Effects of pulsed electric field-assisted osmotic dehydration and edible coating on the recovery of anthocyanins from in vitro digested berries

Berry fruits, such as strawberries and blueberries, are rich sources of anthocyanins. Several studies have been made on the impact of non-thermal treatments on safety, shelf-life and nutritional characteristics of such products, but the effects of these processes on anthocyanin stability during digestion in the gastrointestinal tract are still not completely clear. The aim of this study was to assess the recovery of anthocyanins after simulated gastrointestinal digestion of (1) strawberry samples, pre-treated with pulsed electric field (PEF) at 100 or 200 V\ub7cm 121, prior to osmotic dehydration (OD), and (2) blueberry samples coated with chitosan and procyanidin. After digestion, a significantly higher content of cyanidin-3-O-glucoside and malvidin-3-O-glucoside was quantified by LC-MS/MS in processed strawberry and blueberry samples, compared with the controls. The highest recovery of cyanidin-3-O-glucoside was detected in digested strawberry samples osmotically dehydrated with trehalose. The recovery of malvidin-3-O-glucoside was highest in digested blueberries coated with chitosan and stored for 14 days, compared with untreated samples or samples coated with chitosan and procyanidin. Our study shows the potential of mild PEF treatments combined with OD, or the use of edible coating, to obtain shelf-stable products without substantially affecting the composition or the stability of anthocyanins during digestion in the upper gastrointestinal tract

FOLATE PRODUCTION IN BIFIDOBACTERIA FROM INFANT AND ADULT HUMANS

Folates \u2013 the natural chemically reduced forms of folic acid (vitamin B9) - are cofactors in essential metabolic pathways such as DNA synthesis and methylation pathways. Humans cannot synthesize folate and depend on intake both from the diet (green vegetables, cereals, rice, milk, fermented milk products, etc.) and from indigenous folate synthesizing bacteria of the intestinal microbiota. Low folate levels increase the risk for neural tube defects and may increase the risk for e.g. certain cancer forms, cardiovascular disease and Alzheimer\u2019s. Screening for folate production of the bifidobacteria isolates from human adult and infant (1-6 month old) was performed. Strains typical of infants, such as Bifidobacterium longum subsp. infantis and B. breve, and of adults ( B. adolescentis) were selected for characterization. The aim of the present work was to investigate bifidobacteria from human host of different age with different feeding habits in order to establish a possible correlation between diet and the folate production. Folate is present in many different forms in humans. The detectable forms studied in the present work are 5-CH3-H4, H4 and total folate content. Bifidobacteria strains were cultivated in folate free synthetic media. Validated HPLC method was used to analyze deconjugated folates extracted from bacterial biomass

Folate production in bifidobacteria from omnivores, herbivores and carnivores

Folates are water-soluble B-group vitamin that are cofactors in many metabolic pathways such as DNA synthesis and methylation pathways. Humans cannot synthesize folate and its low status has been implicated in a wide variety of disorders. Naturally occurring food folates occur in abundance in leafy green vegetables, yeast extracts, citrus fruit, liver and kidney. Folate could derived, other than from diet, from indigenous bacteria of the microbiota which posses the ability of de novo folate production. Intestinal bacteria such as bifidobacteria can produce this cofactor by themselves from simple precursors; howewer some bifidobacteria are auxotrophic and have a strict growth requirement for folic acid. The study of folate metabolism in bifidobacteria isolated from different animals, such as omnivorous, herbivorous and carnivorous, could advances the knowledge of host-interaction in relation to endogenous folate production for possible microbiota modulation. We aimed to investigate the production of folate by bifidobacteria isolated from animals differing in diet in order to assess the potential indigenous contribute of folate availability provided by the microbiota.We aimed to investigate the production of folate by bifidobacteria isolated from animals differing in diet in order to assess the potential indigenous contribute of folate availability provided by the microbiota

The potential of bifidobacteria as a source of natural folate

Aims: Nineteen strains of bifidobacteria were screened for main folate forms composition in synthetic folate free and complex folate-containing media. Methods and Results: HPLC was used to analyze deconjugated folates extracted from bacterial biomass. Most strains had a total folate content above 4000 μg/100g DM. The highest value of 9295 μg/100g DM was found in B. catenulatum ATCC 27539 and the lowest in B. animalis subsp. animalis ATCC 25527 containing 220 μg/100g DM. 10 strains grew in synthetic folate free medium (FFM), showing folate autotrophy and suggesting folate auxotrophy of the remaining nine. In the autotrophic strains, a consistently higher folate level was found in FFM as compared to a more complex folate-containing medium, suggesting reduced requirements for folates in the presence of growth factors otherwise requiring folates for synthesis. The contents of total folate, 5-CH3-H4folate and H4folate were strain dependent. 5-CH3-H4folate dominated in most strains. Conclusions: Our results show that bifidobacteria folate content and composition is dynamic, strain-specific and depends on medium. Suitable selection of the growth conditions can result in high levels of folate per cell unit biomass. Significance and Impact of Study: This suggests that certain bifidobacteria may contribute to the folate intake; either directly in foods, such as fermented dairy products, or in the intestine as folate-trophic probiotics or part of the natural microbiota

