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Summary: Raspberry leaves, by‐products in raspberry production, are also a rich source of bioactive phytochemicals. In this study, the changes of phenolic compounds in raspberries leaf extract (RLE) under in vitro digestion and colonic fermentation were further studied by HPLC‐MS analysis and 16S rRNA. The results showed that the phenolic compounds in RLE were relatively stable during in vitro gastric digestion; however, in the subsequent intestinal digestion and colonic fermentation, their content decreased sharply. A large amount of hydroxyphenylpropionic acid, hydroxyphenylacetic acid and urolithins were produced under the action of gut microbiota. Moreover, compared with corresponding control, RLE significantly reduced the ratio of Firmicutes/Bacteroidetes in all volunteers, increased the relative abundances of some beneficial bacteria, Enterococcus, Prevotella, and decreased the relative abundances of potential pathogens, Clostridium and Faecalibacterium. These findings suggest that RLE during in vitro digestion and fermentation has positive effects on gut microbiota and potential value of maintaining intestinal health. [ABSTRACT FROM AUTHOR]

Raspberry extract (RE) is a raspberry product with high anthocyanins and low sugar. In the present study, to evaluate the metabolic behavior of phenolic compounds of RE under in vitro digestion (gastric (GF), gastric to intestinal (G-IF), and colonic fermentation (CF)), the changes of 30 phenolic compounds were investigated by High Performance Liquid Chromatography-Mass Spectrometry. The results showed that phenolic compounds were relatively stable in GF, but rapidly decreased in G-IF and CF. Five anthocyanins accounted for 61.1% of total polyphenol contents (TPCs). Among them, anthocyanins bound to glucose or with two hydroxyl groups on B-ring were metabolized more quickly. The catabolic activity of the human microbiota resulted in the production of a series of low molecular weight phenolics, such as hydroxybenzoic acids. Ellagic acid, accounting for 17.7% of TPCs, was rapidly metabolized to urolithin B and urolithin C in CF. Moreover, urolithin C showed the highest antioxidant activity in all ellagic acid metabolites by DPPH assay. Consequently, the metabolic behavior of phenolic compounds was mainly influenced by pH and intestinal microbiota, which provided the basis for further in vivo and in vitro study and efficient utilization of the extract. • The metabolic behavior of phenolics is mainly influenced by pH and intestinal microbiota. • Most of anthocyanins and flavonoids are metabolized to low molecular phenolic acids. • Ellagic acids are rapidly metabolized to urolithin B and urolithin C in colonic fermentation. • Urolithin C shows higher antioxidant activity than urolithin B and urolithin A. [ABSTRACT FROM AUTHOR]

The free, soluble-bound (esterified and glycosylated) and insoluble-bound phenolics from the dry raspberry pomace without seeds (RP) and raspberry seeds (RS) were obtained by acidic and alkali treatment. The total phenolic contents of different phenolic fractions from RP and RS by the Folin method followed the order: free > esterified ≈ insoluble-bound > glycosylated. Then 18 phenolics from RP and RS were quantified by HPLC-MS. Free phenolics had the highest total tested phenolic contents, while glycosylated phenolics were the lowest. Their antioxidant activity was increased by the increasing phenolic contents of different fractions. Free phenolics in raspberry pomace had the highest antioxidant activity by DPPH assay. RS-esterified phenolics had the hightest tyrosinase inhibitory activity (TIA) by enzyme activity analysis, which was equivalent to the TIA of 1.57 mM vitamin C. Among 9 typical phenolics, quercetin, chlorogenic acid, gallic acid and p -hydroxybenzoic acid on the TIA showed obvious promoting effects, while catechin, epicatechin, and caffeic acid exhibited a significant background effect. Therefore, p -hydroxybenzoic acid and gallic acid in RS-esterified phenolics were of great significance for the TIA. These results are beneficial to the comprehensive evaluation and utilization of the phenolic compounds in raspberry pomace. • Raspberry pomace was divided into free, soluble (esterified and glycosylated) and insoluble phenolics. • Free phenolics of raspberry pomace had the highest phenolic contents and antioxidant activity. • Free and esterified phenolics of raspberry seeds have comparable antioxidant capacity. • Esterified phenolics of raspberry seeds had the strongest tyrosinase inhibitory activity. [ABSTRACT FROM AUTHOR]

• Possible utilization of commercial raspberries at different ripening stage. • Basic data on commercial raspberry production in Shanxi Province, northern China. • Intercropping annual- and biennial-fruiting cultivars can extend the raspberry season. • Unripe raspberries contain high levels of non-anthocyanin phenols. • 'Tulameen' had the largest fruit weight and the highest SAR and TAC. To evaluate the physicochemical properties of raspberries (Rubus idaeus L.) at five ripening stages in Shanxi, northern China (non-traditional area of cultivation), 25 physicochemical indexes including 5 anthocyanins and 10 phenolic compounds by HPLC-MS, fruit weight, moisture content, soluble solids content, sugar-acid ratio (SAR), of three commercial cultivars, cv. Reveille, Tulameen and Heritage, were investigated. The fruit qualities of the three cultivars were close to those of fruit produced in the traditional cultivation areas, especially cv. Tulameen at the overripe stage (Stage 5), which had the largest fruit weight of 4.20 g, and the highest SAR of 4.01 and total anthocyanin content of 103 mg 100 g−1 fresh weight. By intercropping the annual-fruiting 'Heritage' and the biennial-fruiting 'Reveille' and 'Tulameen', the raspberry season in Shanxi, China was extended without a break from mid-June to early October. The unripen raspberries (Stages 1 and 2) with high levels of non-anthoycanin phenols, especially ellagictannin were suitable as a plant-derived polyphenol materials. The ripe raspberries (Stages 3 and 4) with a high anthocyanin level and SAR, were suitable for fresh use and processing. The overripe raspberries (Stage 5) which quickly rotted, with the highest anthocyanin level, moisture content and SAR, were suitable as raw materials for anthocyanin extraction. Cyanidin-3-sophoroside, cyanidin-3-glucoside, and cyanidin-3-rutinoside were the main anthocyanins in cv. Heritage, Tulameen, and Reveille, respectively. Thus, commercial raspberries can be utilized on the basis of their properties and active compounds at different ripening stages, and we provide basic data for their production in Shanxi, northern China. [ABSTRACT FROM AUTHOR]