Modulating flavanone compound for reducing the bitterness and improving dietary fiber, physicochemical properties, and anti-adipogenesis of green yuzu powder by enzymatic hydrolysis.

Yuzu (Citrus junos Sieb.) is a peel-edible fruit with a pleasant aroma, but its bitter taste can impact consumer appeal. In this study, an efficient enzymatic method reduced bitterness in green yuzu powder (GYP). Cellulase KN and naringinase from Aspergillus oryzae NYO-2 significantly decreased naringin and neohesperidin content by over 87 %, while increasing total dietary fiber and soluble dietary fiber by up to 10 % and 51 %, respectively. Insoluble dietary fiber decreased by up to 22 %. Cellulose, hemicellulose, lignin, and pectin contents in enzyme-treated YP decreased by 1.15-2.00-fold, respectively. Enzyme-treated GYP exhibited improved physicochemical properties, including enhanced solubility, oil-holding capacity, and water swelling capacities. 3T3-L1 cells treated with cellulase-treated GYP and naringinase-treated GYP showed lower lipid accumulation and higher lipolysis capability than GYP, along with decreased fatty acid synthase contents. These findings suggest that enzyme-treated GYP holds potential as a functional ingredient in the food industry.

Improvement of branched-chain amino acid production by isolated high-producing protease from Bacillus amyloliquefaciens NY130 on isolated soy/whey proteins and their muscle cell protection.

Branched-chain amino acids (BCAAs) are vital components of human and animal nutrition that contribute to the building blocks of proteins. In this study, 170 protease-producing strains were isolated and screened from soy-fermented foods. Bacillus amyloliquefaciens NY130 was obtained from Cheonggukjang with high production of BCAAs. Optimal production of protease from B. amyloliquefaciens NY130 (protease NY130) was achieved at 42 °C and pH 6.0 for 21 h. It was purified and determined as 27- and 40 kDa. Protease NY130 showed maximum activity at pH 9.0 and 45 °C with Km value of 10.95 mg for ISP and 1.69 mg for WPI. Protease-treated ISP and WPI showed increased sweetness and saltiness via electronic tongue analysis and enhanced the protective effect against oxidative stress in C2C12 myocytes by increasing p-mTOR/mTOR protein expression to 160%. This work possesses potential in producing BCAAs by using protease for utilization in food.

Enhancement of debitterness, water-solubility, and neuroprotective effects of naringin by transglucosylation.

Naringin found in citrus fruits is a flavanone glycoside with numerous biological activities. However, the bitterness, low water-solubility, and low bioavailability of naringin are the main issues limiting its use in the pharmaceutical and nutraceutical industries. Herein, a glucansucrase from isolated Leuconostoc citreum NY87 was used for trans-α-glucosylattion of naringin by using sucrose as substrate. Two naringin glucosides (O-α-D-glucosyl-(1'''' → 6″) naringin (compound 1) and 4'-O-α-D-glucosyl naringin (compound 2)) were purified and determined their structures by nuclear magnetic resonance. The optimization condition for the synthesis of compound 1 was obtained at 10 mM naringin, 200 mM sucrose, and 337.5 mU/mL at 28 °C for 24 h by response surface methodology method. Compound 1 and compound 2 showed 1896- and 3272 times higher water solubility than naringin. Furthermore, the bitterness via the human bitter taste receptor TAS2R39 displayed that compound 1 was reduced 2.9 times bitterness compared with naringin, while compound 2 did not express bitterness at 1 mM. Both compounds expressed higher neuroprotective effects than naringin on human neuroblastoma SH-SY5Y cells treated with 5 mM scopolamine based on cell viability and cortisol content. Compound 1 reduced acetylcholinesterase activity more than naringin and compound 2. These results indicate that naringin glucosides could be utilized as functional material in the nutraceutical and pharmaceutical industries. KEY POINTS: • A novel O-α-D-glucosyl-(1 → 6) naringin was synthesized using glucansucrase from L. citreum NY87. • Naringin glucosides improved water-solubility and neuroprotective effects on SH-SY5Y cells. • Naringin glucosides showed a decrease in bitterness on bitter taste receptor 39.

Production of Prunin and Naringenin by Using Naringinase from Aspergillus oryzae NYO-2 and Their Neuroprotective Properties and Debitterization.

Naringin is a flavanone glycoside in citrus fruits that has various biological functions. However, its bitterness affects the quality, economic value, and consumer acceptability of citrus products. Deglycosylation of naringin using naringinase decreases its bitterness and enhances its functional properties. In this study, eight microbial strains with naringinase activity were isolated from 33 yuzu-based fermented foods. Among them, naringinase from Aspergillus oryzae NYO-2, having the highest activity, was used to produce prunin and naringenin. Under optimal conditions, 19 mM naringin was converted to 14.06 mM prunin and 1.97 mM naringenin. The bitterness of prunin and naringenin was significantly decreased compared to naringin using the human bitter taste receptor TAS2R39. The neuroprotective effects of prunin and naringenin on human neuroblastoma SH-SY5Y cells treated with scopolamine were greater than that of naringin. These findings can widen the potential applications of deglycosylation of naringin to improve sensory and functional properties.