Bioaccessibility Of Phenolics Research Articles

Valorization of Pineapple (Ananas comosus) By-Products in Milk Coffee Beverage: Influence on Bioaccessibility of Phenolic Compounds.

The industrial processing of pineapples generates a substantial quantity of by-products, including shell, crown, and core. Bromelain, a proteolytic enzyme found naturally in pineapple, including its by-products, may positively influence the bioaccessibility of phenolics from milk coffee. Therefore, this study aimed to assess how the inclusion of extracts from pineapple by-products, namely shell, crown and core, could impact the bioaccessibility of coffee phenolics when combined with milk. After measuring the proteolytic activity of pineapple by-products, the standardized in vitro digestion model of INFOGEST was employed to evaluate changes in total phenolic content, total antioxidant capacity, and individual phenolic compounds in different coffee formulations. The results showed that incorporating extracts from the crown or core in both black and milk coffee increased the bioaccessibility of total phenolics (from 93 to 114% to 105-129%) and antioxidants (from 54 to 56% to 84-87%), while this effect was not observed for the shell. Moreover, adding core extracts also enhanced the bioaccessibility of caffeoylquinic acids and gallic acid in milk coffee (from 0.72 to 0.85% and 109-155%, respectively). Overall, the findings of this study highlight that bromelain from pineapple core may have a favorable effect on the recovery of phenolic compounds in milk coffee, possibly due to its ability to cleave proteins. These outcomes point out that industrial by-products can be transformed into economic value by being reintroduced into the production process through suitable treatment instead of disposal.

The physicochemical characteristics and phenolic bioaccessibility of defatted millet bran powder prepared using superfine grinding

Since defatted millet bran (DMB) is considered unpalatable and its poor application performance means that it is only used as animal feed, this product is wasted and underutilized. This study altered the shapes of processed DMB particles using superfine grinding technology, physically overcoming the binding forces within the material. This reduced the particle sizes and surface roughness while increasing the tap density, peak temperature, and angles of repose and slide. Superfine grinding significantly disrupted the cell wall matrix, substantially increasing the total phenolic content (TPC) and antioxidant properties compared to coarse and fine powders. Additionally, the superfine powder exhibited high phenolic compound bioaccessibility (vanillic, protocatechuic, syringic, ferulic, and isoferulic acid, and 2,3-dihydroxybenzoic). These findings highlighted the potential use of superfine grinding technology to expand DMB application as a functional food.

Mangaba pulp fermented with Lacticaseibacillus casei 01 has improved chemical, technological, and sensory properties and positively impacts the colonic microbiota of vegan adults

This study aimed to evaluate the functional, technological, and sensory aspects of mangaba (Hancornia speciosa Gomes) fruit pulp fermented with the probiotic Lacticaseibacillus casei 01 (LC1) during refrigerated storage (7 °C, 28 days). The effects of the fermented mangaba pulp on the modulation of the intestinal microbiota of healthy vegan adults were also assessed. Mangaba pulp allowed high viability of LC1 during storage and after simulated gastrointestinal conditions (≥7 log CFU/g). The fermented mangaba pulp showed lower pH and total soluble solids, and higher titratable acidity, and concentrations of lactic, acetic, citric, and propionic acids during storage compared to non-fermented pulp. Also, it presented a higher concentration of bioaccessible phenolics and volatiles, and improved sensory properties (yellow color, brightness, fresh appearance, and typical aroma and flavor). Fermented mangaba pulp added to in vitro cultured colonic microbiota of vegan adults decreased the pH values and concentrations of maltose, glucose, and citric acid while increasing rhamnose and phenolic contents. Fermented mangaba pulp promoted increases in the abundance of Dorea, Romboutsia, Faecalibacterium, Lachnospira, and Lachnospiraceae ND3007 genera and positively impacted the microbial diversity. Findings indicate that mangaba pulp fermented with LC1 has improved chemical composition and functionality, inducing changes in the colonic microbiota of vegan adults associated with potential benefits for human health.

