Simulated Gastrointestinal Transit Research Articles

The Application of Probiotic Bacteria from Strawberry (Fragaria ananassa × Duch.) in the Fermentation of Strawberry Tree Fruit (Arbutus unedo L.) Extract.

The search for unexplored plant resources that would provide a good basis for the development of novel probiotic functional foods is rapidly increasing. In this context, the strawberry tree fruit (Arbutus unedo L.) is particularly interesting, as it is rich in numerous antioxidant bioactive compounds that have been shown to be beneficial to health, but have not yet found industrial applications. In this work, the probiotic characterization of lactic acid bacteria strain Lactiplantibacillus plantarum DB2, isolated from strawberries (Fragaria ananassa × Duch.), was performed. The tested strain proved to be safe to use, displaying no antibiotic resistance or hemolytic activity. Due to its proven probiotic potential during simulated gastrointestinal transit, its antimicrobial activity, and its coaggregation with pathogens, it was selected for fermentation of an aqueous Arbutus unedo L. extract, which was subsequently microencapsulated and freeze-dried to extend its shelf life and preserve its functional properties. The antioxidant activity of the ferment obtained was maintained (80%), while after microencapsulation and freeze-drying, about 50% and 20% of the antioxidant activity was retained, respectively. In conclusion, this study demonstrates for the first time the application of probiotics isolated from strawberries in the fermentation of strawberry tree extract and monitors the antioxidant activity during post-fermentation formulation, paving the way for a potential industrial application of this underutilized plant.

Enhanced viability and stability of the Lactobacillus reuteri DSM 17938 probiotic strain following microencapsulation in pea and rice protein-inulin conjugates

Probiotics, which offer various health benefits can face challenges in terms of stability during food processing, storage, and gastrointestinal digestion. Therefore, this study aimed to improve the stability and survival of probiotics during various processing conditions and storage. To address this issue, the study was designed to microencapsulate Lactobacillus reuteri DSM 17938 within plant proteins (specifically rice protein (RP) and pea protein (PeP)) and their Maillard reaction conjugated with inulin by spray-drying. The encapsulation efficiency (EE%), stability during storage and temperature, and the viability after simulated gastrointestinal digestion of the microcapsules were examined. The results demonstrate that individual proteins exhibited lower EE%; however, the Maillard conjugates showed increased EE%, with RC (rice protein conjugates) displaying a higher EE% (96.99%) than PC (pea protein conjugates) (92.87%) (p < 0.05). Fourier Transform Infrared Spectroscopy verified the interaction between different functional groups of the proteins and Maillard conjugated and indicated the successful encapsulation of Lactobacillus reuteri DSM 17938 cells. The results also suggested that RC-encapsulated probiotic cells exhibited maximum survival upon gastrointestinal transit, with a decline of only 1.24 and 1.52 log CFU/g after gastric and complete simulated gastrointestinal digestion, respectively. The viability of probiotics encapsulated with RC and PeC showed improvement compared to those encapsulated with RP and PeP, particularly during refrigerated and room temperature storage, thermal challenge, and simulated gastrointestinal transit. Overall, these findings suggest that plant proteins and prebiotic inulin conjugates could serve as promising new encapsulation matrices for the encapsulation of probiotics in food applications.

Lactic acid bacteria naturally associated with ready-to-eat rocket salad can survive the human gastrointestinal transit

