Stability of polyphenols and carotenoids in strawberry and peach yoghurt throughout in vitro gastrointestinal digestion

Bioaccessibility and antioxidant capacity of kefir-based smoothies fortified with kale and spinach after in vitro gastrointestinal digestion

The kefir-based smoothies with kale and spinach were designed as a ready-to-drink and innovative functional snack. Microbiological, physicochemical, as well as pre- and postgastrointestinal total antioxidant capacity (TAC; CUPRAC, DPPH, and FRAP) analyses were conducted. It was determined that the kefir-based smoothies with vegetables had higher ash, carbohydrate, and dietary fiber values. Fructose and glucose contents of smoothy with kale were high, while smoothy with spinach included high sucrose and maltose. The microbiology results revealed that kefir-based vegetable smoothies had minimum Lactobacillaceae viability (>log 7 cfu g-1) for the required functional effect after 14-day storage. Moreover, the addition of kale significantly increased (p < .01) the level of initial TAC (CUPRAC, DPPH, and FRAP) and total phenolic content (TPC) values. After in vitro gastric digestion analysis, smoothie with spinach demonstrated higher TAC and TPC values and the control sample had higher TAC and TPC values compared with a predigestion step. It was found that in vitro intestinal DPPH values were higher for the sample with spinach samples, while the sample with kale had the highest FRAP values. It was also found that the bioaccessibility indexes of plain kefir were determined to be the highest in both in vitro gastric and intestinal procedures. The present study provided novel insights into the in vitro digestion properties of kefir fortified with vegetables. Nevertheless, further studies are needed to identify the functional properties of the milk and plant matrices mixture using in vitro and in vivo trials.

A bigel based formulation protects lutein better in the gastric environment with controlled release and antioxidant profile than other gel based systems

Gel based formulations offer an opportunity to fortify bioactives in food. However, a comparative evaluation of gel systems is scantly available. Thus, this study intended to evaluate the impact of various gel formulations (hydrogel, oleogel, emulsion gel, bigels of different compositions) on the delivery and antioxidant activity of lutein. Ethyl cellulose (EC,15 %w/w) and guar-xanthan gum mixture (1:1,1.5 %w/w) was used as oleogelator and hydrogelator, respectively. The microscopic evaluation indicated an oil-based continuous-phase for bigel with 75% oleogel. An increase in oleogel content enhanced textural and rheological properties. An increase in hydrogel composition (25%-75%) of bigel improved the lutein release (70.4%-83.2%). The highest release of lutein was recorded for emulsion gel (84.9%) and bigel with 25% oleogel (83.2%). The antioxidant activity was comparatively lower in gastric medium than simulated intestinal fluid. It could be inferred that the gel matrix significantly affected the lutein release, antioxidant profile, physiochemical and mechanical characteristics.

Impact of gastrointestinal digestion simulation on brewer's spent grain green extracts and their prebiotic activity

Brewer's spent grain (BSG) is a by-product of the beer industry and a potential source of bioactive compounds. In this study, two methods of extracting bioactive compounds from brewer's spent grain were used - solid-to-liquid conventional extraction (SLE) and solid-to-liquid ohmic heating extraction (OHE) coupled with two ratio combinations of solvents: 60 % and 80 % ethanol:water (v/v). The bioactive potential of the BSG extracts was assessed during the gastrointestinal tract digestion (GID) and the differences in their antioxidant activity, total phenolic content and characterization of the polyphenol profile was measured. The SLE extraction using 60 % ethanol:water (v/v) was the extraction method with higher antioxidant activity (33.88 mg ascorbic acid/g BSG - initial; 16.61 mg ascorbic acid/g BSG - mouth; 15.58 mg ascorbic acid/g BSG - stomach; 17.26 mg ascorbic acid/g BSG - duodenum) and higher content in total phenolics (13.26 mg gallic acid/g BSG - initial; 4.80 mg gallic acid/g BSG - mouth; 4.88 mg gallic acid/g BSG - stomach; 5.00 mg gallic acid/g BSG - duodenum). However, the OHE extraction using 80 % ethanol:water (v/v), had a higher bioaccessibility index (99.77 % for ferulic acid, 72.68 % for 4-hydroxybenzoic acid, 65.37 % for vanillin, 28.99 % for p-coumaric, 22.54 % for catechin) values of polyphenols. All the extracts enhanced (except for SLE for 60 % ethanol:water (v/v) at 2 and 1.5 %, and for 80 % ethanol:water (v/v) at 2 % with Bifidobacterium animalis spp. lactis BB12, where no growth was observed) the growth of the probiotic microorganisms tested (Bifidobacterium animalis B0 - O.D.'s between 0.8240 and 1.7727; Bifidobacterium animalis spp. lactis BB12 - O.D.'s between 0.7219 and 0.8798; Lacticaseibacillus casei 01 - O.D.'s between 0.9121 and 1.0249; and Lactobacillus acidophilus LA-5 - O.D.'s between 0.8595 and 0.9677), demonstrating a potential prebiotic activity of BSG extracts.