Characterization of the active components and bioaccessibility of phenolics in differently colored foxtail millets

Differently colored foxtail millet (Setaria italica) cultivars were compared regarding their amylose, B-complex vitamin, vitamin E, and phenolic compositions, as well as the bioaccessibility of their phenolics in simulated in vitro digestion. Dark-colored foxtail millets contained more thiamine, pyridoxine, and tocopherols, but less riboflavin, than light-colored ones. Phenolics were more abundant in dark-colored cultivars. Insoluble bound fractions accounted for 75%–83% of the total phenolics, with ferulic acid detected as the most plentiful compound. The major bioaccessible phenolic was free ferulic acid, with 100%–120% bioaccessibility, depending on cultivar, followed by p-coumaric acid and isoferulic acid (50%–80%). These relatively high bioaccessibilities were likely due to the release of soluble conjugated or insoluble bound phenolics during digestion. However, the contents of other free phenolics were largely decreased following in vitro digestion, resulting in low bioaccessibility, which also means that the release from the conjugated and bound fractions was poor.

Impact of In Vitro Gastrointestinal Digestion on the Phenolic Bioaccessibility and Bioactive Properties of Insect-Containing Beef Burgers.

Mealworm, migratory locust, and house cricket have recently been recognized by the European Commission as novel foods, thus being suitable in different food applications. In this work, we tested their powders as meat extenders at 5% (w/w) inclusion in beef burgers, considering their ability to vehicle phenolic compounds during simulated in vitro static gastrointestinal digestion (INFOGEST). Insect powders were abundant in different phenolic classes, recording the highest values in locust (LP; 314.69 mg/kg), followed by cricket (CP; 113.3 mg/kg) and mealworm (MWP; 51.9 mg/kg). Following a pan-cooking process, LP burgers were confirmed as the best source of phenolics, with a marked abundance of flavonoids and phenolic acids. Interestingly, the insect powders were found to affect the in vitro gastrointestinal bioaccessibility of phenolic compounds when compared with the CTR burger, likely promoted by the interactions between the phenolic compounds and proteins characterizing the tested insect powders. Among the most discriminant phenolic metabolites at the gastrointestinal level, we found several phenolic acids (mainly hydroxycinnamics), recording the highest content for the digested CP-containing burgers. Finally, stilbenes showed significant correlation values at the intestinal level with both antioxidant and enzymatic activities, while total flavonoids were the most correlated with the inhibition of acetylcholinesterase. Taken together, our preliminary findings demonstrated that insect powders added to beef burgers can promote the bioaccessibility and potential bioavailability of phenolics in the distal tracts of the intestine.

Phytochemical composition and in-vitro bioaccessibility of phenolics in different varieties of tamarillo (Solanum betaceum) fruits: Effect of the high-pressure homogenization and ultrasonication

The phytochemical composition in three different varieties of tamarillo (yellow, red, and purple) cultivated in Northeast India was analysed. The pulp showed good amount of protein, fat, and crude fiber, and the pH and TSS of the tamarillos ranged from 3.70 to 3.94 and 9.6–10.2 °Brix, respectively. Vitamin C was highest in purple tamarillo and all were rich in potassium. Anthocyanins were majorly found in purple tamarillo (0.35 mg C3G/g), while carotenoids were maximum in yellow tamarillo (0.63 mg βCE/100 g). However, both anthocyanins and carotenoids pigments were found in purple and red tamarillo varieties. Through HPLC analyses, six phenolic acids were identified and among them, gallic, chlorogenic, ferulic and rosmarinic acids were the major ones. Pelargonidin-3-O-rutinoside was the major anthocyanin in purple (86.22 µg/g) and red (9.88 µg/g) tamarillo. Three different carotenoids viz. zeaxanthin, β-cryptoxanthin and β-carotene were present in all the varieties of tamarillo. High pressure homogenization and ultrasonication treatments had significant impact on the phytochemical composition. High pressure homogenization at 750 bar and ultrasound for 10 min showed higher phenolics, anthocyanins and carotenoids in the tamarillo varieties and these techniques are recommended for processing of tamarillos. The treated pulp rich in phytochemicals can be used for novel product development.

The Effects of Different Drying Methods on the In Vitro Bioaccessibility of Phenolics, Antioxidant Capacity, and Morphology of European Plums (Prunes domestica L.).

