Effect of in vitro digestion-fermentation of Ca(II)-alginate beads containing sugar and biopolymers over global antioxidant response and short chain fatty acids production

In Vitro Digestion and Fermentation of Cowpea Pod Extracts and Proteins Loaded in Ca(II)-Alginate Hydrogels

Antioxidants derived from food by-products are known for their bioactive properties and impact on human health. However, the gastrointestinal behavior is often poor due to their degradation during digestion. The development of Ca(II)-alginate beads supplemented with biopolymers and enriched with cowpea (Vigna unguiculata) extract could represent a novel environmentally friendly technological solution to produce functional ingredients in the food industry. The present study evaluates the impact of in vitro digestion/fermentation by analyzing global antioxidant response (GAR), production of short-chain fatty acids (SCFAs) as a modulation of gut microbiota, and behavior of proton transverse relaxation times by low-field nuclear magnetic resonance (as an indicator of gelation state and characterization of microstructure). Results revealed that guar gum and cowpea protein preserved a high GAR of total phenolic compounds and antioxidant capacity by ABTS and FRAP methods after digestion/fermentation, promoting an adequate protection of the bioactives for their absorption. Alginate-based beads have great potential as prebiotics, with the guar gum-containing system contributing the most to SCFAs production. Finally, the overall higher mobility of protons observed in the intestinal phase agrees with structural changes that promote the release of phenolic compounds during this stage. Beads are excellent carriers of bioactive compounds (cowpea phenolic compounds and peptides) with potential capacities.

Design of an antioxidant powder additive based on carvacrol encapsulated into a multilayer chitosan-alginate-maltodextrin emulsion

Carvacrol has demonstrated antioxidant activity; however, its high volatility and low water solubility limit its direct application in food matrices. Then, an effective encapsulation system is required to protect it. This study aimed to design and characterize a carvacrol-based additive encapsulated in a spray-dried multilayer emulsion based on chitosan/sodium alginate/maltodextrin. Spray-drying temperature of 120 °C and 3 %(w/w) maltodextrin content maximized both encapsulation efficiency (~97 %) and loading capacity (~53 %). The powder's antioxidant properties were evaluated in two food simulant media: water (SiW) and water-ethanol (SiD). The highest antioxidant activity was observed in SiW for both ABTS•+ (8.2 ± 0.3mgEAG/g) and FRAP (4.1 ± 0.2mgEAG/g) methods because of the reduced release of carvacrol in SiD vs. SiW, as supported by micro- and macrostructural observations by SAXS and microscopy, respectively. An increase from 143 to 157 °C attributable to carvacrol protection and Tg = 44.4 °C (> ambient) were obtained by TGA and DSC, respectively. FT-IR confirmed intermolecular interactions (e.g. -COO- and -NH3+) as well as H-bonding formation. High water solubility (81 ± 3 %), low hygroscopicity (8.8 ± 0.2 %(w/w), poor flowability (CI:45 ± 4), and high cohesiveness (HR:1.8 ± 0.1) between particles were achieved, leading to a powdered antioxidant additive with high potential for applications which required avoiding/reducing oxidation on hydrophilic and hydrophobic food products.

Stachyose in combination with L. rhamnosus GG ameliorates acute hypobaric hypoxia-induced intestinal barrier dysfunction through alleviating inflammatory response and oxidative stress