It was theorized that modernization and the decline in harmless microbial populations associated with food have altered the gut microbiota, impacting host metabolism and immunity. Western dietary patterns, characterized by processed foods and preservation methods, may significantly reduce the microbial population associated with food. To mitigate the consequences of bacterial deprivation, the integration of these diets with fermented foods is commonly proposed. Nonetheless, non-fermented food consumed raw may also be an important source of viable microbial cells for the human microbiome. This study investigates whether salad-associated LAB can survive the gastrointestinal transit (GIT) and contribute to the gut microbiota. LAB strains were quantified and isolated from rocket salad (Eruca vesicaria subsp. sativa), and their survival through GIT was assessed via intervention trials in healthy adults and in vitro. Moreover, bacterial communities in fecal samples were analyzed after three days of rocket salad consumption. Washing with a sodium hypochlorite solution drastically reduced total bacterial load and eliminated viable LAB. The quantity of LAB introduced through salads did not significantly alter the gut microbiota composition. Rocket salads harbored Weissella and Leuconostoc species. A significant increase in Weissella spp. but not in Leuconostoc spp. was observed after the consumption of rocket salad. Simulated GIT experiments suggested that the food matrix and the initial number of ingested viable bacteria may have been important in determining survival. These findings propose that plant products could serve as sources of live LAB for the human gut. Further research with diverse vegetables and longer interventions is needed, encouraging studies on raw, non-fermented foods and their impact on the human intestinal microbiome.

Cupuassu juice fermentation by Lactiplantibacillus plantarum Lp62 produces an antioxidant enriched probiotic beverage.

The present work aimed to produce a cupuassu juice (Theobroma grandiflorum) fermented by the probiotic bacterium Lactiplantibacillus plantarum Lp62 and to analyze its antioxidant potential, antimicrobial activity, and resistance to biological barriers. The fermented beverage showed an increase in the content of phenolics, flavonoids, and antioxidant potential. The culture showed antagonistic activity against pathogens, but this result was not observed when the juice was tested. The probiotic strain remained viable under refrigeration, even in an acidified environment, and survived simulated gastrointestinal transit in vitro. L. plantarum Lp62 showed 30% adherence to HT-29 intestinal cells and proved to be safe in terms of antibiotic resistance and production of virulence factors. Fermentation increased the functional characteristics of cupuassu juice. This drink proved to be a good vehicle for the delivery of the probiotic bacteria L. plantarum Lp62.

Supplementation of Labneh with Passion Fruit Peel Enhanced Survival of E. coli Nissle 1917 during Simulated Gastrointestinal Digestion and Adhesion to Caco-2 Cells.

Passion fruit peel powder (PFPP) was used to supplement the probiotic labneh to increase the activity of Escherichia coli Nissle 1917 (EcN) during production and storage. Labneh was manufactured with PFPP (0.5% and 1%) and analyzed at 0, 7, and 15 days of cold storage for postacidification and sensory properties and viability of EcN, survival of EcN to simulated gastrointestinal tract stress, and adhesion potential of EcN to Caco-2 cells. Acidification kinetics during fermentation showed that supplementation with PFPP reduced the time needed to decrease pH and reach the maximum acidification rate. PFPP addition contributed to postacidification of labneh during storage. PFPP had a beneficial effect (p < 0.05) on counts of EcN in labneh during different storage periods. Consumer preference expectations for labneh enriched with PFPP (0.5% and 1%) were higher than those for the control. PFPP provided a significant protective action for EcN during simulated gastrointestinal transit and had a positive effect on EcN adhesion to Caco-2 cells in vitro, although this decreased during storage with labneh. Labneh supplementation with PFPP can be recommended because of the positive effect on EcN viability and the high nutritional value, which may increase the appeal of the product to consumers.

Assessments of Probiotic Potentials of Lactiplantibacillus plantarum Strains Isolated From Chinese Traditional Fermented Food: Phenotypic and Genomic Analysis.

The lack of rapid and effective approaches to determine the health benefits of strains is one of the main challenges affecting the selection of probiotics from large numbers of candidates. In this study, the probiotic potential of 44 Lactiplantibacillus plantarum strains isolated from different Chinese traditional fermented foods was evaluated, including acid and bile salt resistance, adhesion ability, survival in simulated human gastrointestinal transit, antioxidant activity, bile salt hydrolase (BSH) activity, and antibacterial activity. All tested L. plantarum strains showed high antioxidant capacity, BSH activity, and antibacterial activity. Among the strains, B652, C232, D444, and E932 were identified as the best comprehensive performed strains, which were selected for whole-genome sequencing, in order to provide clear information and identify key genes responsible for functional characteristics in vitro. It demonstrated that the antioxidant activity, adhesion activity, and ability to survive in the simulated gastric environment were found to be closely correlated with antioxidant enzyme encoding genes, cell-surface protein-encoding genes, and stress response genes, respectively. The numbers of functional genes present in strains might decide their performance in probiotic profile evaluation. The outcome of the study could support the development of a novel approach for the screening and identification of probiotics.