Four different drying methods, hot-air-drying (HAD), vacuum-drying (VD), ultrasound-assisted vacuum-drying (US-VD), and freeze-drying (FD), were used to obtain dried plums (Prunes domesticaL.). These prunes were evaluated for their physical properties (such as color, rehydration ratio, and microstructural properties), phenolic compounds, and antioxidant activities before and after being subjected to in vitro digestion. TPC (total phenolic content) of plums ranged from 196.84 to 919.58 mg of GAE (gallic acid equivalent)/100 g of dw, and neochlorogenic acid was the most abundant phenolic compound. FD prunes had the highest levels of phenolics, whereas US-VD caused the most significant loss. During in vitro digestion, the phenolics were present at higher levels at the gastric medium but failed to maintain their stability at the small intestinal stage. Among the samples, FD along with HAD prunes exhibited a higher bioaccessibility index for most of the phenolic compounds. The ratios of TPC, TFC (total flavonoid content), and individual phenolics determined in the digested residues to the initial values of the undigested samples ranged from 0.23 to 31.03%. It could be concluded that the majority of the phenolics were extracted during digestion. Our findings showed that the different drying methods would alter the microstructure, which would affect the extractability and release of phenolics in the simulated digestion model.

Drum drying of whole maize flour enhances bioaccessibility of zeaxanthin, α-tocopherol, phytosterols, phenolics and flavonoids

The aim of the present study was to investigate the effect of drum drying of maize flour at slurry concentration of 30%–40% on phytonutrients content and their bioaccessibility. Content of tocopherols (TP), tocotrienol (TT), carotenoids, phytosterols, polyphenols and flavonoids, and antioxidant activity in drum dried maize was decreased. Bioaccessible content of stigmasterol, β-sitosterol and flavonoids was increased in drum dried maize. Bioaccessible content of campesterol and total phenolics was comparable to the bioaccessible content in raw maize. Bioaccessible content of TP, TT, lutein, zeaxanthin and β-carotene decreased in drum dried samples. DPPH + radical scavenging activity of bioaccessible fraction of drum dried maize was increased. The ferric reducing power was stable and total antioxidant activity decreased in bioaccessible fraction of drum dried sample. Percentage bioaccessibility of α-TP, phytosterols, zeaxanthin, phenolics, flavonoids and antioxidant activity was increased. Bioaccessibility of lutein and β-carotene retained, and γ-TP, δ-TP, α-, γ-, δ-TT decreased in drum dried sample. Overall, phytonutrients content was found to be low in drum dried samples, but there was retention of components in bioaccessible fraction which resulted higher percentage bioaccessibility of maize phytonutrients.

Modification of starch digestibility and phenolic bioaccessibility in phenolic-rich flours by physical treatments with ferulic acid followed by vacuum oven and freeze-drying

Consumer demand for healthy snack products has led to increased efforts to modify glycemic responses of these products. The formation of starch-ferulic acid (FA) complexes through acidified water steeping leads to an increase in RS content and reduction of glycemic responses in animal models. However, the application of these methodologies to commercially relevant phenolic-rich flours (black rice, BR; purple maize, PM) and their impacts on starch digestibility and phenolic bioaccessbility remain unclear. Using an acidified water steeping method previously reported in pure starch, potato starch (PS), BR and PM flour slurries were prepared with FA at a 20:1 and 8:1 ratio in HCl-acidified water (pH 2). The steeping process reduced phenolic content (∼75%) and increased starch digestibility. Ferulic acid loading capacity on PS (22–124 mg/g starch) was greater than for PM and BR flours (8–40 mg/g starch). Ferulic acid bioaccessibility decreased with an increase in its amount in PS and flours. Steeping enhances cyanidin 3-O-glucoside bioaccessibility, while addition of FA decreases its bioaccessibility. The increase in starch digestibility of phenolic-rich flours after steeping with and without FA can be attributed to the limited loading capacity of FA and loss of native phenolics during the steeping process.

Investigating the Probiotic Potential of Vegan Puree Mixture: Viability during Simulated Digestion and Bioactive Compound Bioaccessibility.

