Effect of domestic cooking methods on the anthocyanins and antioxidant activity of deeply purple-fleshed sweetpotato GZ9

Abstract

Purple-fleshed sweetpotatoes (PFSPs) are considered to be a healthy food and there are many methods to process in family. This study aimed to investigate the effects of various domestic cooking on the anthocyanin variation and antioxidant activity of a newly bred purple-fleshed cultivar Guangzishu 9 (GZ9) with anthocyanin content up to 1,500 mg/100g dry weight. As a result, total 15 individual anthocyanins were separated and identified by using UPLC-QTOF-MS. Top three anthocyanins were cyanidin 3-dicaffeoyl sophoroside-5-glucoside, cyanidin 3-caffeoyl- p-coumaryl sophoroside-5-glucoside and peonidin 3-caffeoyl-p-hydroxybenzoyl sophoroside-5-glucoside, which accounting for 57.27% of the total anthocyanin content. Acylated anthocyanins were the major constituents in GZ9, and the type of anthocyanins was dominated by cyanidin. Boiling, steaming and mircrowaving had no significant effect on the total anthocyanin content. But baking, frying, air-frying and stir-frying reduced 11–45% of total anthocyanin content. Through ABTS + radical scavenging capacity and reducing power, antioxidant variations were also observed during different family cooking, and the variation had a strong correlation with total anthocyanin content.

Total Phenolics and Anthocyanins Contents and Antioxidant Activity in Four Different Aerial Parts of Leafy Sweet Potato (Ipomoea batatas L.)

“…The ABTS radical scavenging activity assay was determined by the method of Re et al [ 55 ] with slight modifications. Further details of the main experiment operation of ABTS assay have been described by Liao et al [ 56 ]. Four μL extraction was added to 36 μL of absolute ethanol in a 96-well flat bottom microplate, then added 200 μL ABTS radical solution.…”

Assessing extraction methods and diversity of anthocyanins from purple-fleshed sweet potatoes grown in cooler climates

“…For example, pressurized liquid extraction using acidified methanol yielded a maximum of 210 mg anthocyanins/100g fresh weight of anthocyanin across 335 sweet potato genotypes grown in North Carolina 48 and another study found a maximum of ~96 mg/100g fresh weight across three different cultivars 14 . However, our dry weight average of ~800 mg anthocyanins/100g of lyophilized powder -which may be a better comparison than fresh weight due to lack of effect of water content -sits in the intermediate to high end of the range of other studies that report values in dry weight for other cultivars 36,37,41,44,48 . This could be because freezing may increase the release of anthocyanins from vacuoles while maintaining their stability and protecting them from degradation by polyphenol oxidase.…”

“…Using acidified 75% ethanol as the extraction solvent -selected due to significantly lower toxicity than methanol -we next compared the impact of different cooking methods, namely boiling, blanching and pressure cooking, on anthocyanin levels from sweet potatoes. Previous studies suggest mixed results, with either raw extraction or boiling as the optimal method for anthocyanin release from cells [36][37][38][39] . The cooking process denatures polyphenol oxidase enzymes and disintegrates cell and vacuole membranes to release anthocyanins.…”

The Potential of Sweetpotato as a Functional Food in Sub-Saharan Africa and Its Implications for Health: A Review

“…The second reason was the fact that anthocyanins in sweetpotato occur in acylated forms with various phenolic acids, making the anthocyanins more resistant to heat, pH, and light sensitivity [ 118 ]. In another study, it was reported that air-fried, deep-fried and stir-fried cooking resulted in a decrease of total anthocyanins by 45%, 32%, and 31% respectively, while baking decreased it by 11%, boiling increased it by 6.55%, and the results from steaming and microwaving were inconclusive [ 122 ].…”