Simulated Digestive Conditions Research Articles

Effects of the dose of administration, co-antioxidants, food matrix, and digestion-related factors on the in vitro bioaccessibility of rosmarinic acid – A model study

This study aimed to determine the effect of the administration dose, combinations with co-antioxidants (vitamin C, caffeic acid, chlorogenic acid, catechin, rutin), and different food matrices (cooked and lyophilized hen eggs, chicken breast, soybean seeds, potatoes) on the potential bioaccessibility of rosmarinic acid (RA) in simulated digestion conditions, depending on the digestion stage (gastric and intestinal) and the contribution of physicochemical and biochemical digestion factors.The in vitro bioaccessibility of RA depended on the digestion stage and conditions. The physicochemical factors were mainly responsible for the bioaccessibility of RA applied alone. The higher RA doses improved its bioaccessibility, especially at the intestinal stage of digestion. Furthermore, the addition of vitamin C and protein-rich food matrices resulted in enhanced intestinal bioaccessibility of RA.In the future, the knowledge of factors influencing the bioaccessibility of RA can help enhance its favorable biological effects and therapeutic potential.

Effect of Mollusca shell extracts on inhibition of kimchi over-acidification

Mollusca species shell such as oyster shell (OS) and snail shell (SS), are discarded after taking the meat, and the discarded shell causes the environmental problems. Therefore, recycling shell waste could potentially eliminate the environmental problems. This study aimed to evaluate the potential of OS and SS as natural calcium resources. The minerals, calcium, magnesium, potassium, phosphorus and sodium were analyzed in OS and SS extracts. Among them, the calcium content was the highest: 36.87 (%) and 33.42 (%) in the OS and SS extracts, respectively. Further, the content of ionized bioavailable form of calcium in OS and SS was higher than that of CaCO3 under simulated gastrointestinal digestion conditions. Additionally, OS and SS were added to kimchi, and their inhibitory effect on kimchi acidification was evaluated by assessing pH, titratable acidity and microbial analysis. As the results indicated that the addition of OS and SS had little effect on inhibiting the growth of lactic acid bacteria. However, it was confirmed that calcium neutralizes the organic acids produced during fermentation. Overall, the results of this study provide preliminary information on the re-use of OS and SS extracts as ionized natural calcium supplements and fermentation retardants.

Preparation and characterization of iota carrageenan-cyclodextrin-curcumin fibers and the release nature of curcumin in simulated digestion conditions

Healthy foods, known as functional and medicinal foods, are gaining popularity as they contain reasonable amounts of bioactive compounds (BCs) that can boost immunity. However, the intrinsic water insolubility and instability of BCs limit the design and development of healthy foods. To this end, carriers are effective in overcoming these setbacks. Among the several carrier choices, herein, human-compatible hydrocolloid iota-carrageenan (IC), a food hydrocolloid with the ability to form thermos-reversible gels, is chosen due to its intrinsic non-toxic and inexpensive traits. The ordered network structures of iota-carrageenan have been created by complexing with α-, β-, and γ-cyclodextrin (CD); later, curcumin has been encapsulated. Curcumin release has been tested in aqueous, simulated gastrointestinal, and simulated intestinal conditions. The maximum curcumin release was obtained in the aqueous conditions, and the IC fibers containing 50 mM NaCl displayed the highest curcumin release of 1.55 mg/g, followed by IC50-0.1β-CD of 1.37 mg/g. On the other hand, in IC fibers with 100 mM NaCl, the best release obtained was from IC100-0.1γ-CD and IC100 of 0.84 and 0.83 mg/g, respectively, and the minimum release of 0.39 mg/g was from the IC100-0.5γ-CD fibers. In simulated gastric fluid (SGF) media (pH 1.2), the highest release detected was 0.26 mg/g from the fibers with 50 mM NaCl. However, in simulated intestinal fluid (SIF) conditions (pH 6.8), the maximum achieved release of 1.00 mg/g was from the IC50 fibers, followed by 0.93 mg/g from the IC50-0.1β-CD fibers. Overall, the IC-CD network thermally protects curcumin, and the type of CD impacts its sustained release nature. The outcome is important in designing value-added delivery systems of bioactive compounds required to develop novel functional foods and improve human health.

