Gastrointestinal digestion assays for evaluating the bioaccessibility of phenolic compounds in fruits and their derivates: an overview.

Fruits and their derivatives are sources of phenolic compounds, which contribute to the maintenance of health benefits. In order to exert such properties, these compounds must be exposed to gastrointestinal conditions during digestion. In vitro methods of gastrointestinal digestion have been developed to simulate and evaluate the changes that compounds undergo after being exposed to various conditions. We present, in this review, the major in vitro methods for evaluating the effects of gastrointestinal digestion of phenolic compounds in fruits and their derivatives. We discuss the concept of bioaccessibility, bioactivity, and bioavailability, as well as the conceptual differences and calculations among studies. Finally, the main changes caused by in vitro gastrointestinal digestion in phenolic compounds are also discussed. The significant variation of parameters and concepts observed hinders a better evaluation of the real effects on the antioxidant activity of phenolic compounds, thus, the use of standardized methods in research would contribute for a better understanding of these changes.

Juá (Ziziphus joazeiro Mart.) mucilage and juá by-product phenolic extract improve quality parameters and retain bioactive compounds in fresh-cut pineapple during storage.

This study evaluated the effects of coatings with juá mucilage (JM), juá mucilage incorporated with phenolic extract from juá (JMPE), and juá mucilage with gum arabic (JM-GA) on quality parameters, bioactive compounds and antioxidant activity of fresh-cut pineapple during 9 days at 5 ± 1 °C. JM and JMPE coatings were effective in reducing enzymatic activity, consequently reducing changes in fruit color compared to uncoated fresh-cut pineapple (C). JM coating was more efficient in reducing metabolic activity with the lowest conversion of sugars into glucose, fructose and organic acids. In addition, JMPE coating showed the highest retention of phenolics. On the other hand, JM had a minor reduction in antioxidant activity in FRAP (39.55 %) and ORAC (33.46 %) assay compared to other coatings (p ≤ 0.05). Findings indicate that JM and JMPE are promising for application to preserve the overall quality and to extend the shelf life of fresh-cut pineapple.

Biotransformation of the Brazilian Caatinga fruit-derived phenolics by Lactobacillus acidophilus La-5 and Lacticaseibacillus casei 01 impacts bioaccessibility and antioxidant activity.

This study aims to evaluate the effect of fermentation of fruit purees (seriguela, mangaba, mango, and acerola) with Lacticaseibacillus casei 01 and/or Lactobacillus acidophilus LA-05 on the profile and bioaccessibility of phenolics and antioxidant activity. The physicochemical parameters and sugar and organic acid contents were also measured for evaluating the fermentation system. Fruit purees were adequate substrates for the growth of probiotic cultures, presenting high viability in the product and after simulated gastrointestinal conditions (≥7 log CFU/g). The fermentation with probiotic cultures increased the lactic acid (8.45-15.44 mg/mL), acetic acid (0.05-1.05 mg/mL), and phenolic contents and bioaccessibility, while the pH values and glucose and fructose contents were decreased (p < 0.05). L. acidophilus was found in higher counts in seriguela puree (8.00 ± 0.03), resulting in a higher consumption of maltose, fructose, and glucose, increased phenolic compounds content and bioacessibility and higher antioxidant activity (p < 0.05). The co-cultivation of both probiotic strains showed promising results for mango, mangaba and seriguela purees, resulting in an increased content and bioaccessibility of phenolics and higher antioxidant activity (p < 0.05). Our findings demonstrate for the first time that the Brazilian Caatinga fruit-derived phenolics can be biotransformed by Lactobacillus and amended genera probiotics to bioaccesible phenolics with antioxidant activity. The knowledge obtained from this study will provide fundamental concepts of the use of synergistic probiotics for future fermentation of other fruit purees to increase the bioaccesibility and antioxidant activity of biotransformed phenolic compounds.

Juá fruit (Ziziphus joazeiro) from Caatinga: A source of dietary fiber and bioaccessible flavanols.

Fruits from Ziziphus joazeiro from Mata Paraibana (MP), Borborema (BB), Agreste (AG) and Sertão Paraibano (SP) were assessed to determine their morphological characteristics, nutritional composition, content and bioaccessibility of phenolic compounds and antioxidant activity. In general, juá fruits presented ovoid shape, high moisture (65.33-72.53%), low acidity, with succinic acid being the predominant organic acid, and high dietary fiber content (8.98-10.81%), mostly insoluble fibers (5.72-8.02%). Fruits from MP presented the highest amounts of free phenolic compounds (24.27 mg/100 g) and the highest antioxidant activity in the DPPH, FRAP and ORAC assays. In MP fruits, epigallocatechin gallate (12.04 mg/100 g) was the major compound, while in fruits from other states, phenolic compounds were the major compounds. The bioaccessibility of catechin, epicatechin, epicatechin gallate, epigallocatechin gallate, procyanidin and syringic acid varied among fruits from different regions. Fruits from SP presented the highest phenolic content in the bioaccessible fraction and highest antioxidant activity in all assays. The findings of this study indicate that juá is a non-acidic fruit with highest moisture, source of fiber, majority insoluble fibers and bioaccessible flavanols.

