In the present study, carrot juice prepared was added into skimmed milk before fermentation to produce 10% and 20% (w/w) carrot-fortified skim milk. The influence of carrot juice on the lactic acid content, chemical composition, syneresis, texture, rheology property, and microstructure was evaluated along with a potential of carrot juice as an ingredient with rich dietary fiber and a firm structure with interaction of milk protein and a complex matrix under acidification. The results showed that the pH of yoghurt significantly ( P < 0.01 ) reduced with carrot juice addition, minimizing fermentation time by nearly 1 h and brought about an enhanced postacidification during the storage period while titratable acidity increased. Moreover, carrot juice addition had no significant effect on ferric reducing power and phenolic content ( P > 0.05 ). With 10% and 20% level carrot juice added, the total phenolic content (mg GAEkg−1) increased (37.86 and 38.92, respectively) compared with control (36.91) ( P < 0.05 ). Besides, the addition of carrot juice also showed reduced syneresis, increased apparent viscosity and viscoelastic modulus, stable texture, and a refined microstructure. Overall, this study confirmed that carrot juice has a potential as natural and nutrient composition to obtain firm and compact texture and enhance the beneficial quality of yoghurt.

Total flavonoids were extracted from Ziziphi Spinosae Semen (ZSS) by applying microwave-assisted extraction with low eutectic solvent (DES) as the extractant. This study investigated the effect of 21 different components of DES on the yield of total flavonoids in ZSS. The results revealed that the DES system, which consists of choline chloride and lactic acid with a molar ratio of 2:1, achieved the best flavonoid extraction efficiency. Based on the single-factor test, response surface methodology was used to optimize and determine the optimal process conditions for the extraction of total flavonoids from ZSS with deep eutectic solvent. The maximum flavonoids yields were achieved at 36.24 mg/g within the 50% DES water content, a microwave power of 600 W, a microwave time of 60 s, a liquid-solid ratio of 1:28 mg/mL, an extraction time of 66 min, and an extraction temperature of 93 °C. The macroporous resin was used to recover flavonoids from extracts. The DM130 resin showed higher adsorption/ desorption performance. The total flavonoids of ZSS were extracted using the recovered DES with a yield of 32.58 mg/g and a high reusability of 89.9%.