Analysis of volatile compounds, betaine, and antioxidant effect in goji berry (Lycium barbarum L.) powder extracted by various drying methods and extraction solvents

Goji berry (Lycium barbarum L.), a deciduous solanaceous shrub, were subjected to extraction using five solvents (water, 50% and 70% ethanol, and 50% and 70% methanol) and dried using two methods: freeze drying (FD) and spray drying (SD). To investigate the chemical properties of these various goji berry powders, an examination was conducted on the content of volatile compounds, betaine, antioxidant effect, total phenolic content (TPC), and total flavonoid compounds (TFC) (p < 0.05). The total volatile compound content was highest in SD powder with 50% ethanol extract, showing a 66.7% increase over the control. The betaine content was in the range of 9.25–31.9 mg/g dry weight, and it exhibited a significant increase with higher water concentration in the extraction solvent. Betaine, total phenolic compounds and total flavonoid compounds showed a significant increase in the sequence of SD followed by FD (p < 0.05). Overall, the SD sample showed superior benefits when evaluating volatile compounds, betaine, and antioxidant effect. SD was more suitable for drying goji berry, as it retains its appearance and biological activity.