Stability and antioxidant activity of phenolic compounds during in vitro digestion

The impact of phenolic compounds on the human body depended on the type, content, bioavailability, and antioxidant activity. After digestion, different phenolic compounds had different changes of bioavailability and antioxidant activity, which needed to be considered in the application. In this experiment, the structural stability and antioxidant activity of 27 phenolic compounds (phenolic acids, flavonols, flavonoids, and flavanones) were investigated during the in vitro simulated digestion. This experiment eliminated the influence of food matrix, provide a basis for regularity for the changes of phenolic substances in different materials. Results showed that the bioaccessibility of phenolic compounds with different structures varied, and there was a conformational relationship between the structure and stability. After oral digestion, most of the phenolic compounds underwent degradation and the cellular antioxidant activity (CAA) values decreased to a large extent (p < 0.05). After gastric digestion, the content (p > 0.05) and CAA values (p < 0.05) of most phenolic compounds increased. However, after intestinal digestion, the phenolic compounds were degraded to a greater extent, and different structures of phenolic compounds had different changes in CAA values (p < 0.05). In general, the CAA values of most phenolic compounds after in vitro digestion were lower than the initial value. The 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ehylbenzthiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) values of phenolic acids and flavonols decreased after in vitro simulated digestion (p < 0.05), while the values of DPPH, ABTS, and FRAP of most flavonoids (p < 0.05) increased. The increased oxygen radical absorption capacity (ORAC) values were found in most phenolic acids, flavonols, and flavonoids (p < 0.05), and most flavanones showed unremarkable changes in ORAC values (p > 0.05). In general, the changing trend of chemical-based antioxidant activity was consistent with the content of phenolic compounds.

Identification of Phenolics Profile in Freeze-Dried Apple Peel and Their Bioactivities during In Vitro Digestion and Colonic Fermentation

Freeze-dried apple peel powder (Fd-APP) was subjected to in vitro digestion and colonic fermentation to evaluate the variations in its phenolic composition, bioactivities (antioxidant activity, α-amylase, and α-glucosidase inhibition), and fecal metabolic outputs. A total of 88 phenolics were tentatively identified, of which 51 phenolic compounds were quantitated in Fd-APP sample extracts before digestion, and 34 were released during subsequent phases of digestion. Among these, phenolic acids showed the highest bio accessibility index (BI) of 68%, followed by flavonoids (63%) and anthocyanins (52%). The inhibitory functions of Fd-APP extract against α-amylase and α-glucosidase pre- and post-digestion were moderate and ranged from 41.88 to 44.08% and 35.23 to 41.13%, respectively. Additionally, the antioxidant activities revealed a significant (p ≤ 0.05) decline during the in vitro digestion. However, the colonic fermentation stage presented different products where the intact parent phenolic compounds present in Fd-APP were utilized by gut microbes and produced various phenolic metabolites such as 3- hydroxyphenyl acetic acid (3-HPAA), ferulic acid (FA), 3-(4-hydroxyphenyl) propionic acid (3,4 HPPA) and 4- hydroxybenzoic acid (4-HBA). Furthermore, colonic fermentation of Fd-APP accelerated the production of short-chain fatty acids (SCFAs), with acetic acid being the most prevalent (97.53 ± 9.09 mM). The decrease in pH of fermentation media to 4.3 significantly (p ≤ 0.05) enhanced counts of Bifidobacterium (10.27 log CFU/mL), which demonstrated the potential prebiotic effects of Fd-APP. These findings indicated that the consumption of apple peel as a constituent of novel functional foods may support and protect the intestinal microbiota and consequently promote human health.

Impact of Circular Brewer’s Spent Grain Flour after In Vitro Gastrointestinal Digestion on Human Gut Microbiota