This study aimed to develop a fermented puree mixture containing plant-based ingredients and potential probiotic strains Lacticaseibacillus rhamnosusK3 and Lactobacillus johnsonii K4. The survival of potential probiotic strains, changes in sugar and organic acid concentrations, bioaccessibility of polyphenols, and antioxidant capacity after simulated digestion were examined with sensory quality. The mixture of apple puree, chia seeds, and oat bran or oat flakes was fermented. The sensory quality of the puree mixture was assessed by the quantitative descriptive profile (QDP) method. In vitro digestion was simulated using a static gastrointestinal model. Antioxidant capacity and total polyphenol content were analyzed before and after the digestion phases. All samples changed sensory profiles after fermentation. The overall quality was above six out of ten for every product. Fermentation also changed the organic acid composition, with significant increases in lactic, succinic, and acetic acids. After the digestion process, the survival rate remained above 5.8 log10 CFU/g. As a result of fermentation with potential probiotics, the bioaccessibility of the total phenolics and antioxidant activity increased. These results showed that the addition of potential probiotic strains increases nutritional value and could help with healthy nourishment habits. This knowledge can guide the development of consumer-satisfying products in the food industry, expanding the probiotic food market with innovative alternatives.

Effects of cooking temperature on technological properties and in vitro digestibility of quick‐cooking black and brown rice

AbstractBackground and ObjectivesThe performance of brown (INOV CL) and black (AE 153045 and IAC 600) rice was evaluated at three different cooking temperatures (80°C, 90°C, and 100°C) for the production of quick‐cooking unpolished rice (QCR). The samples were analyzed for physical and pasting properties, bioactive compounds, phenolics bioaccessibility, and in vitro starch digestibility.FindingsThe highest temperature used to prepare the QCR (100°C) promoted the shortest cooking time of the QCR end products and low damaged grain content and bulk density. The anthocyanin content reduced on QCR grains and that of the bioaccessible phenolics increased. As the cooking temperature of QCR preparation increased, the peak viscosities decreased for all studied cultivars as well as starch digestibility.ConclusionsThe results provided scientific, nutritional, and technological evidence concerning the production of quick‐cooking pigmented and unpigmented unpolished rice proving to be an excellent technology to add value to these grains.Significance and NoveltyThis study optimized the method for QCR production, transforming this highly nutritious food into a more convenient and practical product that retains its health benefits.

Effect of Spray Drying on Physicochemical Stability and Antioxidant Capacity of Rosa pimpinellifolia Fruit Extract-Loaded Liposomes Conjugated with Chitosan or Whey Protein During In Vitro Digestion

AbstractSpray drying is a well-established, energy efficient, and scalable process widely used in the food industry, however it may lead to thermal degradation of susceptible compounds, such as (poly)phenols, resulting in biological activity loss to some extent. In this study, we aimed to improve the physicochemical stability and bioaccessibility of (poly)phenols from Rosa pimpinellifolia fruit extract (Rosa extract) loaded in liposomes by generating solid particles via spray drying. Liposomes were conjugated with chitosan (Ch) and whey protein (Wp) to optimize the biopolymer concentrations by monitoring mean particle diameter, polydispersity index, and surface charge. The mean diameter of liposomes ranged between 135 and 210 nm upon optimal addition of Ch (0.4%, w/v) and Wp (4.0%, w/v) which also increased the entrapment efficiency of (poly)phenols from 74.2 to 77.8% and 79.1%, respectively. After spray drying, about 65–76% of the antioxidant capacity were retained in biopolymer-conjugated liposomes (Ch or Wp) while the retention rate was 48% in only spray-dried extract (Rosa extract powder). Compared to unencapsulated Rosa extract, spray drying (Rosa extract powder) and conjugation with Ch (Ch-Lip powder) or Wp (Wp-Lip powder) significantly increased the bioaccessibility of (poly)phenols and preserved their antioxidant capacity. Based on the findings of this study, Ch- or Wp-conjugation of liposomes prior to spray drying could improve physicochemical stability and protect (poly)phenols loaded in liposomes against processing stress and passage through the digestive tract. Further in vitro and in vivo investigations on a variety of bioactive compounds may draw more attention to their potential as functional foods.