High altitude is closely related to intestinal mucosal damage and intestinal microbiota imbalance, and there is currently no effective prevention and treatment measures. In this study, the effects of stachyose (STA), L. rhamnosus GG (LGG) and their combination on inflammatory response, oxidatve stress and intestinal barrier function in mice exposed to acute hypobaric hypoxia were investigated. Our results indicated the combination of STA and LGG could more effectively regulate intestinal microbiota disorders caused by hypobaric hypoxia than STA or LGG alone. When mice were administered with STA + LGG, the content of short chain fatty acids (SCFAs) especially butyric acid significantly increased, which helped intestinal cells to form tight connections, improve the level of anti-inflammatory cytokine (TGF-β) and antioxidant enzymes (SOD, CAT, GSH-Px), and decrease the expression of pro-inlammatory cytokines and hypoxia-inducing factors (IFN-γ, IL-1β, IL-6, TNF-α and HIF-1α), thereby enhance the strong intestinal barrier function. Furthermore, the synbiotics significantly reduced the ratio of Firmicutes to Bacteroidetes, while significantly increased the relative abundance of Rikenella, Bacteroides, Odoribacter, Ruminiclostridium_5 and Gordonibacter, which were correlated with production of SCFAs and anti-inflammatory role. Correlation analysis showed that the protective effect of synbiotics on intestinal barrier function was associated with its anti-inflammatory activity and antioxidant capacity. It provided a strong foundation for further research on the role of STA and LGG in maintaining normal intestinal function at high altitude. Our study has identified and demonstrated a new synbiotic that may be one of the ideal intervention measures for preventing and treating intestinal dysfunction at high altitude.

In vitro gastrointestinal digestion methods of carbohydrate-rich foods

The trend toward healthier food products has led to an increase in the research of in vitro gastrointestinal digestion methods. Among the most used models, static models are the simplest. Most static models have three stages: oral, gastric, and intestinal, simulating the enzymatic, electrolyte, pH, temperature, and bile salt conditions. The studies that have taken the most notice are those related to antioxidant activity, followed by those dealing with proteins and carbohydrates using most of them static in vitro digestion models. The number of these studies has increased over the years, passing from 45 to 415 in a 10-year period (2012-2023) and showing an interest in knowing the impact of food on human health. Nevertheless, published papers report different methodologies and analytical approaches. This review discusses the similarities and differences between the published static in vitro gastrointestinal digestion methods, with a focus on carbohydrates, finding that the most used protocol is Infogest, but with differences, mainly in the type of enzymes and their activity. Regarding in vitro gastrointestinal digestion of carbohydrates, many of the published studies are related to food and biomacromolecules, being the oral phase the most omitted, while the intestinal phase in the most diverse. Other methodologies to study the intestinal phase have been recommended, but the number of in vitro digestion studies using these methodologies (RSIE and BBMV) is still scarce but could represent a good alternative to analyze carbohydrates foods when combining with Infogest. More studies are required in this area.

Fabrication of colon-targeted ethyl cellulose/gelatin hybrid nanofibers: Regulation of quercetin release and its anticancer activity

A colon-targeted delivery system that can efficiently deliver and release quercetin is essential to improve its bioavailability. We previously found that hydrophobic ethyl cellulose (EC) nanofibers could efficiently deliver quercetin to colon, but the release of quercetin was limited. To address this problem, hydrophilic gelatin (GN) was used as a regulator, and quercetin-loaded nanofibers with different mass ratios of EC to GN (3:1, 1:1, 1:2, 1:3) were fabricated by electrospinning. All nanofibers had a cylindrical morphology and high encapsulation efficiency (over 94 %), and there existed molecular interactions among quercetin, EC, and GN. The high GN content reduced the thermal stability of nanofibers but increased their surface wettability. Besides, these nanofibers had good stability in acidic and aqueous foods. Importantly, the release of quercetin in the simulated gastrointestinal fluid was <3 %. The addition of GN was beneficial to the release of quercetin in colon, and nanofibers with EC to GN being 1:3 had a more preferable release performance. The anticancer activity of nanofibers against HCT-116 cells was proved by inhibiting cell viability through the induction of apoptosis. Therefore, these nanofibers are potential carriers for efficient colon-targeted delivery of bioactive compounds in the food industry.

Probiotic Encapsulation: Bead Design Improves Bacterial Performance during In Vitro Digestion

