Enzymatic production of natural sweetener trilobatin from citrus flavanone naringin using immobilised α‐l‐rhamnosidase as the catalyst

Abstract

Summary An efficient and cost‐effective enzymatic production method for preparation of a high‐valued natural sweetener (dihydrochalcone glucoside trilobatin) was developed by the combination of hydrogenation and enzymatic hydrolysis reactions with α‐l‐rhamnosidase as the catalyst in aqueous medium. This technology is adopting the cheap and largely available citrus flavanone naringin as the starting material for trilobatin synthesis, and the present enzymatic technology is possibly utilised by commercial for scale‐up production. The production is a straightforward two‐step process, in which naringin was hydrogenated into naringin dihydrochalcone and followed by removal of the rhamnosyl group of naringin dihydrochalcone by enzymatic hydrolysis using immobilised α‐l‐rhamnosidase as the catalyst. Under optimised conditions, an overall yield of 96% was achieved with a very low loading of α‐l‐rhamnosidase catalyst at 60 °C in a neutral aqueous buffer solution within 2 h. The immobilised α‐l‐rhamnosidase catalyst can be recycled for 10 reactions (90% yield retained).

Effect of selective oxidation and sulphur/phosphorus‐containing compounds on coking behaviour during light naphtha thermal cracking

“…Under the experimental conditions (H 2 ‐H 2 O gas mixture, dew point = 20 °C), the selective oxidation of Mn and Cr was realized according to the XRD pattern. Although the concentration of Mn in HP40 alloy is much lower than that of Cr, the diffusion coefficient of Mn through Cr 2 O 3 is two orders of magnitude higher than that of Cr, and the free formation energy of manganese oxide is much lower . Therefore, the MnCr 2 O 4 spinel phase usually forms on the top of the Cr 2 O 3 phase, and the growth of Cr 2 O 3 is suppressed .…”

“…Although the concentration of Mn in HP40 alloy is much lower than that of Cr, the diffusion coefficient of Mn through Cr 2 O 3 is two orders of magnitude higher than that of Cr, and the free formation energy of manganese oxide is much lower . Therefore, the MnCr 2 O 4 spinel phase usually forms on the top of the Cr 2 O 3 phase, and the growth of Cr 2 O 3 is suppressed . The Cr 2 O 3 phase will evaporate and transform into porous carbides in high temperature carbonaceous environments.…”

Production of high antioxidant activity flavonoid monoglucosides from citrus flavanone with immobilised α‐L‐rhamnosidase in one step

“…In the present study, four flavonoid monoglucosides were prepared from the corresponding diglycosides (Nar DC, NHDC, naringin and hesperidin) by using an immobilised a-L-rhamnosidase (Imm-a-L-Rha) as the catalyst for hydrolysis reactions according to the reported method (Lei et al, 2018). The hydrolysis of diglycosides was performed by adding Imm-a-L-Rha with 169 U g À1 of Imm-a-L-Rha to 100 mg and 200 mg diglycosides in 100 mL water or a mixed solvent (pH = 7).…”

“…The synthetic method (Pd/C-catalysed hydrogenation reaction) followed the reported literature with slight modifications (Lei et al, 2018). 20 mL of 10% NaOH solution and 0.3 mmol of flavanone glycosides (neohesperidin or naringin) were added to a 100-mL flask, 20 mg of palladium on carbon was added, hydrogen gas was introduced, and magnetic stirring was carried out in a water bath at 30°C for 12 h. After the reaction was completed, the mixture was filtered and the palladium carbon was washed with water and recovered.…”

“…Enzymatic synthesis method for Trilobatin, HDC-7-G, prunin, Hes-7-G Enzymatic synthetic methods referred to the reported procedures (Lei et al, 2018). Briefly, 200 mg of flavonoid glycosides (Nar DC or NHDC or naringin or neohesperidin) were added in 100 mL of deionised water or a mixed solvent, and then, the mixtures were placed in a constant temperature water bath shaker at 60°C.…”