Adsorption/desorption of mercury (II) by artificially weathered microplastics: Kinetics, isotherms, and influencing factors

While both mercury (Hg) and microplastics (MPs) are well-studied global pollutants, comparatively little is known about the interactions between them and the mobilization of Hg from MPs into organisms. We examined the affinity of Hg(II) to artificially weathered MPs, including polyamide (w-PA), polyethylene (w-PE), polyethylene terephthalate (w-PET), polyester fibers (w-PEST), polyvinyl chloride (w-PVC), and polylactic acid (w-PLA), along with crumb rubber (CR) and PE collected from a wastewater treatment plant (WWTP-PE). WWTP-PE, CR, and w-PEST had particularly high Hg(II) affinities, which can be attributed to electrostatic interaction and pore filling. The adsorption followed a pseudo-second-order kinetic process and fitted the Freundlich model, suggesting multi-step (mass transfer and intraparticle diffusion) and heterogeneous adsorptions. Hydrochemical conditions (pH, dissolved organic matter (DOM), salinity and co-existent metal ions) all impacted Hg-MP behavior. Changes in Hg speciation and MP surface properties contributed to the different Hg(II) adsorption capacities for the MPs. Weathering of MPs generally increased the adsorption of Hg(II) onto MPs, but CR, PET and PEST did not follow this trend. Less than 3% of adsorbed Hg(II) was mobilized from the MPs in freshwater, but that increased up to 73% under simulated avian digestive conditions, suggesting increased bioavailability of Hg(II) from ingested MPs. Overall, weathered MPs adsorb and retain Hg(II) under environmentally relevant conditions but desorb much of it in simulated avian digestion fluid, suggesting that birds that ingest MPs may have increased Hg(II) exposure.

Effect of starch-based nanoparticles on the viability and stability of probiotics under adverse conditions

ABSTRACT Starch nanoparticles resist digestion in the upper intestine but not in the colon. They are proven to exert prebiotic effects on the human body. Starch-based nanoparticles have generated a great interest in the food and agriculture sector due to their biocompatibility, wide array of natural sources and ease of modification. In the current study, two starch sources (rice and water chestnut) were used to synthesize nanoparticles for the encapsulation of probiotic bacteria. Obtained nanoparticles were characterized for their morphological, molecular, and structural attributes using Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and zeta sizer. Furthermore, free and nano-encapsulated probiotics were subject to simulated gastrointestinal digestion conditions. The average size of rice and water chestnut starch-based nano-capsules ranged from 309 to 427 nm. The encapsulation efficiency was recorded for rice and water chestnut starch as 89% and 95%, respectively. SEM micrographs exhibited entrapment of probiotics in wall materials. The surface of the capsules showed tiny, smooth surface polygonal granules. XRD images showed loss of crystallinity structure following encapsulation. Higher probiotic viability was recorded under simulated gastrointestinal conditions for nano-encapsulated probiotics compared to free probiotics. Conclusively, water chestnut and rice-based starch nanoparticles showed overall the best results regarding the viability of probiotics under stressed conditions.

Characterization and stability investigation of rhein encapsulated microcapsules using different enteric biopolymers with pullulan and Jiuzao glutelin conjugates via Maillard reaction

The poor water solubility and rhein (RH) stability limit its application in the functional food industry. In the present study, the RH-loaded water-in-oil-in-water nano emulsion and microcapsules were prepared using the conjugates of pullulan-Jiuzao glutelin (JG) (m/m, 2:1, PJC-2) obtained by Maillard reaction and enteric-soluble materials (polymethlacrylic acid, hydroxypropyl methylcellulose phthalate, cellulose acetate phthalate, and D-mannitol). The effects of different formulations on the microstructure, physicochemical properties, and storage stability of microcapsules were analyzed. The results showed that microcapsules exhibited stability against different external environments. The encapsulation efficiency of RH in the four enteric-soluble-PJC-2 double-deck microcapsules (70.03 ± 3.24%-91.08 ± 4.78%) was significantly improved than PJC-2 ones (61.84 ± 0.47%). The antioxidant activity and stability of RH in the microcapsules were improved (ABTS, 49.7%-113.93%; DPPH, 40.85%-101.82%; FRA, 62.32%-126.42%; and FCA, 70.58%-147.20%) after in vitro simulated digestion and extreme environmental conditions compared to free RH. This work provides a microcapsule based on PJC-2 with enteric-soluble materials for insoluble functional ingredients to improve solubility, stability, and bioactivity in the food industry.