The stability and release properties of all bioactive capsules are strongly related to the composition of the wall material. This study aimed to evaluate the effect of the wall materials during the encapsulation process by ionotropic gelation on the viability of Lactobacillus fermentum K73, a lactic acid bacterium that has hypocholesterolemia probiotic potential. A response surface methodology experimental design was performed to improve bacterial survival during the synthesis process and under simulated gastrointestinal conditions by tuning the wall material composition (gelatin 25% w/v, sweet whey 8% v/v, and sodium alginate 1.5% w/v). An optimal mixture formulation determined that the optimal mixture must contain a volume ratio of 0.39/0.61 v/v sweet whey and sodium alginate, respectively, without gelatin, with a final bacterial concentration of 9.20 log10 CFU/mL. The mean particle diameter was 1.6 ± 0.2 mm, and the experimental encapsulation yield was 95 ± 3%. The INFOGEST model was used to evaluate the survival of probiotic beads in gastrointestinal tract conditions. Upon exposure to in the vitro conditions of oral, gastric, and intestinal phases, the encapsulated cells of L. fermentum decreased only by 0.32, 0.48, and 1.53 log10 CFU/mL, respectively, by employing the optimized formulation, thereby improving the survival of probiotic bacteria during both the encapsulation process and under gastrointestinal conditions compared to free cells. Beads were characterized using SEM and ATR-FTIR techniques.

Alginate-inulin-chitosan based microspheres alter metabolic fate of encapsulated quercetin, promote short chain fatty acid production, and modulate pig gut microbiota

Quercetin loaded alginate microspheres, fabricated with the inclusion of inulin as a prebiotic source and chitosan as protective coating (ALINCH-Q), were subjected to in vitro colonic fermentation using pig fecal microbiota, with empty microspheres ALINCH-E, unencapsulated quercetin UQ and media only Blank as parallel studies. ALINCH-Q altered quercetin biotransformation towards higher production of 3-hydroxyphenylpropionic acid and 3-hydroxyphenylacetic acid, and further metabolism of 3,4-dihydroxyphenylacetic acid and 4-hydroxyphenylacetic acid compared to UQ. In addition, ALINCH-Q but not ALINCH-E or UQ significantly promoted SCFAs production compared to Blank. Furthermore, the ALINCH-Q microspheres altered the microbial compositions, increased the relative abundance of Lactobacillus, Turicibacter, Eubacterium, and Clostridium, while decreased that of the potentially pathogenic Enterococcus. The results suggest an interplay between the dietary fiber matrix and quercetin in producing these effects, and that ALINCH-Q could serve as a potential targeted delivery vehicle for quercetin to exert beneficial biological effects in the colon.

The modulatory effect of encapsulated bioactives and probiotics on gut microbiota: improving health status through functional food

The gut microbiota can be a determining factor of the health status of the host by its association with some diseases. It is known that dietary intake can modulate this microbiota through the consumption of compounds like essential oils, unsaturated fatty acids, non-digestible fiber, and probiotics, among others. However, these kinds of compounds can be damaged in the gastrointestinal tract as they pass through it to reach the intestine. This is due to the aggressive and changing conditions of this tract. For this reason, to guarantee that compounds arrive in the intestine at an adequate concentration to exert a modulatory effect on the gut microbiota, encapsulation should be sought. In this paper, we review the current research on compounds that modulate the gut microbiota, the encapsulation techniques used to protect the compounds through the gastrointestinal tract, in vitro models of this tract, and how these encapsulates interact with the gut microbiota. Finally, an overview of the regulatory status of these encapsulates is presented. The key findings are that prebiotics are the best modulators of gut microbiota fermentation metabolites. Also, probiotics promote an increase of beneficial gut microorganisms, which in some cases promotes their fermentation metabolites as well. Spray drying, freeze drying, and electrodynamics are notable encapsulation techniques that permit high encapsulation efficiency, high viability, and, together with wall materials, a high degree of protection against gastrointestinal conditions, allowing controlled release in the intestine and exerting a modulatory effect on gut microbiota.

