Preservative Effects of Clove Extract against Alternaria alternata on Postharvest Strawberries and Associated Shifts in Microbial Communities

Yang Wu¹Mingxue Chang¹Yihan Liu¹Tong Chen¹Zexia Li¹Weiwei Li¹Ding-Kun Liu¹Li He¹Huiming Sun^1,2*

• ¹College of Life Sciences, Jinggangshan University, Jiang Xi，Ji’an, China
• ²nstitute of Modern Agricultural Development, Jinggangshan University, Jiang XI，Ji'an, China

Strawberries are susceptible to pathogen infection leading to postharvest decay, with Alternaria bein g one of the common spoilage fungi. Previous studies have shown that clove extract possesses broad -spectrum antimicrobial activity and inhibits various pathogenic fungi of fruits and vegetables. This s tudy targeted Alternaria as the pathogenic fungus, determined the minimum fungicidal concentration (MFC) of clove extract against it, and treated the Fragaria × ananassa 'Benihoppe' strawberries with the MFC concentration. Through quality index measurements and microbial community analysis, the preservation effect and the preservative effects and associated changes were explored. The results sh owed that the MFC of clove extract against Alternaria alternata was 30 mg/mL, which significantly r educed the spore survival rate of Alternaria alternata (40.0%) and increased cell membrane permeabi lity (nucleic acid leakage OD₂₆₀=0.952 at 4 h). The preservation experiment on strawberries demonst rated that 30 mg/mL clove extract significantly delayed quality deterioration. After 8 days of storage, the fruit firmness was 68.3% higher, the VC content was 52.5% higher, and the weight loss rate was 46.4% lower compared to the control group. Microbial community analysis revealed that the abunda nce of pathogenic bacteria (such as certain fungi and spoilage bacteria) on the fruit surface of the trea ted group was generally reduced, while the abundance of beneficial bacteria (such as Bacillus) increa sed, resulting in a more stable community structure. In summary, this study demonstrates that clove e xtract treatment can delay the spoilage of 'Benihoppe' strawberry, and this effect is correlated with di rect antifungal activity against A. alternata and modulation of the epiphytic microbial community str ucture.