Ultrasound-assisted extraction and hydrothermal treatment were used to extract carbohydrates from defatted rice bran (DRB), and the prebiotic activity of the extracted carbohydrates was evaluated in vitro. The ultrasound method proved to be more efficient in the extraction of carbohydrates compared to the hydrothermal treatment. The extracts were mostly composed of glucose, stachyose, and arabinose. DRB carbohydrates were resistant to simulated gastrointestinal conditions and capable of promoting the growth of the probiotics L.acidophilus, L. casei, L. plantarum, and L. rhamnosus, resulting in decreased pH, consumption of sugars (glucose, fructose, and stachyose), and production of acids (lactic, acetic and propionic) over culture time, which are indicative of intense metabolic activity. They also presented positive prebiotic activity scores for all Lactobacillus strains, showing desirable selective stimulatory effects in relation to enteric organisms. These results demonstrate that DRB carbohydrates can be considered a potential source of prebiotics.
Keywords: Carbohydrates; Hydrothermal treatment; Prebiotic activity; Rice bran; Ultrasound-assisted extraction.
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