Structural and functional characterisation of compositionally optimised rice bran and lingonberry dietary fibre‐based gel‐type product enriched with phytochemicals

Abstract

In this study, the model gel-type delivery system containing rice bran (RB), lingonberry (Vaccinium vitisidaea L.) press cake (LPC) and thyme essential oil (Thymus vulgaris L.), was developed and evaluated by their texture, gelation rate and antioxidant activity changes during storage and simulated gastrointestinal digestion. For the structuring of the gel-type RB-LPC matrix, a high-intensity ultrasound (850 kHz; 1.3 W cm À2) treatment at 40°C was applied. The release of total phenols and flavonoids was measured during digestion process by a spectrophotometric method and reversed-phase high-performance liquid chromatography (RP-HPLC), respectively. The contributions of xanthan and alginate as gelling agents to improve the stability of the gel texture protecting it from fast degradation under gastrointestinal digestion enable a controlled release of antioxidants, thus improving their biodistribution. Storage temperature influenced the reduction of antioxidant activity in gels depending on stabiliser used, with the lowest values from those with alginate when stored for 28 days at 4°C. This knowledge can be used to facilitate the selection of the most appropriate plant polysaccharide-based delivery system for specific applications.

Functionalisation of rice bran assisted by ultrasonication and fermentation for the production of rice bran–lingonberry pulp‐based probiotic nutraceutical

“…After, the sample was treated by ultrasound (US) (850 kHz, power 1.3 W cm −2 ) using an ultrasonic device (Meinhardt Ultraschalltechnik, Leipzig, Germany) for 20 min at 40 °C according to the procedure described by Zadeike et al . (2020) and was subjected to the fermentation assay. The ultrasonication procedure was repeated three times.…”

“…The chromatographic analysis of flavonoids and phenolic acids in the sample extract was performed by reversed‐phase high‐performance liquid chromatography (RP‐HPLC) using a Waters 2695 chromatograph equipped with a Waters 2998 photodiode array detector (PDA) detector (Milford, USA) as described by Zadeike et al . (2020).…”

“…The methanolic extract prepared by mixing 0.4 g of solid material or 1 g of ultrasonicated sample with 70% methanol to a volume of 10 mL was analysed. The chromatographic analysis of flavonoids and phenolic acids in the sample extract was performed by reversedphase high-performance liquid chromatography (RP-HPLC) using a Waters 2695 chromatograph equipped with a Waters 2998 photodiode array detector (PDA) detector (Milford, USA) as described by Zadeike et al (2020).…”

“…In order to produce a substrate for the immobilisation of LAB, RB raw material was sterilised at 121 °C for 15 min and cooled to 40 °C, and then, a 10 g subsample was mixed with sterile distilled water in a ratio of 1:4. After, the sample was treated by ultrasound (US) (850 kHz, power 1.3 W cm À2 ) using an ultrasonic device (Meinhardt Ultraschalltechnik, Leipzig, Germany) for 20 min at 40 °C according to the procedure described by Zadeike et al (2020) and was subjected to the fermentation assay. The ultrasonication procedure was repeated three times.…”

“…A 0.3% solution of bile salts was prepared in distilled water. Further assay was performed as described by Zadeike et al (2020). Every 30 min of incubation, a sample was taken from the medium to determine the number of viable cells.…”