Co-encapsulation of curcumin and quercetin with zein/HP-β-CD conjugates to enhance environmental resistance and antioxidant activity

In this study, composite nanoparticles consisting of zein and hydroxypropyl beta-cyclodextrin were prepared using a combined antisolvent co-precipitation/electrostatic interaction method. The effects of calcium ion concentration on the stability of the composite nanoparticles containing both curcumin and quercetin were investigated. Moreover, the stability and bioactivity of the quercetin and curcumin were characterized before and after encapsulation. Fluorescence spectroscopy, Fourier Transform infrared spectroscopy, and X-ray diffraction analyses indicated that electrostatic interactions, hydrogen bonding, and hydrophobic interactions were the main driving forces for the formation of the composite nanoparticles. The addition of calcium ions promoted crosslinking of the proteins and affected the stability of the protein–cyclodextrin composite particles through electrostatic screening and binding effects. The addition of calcium ions to the composite particles improved the encapsulation efficiency, antioxidant activity, and stability of the curcumin and quercetin. However, there was an optimum calcium ion concentration (2.0 mM) that provided the best encapsulation and protective effects on the nutraceuticals. The calcium crosslinked composite particles were shown to maintain good stability under different pH and simulated gastrointestinal digestion conditions. These results suggest that zein–cyclodextrin composite nanoparticles may be useful plant-based colloidal delivery systems for hydrophobic bio-active agents.

Induced Expression of the Acinetobacter sp. Oxa Gene in Lactobacillus acidophilus and Its Increased ZEN Degradation Stability by Immobilization.

Zearalenone (ZEN, ZEA) contamination in various foods and feeds is a significant global problem. Similar to deoxynivalenol (DON) and other mycotoxins, ZEN in feed mainly enters the body of animals through absorption in the small intestine, resulting in estrogen-like toxicity. In this study, the gene encoding Oxa, a ZEN-degrading enzyme isolated from Acinetobacter SM04, was cloned into Lactobacillus acidophilus ATCC4356, a parthenogenic anaerobic gut probiotic, and the 38 kDa sized Oxa protein was expressed to detoxify ZEN intestinally. The transformed strain L. acidophilus pMG-Oxa acquired the capacity to degrade ZEN, with a degradation rate of 42.95% at 12 h (initial amount: 20 μg/mL). The probiotic properties of L. acidophilus pMG-Oxa (e.g., acid tolerance, bile salt tolerance, and adhesion properties) were not affected by the insertion and intracellular expression of Oxa. Considering the low amount of Oxa expressed by L. acidophilus pMG-Oxa and the damage to enzyme activity by digestive juices, Oxa was immobilized with 3.5% sodium alginate, 3.0% chitosan, and 0.2 M CaCl2 to improve the ZEN degradation efficiency (from 42.95% to 48.65%) and protect it from digestive juices. The activity of immobilized Oxa was 32-41% higher than that of the free crude enzyme at different temperatures (20-80 °C), pH values (2.0-12.0), storage conditions (4 °C and 25 °C), and gastrointestinal simulated digestion conditions. Accordingly, immobilized Oxa could be resistant to adverse environmental conditions. Owing to the colonization, efficient degradation performance, and probiotic functionality of L. acidophilus, it is an ideal host for detoxifying residual ZEN in vivo, demonstrating great potential for application in the feed industry.

Microbial inulinase promotes fructan hydrolysis under simulated gastric conditions.

Fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) have emerged as key contributors to digestive discomfort and intolerance to certain vegetables, fruits, and plant-based foods. Although strategies exist to minimize FODMAP consumption and exposure, exogenous enzyme supplementation targeting the fructan-type FODMAPs has been underexploited. The objective of this study was to test the hydrolytic efficacy of a food-grade, non-genetically engineered microbial inulinase preparation toward inulin-type fructans in the INFOGEST in vitro static simulation of gastrointestinal (GI) digestion. Purified inulin was shown to undergo acid-mediated hydrolysis at high gastric acidity as well as predominantly inulinase-mediated hydrolysis at lower gastric acidity. Inulinase dose-response simulations of inulin, garlic, and high-fructan meal digestion in the gastric phase suggest that as little as 50 inulinase units (INU) and up to 800 INU per serving promote fructan hydrolysis better than the control simulations without inulinase. Liquid chromatography-mass spectrometry (LC-MS) profiling of fructo-oligosaccharides (FOS) in the gastric digestas following inulinase treatment confirms the fructolytic activity of inulinase under simulated digestive conditions. Altogether, these in vitro digestion data support the use of microbial inulinase as an exogenous enzyme supplement for reducing dietary fructan-type FODMAP exposure.

Catabolism of Dictyophora indusiata Polysaccharide and Its Impacts on Gut Microbial Composition during In Vitro Digestion and Microbial Fermentation.

Dictyophora indusiata is one of the most famous edible mushrooms in China. D. indusiata polysaccharide (DP) has attracted increasing attention because of its multiple beneficial effects. In this study, the in vitro simulated digestion and microbial fermentation were designed to reveal the potential catabolic property of DP and its impacts on the modulation of gut microbial composition. The results showed that the reducing sugar content, total polysaccharides content, molecular weight, and rheological property of DP were not significantly altered under in vitro simulated digestive conditions. However, the molecular weight, apparent viscosity, and total polysaccharides content of indigestible DP (DPI) significantly decreased during in vitro fecal fermentation, and the reducing sugar content and the release of free monosaccharides notably increased, suggesting that DP could be degraded and used by gut microbiota. Additionally, the relative abundances of several beneficial bacteria, such as Bacteroides, Catenibacterium, Parabacteroides, and Megamonas, increased significantly, indicating that DP can regulate the composition and abundance of gut microbiota. Moreover, DP could also promote the production of SCFAs, thus changing the acid-base environment of the large intestine. The results of this study are beneficial for deeply clarifying the catabolic behavior of DP in the gastrointestinal tract, which can provide a theoretical basis for developing microbiota-directed products based on DP.

Co-incorporation of probiotics into 3D printed custard cream with hydrophilic and hydrophobic bioactives

There is an emerging need for food with specific functionality and nutrition. This work investigated the feasibility of developing 3D printed custard cream co-enriched with probiotics, hydrophilic and hydrophobic bioactives. The effect of EGCG and resveratrol on survival of probiotics encapsulated in 3D printed custard cream during storage, heating, and simulated gastrointestinal conditions were investigated. The addition of bioactives and probiotic coacervates didn't exhibit great influence on the emulsion structure, gel-like rheological behavior and great printing properties of the resulting custard cream samples. The cell survival of encapsulated probiotics in the custard cream with bioactives was prominently increased during storage at 4 °C as well as under heating at 63 and 75 °C. The co-encapsulation of probiotics, EGCG and resveratrol in the custard cream improved the viability of probiotic in the gastrointestinal tract. There was only a 0.85 log and 1.52 log loss of probiotic viability in the custard cream after digestion in simulated gastric and small intestinal digestion conditions. Meanwhile, EGCG and resveratrol in this sample showed a maximum release after simulated digestion, which reached 68.10% and 71.69% release at the end of digestion. Therefore, the co-encapsulation of EGCG, resveratrol with probiotic in this 3D printable custard cream delivery system would be an efficient approach to simultaneous delivery bioactives and probiotic in the gastrointestinal tract with synergistic beneficial effects.

In vitro antidiabetic and antihypercholesterolemic activities of camel milk protein hydrolysates derived upon simulated gastrointestinal digestion of milk from different camel breeds

