Study On Low Temperature Plasma Sterilization And Fresh-keeping Technology Of Fresh-cut Pitaya

The pitaya is one kind of cactus plant,which is a tropical fruit distributed from Central America to the northern part of South America.It is also planted in China and mainly distributed in the south.Because of its delicious and nutritious,pitaya has become one of the favorite fruits for consumers.With the development of the times,people have more convenient consumption,minimalist consumption demand,nonfresh-cut whole fruit because of its peeling,slicing and other tedious steps have been unable to meet the fast-era consumer population,so the demand for fresh-cut pitaya is increasing.However,there is no applicable method to keep the fresh-cut pitaya so far.In this study,the plasma-activated water was used to keep the fresh-cut pitaya fresh to improve its storage capacity and shelf life.The research contents and results are as follows:Through the study of the stability of active particles in plasma-activated water,it was considered that active nitrogen species(such as nitric oxide free radicals and nitrite)were played the main germicidal efficacy,while reactive oxygen species take the second place,and the decreased p H value is also one of the reasons for bactericidal efficacy.The effects of plasma-activated water own microorganisms were analyzed,including the germicidal efficacy of plasma active water,the total colony growth of fresh-cut pitaya during storage and the shelf life of fresh-cut pitaya.Through the singlefactor experiments of three influencing factors: plasma power of plasma-activated water,water-making time of plasma-activated water and soaking time of fresh-cut pitaya,taking the germicidal efficiency as the evaluation index,the optimal technology of fresh-cut pitaya was obtained.The results showed that the plasma-actived water of PAW-60 W group had better germicidal efficacy,and the optimum sterilization and fresh-keeping technology of PAW was as follows: plasma power of plasma-activated water was 60 W,water-making time of plasma-activated water was 60 s,soaking time of fresh-cut pitaya was 60 s.The K value of fresh-cut pitaya was 1.21,and the shelf life of fresh-cut pitaya was 9.35 h at 4℃ after sterilization with plasma-activated water.Compared with the fresh-cut pitaya without plasma-activated water sterilization treatment(shelf life=5.51 h),its shelf life can be prolonged by 3.84 h.The sensory quality of fresh-cut pitaya were analyzed by hardness tester and other machines.It is considered that plasma-activated water does not affect the flavor of fresh-cut pitaya,but improves the sensory score of fresh-cut pitaya to a certain extent,for the quality of fresh-cut pitaya,plasma-activated water can reduce the weight loss rate of fresh-cut pitaya,delay the softening of fresh-cut pitaya,and improve the marketability of fresh-cut pitaya.The enzyme activities of POD,PPO and CAT in fresh-cut pitaya were analyzed by enzyme labeling instrument and respiratory rate meter.The results showed that PAW could increase the activities of POD and PPO,delay the peak activity of POD and PPO,maintain the expression activity of PPO in a stable state during storage,and keep it in a stable state for CAT,reduce the permeability of cell membrane of fresh-cut pitaya,enhance its resistance to foreign microorganisms,and make the respiration rate more stable.