Salmonella enterica subsp. enterica virulence potential can be linked to higher survival within a dynamic in vitro human gastrointestinal model

Salmonella enterica subsp. enterica is one of the leading causes of human foodborne infections and several outbreaks are now associated with the consumption of fresh fruit and vegetables. This study aims at evaluating whether Salmonella virulence can be linked to an enhanced ability to survive successive digestive environments. Thirteen S. enterica strains were selected according to high and low virulence phenotypes. Lettuce inoculated separately with each S. enterica strain was used as food matrix in the TNO gastrointestinal model (TIM-1) of the human upper gastrointestinal tract. During the passage in the stomach, counts determined using PMA-qPCR were 2–5 logs higher than the cultivable counts for all strains indicating the presence of viable but non-cultivable cells. Bacterial growth was observed in the duodenum compartment after 180 min for all but one strain and growth continued into the ileal compartment. After passage through the simulated gastrointestinal tract, both virulent and avirulent S. enterica strains survived but high virulence strains had a significantly (p = 0.004) better average survival rate (1003 %–3753 %) than low virulence strains (from 25 % to 3730%). The survival rates of S. enterica strains could be linked to the presence of genes associated with acid and bile resistance and their predicted products. The presence of single nucleotide polymorphisms may also impact the function of virulence associated genes and play a role in the resulting phenotype. These data provide an understanding of the relationship between measured virulence potential and survival of S. enterica during dynamic simulated gastrointestinal transit.

Autochthonous Lactobacillus paracasei subsp. paracasei strains isolated from Caciocavallo cheese: identification and in-vitro investigation on potential probiotic and functional properties

Background: In recent years consumers, due to the growing interest for functional foods, have put particularly attention on products enriched with probiotic lactic acid bacteria for their ability to give human benefit by their assumption. Microorganisms to be considered as probiotic should be able to survive to gastrointestinal juices and colonize the intestinal tract to provide benefits to human health. The aim of the study consisted of the in vitro investigation of novel LAB strains, isolated during cheesemaking and ripening of Caciocavallo cheese, and on their probiotic potential for food application. Methods: In order to select potential probiotic bacteria, LAB isolates were preliminarily screened for their survival to simulated gastro-intestinal transitand assayed for other activities of probiotic and functional interest. Thanks to promising attitude as potential probiotics, four strains were tested to evaluate their adhesion ability on Caco-2 cell lines used as intestinal cell model. Microbiological data were analysed by one-way analysis of variance (ANOVA). Comparisons of means were carried out using post-hoc Tukey’s test. For vitro adhesion experiments, statistical significance was evaluated by Kruskal-Wallis test for equal medians. Results: Twenty-five LAB, presumptively identified as Lactobacillus spp., were isolated from cheese during 60 days of ripening and screened for their survival to simulated gastrointestinal transit. Sixteen isolates that showed a survival rate ≥85% were identifiedas 10 different profiles of Lb. paracasei subsp. paracasei. The 10 strains tolerated high concentration of bile salts by Minimal Inhibitory Concentration and growth rate assays and showed susceptibility or moderate susceptibility against antibiotics of human and veterinary importance, except for the resistanceto the class of aminoglycoside antibiotics. Eight out 10 strains showed in vitro cholesterol-lowering ability, whereas all strains showed antioxidant activity of their cell-free supernatants. Moreover, the four strains with highest survival to simulated gastrointestinal transit showed the ability to adhere to Caco-2 cells. Conclusion: The results suggest that some strains may be effective probiotics to be use as tool to design probiotic dairy products after confirmation probiotic activities in further in vivo studies. Findings of the present study suggest that four strains showed good or strong adherent ability on Caco-2 cell monolayer, that is one of prerequisite that probiotic bacteria must have to perform their functional properties. Keywords: adhesion, antioxidant activity, bile salts, cholesterol assimilation, dairy products, gastrointestinal resistance, probiotic lactobacilli.