Milk protein hydrolysates derived from 4 camel breeds (Pakistani, Saheli, Hozami, and Omani) were evaluated for in vitro inhibition of antidiabetic enzymatic markers (dipeptidyl peptidase IV and α-amylase) and antihypercholesterolemic enzymatic markers (pancreatic lipase and cholesterol esterase). Milk samples were subjected to in vitro simulated gastric (SGD) and gastrointestinal digestion (SGID) conditions. In comparison with intact milk proteins, the SGD-derived milk protein hydrolysates showed enhanced inhibition of α-amylase, dipeptidyl peptidase IV, pancreatic lipase, and cholesterol esterase as reflected by lower half-maximal inhibitory concentration values. Overall, milk protein hydrolysates derived from the milk of Hozami and Omani camel breeds displayed higher inhibition of different enzymatic markers compared with milk protein hydrolysates from Pakistani and Saheli breeds. In vitro SGD and SGID processes significantly increased the bioactive properties of milk from all camel breeds. Milk protein hydrolysates from different camel breeds showed significant variations for inhibition of antidiabetic and antihypercholesterolemic enzymatic markers, suggesting the importance of breed selection for production of bioactive peptides. However, further studies on identifying the peptides generated upon SGD and SGID of milk from different camel breeds are needed.

Enhancement of solubility, thermal stability and bioaccessibility of vitexin using phosphatidylcholine-based phytosome

Vitexin is a C-glycosylated flavonoid which has many biological activities. However, extremely low aqueous solubility and poor bioaccessibility of vitexin greatly limits its application. In this study, phytosome technology was applied to improve these limitations using soybean phosphatidylcholine (SPC) and egg yolk phosphatidylcholine (EPC) as carrier agents. The effect of types of carrier agents and ratios of vitexin to carrier agent on the physicochemical properties, solubility, and thermal stability of vitexin-loaded phytosomes was investigated. The phytosome produced using EPC showed high encapsulation yield of 97.60%, encapsulation efficiency of 98.27%, solubility of 89.15%, total phenolic content (TPC) of 114.44 mg GAE/g phytosome, ferric reducing antioxidant power (FRAP) of 15.77 mmol Trolox/g phytosome and DPPH radical scavenging activity of 9.49 mmol Trolox/g phytosome. The phytosomal preparations using the ratio of vitexin to EPC of 1:3 could improve physical and chemical properties of vitexin-loaded phytosomes. Furthermore, phytosome technology could promote greater bioaccessibility and antioxidant activity of vitexin under thermal and simulated gastrointestinal digestion conditions compared to unprocessed vitexin. The results suggest that phytosome technology has ability to overcome the limitation and enable the application of vitexin.

Process Optimization, Structural Characterization, and Calcium Release Rate Evaluation of Mung Bean Peptides-Calcium Chelate

To reduce grievous ecological environment pollution and protein resource waste during mung bean starch production, mung bean peptides-calcium chelate (MBP-Ca) was synthesized as a novel and efficient calcium supplement. Under the optimal conditions (pH = 6, temperature = 45 °C, mass ratio of mung bean peptides (MBP)/CaCl2 = 4:1, MBP concentration = 20 mg/mL, time = 60 min), the obtained MBP-Ca achieved a calcium chelating rate of 86.26%. MBP-Ca, different from MBP, was a new compound rich in glutamic acid (32.74%) and aspartic acid (15.10%). Calcium ions could bind to MBP mainly through carboxyl oxygen, carbonyl oxygen, and amino nitrogen atoms to form MBP-Ca. Calcium ions-induced intra- and intermolecular interactions caused the folding and aggregation of MBP. After the chelation reaction between calcium ions and MBP, the percentage of β-sheet in the secondary structure of MBP increased by 1.90%, the size of the peptides increased by 124.42 nm, and the dense and smooth surface structure of MBP was transformed into fragmented and coarse blocks. Under different temperatures, pH, and gastrointestinal simulated digestion conditions, MBP-Ca exhibited an increased calcium release rate compared with the conventional calcium supplement CaCl2. Overall, MBP-Ca showed promise as an alternative dietary calcium supplement with good calcium absorption and bioavailability.