Prebiotic activity of monofloral honeys produced by stingless bees in the semi-arid region of Brazilian Northeastern toward Lactobacillus acidophilus LA-05 and Bifidobacterium lactis BB-12.

This study assessed the in vitro prebiotic effects of honeys from Ziziphus joazeiro Mart. (juazeiro; J) and Mimosa arenosa Willd Poir (jurema branca; JB) produced by native stingless bees, namely Melipona subnitida Ducke (jandaíra; J) and M. scutellaris Latrelle (uruçu; U), in the Brazilian Northeastern semi-arid region toward the probiotics Lactobacillus acidophilus LA-05 and Bifidobacterium animalis subsp. lactis BB-12. Cells of the probiotic strains were enumerated over 48 h of cultivation in broths containing each honey (JJ, JU, JBJ or JBU) as a sole carbon source. The metabolic activities of probiotic strains in these media were assessed by measuring changes in pH values and sugars, organic acids and phenolics contents. All honeys (20 or 30 g/L) exerted growth promoting effects and displayed positive prebiotic activity scores (0.94-1.22) on tested probiotics. JJ showed the highest (p < 0.05) stimulatory effects on probiotics growth and prebiotic scores. At the end of the cultivation period, counts of L. acidophilus LA-05 and B. lactis BB-12 increased (p < 0.05) more than 2 log in broths regardless the monofloral honey added. The pH values and sugars contents decreased (p < 0.05), while the organic acids contents increased (p < 0.05) during cultivation of probiotics in broths containing JJ, JU, JBJ or JBU as carbon source. After 48 h of cultivation, contents of gallic, caftaric and caffeic acid, catechin and procyanidins (B1 and B2) decreased (p < 0.05) in media containing JJ, JU, JBJ or JBU despite of the inoculated probiotic. JJ honey presented overall the better stimulatory effects on the growth and metabolism of L. acidophilus LA-05 and B. lactis BB-12. These results showed for the first time the potential prebiotic properties of four monofloral honeys produced by stingless bees in the Brazilian Northeastern semi-arid region.

Effects of probiotics on the content and bioaccessibility of phenolic compounds in red pitaya pulp.

This study assessed the effects of the incorporation of Lactobacillus acidophilus LA-05 or Bifidobacterium animalis ssp. lactis BB-12 in the content and bioaccessibility of phenolics in red pitaya pulp. The oxygen radical absorbance capacity (ORAC) of the dialyzed (bioaccessible) fraction of red pitaya pulp fermented by these probiotics was also assessed. After 48 h of cultivation in red pitaya pulp, the pH and sugar contents decreased, while organic acids and viable counts of the tested probiotics increased (p < 0.05). After exposure to simulated gastrointestinal conditions the viable counts of L. acidophilus LA-05 and B. lactis BB-12 in fermented red pitaya pulp were close to 8 and 7 log CFU/mL, respectively. Fermentation with probiotics decreased (p < 0.05) the contents of phenolic acids and flavonoids in red pitaya pulp. Both, L. acidophilus LA-05 and B. lactis BB-12 increased the presence of phenolics in the non dialyzed fraction of the red pitaya pulp. The bioaccessibility of catechin, epigallocatechin gallate, and procyanidin B2 increased (p < 0.05) in red pitaya pulp fermented by L. acidophilus LA-05 or B. lactis BB-12. The bioaccessible fraction of red pitaya pulp fermented by L. acidophilus LA-05 or B. lactis BB-12 showed higher antioxidant activity than that of the non-fermented red pitaya pulp. These findings indicate the fermentation of red pitaya by probiotics as an alternative to increase the bioaccessibility of specific phenolics, as well as the antioxidant activity in this fruit.

Juçara fruit (Euterpe edulis Mart.): Sustainable exploitation of a source of bioactive compounds.

Juçara (Euterpe edulis Martius) is a palm tree widely distributed in the Atlantic Forest, which produces round fruits that recently gained worldwide attention, mainly for its resemblance to fruits of Euterpe oleracea and Euterpe precatoria Martius used to produce açaí. Juçara fruits stand out for their high nutritional value, which contain different kinds of nutrients, including fatty acids, protein, fibers, minerals and vitamins, and bioactive compounds such as anthocyanins, non-anthocyanin flavonoids and phenolic acids, which are associated with potent biological activities. The main objective of this work is to present the available compositional data regarding juçara fruits to produce a comprehensive source of recent information on important chemical constituents and the potential health benefits of these fruits in reference to the species E. oleracea and E. precatoria. In addition, information on botanical aspects, production chain and markets are presented.