Brewer’s spent grain (BSG) solid residues are constituted by dietary fibre, protein, sugars, and polyphenols, which can have potential effects on human health. In this study, for the first time, the flours obtained from solid residues of solid-liquid extraction (SLE) and ohmic heating extraction (OHE) were applied throughout the gastrointestinal digestion simulation (GID), in order to evaluate their prebiotic potential and in vitro human gut microbiota fermentation. The results showed that the digestion of BSG flours obtained by the different methods lead to an increase throughout the GID of total phenolic compounds (SLE: from 2.27 to 7.20 mg gallic acid/g BSG—60% ethanol:water (v/v); OHE: 2.23 to 8.36 mg gallic acid/g BSG—80% ethanol:water (v/v)) and consequently an increase in antioxidant activity (ABTS—SLE: from 6.26 to 13.07 mg ascorbic acid/g BSG—80% ethanol:water (v/v); OHE: 4.60 to 10.60 mg ascorbic acid/g BSG—80% ethanol:water (v/v)—ORAC—SLE: 3.31 to 14.94 mg Trolox/g BSG—80% ethanol:water (v/v); OHE: from 2.13 to 17.37 mg Trolox/g BSG—60% ethanol:water (v/v)). The main phenolic compounds identified included representative molecules such as vanillic and ferulic acids, vanillin and catechin, among others being identified and quantified in all GID phases. These samples also induced the growth of probiotic bacteria and promoted the positive modulation of beneficial strains (such as Bifidobacterium spp. and Lactobacillus spp.) present in human faeces. Moreover, the fermentation by human faeces microbiota also allowed the production of short chain fatty acids (acetic, propionic, and butyric). Furthermore, previous identified polyphenols were also identified during fecal fermentation. This study demonstrates that BSG flours obtained from the solid residues of SLE and OHE extractions promoted a positive modulation of gut microbiota and related metabolism and antioxidant environment associated to the released phenolic compounds.

Stirred Yogurt as a Delivery Matrix for Freeze-Dried Microcapsules of Synbiotic EVOO Nanoemulsion and Nanocomposite

Nowadays, dairy products are considered a good matrix to deliver many functional substances either vital oils or probiotic cells. Two models of microcapsules were produced from co-encapsulation of extra virgin olive oil (EVOO) nanoemulsion or nanocomposite and synbiotic bacteria (maltodextrin with Lactobacillus acidophilus and Bifidobacterium bifidum) using the freeze-drying technique. These models of microcapsules were added to stirred yogurt, and then its storage effect on microbiology, chemically, and sensory properties were evaluated for 21 days. The average droplet size and zeta potential distribution of EVOO nanoemulsion and nanocomposite were investigated. Also, oxidative stability, microencapsulation efficiency, release profile, and antioxidant activity were studied. The results showed that the average particle size of EVOO nanoemulsion and nanocomposite ranged between 416 and 475 nm, while zeta potential was -39.6 and -33.6 mV, respectively. The induction period of EVOO extracted from nanoemulsion and nanocomposite microcapsules models was 11.30 and 8 h. The microencapsulation efficiency of probiotic and EVOO was determined at 88.84 and 65.61% for the nanoemulsion microcapsules model, while the nanocomposite microcapsules model showed 98.49 and 72%. The two models of microcapsules have boosted the viability of probiotic bacteria inside stirred yogurt than free cells. Also, the presence of microcapsules did not affect the viability of stirred yogurt starter cultures, and high values for the total solid and protein were detected. Therefore, the results recommended that stirred yogurt is a good delivery carrier for highly antioxidant and healthy microcapsules of synbiotic EVOO nanoemulsion and nanocomposite.

Effect of In Vitro Gastrointestinal Digestion on Amino Acids, Polyphenols and Antioxidant Capacity of Tamarillo Yoghurts

Laird’s Large tamarillo powder is high in protein (10%) essential amino acids (EAAs), gamma-aminobutyric acid (GABA) and polyphenols (0.6% phenolics plus anthocyanins) and fibre 25%. This study aimed to investigate, using a standardized static in vitro digestion model, the stability of amino acids and antioxidant capacity of polyphenols in yoghurt fortified with 5, 10 and 15% tamarillo powder either before (PRE) or after (POS) fermentation. Compared to plain yoghurt, the fruit polyphenols (rutinosides and glycosides) were retained and substantial increases in FEAAs (free essential amino acids), total phenolic content (TPC) and antioxidant activity were observed particularly at the end of intestinal phase of digestion. Together with SDS-PAGE results, peptides and proteins in tamarillo yoghurts were more easily digested and therefore may be better absorbed in the small intestine compared to the control. TPC and antioxidant activity of fortified yoghurts increased significantly after in vitro digestion. Relatively high bioaccessibilty of chlorogenic acid and kaempferol-3-rutinoside in digested PRE samples was observed. The results suggest that the yoghurt matrix might protect some compounds from degradation, increasing bioaccessibility and in the small intestine allow increased absorption and utilization possible. Fortification would deliver intact polyphenols and fibre to the large intestine and improve gut health. Further research of acceptability, shelf life, and then trials for health effects should be implemented.