Identification and Transferability of Tetracycline Resistance in Streptococcus thermophilus during Milk Fermentation, Storage, and Gastrointestinal Transit

The existence of antibiotic-resistant bacteria in food products, particularly those carrying acquired resistance genes, has increased concerns about the transmission of these genes from beneficial microbes to human pathogens. In this study, we evaluated the antibiotic resistance-susceptibility patterns of 16 antibiotics in eight S. thermophilus strains, whose genome sequence is available, using phenotypic and genomic approaches. The minimal inhibitory concentration values collected revealed intermediate resistance to aminoglycosides, whereas susceptibility was detected for different classes of β-lactams, quinolones, glycopeptide, macrolides, and sulfonamides in all strains. A high tetracycline resistance level has been detected in strain M17PTZA496, whose genome analysis indicated the presence of the tet(S) gene and the multidrug and toxic compound extrusion (MATE) family efflux pump. Moreover, an in-depth genomic analysis revealed genomic islands and an integrative and mobilizable element (IME) in the proximity of the gene tet(S). However, despite the presence of a prophage, genomic islands, and IME, no horizontal gene transfer was detected to Lactobacillus delbrueckii subsp. lactis DSM 20355 and Lactobacillusrhamnosus GG during 24 h of skim milk fermentation, 2 weeks of refrigerated storage, and 4 h of simulated gastrointestinal transit.

In Vitro Evaluation of Probiotic Properties of Indigenous Yeasts Isolated from Nigerian Fermented Food Products

Probiotics are living microbial food supplements which beneficially affect the host by improving the intestinal microbial balance. Before an organism can be designated as probiotic there are certain criteria that must be fulfilled. These include acid and bile tolerance, antimicrobial activity, ability to co-aggregate, hydrophobicity etc. One hundred and eighty one indigenous yeast isolates recovered from various fermented food products of Nigeria were characterized and grouped using phenotypic methods. Forty two selected yeast isolates were identified using molecular method which involved sequencing of D1 and D2 domain of the large subunit of ribosomal DNA. Then nine indigenous Saccharomyces cerevisiae were evaluated for their probiotic characteristics such as acid and bile tolerance, transit in simulated gastric and intestinal juices, autoaggregation and hydrophobicity. Saccharomyces cerevisiae SC10 was included as a positive control. The S. cerevisiae were able to grow in the presence of acidic medium with pH as low as 2 and 3. In the minimum inhibitory concentration test with 0-1% ox bile, all the S. cerevisiae tested were able to grow. The growth for 3% bile tolerance test ranged from 4.81 to 5.35 log cfu/ml. These isolates were able to survive in simulated gastro-intestinal transit. All the yeast isolates exhibited bile salt deconjugation activity against sodium glycodeoxycholate and were able to grow in the presence of all other bile salts investigated. Autoaggregation ability (an adhesive property) of the indigenous yeast isolates ranged from 89.80% for S. cerevisiae BK19 to 99.91% for S. cerevisiae OB03. The native yeast isolates also exhibited high percentage hydrophobicity, another adhesive property of probiotics. The values obtained ranged from 31.62 to 83.45% for isolates AG23A and OB 17. These observations indicate that the native yeast isolates from Nigerian fermented foods have the potential of being use as probiotics for making functional foods.