In vitro bioaccessibility of biguanide‐related compounds and phenolics from yellow, red, and purple‐fleshed potatoes

AbstractBackgroundDiabetes type II is growing rapidly as a result of the global shift in dietary and lifestyle habits. Although there are many pharmacological treatments for diabetes, incorporating foods with antidiabetic components into daily diet will be helpful. The present study compared the difference in the bioaccessibility of biguanide‐related compounds (BRCs, antidiabetic compounds) and phenolics from yellow, red, and purple potatoes.ResultsColor‐based averaged results showed that only biofortified red‐fleshed advanced potato clones showed higher bioaccessibility (14%) of BRCs compared to light yellow potatoes. Among all the tested compounds, only BRCs were released to maximum extent in the intestinal phase from all varieties and advance clones. This is the first report that revealed potatoes to be a good source of BRCs due to their high bioaccessibility. Bioaccessibility of phenolic compounds from boiled potatoes was 1.1‐fold higher in red colored, whereas almost 2‐fold higher in purple potatoes. Compared to light yellow potatoes, bioaccesibility of 3‐caffeoylquinic acid, 5‐O‐caffeoylquinic acid and 4‐O‐caffeoylquinic acid was 5.1, 5.7, 4.6 fold higher in boiled red potatoes, respectively, and 4.6, 3.7, and 6.9 fold higher in boiled purple potatoes, respectively. Total anthocyanins showed color‐dependent bioaccessibility and were 3.2 and 16.2 fold more bioaccessible from red and purple boiled potatoes, respectively, compared to light yellow potatoes.ConclusionDue to high bioaccessibility of phenolics, anthocyanins, and BRCs, purple and red potatoes can play pivotal role in health improvement of consumers worldwide. However, further detailed bioavailability studies are required to confirm these results.

Quality of High-Fibre Pasta Supplemented with Watermelon Rind Powder with Different Particle Sizes.

Watermelon rind, a by-product of watermelon juice processing, contains large amounts of dietary fibre and phenols with antioxidant capacity. The use of agro-industrial by-products would both improve economic benefits and reduce environmental emissions. The aim of this research is to examine the effect of the particle size of watermelon rind powder on the quality of high-fibre pasta. The nutritional, physical and physicochemical quality of three samples of watermelon rind powder, sieved through three sieves with aperture size of 400, 210 and 149 μm, were analysed. Durum wheat semolina with watermelon rind powder mass fraction of 10 % were mixed and used to make pasta. Nutritional, textural and cooking quality, sensory acceptability, in vitro glycaemic index and antioxidant bioaccessibility of high-fibre pasta with added watermelon rind powder of different particle sizes were evaluated and compared. When the sieve aperture size was reduced from 400 to 149 µm, the soluble dietary fibre and total phenolic contents of watermelon rind powder were increased by 35 and 15 %, respectively, while its insoluble dietary fibre content was decreased by 21 %. Decrease in sieve aperture size from 410 to 149 µm reduced phenolic bioaccessibility of the fortified pasta from 63 to 57 %, but enhanced its predicted glycaemic index from 50 to 69. It also decreased the pasta hardness by 13 %, but improved its elongation rate and tensile strength by 13 and 40 %, respectively. The finer the particles of the watermelon rind powder, the longer the optimal cooking time, the higher the water absorption index, and the lower the cooking loss of the supplemented pasta. Consumers did not notice any significant differences in the overall acceptability among all pasta samples. The particle size of the watermelon rind powder had a major effect on nutritional value, texture and cooking quality of the fortified pasta. In particular, the predicted glycaemic index and antioxidant bioaccessibility of high-fibre pasta were significantly affected by the particle size of the dietary fibre material used in the recipe.

Comprehensive LC‐MS/MS phenolic profiling of Arum elongatum plant and bioaccessibility of phenolics in their infusions

AbstractArum elongatum has various bioactive compounds including phenolic acids and flavonoids that may have beneficial effects on human health. The main objectives of this study were to determine the phenolic profile of the A. elongatum plant together with the total phenolic (TPC), total flavonoid contents (TFC), and total antioxidant capacities of A. elongatum infusions throughout gastrointestinal digestion. The samples used in the present study were obtained from two cities (C1 and C2) in Türkiye. According to the results, while the primary compounds found in sample C1 were vanillic acid (51.29 ± 2.61 ng/mg), p‐coumaric acid (48.36 ± 2.84 ng/mg) and O‐coumaric acid (156.02 ± 0.67 ng/mg); chlorogenic acid (50.63 ± 0.65 ng/mg), scutellarin (144.34 ± 0.74 ng/mg), and O‐coumaric acid (53.34 ± 0.97 ng/mg) were the major compounds in C2 sample showing the differences between different locations. In addition to these, although both TPC and TFC values for C2 infusion (2960 ± 104 mg GAE/100 g and 397 ± 50 mg CE/100 g, respectively) were found to be higher than the infusion of sample C1, there were no significant differences between the TPC and TFC results after intestinal digestion (p > 0.05). Besides, TPC of the bioaccessible fractions of these two samples didn't show a significant difference (p > 0.05), whereas C1 infusion (202 ± 21%) presented a higher value than the C2 infusion (143 ± 12%) for their bioaccessible TFC value. Our results indicated that A. elongatum infusion may be a potential herbal tea due to its rich phenolic content, making it a suitable substitute for widely used herbal teas.