Tannat Grape Skin: A Feasible Ingredient for the Formulation of Snacks with Potential for Reducing the Risk of Diabetes

In the present work the feasibility of Tannat grape skin (TGS) as a functional ingredient in the formulation of two snacks (yogurt and biscuits) was studied. The research provided novel information on the effects of the food matrix and digestion process, under simulated human oral gastrointestinal conditions, in the bioaccessibility of TGS bioactive compounds composing of the snacks with health promoting properties (antioxidant, anti-inflammatory, and antidiabetic). TGS polyphenolic profile was analyzed by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) finding mainly flavonoids, phenolic acids, and anthocyanins, which may exert antioxidant, anti-inflammatory, and carbohydrase inhibition capacities. TGS digest showed antioxidant and antidiabetic potential compared to the undigested sample (p < 0.05). Yogurt and biscuits with TGS were developed with the nutrition claims “no-added sugars” and “source of fiber” and were digested in vitro to evaluate the bioaccessibility of compounds with health promoting properties after food processing and digestion. After in vitro simulation of digestion, bioactive properties were enhanced for control and TGS snacks which may be attributed to the formation/release of compounds with health-promoting properties. Biscuits showed significant increase in ABTS antioxidant capacity and yogurt showed increased α-glucosidase inhibition capacity by the addition of TGS (p < 0.05). Polyphenols from TGS and bioactive peptides from snacks which may be released during digestion might be responsible for the observed bioactivities. Consumer’s acceptance of TGS yogurt and biscuits showed scores of 6.3 and 5.1 (scale 1−9), respectively, showing TGS yogurt had higher overall acceptance. Sensory profile assessed by check-all-that-apply + just-about-right (CATA+JAR) showed most of the attributes were evaluated as “just about right”, supporting good food quality. The developed yogurt presented adequate shelf-life parameters for 28 days. TGS yogurt with higher acceptability showed reduced ROS formation (p < 0.05) induced by tert-butyl hydroperoxide (1 mM) in CCD-18Co colon cells and RAW264.7 macrophages when pre-treated with concentrations 500−1000 and 100−500 µg/mL of the digests, respectively. Moreover, TGS yogurt digest pre-treatment reduced nitric oxide (NO) production (p < 0.05) in lipopolysaccharide (LPS)-induced RAW264.7 macrophages, showing anti-inflammatory potential. Bioactive peptides generated during lactic fermentation and digestion process may be contributors to intracellular effects. In conclusion, yogurt and biscuits with Tannat grape skin addition were obtained with nutrition claims “no-added sugars” and “source of fiber” with the potential to modulate key biochemical events associated with diabetes pathogenesis.

Effect of an Emulsified Formulation on Vegetable Carotenoid Bioaccessibility

We investigated the effect of neutral lipids, polar lipids, and an emulsified formulation (EMF) on carotenoid bioaccessibility in an in vitro digestion assay of vegetables. These reagents enhanced carotenoid bioaccessibility. Contrary to our previous report, they also exhibited effects on lutein. Bile extracts/pancreatin concentrations also participated in the bioaccessibility. The EMF, which consisted of lower amounts of oil, had the same effect on lutein as rapeseed oil. These reagents also showed effects in the aging model, with more reduced bile extract/pancreatin concentrations, suggesting that lipids and EMF contributed to carotenoid bioaccessibility in bile/pancreatic juice secretions due to aging and disease.

Are olive pomace powders a safe source of bioactives and nutrients?

BACKGROUND

The olive oil industry generates significant amounts of semi-solid wastes, namely olive pomace. Olive pomace is a by-product rich in high-value compounds (e.g. dietary fibre, unsaturated fatty acids, polyphenols) widely explored to obtain new food ingredients. However, conventional extraction methods frequently use organic solvents, while novel eco-friendly techniques have high operational costs. The development of powdered products without any extraction step has been proposed as a more feasible and sustainable approach.

RESULTS

The present study fractionated and valorized the liquid and pulp fraction of olive pomace obtaining two stable and safe powdered ingredients, namely a liquid-enriched powder (LOPP) and a pulp-enriched powder (POPP). These powders were characterized chemically, and their bioactivity was assessed. LOPP exhibited a significant amount of mannitol (141 g kg^-1 ), potassium (54 g kg^-1 ) and hydroxytyrosol derivatives (5 mg g^-1 ). POPP exhibited a high amount of dietary fibre (620 g kg^-1 ) associated with a significant amount of bound phenolics (7.41 mg GAE g^-1 fibre DW) with substantial antioxidant activity. POPP also contained an unsaturated fatty acid composition similar to that of olive oil (76% of total fatty acids) and showed potential as a reasonable source of protein (12%). Their functional properties (solubility, water-holding and oil-holding capacity), antioxidant capacity and antimicrobial activity were also assessed, and their biological safety was verified.

CONCLUSIONS

The development of olive pomace powders for application in the food industry could be a suitable strategy to add value to olive pomace and obtain safe multifunctional ingredients with higher health-promoting effects than dietary fibre and polyphenols. © 2020 Society of Chemical Industry.

