Antifungal efficacy of kenaf seed peptides mixture in cheese, safety assessment and unravelling its action mechanism against food spoilage fungi

This study investigated the preservation efficacy of kenaf seed peptides mixture(KSPM)in extending the shelf-life of cream cheese matrix and the effect on its physicochemical properties.Also,the safety of KSPM towards mammalian cells and the underlying fungicidal mode of action in-vitro and in-silico were assessed.The KSPM at 500 and 1000 mg/kg effectively prolonged the shelf-life of cream cheese for up to 11-21 days when stored at 25℃ and 4℃,and significantly reduced the inoculated conidia counts by~3 log_(10) conidia/g.The safety assessment showed that KSPM maintained the proliferation of normal cell lines up to 30 mg/mL.The cell surface potential energy and hydrophobicity of fungi were altered due to the potent interactions between the peptides and the cell envelope,with KSPM causing significant fungal cell wall permeability and subsequent disruption of the cytoplasmic membrane integrity.KSPM treatment induced morphological destruction of conidia and mycelium and caused a significant loss of fungal cellular materials including K^(+),sugar,protein and nucleic acids(DNA and RNA),indicating irreversible damage to the fungal cytoplasmic membrane.The in-silico molecular docking study revealed that the peptides mixture efficiently interacted with fungal mannoprotein via the formation of hydrogen bonding,electrostatic interactions and hydrophobic forces.The molecular dynamics simulation showed that the peptide KPTGMR was tightly embedded into the fungal phospholipid bilayer membrane and inserted into the phosphate head groups which led to the formation of gaps,suggesting a transmembrane pore or channel action mechanism.

Physicochemical characteristics,GABA content,antimicrobial and antioxidant capacities of yogurt from Murrah buffalo milk with different fat contents

This study aimed to prepare yogurt from Murrah buffalo milk with high GABA content and low fat content while keeping the physicochemical characteristics,antimicrobial effects,and antioxidant capacity within acceptable levels.Yogurt samples were prepared using buffalo milk by adjusting the fat content to 0.2%,3.5%,and 6.5%.The results showed that the fat content had no significant effects on the pH,titratable acidity,water activity,and cell viability.However,the fat content significantly affected the viscosity,particle size,and texture profile analysis of the yogurt.The GABA content was significantly higher in the 0.2%fat yogurt(61.57±3.22 mmol L^(-1))compared to the 3.5%fat yogurt(43.64±1.99 mmol L^(-1))and 6.5%fat yogurt(27.84±2.64 mmol L^(-1)).Glutamic acid and proline were the most abundant amino acids in the yogurt.In contrast,saturated fatty acids(butyric,lauric,myristic,palmitic,stearic,and oleic)and linoleic acid were abundant.Yogurt with 3.5%fat showed significantly high antioxidant capacity and antimicrobial effects on E.coli O157 and Salmonella sp.Based on the results,fat content significantly affects the rheological properties,GABA content,and antioxidant and antimicrobial capacities of yogurt.In the future,3.5%fat should be chosen as the optimized formula for large-scale yogurt production from Murrah buffalo milk.