Enhancing date seed phenolic bioaccessibility in soft cheese through a dehydrated liposome delivery system and its effect on testosterone-induced benign prostatic hyperplasia in rats.

The consumption of dairy products, including soft cheese, has been associated with numerous health benefits due to their high nutritional value. However, the phenolic compounds bioaccessibility present in soft cheese is limited due to their poor solubility and stability during digestion. So, this study aimed to develop an innovative soft cheese enriched with date seed phenolic compounds (DSP) extracted ultrasonically and incorporated into homogeneous liposomes and study its attenuation effect on testosterone-induced benign prostatic hyperplasia (BPH) in rats. Date seed phenolic compounds were extracted using 98 and 50% ethanol along with water as solvents, employing ultrasonication at 10, 20, and 30-min intervals. The primary and secondary DSP-liposomes were prepared and dehydrated. The particle size, zeta potential, encapsulation efficiency, and morphology were measured. Incorporating dehydrated liposomes (1-3% w/w) into soft cheese and their impact on BPH using male Sprague-Dawley rats was assessed. After inducing BPH, rats were fed a cheese diet with dehydrated DSP-liposomes. Over 8 weeks, parameters including nutrition parameters, prostate enlargement analysis, biochemical parameters, hormones level, oxidative stress, and cytokines were analyzed. The results showed that ultrasound-assisted extraction effectively reduced the extraction time and 30 min extraction EtOH 50% was enough to extract high yield of phenolic compounds (558 mg GA/g) and flavonoids (55 mg qu/g) with high antioxidant activity (74%). The biological results indicate that prostate weight and prostate index% were diminished in the treatment groups (1 and 2) compared to the BPH control group. The high antioxidant content present in the DSP-liposomes acted as the catalyst for suppressing the responses of the inflammatory cytokines, inhibiting the anti-inflammatory IL-10 production, and suppressing the elevated levels of lipid peroxidation products compared to the BPH group. The treatment group (2) supplemented with dehydrated secondary DSP-liposomes exhibited the most significant variance (p < 0.05) as opposed to the BPH group. Liposomal encapsulation was proved to be a feasible approach for administering DSP in soft cheese, thereby establishing new functional food category possessing prophylactic properties against the advancement of BPH in rats.

The addition of polysaccharide gums to Aronia melanocarpa purees modulates the bioaccessibility of phenolic compounds and gut microbiota: A multiomics data fusion approach following in vitro digestion and fermentation

This study aimed to determine how the addition of gellan, guar, locust bean, and xanthan gums affected the polyphenol profile of Aronia melanocarpa puree and the human gut microbiota after in vitro gastrointestinal digestion and large intestine fermentation. The different gums distinctively affected the content and bioaccessibility of phenolics in Aronia puree, as outlined by untargeted metabolomics. The addition of locust bean gum increased the levels of low-molecular-weight phenolics and phenolic acids after digestion. Gellan and guar gums enhanced phenolic acids' bioaccessibility after fermentation. Interactions between digestion products and fecal bacteria altered the composition of the microbiota, with the greatest impact of xanthan. Locust bean gum promoted the accumulation of different taxa with health-promoting properties. Our findings shed light on the added-value properties of commercial gums as food additives, promoting a distinctive increase of polyphenol bioaccessibility and shifting the gut microbiota distribution, depending on their composition and structural features.

Exploring the Antioxidant Potential of Blackberry and Raspberry Leaves: Phytochemical Analysis, Scavenging Activity, and In Vitro Polyphenol Bioaccessibility.

