Kombuchas from Green and Black Tea Modulate the Gut Microbiota and Improve the Intestinal Health of Wistar Rats Fed a High-Fat High-Fructose Diet.

The Western diet can negatively affect the gut microbiota and is associated with metabolic disorders. Kombucha, a tea fermented by a symbiotic culture of bacteria and yeast (SCOBY), is known for its bioactive properties and has become popular in the last years. In this study, we evaluated the effects of regular kombucha consumption on the gut microbiota and on outcomes related to the intestinal health of Wistar rats fed a high-fat high-fructose diet. After eight weeks receiving a standard diet (AIN-93M) (n = 10) or a high-fat and high-fructose diet (HFHF) (n = 30) to induce metabolic disorders, the animals were subdivided into four groups: AIN-93M (n = 10); HFHF (n = 10); GTK (HFHF + green tea kombucha (n = 10); and BTK (HFHF + black tea kombucha; n = 10) for 10 weeks. Although body composition did not differ among the groups, the HFHF diet was associated with metabolic alterations, and stimulated the growth of gram-negative bacteria such as Proteobacteria and Bacteroides. Kombucha ingestion could somewhat modulate the gut microbiota, attenuating the effects of a Western diet by increasing propionate production and favoring the growth of beneficial bacteria, such as Adlercreutzia in the GTK group. Our results suggest that regular kombucha consumption may be beneficial to intestinal health, which can be mostly attributed to its high content and diversity of phenolic compounds.

Thermal resistance and high-performance microwave decontamination assessment of Bacillus endospores isolated from food-grade herbal extracts.

Generally, endospore contamination can occur from different sources during product manufacturing in many industries and therefore lower its quality by affecting physicochemical properties and shelf-life. Bacterial endospores can germinate inside the product and produce several enzymes, which can cause several undesirable changes. This study assessed the spores thermal resistance and applied a microwave decontamination technique toward herbal extracts (Tilia tomentosa and Centella asiatica) containing ethanol or glycerol. Based on 16S rRNA analysis, the detected contaminant endospores belonged to different Bacillus species, namely B. subtilis, B. zhangzhouensis, and B. pumilus. The thermal resistance assessment using inoculated endospores in the actual products revealed B. pumilus T2 as the most resistant endospore to the heat treatments tested in both T. tomentosa and C. asiatica extracts. Finally, a high-performance microwave technique was used to decontaminate T. tomentosa extract against the mixture of Bacillus spores. Results from the microwave technique indicate that the increase of temperature from 100°C to 105°C not only decontaminated the product but also could dramatically decrease the effective thermal treatment time (10 times), which can benefit the product quality. The results provided in this study considerably contribute to improving an original decontamination method for products containing glycerol and ethanol with the most negligible effect on product quality.

Evaluation of red chicory extract as a natural antioxidant by pure lipid oxidation and yeast oxidative stress response as model systems.

The search for renewable and abundant sources of antioxidants has recently focused on agricultural byproducts, especially promising due to their natural origins and low costs. In particular, plant raw materials are sources of important compounds such as dietary fiber, carotenoids, tocopherols, and polyphenolics, which are mostly discarded during harvesting and processing. Among these vegetal crops, red chicory is attractive because of the large quantity of its byproducts (residues as leaves and stems); moreover, there is no information on its role as a food and feed ingredient. In this study, red chicory leaf residue was evaluated as a natural substitute for synthetic antioxidants for the food and feed industry. After lyophilization, a red chicory extract (RC) was characterized for its phenolic profile and its oxidative stability as compared to BHT. RC was shown to reduce lipid peroxidation of different oils in the Rancimat test. In addition, the antioxidant property of RC was studied in a model system by evaluating the Saccharomyces cerevisiae response to oxidative stress by means of gene expression. In this analysis, the RC extract, added to the yeast culture prior to oxidative stress induction, exhibited a pleiotropic protective effect on stress responsive genes.