software. Overall, it can be noted that extraction process can be improved by controlling operating time and temperature, avoiding unnecessary overuse of costly solvent.

Betalains and their applications in food: The current state of processing, stability and future opportunities in the industry

“…In the interest of obtaining, studying, and evaluating the potential applicability of betalain pigments for the industry, multiple studies have been focused on the optimization of conventional extraction processes, using response surface methodology (RSM) ( Kumar et al, 2017 , Singh et al, 2017 , Zin et al, 2020a , Zin et al, 2019 ) and multivariate analysis by principal components analysis (PCA) ( Neagu and Barbu, 2014 , Silva et al, 2020 ) to maximize yields and maintain their stability. The betalains extraction conditions from natural sources that have been optimized and/or suggested according to some results of the most recent studies are listed in Table 2 .…”

“… 20 min stirring speed of 300 rpm Fathordoobady et al, 2016 betacyanins 10 mL/g ethanol:water 70:30 room temp. 20 min stirring speed of 300 rpm Fathordoobady et al, 2016 Red amaranth ( Amaranthus cruentus ) betacyanins 40 mL/g water (pH 5) 100 50 °C 60 min Das et al, 2019 Red beetroot ( Beta vulgaris L.) betacyanins and betaxanthins 75 mL/g water 100 30 °C 30 min stirring speed of 40 rpm Silva et al, 2020 betanin 5 mL/g water (acidified with 0.5% citric acid and 0.1% ascorbic acid) 100 70 °C Neagu & Barbu, 2014 betalamic acid, betacyanin and betaxanthin 33 mL/g water 100 60 °C 84 min Swamy et al, 2014 Red beetroot ( Beta vulgaris L.) peel betacyanins and betaxanthins 1.25 mL/g ethanol:water 15:85 20 °C 60 min stirring speed of 215 rpm Zin et al, 2020 Red beetroot ( Beta vulgaris ) powder betalains 100 mL/g ethanol:water (pH 5) 50:50 30 °C Pandey et al, 2018 Beetroots ( Cylindra type ) peel betacyanins and betaxanthins 10 mL/g ethanol:water 25:75 50 °C 50 min Zin et al, 2019 Red dragon fruit ( Hylocereus polyrhizus ) peel …”

“…Aqueous methanol solution has been found the most effective for extracting betalains from Bougainvillea glabra floral bracts ( Kumar et al, 2017 ) and Xoconostle ( Opuntia joconostle ) fruit ( Sanchez-Gonzalez et al, 2013 ). Ethanol solutions have provided a higher yield of betalains from glasswort ( Salicornia fruticosa ) ( Mohamed et al, 2018 ), Hylocereus polyrhizus flesh ( Fathordoobady et al, 2016 ), red beet root ( Beta vulgaris L.) peel ( Zin et al, 2020a ) and powder ( Pandey et al, 2018 ), and beet-roots ( Cylindra type ) peel ( Zin et al, 2019 ). In addition, ethyl acetate is used to extract Alternanthera sessilis ( Yap et al, 2019 ).…”

Eat Tasty and Healthy: Role of Polyphenols in Functional Foods

“…Citrus peels have been also studied to recover high-value bioactive compounds like flavones (apigeninglucoside and diosmetin-glucoside) and flavanones (eriocitrin and hesperidin) from lemon peel and phenolic acids (hydroxybenzoic and caffeic acids) and flavanones (hesperidin and narirutin) from orange peel and pulp [19]. Potato peel has been reported as containing phenolic acids and beetroots peel and pulp contain flavonoids, phenolic acids and betalains, which exhibited good antioxidant activity and hepatoprotective effects [20]. One of the most recently studied food material was onion and garlic skin/peel, which generates huge volume of wastes especially rich in quercetin derivatives as well as other aglycone flavonoids exhibiting bioactivities like antioxidant, antimicrobial, antispasmodic, and antidiabetic activity [21].…”

Optimal drying conditions for valorization of industrial apple pomace: Potential source of food bioactive compounds

“…Thus, for every amount of the apples that are processed, an estimate of 25% is waste, and most of these are thrown away to the environment, however, there are attempts to utilize them as animal feed ingredients. Recently, it has been proved that these substances contain huge amount of bioactive compounds especially pectin and polyphenols (Cao et al, 2009;Kolodziejczyk et al, 2009;Virot et al, 2010;Bodor et al, 2020;Zin et al 2020). Being rich in bioactive compounds, particularly pectin and polyphenols, extracts of the apple pomace have a potential to be used as green food additives.…”