Effect Of Ultra-high Pressure And Heat Treatment On Sterilization And Quality Of Seabuckthorn Pulp

Hippophae rhamnoides berry is rich in nutrients and active ingredients,however,most of the chemicals are sensitive to heat,which significantly causes the loss of sensory and active components.In this paper,the seabuckthorn pulp was treated with ultra-high pressure(UHP)sterilization.The sterilization techniques was firstly optimized on the pulp.Based on the requirements of commercial sterilization,we studied the changes of the microbial growth,quality,fatty acids,amino acids,sensory,antioxidant activity and volatile compounds of the pulp treated with UHP during storage at room temperature of 25~oC and low temperature of 4 ~oC.The samples treated with UHP and those treated with conventional heating treatment were also compared during low temperature storage.The results showed that:1.UHP treatment effectively killed microorganisms in seabuckthorn pulp.The sterilizing effect showed a positive correlation with pressure and time.The optimum conditions of UHP sterilization by response surface method were as:the pressure at500MPa,pressure holding time for 20min and the initial temperature of the sample at 30 ~oC.2.UHP effectively restrained the growth and reproduction of Penicillium expansum,Staphylococcus auras and Saccharomyces cerevisiae in the pulp during low temperature storage.UHP treatment showed an better inhibition of microbes than the heat treatment.3.Compared with the heat treatment(HT),UHP had no significant effects on total soluble solids and titratable acid contents,pH,fatty acids and amino acids contents.The pulp treated with UHP had better quality during storage at 4 ~oC than that at 25 ~oC.The texture,color,clarification and sensory of the treated pulp decreased during storage at 4 ~oC,however,the pulp treated with UHP had a slow decreasion.4.During storage at 4 ~oC,the contents of total volatile components and alcohols and esters in UHP-treated pulp were significantly higher than those of heat-treated,and the contents of aldehydes and acids were significantly lower than that of the HT.With the extension of storage,the difference of the content of the volatile substance between UHP-treated and heat-treated pulp gradually closed,however,UHP-treated pulp had more volatile compounds.5.The pulp treated with UHP had a higher level of total phenols,total flavonoids,total carotenoids,Vc and antioxidants during storage at 4 ~oC.DPPH·and ABTS·scavenging ability of the pulp treated with UHP and heat decreased during low temperature storage,however,UHP treated one had a slow decreasion.Meanwhile,the pulp treated with UHP had a higher antioxidant ability at low temperature storage than that at room temperature.In conclusion,UHP treatment effectively kills microorganisms in the seabuckthorn pulp,and the sterilizing effect showed a positive correlation with pressure and time.Compared with HT,the pulp treated with UHP had lower the microorganism growth and better of quality,sensory and antioxidant ability during cool storage.