Bioaccessibility assay, antioxidant activity and consumer-oriented sensory analysis of Beta vulgaris by-product encapsulated in Ca(II)-alginate beads for different foods

Bioaccessibility analysis and antioxidant activity along in vitro digestion and a consumer-oriented sensory analysis were conducted in three potential functional foods based on Ca(II)-alginate beads containing bioactive compounds extracted from beet stems. Ca(II)-alginate beads per se, and two selected products (cookies and turkish delights supplemented with the beads) were prepared. Regarding the beads, among the attributes rated by consumers, visual appreciation predominates, being color in the just-as-right (JAR) category and in the like preference. Instead, both flavor and sweet taste were attributes highly penalized and should be improved in beads to be accepted as food per se. A higher percentage of customers preferred cookies and turkish delights instead of only beads, considering global satisfaction. Regarding in vitro digestion, there was a significant content of phenolic compounds in the products with beads, showing a bioaccessibility greater than 80% (for cookies) and 26% (for turkish delights). Also, the antioxidant capacity measured by ABTS ranged between 50 and 109% for cookies and turkish delights, being lower when measured by FRAP (between 20 and 30%, respectively). Thus, including the beads with beet stem extract in both products leads to a significant increase in the content of phenolic compounds and in the antioxidant capacity compared to their counterparts, protecting the compound during oral and gastric phases. These results allow the generation of improved Ca(II)-alginate systems with promising functional properties for the development of ingredients and functional foods.

Arenga pinnata Resistant Starch Modulate Gut Microbiota and Ameliorate Intestinal Inflammation in Aged Mice

This study aimed to compare the regulatory effects of Arenga pinnata retrograded starch (APRS), Arenga pinnata starch (APS), and whole Arenga pinnata flour (APF) on gut microbiota and improvement of intestinal inflammation in aged mice. APF, APS, and APRS altered gut microbiota composition and exhibited different prebiotic effects. Bifidobacterium showed the greatest increase in feces of aged mice fed APF. The abundance of genus Lachnospiraceae_NK4A136 was highest in the APS group. APRS supplementation led to a greatest increasement in abundance of Lactobacillus, Roseburia, and Faecalibacterium prausnitzii. APRS induced significantly more short-chain fatty acid (SCFAs) production than APF and APS. APF, APS, and APRS treatments improved intestinal inflammation in aged mice and the order of ameliorative effect was APRS > APS > APF. APRS significantly decreased relative mRNA expression of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) and increased anti-inflammatory cytokines (IL-10). In addition, APF, APS, and APRS significantly downregulated the relative mRNA expression of senescence-associated gene p53 and upregulated the expression of anti-aging gene Sirt1. These results provide potentially useful information about the beneficial effects of Arenga pinnata products on human health.

Tannin-rich extracts improve the performance of amidated pectin as an alternative microencapsulation matrix to alginate

Microencapsulation of tannin extracts through extrusion-gelation method was performed comparing two alternative encapsulation matrices: alginate and amidated pectin. The microstructure of the generated microbeads was studied, as well as their microencapsulation efficiency and release properties. Overall, pectin-based beads performed better than their alginate-based counterparts. This, combined with a greater incorporation of tannins in the feed formulations led to a higher tannin load in the final beads. The best microencapsulation efficiency was given by pectin microbeads loaded with 10% tannin extract (w/w), but the final tannin content could be further increased by adding a 20% (w/w) concentration of the extracts. During a 14-days storage, only a marginal loss of tannins was recorded for pectin-based microbeads. The results reveal that great potential exists in producing pectin-based microbeads in presence of tannins, which allow better loading capacities and improving structural properties, thanks to the interactions between the tannins and the amidated polysaccharide.

New Sensor to Measure the Microencapsulated Active Compounds Released in an Aqueous Liquid Media Based in Dielectric Properties in Radiofrequency Range

In recent years, the general and scientific interest in nutrition, digestion, and what role they play in our body has increased, and there is still much work to be carried out in the field of developing sensors and techniques that are capable of identifying and quantifying the chemical species involved in these processes. Iron deficiency is the most common and widespread nutritional disorder that mainly affects the health of children and women. Iron from the diet may be available as heme or organic iron, or as non-heme or inorganic iron. The absorption of non-heme iron requires its solubilization and reduction in the ferric state to ferrous that begins in the gastric acid environment, because iron in the ferric state is very poorly absorbable. There are chemical species with reducing capacity (antioxidants) that also have the ability to reduce iron, such as ascorbic acid. This paper aims to develop a sensor for measuring the release of encapsulated active compounds, in different media, based on dielectric properties measurement in the radio frequency range. An impedance sensor able to measure the release of microencapsulated active compounds was developed. The sensor was tested with calcium alginate beads encapsulating iron ions and ascorbic acid as active compounds. The prediction and measurement potential of this sensor was improved by developing a thermodynamic model that allows obtaining kinetic parameters that will allow suitable encapsulation design for subsequent release.

