Antifungal Property Of Glycinin Basic Peptide And Its Application Research

Glycinin basic peptide（GBP）,a basic subunit of soybean glycinin stemming from natural soybean,is a cationic peptide with a molecular weight and has the advantages of higher heat resistance,stable nature,anti-microbial properties.In order to obtain a safe,efficient and natural preservative that can be applied to food,this study mainly research the antifungal activities of GBP and its antifungal mechanism,explore the effects of GBP on sensory properties,cooking properties and the structure properties of the fresh wet noodles.Additionally,the preservative effect of GBP on fresh wet noodles was studied.The main results were obtained as follows:（1）The inhibitory activity of GBP against Penicillium sp.and A.niger was evaluated by measuring the diameter of the transparent inhibition zone.The increases of the diameter of inhibition zone showed that GBP has significant antifungal effect.Minimum inhibition concentration of GBP against Penicillium sp.and A.niger were 1.2 and 1.6 mg/mL,respectively.GBP had a strong inhibitory effect on spore germination in the two tested fungi proportional to concentration.GBP exhibited a significant inhibition in mycelium growth of Penicillium sp.and A.niger at 2.4 mg/mL concentrations with inhibition percentages of 63.3 % and 56.7 %,respectively.（2）The electric conductivity and the concentrations of K⁺、Ca²⁺of hyphae suspension were determined to explore the possible mode of action of GBP in Penicillium sp.and A.niger.The increases in electric conductivity and the concentrations of K⁺、Ca²⁺of hyphae suspension indicated that GBP could damage the cytoplasmic membranes and cause leakage of ions in cells.Compared to control,the downtrend of pH value of hyphae suspension treated with GBP with the increasing time was not significant.The result showed that GBP can reduce the ability of moving protons in the cell to extracellular of proton pump in the cell membrane.The result of determining the ergosterol content demonstrated that the GBP can inhibit synthetic of ergosterol on cell membrane,thus inhibiting the growth of bacteria cells.（3）The effecets of GBP on the sensory quality,cooking properties and the structure properties were studied.GBP added in fresh wet noodles not only increased the toughness,sensory quality of fresh wet noodles,but also increased the bonding,chewiness,shear force and tensile parameters.However there was no change in color.Therefore,GBP has potential as a preservative used in fresh wet noodles for increasing nutrition and improving the sensory quality.（4）The total bacterial count and fungal count were measured to research preservative effect of GBP on fresh wet noodles during storage.Compared to control,GBP could effectively reduce the total bacterial count and fungal count in fresh wet noodles.The result of sensory evaluation showed that GBP could delay deterioration of fresh wet noodles.These results indicated that GBP can significantly inhibit the growth of pathogenic bacteria in fresh wet noodles and prolong its shelf life.Therefore,GBP has the preservative effect on fresh wet noodles.