Carrots are known as the “King of Vegetables” and are widely consumed for their rich nutritional content, bioactive substances, unique flavor and texture. The ultrasonic (40 KHz, 10 min) combined with ascorbic acid (2%, w/v)-calcium chloride (1%, w/v) osmotic pre-treatment (H/UAA-CaCl₂) can improve the color quality of freeze-dried carrots (FDC) by preserving the carotenoid, however, the effects of H/UAA-CaCl₂ on the product’s flavor quality is still unclear. Moreover, there is a lack of systematic research on the relationship between carotenoid monomers, carotenoid degradation products, and product flavor.

The Fruit and Vegetable Processing and Nutrition Health Innovation group of Institute of Food Science and Technology (IFST), Chinese Academy of Agricultural Sciences (CAAS) has successfully independently investigated the changes in carotenoids monomers and volatiles (including β-carotene-metabolites) of FDC treated by H/UAA-CaCl₂ during a 120-day storage period.

The results of HS-SPME/GC–MS showed that caryophyllene was the dominant volatile compound (70.80–275.74 µg/g, d.b) in FDC, and 144 volatile compounds were detected in 6 samples. Besides, 23 volatile compounds were significantly correlated with β-carotene content (p < 0.05), and β-carotene degraded to off-flavor compounds (β-ionone: 22.85–117.26 µg/g, β-cyclocitral: 0–113.84 µg/g and dihydroactindiolide: 4.04–128.37 µg/g) that had adverse effects on FDC flavor. However, UAA-CaCl₂ effectively preserved the total carotenoid content (793.37 µg/g), and HUAA-CaCl₂ reduced the off-odors (such as β-cyclocitral and isothymol) formation at the end of storage. These results indicated that (H)UAA-CaCl₂ treatments were conducive to the maintenance of carotenoids and the flavor quality of FDC.

The above research was published in the JCR Q1 journal Food Research International (IF: 8.1). Lyu Ying is the first author of the paper, Prof. Bi Jinfeng and Prof. Chen Qinqin are the co-corresponding authors. This work was supported by the Science and technology project in Gansu Province (21ZD4NA01) and the Agricultural Science and Technology Innovation Program, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences (CAAS-ASTIP-2022-IFST). The support of the China Scholarship Council (202108210257) for the first author is acknowledged.

https://doi.org/10.1016/j.foodres.2023.113050