Digestive Stability and Bioaccessibility of Antioxidants in Prickly Pear Fruits from the Canary Islands: Healthy Foods and Ingredients

Abstract

Although prickly pear fruits have become an important part of the Canary diet, their native varieties are yet to be characterized in terms of betalains and phenolic compounds. To exert potential health benefits, these antioxidants must be released from the food matrix and be stable in the gastrointestinal tract. Our aim was to characterize the betalain and phenolic profile of four prickly pear varieties from the Canary Islands (Spain) and determine their digestive stability and bioaccessibility via in vitro gastrointestinal digestion. Digestive studies were performed considering the (i) importance of the edible fraction (pulps) and (ii) potential of fruit peels as by-products to obtain healthy ingredients. Betalains and phenolic profiles were analyzed by HPLC-DAD-ESI/MS and HPLC-DAD-MS/QTOF. Pulps in Colorada and Fresa varieties presented high indicaxanthin and betanin content, respectively. Despite low pH in the gastric phase, betalains were stable to reach the intestinal phase, although indicaxanthin presented a higher bioaccessibility. Blanco Buenavista peels contained a distinct flavonoid profile including a new isorhamnetin-hexosyl-rhamnoside. Phenolic compounds were abundant and highly bioaccessible in fruit peels. These findings suggest that prickly pear pulps are rich in bioaccessible betalains; and that their peels could be proposed as potential by-products to obtain sustainable healthy ingredients.

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

“…This observed better stability and recovery of betalains in Opuntia dillenii pulp (PU) was also observed for their phenolic compounds during in vitro gastrointestinal digestion (Table 2). Previous published studies on the stability of piscidic acid from Opuntia ficusindica fruits of different varieties showed losses of this phenolic acid of 53-71% [10] during digestion, being slightly lower values than those obtained in the present work related to Opuntia stricta var. Dillenii (59-97%).…”

“…The most important betalain s degradation was observed at the intestinal phase, where this betalain suffered a significant degradation (up to 78%), probably due to the intestinal environmental conditions. This fact was previously reported for Opuntia ficus-indica edible and inedible tissue of pricky pear fruits [10] and other cactus fruits such as cactus berry fruits (Myrtillocactus geometrizans) [17].…”

“…Stability values for individual betalains from Opunta stricta var. Dillenii pulp (PU) (Table S2) were higher than the reported ones for several authors in other betalain-rich fruit pulps [10,17,36]. Some of these authors reported that betalains are only stable at pH from 3-7, which explains their decay in the gastric phase, where they observed losses between 21% in Opuntia ficus-indica Colorada pulp fruit variety [10] and <25% in red dragon fruit juice [8], which were related to the gastric-like environment.…”

“…Dillenii pulp (PU) (Table S2) were higher than the reported ones for several authors in other betalain-rich fruit pulps [10,17,36]. Some of these authors reported that betalains are only stable at pH from 3-7, which explains their decay in the gastric phase, where they observed losses between 21% in Opuntia ficus-indica Colorada pulp fruit variety [10] and <25% in red dragon fruit juice [8], which were related to the gastric-like environment. This fact was also previously reported for betalain compounds' stability and recovery from the edible fractions of other cactus fruits such as cactus berry fruits (Myrtillocactus geometrizans) [17] during in vitro gastrointestinal digestion studies.…”

“…in fresh whole fruit (FWF), and 35.17 ± 1.76 mg/100 g f.w. in fresh peel (PE) (Table S2, Supplementary Materials) This betalain was not present in Opuntia ficus-indica fruits [4,10] but could be identified in other cactus fruits such as garambullo (Myrtillocactus geometrizans) [17], which contains 5876.9 µg/g dry weight. Moussa- Ayoub et al (2016) [11] reported that O. Dillenii fruit juice had a high content of betacyanins and a very small amount of betaxanthins.…”