Development of gastro-resistant coated probiotic granulates and evaluation of viability and release during simulated upper gastrointestinal transit

Probiotics have become one of the most consumed food supplements worldwide. Many probiotic strains are sensitive to low pH and bile concentrations encountered in the gastrointestinal tract upon oral ingestion. This study aimed at developing gastro-resistant probiotic granulates releasing viable cells in the small intestine. Fatty alcohols were investigated as potential coating materials. Cetostearyl alcohol was selected and combined with different plasticizers to further optimize the coating properties. Combining cetostearyl alcohol with olive oil and beeswax in selected concentrations was found promising, and the coatings were applied to L. acidophilus LA3 and B. longum BB536, using hot-melt fluid bed coating. Viability in and release from the coated probiotic granulate was investigated, using a physiological relevant in vitro model simulating conditions in the human stomach, duodenum, jejunum and ileum. L. acidophilus LA3 coated with cetostearyl alcohol and olive oil in the ratio 95:5 (w/w) resulted in significantly higher viability after simulated gastrointestinal transit, compared to the uncoated probiotic powder. Furthermore, the coating showed no release of viable cells after simulated gastric transit. Released viable cells were detected after the remaining steps in the in vitro model, indicating that the coating system provides gastric protection and release during intestinal transit.

Effect of whey protein concentrate on probiotic viability and antioxidant properties of yogurt during storage and simulated gastrointestinal transit

The present work investigated the effects of whey protein concentrate (WPC) on probiotic yogurt. Five different concentrations of WPC (0 - 10%) were evaluated. The results showed positive effects of WPC on yogurt’s properties under simulated gastrointestinal (GI) transit and long-term storage. In vitro digestion of WPC-fortified yogurt during GI transit markedly promoted the antioxidant activities in a concentration-dependent manner. WPC supplementation was also shown to significantly enhance the viability of probiotics under GI transit and during refrigerated storage, to the recommended level for health benefits on daily intake. The optimal concentration for retention of physicochemical properties (water holding capacity and texture profile) of the yogurt during refrigerated storage for 28 days was 5% (w/w), while the addition of 10% (w/w) WPC yielded the highest radical-scavenging activity (15.3 ± 0.1 mg Trolox Eq./g), reducing power (575.3 ± 2.3 g Trolox Eq./g), and Fe2+-chelating ability (13.5 ± 0.02 mg EDTA Eq./g) under both gastric and pancreatic digestion conditions. The results obtained suggest that WPC-fortification promoted the overall quality of probiotic yogurt by improving its antioxidant activities and probiotic viability, as well as extending its shelf-life.

Development of coffee kombucha containing Lactobacillus rhamnosus and Lactobacillus casei: Gastrointestinal simulations and DNA microbial analysis

Kombucha is produced with a symbiotic culture of bacteria and yeast (SCOBY). Sugared coffee has potential as a fermentation substrate for kombucha production. Objectives of this study were to: (1) produce coffee kombucha (CK) with Lactobacillus rhamnosus (LG) and Lactobacillus casei (LC) and characterize its microbial diversity, (2) evaluate the physicochemical properties and determine viability of CK inoculums under simulated gastric and intestinal conditions during refrigerated storage. Coffee was fermented for 8 days at 23 °C. LG and LC were inoculated into CK (5% v/v) and stored for 15 days at 4 °C. Acetobacteraceae were predominant for the control and Lactobacillaceae for both treatments after 15 days. CK with LG or LC stored for 15 days had 7.44 and 8.77 log CFU/mL, respectively, after exposure to simulated gastric and intestinal conditions. The DNA sequencing analysis revealed that the addition of LG and LC to the CK shifted the proportion of microbial families from Acetobacteraceae to Lactobacillaceae. This study suggests that added Lactobacilli can subsist in CK for 15 days and survived simulated gastrointestinal transit.

Physicochemical properties and antioxidant activity of gluten-free riceberry-cheese cracker under simulated gastrointestinal transit.

This study aimed to develop a gluten-free cracker by substituting wheat flour (WF) with riceberry flour (RB) combined with cheese's milk proteins to replace gluten. The effect of substitution of WF with RB at 50 and 100% (RB50 and RB100, respectively) on cracker properties were evaluated. The results showed that water activity, hunter colour value (L*), hardness, and thickness decreased with an increase in the RB content. This related to a compact structure and a weaker crystallinity of RB cracker when compared with WF-based cracker. The substitution of WF with RB50 and RB100 in cracker significantly (P < 0.05)increased the phytochemical content resulting in increased antioxidant properties.The synergistic effect of the bioactive compound of RB and the bioactive peptides originating from cheese's milk proteins on antioxidant capacity was observed under simulated GI digestion. The greatest increase in the ABTS•+ radical scavenging activity and reducing power was observed in the RB100 cracker at the intestinal digestive phase with the values of 15.74 ± 0.27 and 3.70 ± 0.06mg Trolox eq./g sample, respectively. The results suggest that the substituted 100% RB combined with cheese's milk proteins have a potentiality to be developed into a novel gluten-free product with enhanced antioxidant properties.