In vitro phenols bioaccessibility and antioxidant activity of goat milk yogurt fortified with Rhus coriaria leaf powder

Goat yogurt samples fortified with 20% (w/v) Rhus coriaria leaf powder were in vitro digested in order to evaluate the total phenolic content (TPC), antioxidant activity (AA), and bioaccessibility of phenolic compounds in the digestate. After digestion, TPC and AA values of the R. coriaria-fortified yogurts increased compared to the undigested yogurts (P < 0.001). In particular, TPC has increased about twice; whereas, AA values have increased about 10 and 6 times, for ABTS and FRAP assays, respectively. The bioaccessibility index was well above the 100% for all identified phenols; except for (-)-epicatechin (82.04%), rutin (51.51%), and gallic acid (5.42%). This different behavior highlighted that the bioaccessibility was modulated by both the yogurt-polyphenol complexes and phenol stability under digestion system. These findings can contribute to elucidate the influence of in vitro digestion on antioxidant capacity and polyphenols recovery infortified yogurts, and may help in the design of dairy products with better functional quality PRACTICAL APPLICATION: Rhus coriaria L. (Sumac) is a polyphenol-rich Mediterranean plant that may be used as functional ingredient to enrich fermented food such as yogurt. However, in fortified yogurts the evaluation of bioaccessibility, that is, the compounds released from the yogurt and stable in the digestive environment, thus able to exert their biological effects on the gastrointestinal system, is more important than the content of these compounds in the corresponding food. This study highlighted the phenolic content, antioxidant activity, and bioaccessibility of phenolic compounds in goat milk yogurt fortified with R. coriaria leaf powder after simulated gastro-pancreatic digestion.

Impact of In Vitro Gastrointestinal Digestion on the Bioaccessibility of Phytochemical Compounds from Eight Fruit Juices

Fruits contain a number of useful substances including antioxidants. Their bio-accessibility after passing through the digestive tract is of primary importance when considering their benefits. In this respect, we investigated the effect of in vitro digestion on the phytochemicals of eight fruit juices. Freshly prepared juices from pomegranate, orange and grapefruit were used as well as commercially available juices from cherry, black grapes and aloe vera, blackberry and chokeberry, and two types of chokeberry and raspberries. Spectrophotometric and HPLC methods were used in order to analyse the sugar content, the total phenolic (TPC) and flavonoid contents (TFC), anthocyanins, phenolic acids and antioxidant activity. Principle component analysis was used to explain the differentiation among the types of fruit juice. Sugar recovery variation was between 4-41%. The bio-accessibility of TPC ranged from 13.52-26.49% and of flavonoids between 24.25-67.00%. The pomegranate juice and the juice of black grapes and aloe vera kept 58.12 and 50.36% of their initial anthocyanins content, while for the other samples less than 1.10% was established. As a result, a maximum of 30% remaining antioxidant activity was measured for some of the samples, but for most this was less than 10%. In conclusion, fruit juices are a rich source of biologically active substances, but a more detailed analysis of food transformation during digestion is needed.

Simulated digestion of an olive pomace water-soluble ingredient: relationship between the bioaccessibility of compounds and their potential health benefits

Olive pomace is a semisolid by-product with great potential as a source of bioactive compounds. Using its soluble fraction, a liquid-enriched powder (LOPP) was obtained, exhibiting a rich composition in sugars, polyphenols and minerals, with potential antioxidant, antihypertensive and antidiabetic health benefits. To validate the potential of LOPP as a functional ingredient the effect of the gastrointestinal tract on its bioactive composition and bioactivities was examined. Polyphenols and minerals were the most affected compounds; however, a significant bioaccessibility of potassium and hydroxytyrosol was verified (≥57%). As a consequence, the LOPP bioactivities were only moderately affected (losses around 50%). For example, 57.82 ± 1.27% of the recovered antioxidant activity by ORAC was serum-available. From an initial α-glucosidase inhibition activity of 87.11 ± 1.04%, at least 50% of the initial potential was retained (43.82 ± 1.14%). Regarding the initial ACE inhibitory activity (91.98 ± 3.24%), after gastrointestinal tract losses, significant antihypertensive activity was retained in the serum-available fraction (43.4 ± 3.65%). The colon-available fraction also exhibited an abundant composition in phenolics and minerals. LOPP showed to be a potential functional ingredient not only with potential benefits in preventing cardiovascular diseases but also in gut health.

