Yuanping Lv

The evolution of volatile compounds during the ripening of Chinese horse bean-chili-paste (CHCP) was investigated in this study. GC×GC-TOF/MS allowed an identification of 748 volatiles in three CHCP samples, respectively, ripened for 3 months (M3), 12 months (M12) and 24 months (M24), and it showed that a longer ripening resulted in a richer diversity of the volatiles. In addition, M3 contained more aldehydes and organic acids in content and M12 had more alcohols, ketones, and esters, while M24 was abundant in heterocyclics. A total of 69 among the 748 volatiles were discriminated as the key flavor compounds of CHCP by method of Fisher ratio together with odor activity value and flavor dilution, including 12 alcohols, 9 aldehydes, 4 ketones, 5 organic acids, 16 esters, 4 phenols, 6 sulfur-containing compounds, and 13 heterocyclics. Further, principal component analysis suggested that some key aldehydes contributed the flavor of M3, while some key alcohols, esters and heterocyclics existed in M12, and some key phenols and heterocyclics were in M24. Varying of the key flavor volatiles during CHCP ripening gave it different fragrance configurations. Results presented details for the volatile profiles of CHCP during the natural ripening period, beneficial to shorten fermentation time by functional microorganisms, and could enrich the desire flavors.

In this work, anthocyanin of rose residue was microencapsulated, using spray-drying (1:1 (w/w) of GA to MD, the inlet air temperature was170°C, the drying airflow rate was 5.0 m³/min, feed rate was 0.36 L/h) and freeze-drying (processing 48 h at −52°C, vacuum degree was 0.45 mbar) with gum arabic and maltodextrin as external materials. The total phenolic content (TPC), anthocyanin content (ACN), antioxidant activity, moisture content, water activity (A_w), solubility, hygroscopicity, colorimetric property, particle micromorphology and size distribution of the microencapsulated anthocyanin were measured. Thermal degradation kinetic and thermodynamic parameters of ACN extracts and microcapsules in the accelerated model were determined. The spray-dried powder (SDP) presented a spherical shape while the freeze-dried powders (FDP) were in indefinite and laminated structures with more homogeneous distribution. After microencapsulation, the retention rate of TPC and ACN was 86.00% and 75.85% for SDP, 91.44% and 95.12% for FDP, respectively. Both of spray-dried and freeze-dried strategy provided efficient preservation for rose residues, enabling them to have lower moisture content, water activity, significantly higher solubility (P < .05) compared with the rose anthocyanin extracts (RAE), and have high-fidelity color that was similar to RAE. Meanwhile, the antioxidant activity of the microcapsules decreased with the deteriorating of bioactive compounds. In the degradation kinetic study of anthocyanin at the temperature 70, 80, 90°C, both FDP and SDP had longer half-life duration, lower absolute value of activation entropy, and better effect of freeze-drying embedding method compared to RAE. Therefore, microencapsulation, especially by freeze-drying method, could efficiently enhance the stability of anthocyanin in rose residue during thermal processing and storage, and thus greatly facilitate the utilization of by-product of rose essential oil. Abbreviations: RAE: rose anthocyanin extracts; GA: gum arabic; MD: maltodextrin; SDP: spray-dried powders; FDP: freeze-dried powders; TPC: total phenolic content; ACN: anthocyanin content