Produzione di folato in bifidobatteri: produzione di 5-metil-tedraidrofolato e tetraidrofolato in periodi diversi di crescita

I folati sono essenziali per la sintesi di DNA e proteine. Sono presenti in alcuni alimenti e microorganismi. Il 5-metil-tedraidrofolato e’ una forma di folato piu’ stabile e biodisponibile del tetraidrofolato. Tale ricerca ha studiato il contenuto di 5-metil-tedraidrofolato e tetraidrofolato in specie diverse di bifidobatteri ed in momenti differenti di crescita. Due ceppi di Bifidobacterium longum subsp. longum B2160 e B. breve B1501 appartenenti alla “Bologna University Scardovi Collection of Bifidobacteria” (BUSCOB) sono stati coltivati in terreno privo (FFM) o con aggiunta di folato. Un metodo di HPLC validato e’ stato utilizzato per l’analisi di folati estratti dai bifidobatteri. Bifidobacterium longum subsp. longum B2160 e B. breve B1501 contenevano un quantitativo di tetraidrofolato superiore (2673 e 1718µg/100g di biomassa, rispettivamente) al 5-metil-tedraidrofolato (51 e 62µg/100g) durante la fase di crescita esponenziale. Tale prevalenza non cambiava nel tempo ma il livello di tetraidrofolato diminuiva all’approcciare della fase stazionaria. La quantita’ di 5-metil-tedraidrofolato rimaneva bassa ed indipendente dalla crescita. Tale risultato contrasta con la maggior parte dei ceppi di bifidobatteri finora studiati, dove il 5-metil-tedraidrofolato e’ presente in quantita’ superiori rispetto al tetraidrofolato. Il contenuto di folati e’ dunque dinamico e dipendente dal ceppo e dal suo stato fisiologico. Per una corretta selezione di ceppi probiotici e’ necessario tenere cio’ in considerazione

Isolation, identification and characterization of yeasts from fermented goat milk of the Yaghnob valley in Tajikistan

The geographically isolated region of the Yaghnob Valley, Tajikistan, has allowed its inhabitants to maintain a unique culture and lifestyle. Their fermented goat milk constitutes one of the staple foods for the Yaghnob population, and is produced by backslopping, i.e., using the previous fermentation batch to inoculate the new one. This study addresses the yeast composition of the fermented milk, assessing genotypic, and phenotypic properties. The 52 isolates included in this study revealed small species diversity, belonging to Kluyveromyces marxianus, Pichia fermentans, Saccharomyces cerevisiae, and one Kazachstania unispora. The K. marxianus strains showed two different genotypes, one of which never described previously. The two genetically different groups also differed significantly in several phenotypic characteristics, such as tolerance toward high temperatures, low pH, and presence of acid. Microsatellite analysis of the S. cerevisiae strains from this study, compared to 350 previously described strains, attributed the Yaghnobi S. cerevisiae to two different ancestry origins, both distinct from the wine and beer strains, and similar to strains isolated from human and insects feces, suggesting a peculiar origin of these strains, and the existence of a gut reservoir for S. cerevisiae. Our work constitutes a foundation for strain selection for future applications as starter cultures in food fermentations. This work is the first ever on yeast diversity from fermented milk of the previously unexplored area of the Yaghnob Valley

Competition for attachment of aquaculture candidate probiotic and pathogenic bacteria on fish intestinal mucus:

Probiotics for aquaculture are generally only selected by their ability to produce antimicrobial metabolites; however, attachment to intestinal mucus is important in order to remain within the gut of its host. Five candidate probiotics (AP1–AP5), isolated from the clownfish, Amphiprion percula (Lacepéde), were examined for their ability to attach to fish intestinal mucus and compete with two pathogens, Aeromonas hydrophila and Vibrio alginolyticus. Two different radioactive isotopes were used to quantify competition between pathogens and probionts. Attachment of the pathogens was enhanced by the presence of the candidate probiotics. However, the addition of the candidate probiotics after the pathogens resulted in reduced pathogen attachment