Extraction,Anti-bacterial Mechanism And Fresh-keeping Effect Of Procyanidins From Grape Seeds

Grape is one of the most widely cultivated fruites in the world.Grapes can not only be ate,but also can be used in the production of canned foods,drinks and wine.At present,the wine grape pomace is often used as fertilizer,feedstuff or discarded in our country. This paper studied the technology for extracting procyanidins from grape seed, purification,antagonistic property and mechanism, the antiseptic effect of grape seed extract in chilled chicken breast. The results were described as follows:(1)The optimal extraction conditions of proanthocyanidns from grape seeds were determined by using the single factor experiments and response surface analysis.Results:ethanol concentration was 60%,ratio of raw material to solvent was 1:7.5,temperature was 43℃.The predicted values was 83.11mg/g, the measured value of procyanidins yield from grape seeds was 79.62%. Ultrasonic extraction of procyanidins was optimized by single factor and orthogonal experiment. The optimized ultrasonic extraction was determined as follows:concentration of ethanol 60%,ratio of raw material to solvent was1:25,ultrasonic power 80,ultrasonic time35,and the(2)AB-8 macroporous resin was used in the sepaeration and purification of procyanidins from grape seeds.The best conditions for adsorption and desorption on the resin of procyanidins were researched.The optimal adsorption conditions were:the adsorption speed,1.2mg/mL,flow rate,2mL/min,pH,4,solution volume,80mL,and the best adsorption rate was 94.55%.The optimal desorption conditions were:solvent 60% ethanol,pH,6, the desorption speed, 1mL/min,ethanol solution,150mL,and the best desorption rate was 85.07%.The content of procyanidins after purification reached 98.5%.(3)Antimicrobial activity of procyanidins in grape seeds were tested against bacterium.Results showed that the procyanidins have selective antibacterial property.Compared with gram-positive bacterium, effect of gram-negative bacterium on procyanidins is not obvious.The procyanidins had the most powerful antibacterial activity in meta-acid and neutral environment.UV for a short period of time had little influence on the antimicrobial effects.The stability would decrese when the temperature rose to more than 60℃. Procyanidins effectively inhibited the growth of S.aureus, and the minimum inhibitory concentration (MIC) of procyanidins was 4.0mg/mL. After treated with procyanidins, the total content of cell soluble proteins significantly decreased, compared with the control. Relative electrical conductivity and the leakage of macromolecules with ultraviolet absorption increased. And the greater the concentration of procyanidins, the more apparent inhibiting effects. Scanning electron microscope photograph showed the bacterial surface was wrinkled and cell wall was destroyed. The results suggested that grape seed procyanidins cause the inhibition in the bacterial reproduction or kill the bacterial cells by affecting the permeability of cell and reducing the intracellular protein.(4)Through the tset of total bacterial number,sensory quality evaluation and physicochemical indexes in cold fresh chicken during storage,the refreshing effects of the procyanidins from grape were tested.Through the comprehensive assessment showed that cold fresh chicken coated with peocyanidins exhibited a obvious preservation effect.The changes in total bacterial number,degradation of protein and lipid peroxidation were effectively controlled and the shelf life were prolonged.