Polyphenol Extraction by Different Techniques for Valorisation of Non-Compliant Portuguese Sweet Cherries towards a Novel Antioxidant Extract

Currently, there is special interest in the recovery of polyphenols from non-compliant fruits that have no market value; efforts to find value-added solutions for these food areas are a key option for a sustainable bio-economy. Saco cherries are a traditional Portuguese cherry variety, and although they are a nutritionally important food, rich in powerful dietary polyphenols, significant amounts of these cherries are not sold due to their small size. In this context, this work aimed to select the best method to produce novel antioxidant polyphenol-rich extracts from low calibre and non-compliant Saco cherries. Based on the results, microwaves-assisted extraction (MAE) allowed us to obtain a polyphenol-rich extract with a high antioxidant capacity (50.46 ± 1.58 mg Trolox equivalent (TE)/g dry extract (DE) by oxygen radical absorbance capacity (ORAC), 10.88 ± 0.38 mg ascorbic acid equivalent (AA)/g DE by 2-azinobis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), and 9.58 ± 0.42 mg TE/g DE by 2,2-diphenyl-1-picrylhydrazyl (DPPH)) and a high content of polyphenols, namely, hydroxycinnamic acids (neochlorogenic and p-coumaric acids) and anthocyanins (cyanidin-3-rutinoside and cyanidin-3-glucoside), compared with those of conventional extractions with low and high temperature and ultrasound-assisted extraction. The antioxidant extract produced from MAE could be a new alternative for the valorisation of non-compliant cherries since these extracts proved to be a functional ingredient due to the high content of antioxidants, which are linked to the prevention of diseases.

Cereal bars functionalized through Bifidobacterium animalis subsp. lactis BB-12 and inulin incorporated in edible coatings of whey protein isolate or alginate

Currently, cereal bars are gaining interest globally because of their nutritionally balanced and convenient nature. One healthy strategy is to add probiotics to cereal bars, to make them a functional food product. So, in this study a cereal bar functionalized with edible coatings of whey protein isolate (WPI) and alginate (ALG) incorporated with Bifidobacterium animalis subsp. lactis BB-12 and inulin was developed and evaluated for its consumer acceptability and physicochemical and microbiological properties, throughout 90 days of storage. WPI-coated cereal bars were shown to be the solution that better maintained the level of the incorporated probiotic strain when compared to the ones coated with ALG, throughout storage and throughout in vitro gastrointestinal digestion. The physicochemical properties of the bars, namely aw, moisture content, color and texture, were not altered during the storage period. The sensory evaluation showed that coated bars were accepted as well as control bars. Moreover, the consumers appreciated better the odor and flavor of WPI-coated bars than those of ALG-coated bars.

Effects of hot air, microwave and vacuum drying on drying characteristics and in vitro bioaccessibility of medlar fruit leather (pestil)

The effects of microwave (90 W and 180 W), hot air (60 and 70 °C) and vacuum (60 and 70 °C with 200 and 300 mbar) drying methods on drying characteristics, total phenolic content, antioxidant capacity, color and in vitro gastrointestinal digestion of medlar pestil were investigated. Medlar showed a good potential for pestil production while being the most applicable in microwave treatments. For drying kinetics, five thin-layer drying models were applied and the Page and Modified Page were the best fitted models. L*, b*, chroma and hue angle decreased while a* generally increased in dried pestils. Dried samples showed a general decrement in phenolics and antioxidant capacity. According to in vitro gastrointestinal digestion, intestinal phase of all the samples resulted with an increment in phenolics, FRAP and DPPH compared to undigested extracts. In conclusion, different drying methods may affect the release of phenolics and antioxidant capacity, while leading to increased bioaccessibility during intestinal digestion.

Prebiotics from Seaweeds: An Ocean of Opportunity?

Seaweeds are an underexploited and potentially sustainable crop which offer a rich source of bioactive compounds, including novel complex polysaccharides, polyphenols, fatty acids, and carotenoids. The purported efficacies of these phytochemicals have led to potential functional food and nutraceutical applications which aim to protect against cardiometabolic and inflammatory risk factors associated with non-communicable diseases, such as obesity, type 2 diabetes, metabolic syndrome, cardiovascular disease, inflammatory bowel disease, and some cancers. Concurrent understanding that perturbations of gut microbial composition and metabolic function manifest throughout health and disease has led to dietary strategies, such as prebiotics, which exploit the diet-host-microbe paradigm to modulate the gut microbiota, such that host health is maintained or improved. The prebiotic definition was recently updated to "a substrate that is selectively utilised by host microorganisms conferring a health benefit", which, given that previous discussion regarding seaweed prebiotics has focused upon saccharolytic fermentation, an opportunity is presented to explore how non-complex polysaccharide components from seaweeds may be metabolised by host microbial populations to benefit host health. Thus, this review provides an innovative approach to consider how the gut microbiota may utilise seaweed phytochemicals, such as polyphenols, polyunsaturated fatty acids, and carotenoids, and provides an updated discussion regarding the catabolism of seaweed-derived complex polysaccharides with potential prebiotic activity. Additional in vitro screening studies and in vivo animal studies are needed to identify potential prebiotics from seaweeds, alongside untargeted metabolomics to decipher microbial-derived metabolites from seaweeds. Furthermore, controlled human intervention studies with health-related end points to elucidate prebiotic efficacy are required.