The goal of this research was nutritional evaluation through the phytochemical analysis of blackberry and raspberry leaves, the screening of their biological activity (antioxidant capacity and inhibition of lipid peroxidation), and the investigation of the effect of in vitro gastrointestinal digestion (GID) of blackberry and raspberry leaves on the bioaccessibility of polyphenol subclasses. The concentrations of the analyzed liposoluble antioxidants were higher (p < 0.05) in blackberry leaves compared to raspberry leaves, while a significant (p < 0.05) higher content of water-soluble antioxidants was registered in raspberry leaves (with a total polyphenol content of 26.2 mg GAE/g DW of which flavonoids accounted for 10.6 mg/g DW). Blackberry leaves had the highest antioxidant capacity inhibition of the superoxide radicals (O2•-), while raspberry leaves registered the highest inhibition of hydroxyl radicals (•OH), suggesting a high biological potency in scavenging-free radicals under in vitro systems. The maximum inhibition percentage of lipid peroxidation was obtained for blackberry leaves (24.86% compared to 4.37% in raspberry leaves), suggesting its potential to limit oxidative reactions. Simulated in vitro digestion showed that hydroxybenzoic acids registered the highest bioaccessibility index in the intestinal phase of both types of leaves, with gallic acid being one of the most bioaccessible phenolics. The outcomes of this investigation reveal that the most significant release of phenolic compounds from blackberry and raspberry leaves occurs either during or after the gastric phase. Knowledge about the bioaccessibility and stability of polyphenol compounds during digestion can provide significant insights into the bioavailability of these molecules and the possible effectiveness of plant metabolites for human health.

The effects of different enzymes on the liberation of bound phenolics from rice bran dietary fibre and their antioxidant activities

Bound phenolics are the main phytochemicals and important contributors to the health benefits of whole grains. The commonly used chemical methods for bound phenolic release are not appropriate for processing of food materials. The effects of cellulase and feruloyl esterase on releasing bound phenolics from rice bran dietary fibre (RBDF) and the auxiliary effects of autoclaving pretreatment were investigated in the present study to find a method to effectively increase bioaccessible phenolics in RBDF. The results showed that cellulase (CT) and feruloyl esterase (FT) alone and combined application (CFT) released limited bound phenolics. Autoclaving pretreatment could enhance the release of bound phenolics by enzymatic treatments significantly with 1.74, 5.56 and 1.76 folds increases when compared with the above mentioned enzymolysis, respectively. Moreover, the total quantity of phenolic compounds released from RBDF via combined enzymolysis of cellulase and feruloyl esterase with autoclaving pretreatment (A-CFT) were comparable with that via alkaline hydrolysis previously reported. The predominant phenolic compounds released by A-CFT from RBDF were vanillin and ferulic acid, while ferulic and p-couramic acids accounted for 99.30% of the sum of phenolics released by alkaline hydrolysis. The DPPH scavenging, FRAP and ORAC antioxidant activities of the enzymatic hydrolysates were positive correlated with their total phenolic contents. The phenolics released by A-CFT showed lower antioxidant activity than those by alkaline hydrolysis, which may ascribe to the difference in phenolic profiles between methods. This study provides a new approach for processing whole grain and the by-products for functional foods materials with higher phenolic bioaccessibility.

Quinoa treated by an optimized method of microwave heating and their effect on antioxidant activity and phenolic compounds after in vitro gastrointestinal digestion

ABSTRACT Heating by microwave irradiation could be an alternative for cooking quinoa and improving its content of phenolic compounds, which have health-promoting properties. The goal of this study was to improve the bioaccessibility of phenolics content and antioxidant activity of quinoa using an optimized method of microwave irradiation. The best microwave irradiation conditions obtained by maximizing the responses were 100% irradiation power and 14 min of irradiation time. The predicted and experimentally validated values for total phenols, flavonoids, and antioxidant activity were as follows: 686.46 vs 749.67 ± 36.62 µg GAE/g; 743.94 vs 803.37 µg QE/g and 4.20 vs 4.61 µM TE/g, respectively. At the gastric level, heating by microwave irradiation promoted the bioaccessibility (>100%) of total phenols, flavonoids, and antioxidant activity, as well as gallic and coumaric acids, quercetin, and kaempferol greater. The heating treatment by microwave in quinoa could be useful to obtain new products with bioactivity potential at gastric and intestinal levels.