Immobilization of PR4A3 enzyme in pluronic F127 polymeric micelles against colorectal adenocarcinoma cells and increase of in vitro bioavailability

Traditional therapy for malignant neoplasms involving surgical procedures, radiotherapy and chemotherapy aims to kill neoplastic cells, but also affects normal cells. Therefore, exogenous proteases are the target of studies in cancer therapy, as they have been shown to be effective in suppressing tumors and reducing metastases. Pluronic F127 (F127) is a copolymer of amphiphilic blocks that has shown significant potential for drug administration, as it is capable of incorporating hydrophobic drugs and self-assembling in micrometers of nanometric size. This study investigated the effects of immobilization of the alkaline protease PR4A3 with pluronic F127 micelles on the enzyme-induced cytotoxicity. Protease immobilization was demonstrated through UV–visible and circular dichroism (CD) spectroscopies, as the enzyme interacts with the polymeric micelle of Pluronic F127 without changing its secondary structure. In addition, the immobilized form of the enzyme showed greater bioavailability after passing through the simulated gastrointestinal transit. Cell viability was assessed using the tetrazoic methylthiazole (MTT) assay. The results open perspectives for new research and development for PR4A3 in the treatment of colorectal carcinoma.

Potential Application of Apilactobacillus kunkeei for Human Use: Evaluation of Probiotic and Functional Properties.

Apilactobacillus kunkeei is an insect symbiont with documented beneficial effects on the health of honeybees. It belongs to fructophilic lactic acid bacteria (FLAB), a subgroup of lactic acid bacteria (LAB) notably recognized for their safe status. This fact, together with its recurrent isolation from hive products that are traditionally part of the human diet, suggests its possible safe use as human probiotic. Our data concerning three strains of A. kunkeei isolated from bee bread and honeybee gut highlighted several interesting features, such as the presence of beneficial enzymes (β-glucosidase, β-galactosidase and leucine arylamidase), the low antibiotic resistance, the ability to inhibit P. aeruginosa and, for one tested strain, E. faecalis, and an excellent viability in presence of high sugar concentrations, especially for one strain tested in sugar syrup stored at 4 °C for 30 d. This datum is particularly stimulating, since it demonstrates that selected strains of A. kunkeei can be used for the probiotication of fruit preparations, which are often used in the diet of hospitalized and immunocompromised patients. Finally, we tested for the first time the survival of strains belonging to the species A. kunkeei during simulated gastrointestinal transit, detecting a similar if not a better performance than that showed by Lacticaseibacillus rhamnosus GG, used as probiotic control in each trial.

Lactobacillus plantarum L15 Alleviates Colitis by Inhibiting LPS-Mediated NF-κB Activation and Ameliorates DSS-Induced Gut Microbiota Dysbiosis.

Previous studies have suggested that the Lactobacillus plantarum bacteria strain could be effective in ulcerative colitis (UC) management. However, its effects are strain-specific and the related mechanisms for its attenuating effects on UC remain unclear. This study aimed to elucidate the underlying mechanisms for the protective effect of L. plantarum on UC. Firstly, 15 L. plantarum strains were screened for potential probiotic characteristics with good tolerance to simulated human gastrointestinal transit and adhesion. Secondly, the inflammatory response of selected strains to the Caco-2 cells induced by lipopolysaccharide (LPS) was measured. Finally, an in vivo mouse model induced by dextran sulfate sodium (DSS) was used to assess the beneficial effects and likely action mechanisms the successfully screened in vitro strain, L. plantarum L15. In vitro results showed that L. plantarum L15 possessed the highest gastrointestinal transit tolerance, adhesion and reduction of pro-inflammatory abilities compared to the other screened strains. In vivo, high dose of L. plantarum L15 supplementation increased the body weight, colon length and anti-inflammatory cytokine production. Pro-inflammatory cytokine production, disease activity index (DAI) levels and myeloperoxidase (MPO) parameters decreased using this strain. In addition, L. plantarum L15 alleviated the histopathological changes in colon, modulated the gut microbiota, and decreased LPS secretion. The activities of this strain down-regulated the expression of TLR4 and MyD88 genes as well as genes associated with NF-κB signaling pathway. Our findings present L. plantarum L15 as a new probiotic, with promising application for UC management.