Antioxidant activity of milk and polyphenol-rich beverages during simulated gastrointestinal digestion of linseed oil emulsions

Polyunsaturated fatty acids (PUFA) are associated with health benefits. However, high PUFA intake increases the risk of lipid oxidation and formation of potentially toxic lipid oxidation species. The objective of this study was to determine the antioxidant activity of milk fractions (whole milk, skim milk, acid whey, ultrafiltration (UF) permeate) and polyphenol-rich beverages (green tea, grape juice) during simulated gastrointestinal digestion. We also determined the effect of milk and polyphenol-rich beverages on the formation of advanced oxidation species during in vitro digestion of PUFA-rich emulsion. Antioxidant activity during digestion of milk fractions emphasized the important role of proteins (more specifically caseins) and the contribution of fat to the antioxidant capacity of milk. In comparison to milk, the antioxidant activity of polyphenol-rich beverages was at least four times higher. During digestion of a PUFA-rich emulsion, the formation of 4-hydroxyhexanal (4-HHE) and 4-hydroxynonenal (4-HNE) in the intestinal phase were respectively reduced by 60% and 75%, in the presence of milk or polyphenol-rich beverages. Further reduction was observed when the emulsion was co-digested with both, milk and polyphenol-rich beverages (89% for 4-HHE and 93% for 4-HNE). These results suggest that the combination of milk and polyphenol-rich beverages increases the antioxidant activity and synergistically reduces the formation of toxic lipid oxidation species during simulated digestion of PUFA-rich foods.

Effects of simulated digestion on the phenolic composition and antioxidant activity of different cultivars of lychee pericarp

Background

Lychee pericarp is rich in phenolic and has good antioxidant activity. The effects of simulated gastric (SGF) and intestinal fluid (SIF) digestion on the contents, composition, and antioxidant activities of the phenolic substances in the pericarp of different lychee cultivars (cv Jizui, Lizhiwang, Guiwei, Yuhe, Nuomici and Guihong) were investigated.

Results

Compared with distilled water (DW) treatment, the total phenolic content (TPC) and total flavonoid content (TFC) in the pericarp of different lychee cultivars decreased after SGF digestion; especially, the TFC in "Lizhiwang" decreased by 41.5%. The TPC and TFC of lychee pericarp also decreased after SIF digestion. However, the TPC in "Jizui", "Guiwei" and "Yuhe" increased. The SGF and SIF also had different effects on the FRAP and ABTS antioxidant activities of different lychee cultivars. The SGF digestion decreased the ABTS antioxidant capacity of lychee pericarp but enhanced the FRAP value of some lychee cultivars. However, the SIF digestion decreased the FRAP antioxidant activity of different lychee cultivar pericarps but enhanced the ABTS antioxidant capacity of lychee. The HPLC results showed that lychee pericarp had relatively high contents of procyanidin B2 and procyanidin A2. After SIF digestion, caffeic acid and isoquercitrin could not be detected in any of the lychee varieties. However, quercetin-3-rutinose-7-rhamnoside and isoquercitrin were increased after SGF digestion.

Conclusions

Lychee pericarp could be used as an inexpensive functional food ingredient.

Flavonoids, phenolic acids, carotenoids and antioxidant activity of fresh eating citrus fruits, using the coupled in vitro digestion and human intestinal HepG2 cells model

With in-vitro digestion and human intestinal HepG2 cells, we analyzed the bioaccessibility and cell uptake of phytochemicals and determined the cellular antioxidant capacity (CAA) of fresh eating citrus fruits. The results showed that CAA of citrus fruits was higher in digesta than in extracts, and the CAA is strongly correlated with naringenin and beta-carotene uptake (p < 0.05). During in vitro digestion, vanillic acid and p-coumaric decreased, and ferulic acid increased in all citrus fruits significantly (p < 0.05); other phytochemicals varied among the fruits. During uptake, hydroxybenzoic acids, hesperidin, narirutin, naringenin and neohesperidin were detected in cells, Zeaxanthin, lutein, beta-cryptoxanthin and beta-carotene could be detected in the citrus varieties except for pummel, but hydroxycinnamic acids and hesperitin were not detected in cells. This work provides insights into the bioaccessibility and cell uptake of phytochemicals and cellular antioxidant activity of fresh eating citrus fruits.

