Free and Bound Phenolic Compounds Present in Orange Juice By-Product Powder and Their Contribution to Antioxidant Activity

Abstract

Interest in fruit/vegetable consumption is not always linked to a particular diet but rather derives from their high antioxidant activity (AOA), with potential health benefits provided, in part, by polyphenols. Although phenols can be found in free form (FP) or bound to plant tissues (BP), the experimental methodology most frequently used for the quantification of total phenols (TP) is based on the extraction of a portion of FP, which may justify the lack of correlation often found between them and AOA. In this context, four successive extractions were performed to obtain FP and BP of powdered orange juice by-product, and their contribution to the AOA was studied. The first extract (MeOH, 30 °C) can be assumed to be one of the conventional methods for the quantification of TP. Re-extraction with MeOH (60 °C) afforded the FP. Two subsequent basic and acidic extractions yielded the BP. Although the FPs were the most abundant, the AOA (DPPH method) of the last fraction of BP was of the same order found in the first fraction of FP. This highlights the interest in extracting the BP from the by-product of orange juice if its antioxidant capacity is to be exploited.

In Vitro Bioaccessibility of Bioactive Compounds of Freeze-Dried Orange Juice Co-Product Formulated with Gum Arabic and Modified Starch

“…OJC showed a water content higher than x w found in the literature for orange peel (72.5 g/100 g) [ 17 ], possibly because some pulp remained in the co-product used as raw material in this work after orange juice extraction. The freeze-drying process decreased ( p < 0.05) the water content by around 95%, to 3.12–4.46 g/100 g, similar values to previous studies [ 18 ] and of the same order of those suggested by other authors for quality freeze-dried products [ 19 ].…”

Chemical Composition and Phytochemical Screening of Juniperus Phoenicea L.: Evaluation of Antioxidant Activity, Minerals, and Bioactive Compounds

“…The capacity of phenolic compounds to donate electrons or hydrogen atoms to free radicals or reactive oxygen species makes them known for their antioxidant properties. Important biomolecules like proteins, lipids, and DNA are shielded from oxidative damage by this mechanism, which also successfully neutralizes these dangerous substances (46). Previous studies that used different solvents or methods to assess the total phenol content of Juniperus phoenicea leaves or fruits can provide a basis for comparison with the current findings.…”

Composition of Powdered Freeze-Dried Orange Juice Co-Product as Related to Glucose Absorption In Vitro

“…The orange juice waste used as raw material was provided by the Belles Arts Sant Carles cafeteria of the Universitat Poltècnica de València (Spain) in February 2022. To obtain the co-product powder (CoP), the residue, after completely removing the central column and seeds, was crushed and emulsified (Robot coupe blixer2, Valencia, Spain) and water was added at a ratio of 1/0.38 to facilitate the process and create a homogeneous mixture [ 20 ]. Emulsification was carried out for 5 min per 750 g of residue.…”

“…The main flavonoids present in each fraction were analysed. In both cases, the method described by Camacho et al [ 20 ] was used. Briefly, 1 g of sample was extracted with MeOH at 30 °C and the filtrate obtained was extracted again with the same solvent but at 60 °C.…”