Characterization, Stability, and Bioaccessibility of Betalain and Phenolic Compounds from Opuntia stricta var. Dillenii Fruits and Products of Their Industrialization

Abstract

The aim of the present study was the full characterization, quantification, and determination of the digestive stability and bioaccessibility of individual betalain and phenolic compounds of Opuntia stricta, var. Dillenii fresh fruits (peel, pulp, and whole fruit) and of the products of the industrialization to obtain jam (raw pressed juice (product used for jam formulation), by-product (bagasse), and frozen whole fruit (starting material for jam production)). Opuntia stricta var. Dillenii fruits and products profile showed 60 betalain and phenolic compounds that were identified and quantified by HPLC-DAD-ESI/MS and HPLC-DAD-MS/QTOF, being 25 phenolic acids (including isomers and derivatives), 12 flavonoids (including glycosides), 3 ellagic acids (including glycosides and derivative), and 20 betanins (including degradation compounds). In vitro gastrointestinal digestion was performed by INFOGEST^® protocol. Fruit pulp showed the greater content of total betalains (444.77 mg/100 g f.w.), and jam only showed very low amounts of two betanin degradation compounds, Cyclo-dopa-5-O-β-glucoside (and its isomer) (0.63 mg/100 f.w.), and two Phyllocactin derivatives (1.04 mg/100 g f.w.). Meanwhile, fruit peel was the richer tissue in total phenolic acids (273.42 mg/100 g f.w.), mainly in piscidic acid content and total flavonoids (7.39 mg/100 g f.w.), isorhamnetin glucoxyl-rhamnosyl-pentoside (IG2) being the most abundant of these compounds. The stability of betalains and phenolic compounds during in vitro gastrointestinal digestion is reported in the present study. In Opuntia stricta var. Dillenii pulp (the edible fraction of the fresh fruit), the betanin bioaccessibility was only 22.9%, and the flavonoid bioaccessibility ranged from 53.7% to 30.6%, depending on the compound. In non-edible samples, such as peel sample (PE), the betanin bioaccessibility was 42.5% and the greater bioaccessibility in flavonoids was observed for quercetin glycoside (QG1) 53.7%, the fruit peel being the most interesting material to obtain antioxidant extracts, attending to its composition on antioxidant compounds and their bioaccessibilities.

Keywords: Opuntia stricta var. Dillenii; betalains; bioaccessibility; by-products; fruit jam; fruit tissues; in vitro gastrointestinal digestion; phenolic compounds; stability.

Figure 1

Opuntia stricta var. Dillenii cactus and cactus from Canary Islands, Spain.

Figure 2

Scheme of Opuntia stricta var. Dillenii samples. (A) Fresh fruit samples (whole fruit FWF, peel PE, pulp PU), and (B) samples from jam production: frozen whole fruits, FRWF; raw juice, JU; by-product (bagasse), BA; jam, JA.

Figure 3

HPLC-DAD chromatogram of betalains and phenolic compounds in Opuntia stricta var. Dillenii from (a) whole fruit at 280 nm (zoom chromatogram 0–10 min, a1), 370 nm (zoom chromatogram 25.5–50 min, a2), and all chromatograms with UV-vis detection: 280, 370, 480, and 535 nm (a3), (b) by-product (bagasse) from the industrialization, chromatogram at 280 nm (zoom chromatogram 0–10 min, b1) and at 370 nm (zoom chromatogram 25.5–50 min, b2) (c) and Opuntia stricta var. Dillenii‘s jam chromatograms at 280 nm (zoom chromatogram 0–10 min, c1) and at 370 nm (zoom chromatogram 25.5–50 min, c2). Numbers correspond to the identified compounds indicated in Table 1.

Figure 4

Betalains content (mg/100 g fresh weight) in Opuntia stricta var. Dillenii fruit tissues (peel, pulp, and whole fruit), jam production products (intermediate juice and jam), and by-product (bagasse); (a) betanin and isobetanin; (b) 2′-O-apiosyl-4-O-phyllocactin and 5″-O-E-sinapoyl-2′-apyosil-phyllocactin; (c) neobentanin.

Figure 5

Phenolic compounds content (mg/100 g fresh weight) in Opuntia stricta var. Dillenii fruit tissues (peel, pulp, and whole fruit), jam production products (intermediate juice and jam), and by-product (bagasse) (a) phenolic acids: piscidic acid, piscidic acid isomer I, and piscidic acid isomer II; (b) flavonoids: quercetin glycoside(QG1)—quercetin hexosyl pentosyl rhamnoside, isorhamnetin glucoxyl-rhamnosyl-rhamnoside(IG1), and isorhamnetin glucoxyl-rhamnosyl-pentoside (IG2).

Figure 6

Bioactive content (mg/100 g fresh weight) in Opuntia stricta var. Dillenii fruit tissues (peel, pulp, and whole fruit), jam production products (intermediate juice and jam), and by-product (bagasse) during in vitro gastrointestinal static digestion. (a) Betanin, (b) isobetanin, (c) neobentanin, (d) 2′-O-apiosyl-4-O-phyllocactin, (e) piscidic acid, (f) quercetin glycoside (QG1)—quercetin hexosyl pentosyl rhamnoside, (g) isorhamnetin glucoxyl-rhamnosyl-rhamnoside (IG1), and (h) isorhamnetin glucoxyl-rhamnosyl-pentoside (IG2).