In vitro digestion models suitable for foods: Opportunities for new fields of application and challenges

In vitro digestion assays simulate the physiological conditions of digestion in vivo and are useful tools for studying and understanding changes, interactions, as well as the bioaccessibility of nutrients, drugs and non-nutritive compounds. The technique is widely used in fields such as nutrition, pharmacology and food chemistry. Over the last 40 years, more than 2500 research articles have been published using in vitro digestion assays (85% of which have been published in the last two decades) to elucidate multiple aspects such as protein digestibility, nutrient interactions or the viability of encapsulated microorganisms. The most recent trend in the use of this technique involves the determination of the antioxidant activity of bioactive compounds after digestion. However, the inability to reproduce certain in vivo digestion events, as well as the multiple models of in vitro digestion, point to a need to optimize and validate the method with in vivo assays to determine its limitations and uses. The purpose of this paper is to provide an overview of the current state of the art of in vitro digestion models through an analysis of how they have evolved in terms of the development of digestion models (parameters, protocols, guidance) and taking into consideration the boom in new fields of application.

Reversed Phase HPLC-DAD Profiling of Carotenoids, Chlorophylls and Phenolic Compounds in Adiantum capillus-veneris Leaves

Adiantum capillus-veneris is important endangered fern species with several medicinal properties. In this study, the leaves samples were extracted and separated using reversed phase HPLC with DAD for carotenoids, chlorophylls and phenolic compounds. Separation of carotenoids and chlorophylls were carried out using a tertiary gradient system of water, MTBE and methanol-water, while a binary gradient system of methanol-water-acetic acid was used for phenolic profiling. Results revealed eight carotenoids, four pheophytins, and two chlorophylls. Lutein (806.0 μg/g), chlorophyll b′ (410.0 μg/g), chlorophyll a (162.4 μg/g), 9′-Z-neoxanthin (142.8 μg/g) and all-E-violaxanthin (82.2 μg/g) were present in higher amounts. The relatively high amounts of lutein may be one of the key indicator of beneficial antioxidant properties. The phenolic profile revealed a total of 13 compounds, namely 4-hydroxybenzoic acid, chlorogenic acid, caftaric acid, kaempferol glycosides, p-coumaric acid, rosmarinic acid, 5-caffeoylquinic acid, and quercetin glycosides. Kaempferol-3-sophorotrioside (58.7 mg/g), chlorogenic acid (28.5 mg/g), 5-O-caffeoylquinic acid (18.7 mg/g), coumaric acid (11.2 mg/g), and its derivative (33.1 mg/g) were present in high amounts. These results suggest that the reversed phase HPLC profiling of Adiantum leaves provides a better understanding in to the actual composition of bioactive compounds, which may be responsible for the potential medicinal properties. Adiantum leaves rich in important bioactive phytochemicals can be used as a possible source of nutraceuticals or as a functional food ingredient.

Effects of pectin on lipid digestion and possible implications for carotenoid bioavailability during pre-absorptive stages: A review

Pectin, an abundant polysaccharide in the human diet, has structural characteristics and functional properties that are strongly dependent on the food matrix (e.g., origin, type, cultivar/variety, ripening stage, style and intensity of processing). These polysaccharides have a strong effect on lipid digestion, which is required for the liberation of carotenoids from emulsified lipid droplets in the gastrointestinal content and for the formation of micelles, in which the carotenoids must be incorporated before absorption. Only micellarized carotenoids can be absorbed and subsequently exert protective effects on human health. The alteration of lipolysis by pectin can occur through several mechanisms; however, they have not been linked directly to carotenoid micellarization. This paper provides an overview of the effects of the properties of pectin on the ion concentration in the digestive content, the viscosity of the digestive medium, the properties of the lipid droplet surfaces and lipase activity and analyzes the impact of these events on lipid digestion and subsequent carotenoid micellarization.

New Challenges for the Design of High Value Plant Products: Stabilization of Anthocyanins in Plant Vacuoles

In the last decade plant biotechnologists and breeders have made several attempt to improve the antioxidant content of plant-derived food. Most efforts concentrated on increasing the synthesis of antioxidants, in particular anthocyanins, by inducing the transcription of genes encoding the synthesizing enzymes. We present here an overview of economically interesting plant species, both food crops and ornamentals, in which anthocyanin content was improved by traditional breeding or transgenesis. Old genetic studies in petunia and more recent biochemical work in brunfelsia, have shown that after synthesis and compartmentalization in the vacuole, anthocyanins need to be stabilized to preserve the color of the plant tissue over time. The final yield of antioxidant molecules is the result of the balance between synthesis and degradation. Therefore the understanding of the mechanism that determine molecule stabilization in the vacuolar lumen is the next step that needs to be taken to further improve the anthocyanin content in food. In several species a phenomenon known as fading is responsible for the disappearance of pigmentation which in some case can be nearly complete. We discuss the present knowledge about the genetic and biochemical factors involved in pigment preservation/destabilization in plant cells. The improvement of our understanding of the fading process will supply new tools for both biotechnological approaches and marker-assisted breeding.

Anthocyanins in obesity-associated thrombogenesis: a review of the potential mechanism of action

Platelet dysfunction, oxidative stress and dyslipidemia are important contributors to pro-thrombotic progression particularly in obese and hyper-cholesterolemic populations.