In Vitro Bioaccessibility of Bioactive Compounds from Citrus Pomaces and Orange Pomace Biscuits.

Adriana Maite Fernández-Fernández,Roberto Larcher,Alejandra Medrano-Fernandez,Tiziana Nardin,Adriana Gámbaro,María Dolores Del Castillo,Eduardo Dellacassa

doi:10.3390/molecules26123480

Abstract

The present investigation aimed to provide novel information on the chemical composition and in vitro bioaccessibility of bioactive compounds from raw citrus pomaces (mandarin varieties Clemenule and Ortanique and orange varieties Navel and Valencia). The effects of the baking process on their bioaccessibility was also assessed. Samples of pomaces and biscuits containing them as an ingredient were digested, mimicking the human enzymatic oral gastrointestinal digestion process, and the composition of the digests were analyzed. UHPLC-MS/MS results of the citrus pomaces flavonoid composition showed nobiletin, hesperidin/neohesperidin, tangeretin, heptamethoxyflavone, tetramethylscutellarein, and naringin/narirutin. The analysis of the digests indicated the bioaccessibility of compounds possessing antioxidant [6.6–11.0 mg GAE/g digest, 65.5–97.1 µmol Trolox Equivalents (TE)/g digest, and 135.5–214.8 µmol TE/g digest for total phenol content (TPC), ABTS, and ORAC-FL methods, respectively; significant reduction (p < 0.05) in Reactive Oxygen Species (ROS) formation under tert-butyl hydroperoxide (1 mM)-induced conditions in IEC-6 and CCD-18Co cells when pre-treated with concentrations 5–25 µg/mL of the digests], anti-inflammatory [significant reduction (p < 0.05) in nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 macrophages], and antidiabetic (IC50 3.97–11.42 mg/mL and 58.04–105.68 mg/mL for α-glucosidase and α-amylase inhibition capacities) properties in the citrus pomaces under study. In addition, orange pomace biscuits with the nutrition claims “no-added sugars” and “source of fiber”, as well as those with good sensory quality (6.9–6.7, scale 1–9) and potential health promoting properties, were obtained. In conclusion, the results supported the feasibility of citrus pomace as a natural sustainable source of health-promoting compounds such as flavonoids. Unfractionated orange pomace may be employed as a functional food ingredient for reducing the risk of pathophysiological processes linked to oxidative stress, inflammation, and carbohydrate metabolism, such as diabetes, among others.

Highlights

During commercial juice production, large amounts of industrial waste are generated which are composed of pulp, seeds, and peels that account for about 50% of the total weight of citrus fruit
Other flavonoids found in mandarin and orange pomaces, following nobiletin, were hesperidin/neohesperidin, tangeretin, heptamethoxyflavone, tetramethylscutellarein, and naringin/narirutin
The results suggest that phenolic compounds, including hesperidin, which have been detected in the samples under study (Table 1) could contribute to the reduction in cellular oxidative stress observed in the present investigation

Summary

Introduction

Large amounts of industrial waste are generated which are composed of pulp, seeds, and peels that account for about 50% of the total weight of citrus fruit. The use of this waste is fundamental for the fruit processing industry, for economic reasons, and to reduce the severe environmental impact that it could produce [1]. Chronic inflammation and oxidative stress are related to diabetes pathogenesis [3]. Some strategies (such as inhibition of carbohydrases and reduction in oxidant species) have been previously reported for diabetes control [4,5,6].

Objectives

Methods

Results

Conclusion