Probiotic Yogurt Fortified with Chickpea Flour: Physico-Chemical Properties and Probiotic Survival during Storage and Simulated Gastrointestinal Transit.

In the present study, probiotic yogurt with Lactobacillus acidophilus LA5 and Bifidobacterium BB12 was produced via fortification with chickpea flour (0, 1, 2.5, 5% w/v). During refrigerated storage for five weeks, probiotics maintained a viable count above the minimum therapeutic level (106 CFU/g) in all yogurt types. Although there was no significant (p > 0.05) positive effect of chickpea flour on probiotic viability during storage, the addition of chickpea flour has beneficial effects on the viability of both probiotic species in the presence of gastric and intestinal juices, with 0.3% bile. This study also evaluated the physio-chemical properties of probiotic yogurt during storage. Some physicochemical properties of yogurt, such as water holding capacity and susceptibility to syneresis, were enhanced by the addition of chickpea flour. Hence, chickpea flour could be an attractive pulse ingredient in the production of probiotic yogurts for health-conscious consumers.

Effect of the carrier material, drying technology and dissolution media on the viability of Lactobacillus fermentum K73 during simulated gastrointestinal transit.

The goal of this study was to determine the effect of the carrier material, drying technology and dissolution media during the passage of L. fermentum K73 through a dynamic in vitro digestion system (IViDiS). The carrier materials were (i) culture medium with growing micro-organisms and (ii) culture medium with maltodextrin : sweet whey [0.6 : 0.4]. The carrier materials were dried by spray-drying and freeze-drying to obtain four types of powders. The dissolution media consisted of water and 1% fat milk. The powders were tested using an in vitro dynamic digestion system (IViDiS). The results showed that powders derived from culture medium had the highest protective effect on the viability of L. fermentum K73 in both dissolution media and that survival increased when the powders were tested in milk. The modified Gompertz model was used to model L. fermentum K73 behaviour during the digestion process. The model showed that cells entrapped in culture medium had the longest lag phase and the slowest inactivation rate when evaluated in milk.

Effect of whey protein and riceberry flour on quality and antioxidant activity under gastrointestinal transit of gluten-free cookies

The objective of this study was to develop nutritionally enriched gluten-free cookies by using whey protein concentrate (WPC) and rice (var. riceberry) flour (RB). The effects of WPC and/or RB on physicochemical properties, antioxidant activity under simulated gastrointestinal (GI) transit, and sensorial acceptability of cookies were evaluated and compared to those with wheat flour-based cookies. The bioactive contents, total polyphenols and gamma amino-butyric acid, significantly increased with increasing RB (P < 0.05). The physical properties showed that colour parameters (L*, a* and b*), water activity, and hardness values of cookies significantly increased as the amount of WPC increased up to a level of 50%. Incorporation of 50% WPC showed markedly the highest antioxidant activity under GI digestion with the values of 4.72 ±0.02 mg Trolox eq./g (ABTS), 3.12 ±0.06 mg Trolox eq./g (FRAP), and 26.57 ±0.66 mg EDTA eq./g (metal chelating activity). The overall results showed that cookies with acceptable quality and improved nutrition and antioxidant activity could be produced by complete replacement of wheat flour with the WPC and/or RB. However, in order to obtain the desired cookie characteristics, the ratio of WPC to RB should be developed.