Modified whey protein isolate gel prepared by thermal aggregation combined with transglutaminase crosslinking achieves Casein-like slow digestion in vitro and in vivo

Our study aimed to fabricate a modified slow-digestive whey protein isolate (WPI), which can supply enough branched-chain amino acids (BCAAs) during long-term fasting. The WPI aqueous solution (10 % w/v) was treated by heat (80 ℃) to unfold the protein tertiary structure, and subsequently treated with transglutaminase to form a gel via cross-linking. The powder of the WPI gel was obtained by spray drying, which can dissolve in water easily and self-assemble into gels again. This modified WPI contained protein aggregates with high molecular weight, and kept a stable gel-like structure under simulated gastric digestion conditions (pH = 3, 37 ℃). A dense honeycomb internal microstructure of the freeze-dried gel was observed. Further, we found that the WPI gel successfully achieved a casein-like digestible ratio (37.37 %) and released more BCAAs (0.18 mg/mL) than casein during the 4 h of in vitro simulated digestion based on the INFOGEST method. Finally, our results showed that the C57BL/6 mice oral administrated with the modified WPI gel had consistently higher BCAAs concentration (0.052 mg/mL) in their blood serum than the mice with normal WPI intake during the 6 h of in vivo digestion.

Baked mango slices coated with Lactiplantibacillus plantarum immobilized in pectic extracts

The incorporation of probiotic bacteria into plant-based products for the development of functional foods is a challenge because microorganisms must overcome adverse conditions throughout processing, storage and digestive conditions. In this work, baked mango (Mangifera indica L) snacks coated with Lactiplantibacillus plantarum CIDCA 83114 were prepared by immobilizing microorganisms into protective matrices composed of pectins and calcium.To achieve this goal, mango slices were firstly cooked at 90 °C for 60 min. Then, they were coated with suspensions containing pectins extracted from mango peels, microorganisms and calcium and submitted to a moderate time/temperature treatment (50 °C/30 min). The final product, containing 9.38±0.51 log CFU/g snack, was stored at 25 °C for up to 45 days at different relative humidities (RH) (22, 33, 44, 85%) and exposed to simulated digestive conditions. During in vitro digestion assays, probiotic counts were > 7 log CFU/g snack in saliva, gastric, and intestinal stages. Bacterial counts along storage were >6 log CFU/g snack in all the conditions assayed and snacks retained their crispness at RH lower than 33%. The addition of probiotics, pectins and calcium did not cause noticeable changes of color, and snacks were sensorily accepted by consumers. These results support the incorporation of L. plantarum CIDCA 83114 in the formulation of snacks submitted to thermal treatments, retaining an overall acceptability in terms of crispness, and sensory attributes.

Antiviral Activities of Asarones and Rhizomes of Acorus gramineus on Murine Norovirus.

Noroviruses (NVs) are a major cause of foodborne diseases worldwide. The rhizomes of Acorus gramineus (AGR) have been used as a traditional medicinal plant and a food additive. In this study, AGR and its bioactive components—α-asarone and β-asarone—showed significant antiviral activities against murine NV (MNV) with pre-treatment, with more than two log reductions in viral plaques. They also demonstrated strong inhibition on binding to A- and O-type saliva by the recombinant P domain derived from human NV (HuNV) GII.4. Both α- and β-asarones also inhibited the binding of the P domain to the receptor at 0.125–1 mM in a concentration-dependent manner and induced a marked reduction in Tm, suggesting that they may reduce structural stability and block receptor binding by the P domain. In simulated digestive conditions, the AGR extract, α-asarone, or β-asarone further showed a significant reduction of MNV plaques by 1.5–2.8 logs. The asarones show a potential for development as a scaffold for anti-NV agents.

Survival of human coronavirus 229E at different temperatures on various food-contact surfaces and food and under simulated digestive conditions

