Impact of drying methods on natural antioxidants, phenols and flavanones of immature dropped Citrus sinensis L. Osbeck fruits

Abstract

Citrus fruits are famous for nutritional value and studies are there for extraction of secondary metabolites from citrus waste. An attempt was made to quantify antioxidants, flavonoids and phenols from dropped fruits of 8–24 mm size, to find the impact of freeze and hot-air oven drying techniques on extraction. Flavonoids (hesperidin, narirutin/isonaringin, diosmin and didymin/neoponcirin) were quantified through high performance liquid chromatography (HPLC) and total phenols (TPC) were estimated by Folin-Ciocalteu method. Antioxidant capacity was adjudged by azino-bis [3-ethylbenzthiazoline-6-sulfonic acid] (ABTS), 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH) and Ferric Reducing Antioxidant Power (FRAP). Freeze dried fruits of 10 mm and 12 mm retained maximum hesperidin content (22.383% and 21.560%) in comparison to hot-air oven counterparts (18.377% and 15.090%). Narirutin/isonaringin (1.343% and 1.191%), diosmin (5.293% and 3.234%) and didymin/neoponcirin (1.187% and 1.113%) content were found higher in 8 mm and 10 mm freeze dried fruits. The antioxidant capacity (7.548–11.643 mmol L−1 Trolox, 8.164–14.710 mmol L−1 Trolox, 4.008–5.863 mmol L−1 Trolox by ABTS, DPPH and FRAP assays) and TPC were found higher in freeze dried samples. Significant correlation was found between antioxidant capacity, TPC and flavonoids at p < 0.01. Freeze drying technique can be adopted for retaining and quality extraction of bioactive compounds from immature dropped fruits for further use in nutraceutical industries.

Variations of Bioactive Phytochemicals and Antioxidant Capacity of Navel Orange Peel in Response to Different Drying Methods

“…The high correlations between DPPH with didymin ( r = −0.529, p < 0.01) and between FRAP with 3,3′,4′,5,6,7-hexamethoxyflavone were found in the present study, suggesting these two compounds might be potent antioxidants in the orange peel. In line with our results, a high correlation between didymin and DPPH ( r = 0.83, p < 0.01) was found in a recent report studying immature dropped Citrus sinensis L. Osbeck fruits [ 31 ].…”

Mangifera indica L. Leaves as a Potential Food Source of Phenolic Compounds with Biological Activity

“…These are well known to be good for health and can be obtained through tea, vegetable, and fruit intake. In particular, phenolic and carotenoid compounds in leafy vegetables or fruits have excellent antioxidant properties in scavenging free radicals [ 2 , 3 , 4 ]. In this context, Mangifera indica L. (mango) has proven to be a good example.…”

A review on phytochemical and pharmacological facets of tropical ethnomedicinal plants as reformed DPP-IV inhibitors to regulate incretin activity

“…The previous studies conducted on fruits of Citrus sinensis demonstrated that freeze drying technique expressed a higher content of phenol and also antioxidants. Flavonoids (hesperidin) were found to be decreased during heat drying (170). Due to the heat-sensitive nature of phenol compounds and the activation of polyphenol oxidase and peroxidase during the thermal drying process, phenolic compounds are destroyed.…”

“…In contrast, polyphenol oxidase enzyme activity was reduced in freeze drying, which was conducted at a lower temperature. So, instead of using a heat drying process, freeze drying is the best alternative for preserving and quality extraction of bioactive compounds (170). A study on the preservation of antioxidant capacity and health-promoting components in frozen baby mustard also found that blanching before freezing diminishes antioxidant capacity levels as well as the contents of highcontent glucosinolates and ascorbic acid (171).…”