Advances of plant-based structured food delivery systems on the in vitro digestibility of bioactive compounds

Food researchers are currently showing a growing interest in in vitro digestibility studies due to their importance for obtaining food products with health benefits and ensuring a balanced nutrient intake. Various bioactive food compounds are sensitive to the digestion process, which results in a lower bioavailability in the gut. The main objective of structured food delivery systems is to promote the controlled release of these compounds at the desired time/place, in addition to protecting them during digestion processes. This review provides an overview of the influence of structured delivery systems on the in vitro digestive behavior. The main delivery systems are summarized, the pros and cons of different structures are outlined, and examples of several studies that optimized the use of these structured systems are provided. In addition, we have reviewed the use of plant-based systems, which have been of interest to food researchers and the food industry because of their health benefits, improved sustainability as well as being an alternative for vegetarian, vegan and consumers suffering from food allergies. In this context, the review provides new insights and comprehensive knowledge regarding the influence of plant-based structured systems on the digestibility of encapsulated compounds and proteins/polysaccharides used in the encapsulation process.

Effects of in vitro digestion-fermentation over global antioxidant response and short chain fatty acid production of beet waste extracts in Ca(ii)-alginate beads

The aim of the present work was to analyze the effect of in vitro gastrointestinal digestion-fermentation on antioxidant capacity, total phenols and production of short chain fatty acids (SCFAs) from biocompounds derived from beet waste (leaf and stem) encapsulated in different formulations of Ca(ii)-alginate beads. The encapsulated systems presented higher antioxidant capacity in different phases (digested and fermented) than the extracts without encapsulation, making Ca(ii)-alginate beads a suitable delivery vehicle. Levels of total phenolic compounds and antioxidant capacity of the fermented fraction were up to ten times higher than those of the digested fraction, boosted by the contribution of bioactive compounds from the by-product of beet as well as by sugars and biopolymers. Among the formulations used, those that had excipients (sugars and/or biopolymers) presented a better overall antioxidant response than the beads with just alginate. Guar gum and sucrose lead to a promising enhancement of Ca(ii)-alginate beads not only for preservation and protection but also in terms of stability under in vitro digestion-fermentation and production of SCFAs.

High-intensity ultrasound-assisted extraction of phenolic compounds from cowpea pods and its encapsulation in hydrogels

Currently and according to the growing worldwide interest in the revaluation of agricultural by-products, the use of legumes waste presents great potential to obtain bioactive compounds. In this context, an extract rich in phenolic compounds was obtained from Vigna unguiculata (cowpea) pods by optimizing the high-intensity ultrasound conditions (10 min and 36% of amplitude) using response surface methodology. Then, the extract was encapsulated in Ca(II)-alginate beads with the addition of arabic or guar gums or cowpea isolated proteins. A complete morphological study by image analysis and microstructural evaluation by SAXS has been carried out. Results showed that beads containing alginate and alginate-guar gum have the highest loading efficiency of total phenolic compounds (47 ± 5%) and antioxidant activity (44 ± 3%). However, the coupled effect of the cowpea extract and the isolated proteins (at it higher concentration) increased the antioxidant capacity of the beads due to the contribution of the phenolic compounds and the amino acids with anti-radical activity, reaching a value of 67 ± 3 % of inhibition of ABTS.+. Finally, the microstructural analyses revealed that cowpea pod extract increased the interconnectivity of the rods due to the presence of trivalent cations, conferring versatility, and larger coordination to the network. Also, it was observed that the addition of cowpea proteins produced more interconnected bigger and fewer compacts rods than beads containing only alginate, increasing 12 and 49 % the interconnection and the size, respectively, and decreasing 10 % their compactness. This research demonstrated the use of cowpea sub-products as a source of bioactive compounds that further modulate the microstructure of the hydrogel network, and the outstanding potential for being incorporated in techno-functional foods by using Ca(II)-alginate as a carrier.