The COVID-19 pandemic caused by SARS-CoV-2 has had a major impact on human health and the global economy. Various transmission possibilities of SARS-CoV-2 have been proposed, such as the surface of food in the cold chain and food packaging, as well as the fecal-oral route, although person-to-person contact via droplets and aerosols has been confirmed as the main route of transmission. This study evaluated the survivability of HCoV-229E, a SARS-CoV-2 surrogate, in suspension, on food-contact surfaces and on food at various temperatures, and in simulated digestive fluids by TCID50 assay. In suspension, HCoV-229E survived after 5 days at 20 °C with a 3.69 log reduction, after 28 days at 4 °C with a 3.07 log reduction, and after 12 weeks at –20 °C with a 1.18 log reduction. On food-contact surfaces, HCoV-229E was not detected on day 3 on stainless steel (SS), plastic (LDPE), and silicone rubber (SR) at 20 °C with a 3.28, 3.24 and 3.28 log reduction, respectively, and survived after 28 days on SS and LDPE at 4 °C with a 3.13 and 2.88 log reduction, respectively, and survived after 12 weeks on SS, LDPE, and SR at –20 °C with a 1.92, 1.32 and 1.99 log reduction, respectively. On food, HCoV-229E was not detected on day 3 on lettuce and day 4 on chicken breast and salmon at 20 °C with a 3.61, 3.26 and 3.08 log reduction, respectively, and on day 14 on lettuce and day 21 on chicken breast and salmon at 4 °C with a 3.88, 3.44 and 3.56 log reduction, respectively. The virus remained viable for 12 weeks in all foods at –20 °C with 2–2.47 log reduction. In addition, in simulated digestive fluid experiments, HCoV-229E was relatively resistant in simulated salivary fluid (SSF; pH 7, 5), fed state simulated gastric fluid (FeSSGF; pH 3, 5, 7), and fasted state simulated intestinal fluid (FaSSIF; pH 7). However, the virus was less tolerant in fasted state simulated gastric fluid (FaSSGF; pH 1.6) and fed state simulated intestinal fluid (FeSSIF; pH 5). Therefore, this study suggested that HCoV-229E remained infectious on various food-contact surfaces and foods; in particular, it survived longer at lower temperatures and survived depending on the pH of the simulated digestive fluid.

ROS-responsive hyaluronic acid hydrogel for targeted delivery of probiotics to relieve colitis

Probiotics are generally used as therapeutic intervention in inflammatory bowel disease. However, the low survival rate in harsh gastrointestinal environment and limited retention in intestine greatly restrict their health benefits. To address this problem, a ROS-responsive hydrogel based on hyaluronic acid (HA) was developed for encapsulation and targeted delivery of probiotics. The hydrogel was prepared facilely by physiological crosslink with methacrylated HA and thiolated thioketal. As a model probiotic, Lactobacillu reuteri showed a significantly increased survival rate in simulated digestive conditions after encapsulated in hydrogel. The negative properties conferred the hydrogel preferential adhesions to inflammation sites. Meanwhile, the excess reactive oxygen species (ROS) produced by inflamed colon tissues selectively cleaved thioketal linkages resulted in hydrogel degradation and local probiotics release. Furthermore, the hydrogel exerted an appropriate ROS-scavenge capacity and protected HT-29 cells from oxidative damage. Animal experiments indicated that hydrogel-encapsulated L. reuteri could remarkably alleviate the symptoms and improve the survival rate of mice with dextran sulfate sodium (DSS)-induced colitis. These results suggested that the biocompatible hydrogel may be a delivery platform to target inflamed intestines and expand the application of probiotics as pharmaceuticals.

Association of carob galactomannans with probiotic bacteria in synbiotic fermented milk and colon targeted-release carrier

For the first time, this study presented the use of raw locust bean gum (LBG) as a prebiotic, with one probiotic strain in synbiotic fermented milk or combined with Na-alginate as a biopolymer, for a targeted release of bacteria under colon-like conditions. For this purpose, the fermentative characteristics (biomass, pH), bacterial survival, and developed viscosities of the stored fermented milks were determined. The survival rates of microencapsulated bacteria using the emulsion technique under simulated gastrointestinal conditions (stomach: pH 2 + 0.3% pepsin; colon: pH 6.5 + 1% pancreatin + 0.3% bile) were also evaluated. Results showed that all the tested bacteria maintained better biomass and acidifying activities in the presence of LBG, especially at 2%. During cold storage, the viscosities of the LBG-fermented milks were regulated and better appreciated, especially at 2%. Lactobacillus rhamnosus LbRE-LSAS and Bifidobacterium animalis subsp. lactis Bb12 microencapsulated separately in Ca-alginate-raw carob gum maintained good survival rates (51 - 66%) as compared to free cells (21 - 59%) under simulated digestive conditions, and were released under colon-like conditions. Therefore, the formulation of LBG-enriched fermented milks containing probiotic bacteria could represent a very good candidate for industrial application. Ca-alginate-raw LBG beads for the specific release of probiotics in the colon could benefit consumers with celiac disease or other digestive disorders because LBG is naturally gluten-free.