The Research Of Without Water Cleaning Technique For Thompson Seedless Raisins

Xinjiang characteristic agricultural products green raisins made by drying in the room,and its hygiene and safety quality are bad since it can't be rinsed,hence it can't enter the high-end market and foreign market and always found in the low-end market.Based on Thompson seedless raisins as raw material,ethanol-ultrasonic cleaning and high density CO₂were used respectively to clean,and compared with ultrasonic rinsing.Plus,the cleaning effect,sterilizing effect,drying agent effect and short-term storage quality after cleaning were studied,the results are as follows:(1)Under different conditions,green raisins were rinsed through ethanol-ultrasonic,cleanliness index was no obvious enlarged at the second time;The sterilization effect of ultrasonic frequency on raisins was significant,and the effects of cleaning,sterilization and drying of raisins were the best on the condition of 40 k Hz,while the soluble sugar content was the lowest in the cleaning medium.With the increase of ultrasonic time,the cleanliness,sterilization effect of raisins and the removal efficiency of the drying agent increased,but the soluble sugar dissolved rapidly.Concentration of ethanol was inversely proportional to the cleaning effect;Temperature and liquid material ratio of cleaning medium had no obvious effect on cleanliness and sterilization of raisins,but the soluble sugar content and cleanliness of drying agent had significant effects,with temperature more than 30?,and liquid-material ratio greater than 2 m L/g,soluble sugar dissolution increased rapidly,promoting the cleanliness of drying agent enlarged.(2)The best condition of ethanol-ultrasonic cleaning are:Room temperature,85%(V/V)ethanol solution,liquid material ratio 1.5 m L/g,ultrasonic frequency 40 k Hz,cleaning twice,ultrasonic time 1min/times,compared with ultrasonic raisins washing.Ethanol-ultrasonic cleaning and ultrasonic rinsing both have good cleaning effect.The cleanliness index were 0.93 and 0.98 respectively.The total ash and acid insoluble ash of ethanol-ultrasonic cleaning were 13.230 mg/100g and 6.665 mg/100g,all below than of ultrasonic rinsing.However,the soluble sugar content was 139.335 mg/100g,which was much less than the ultrasonic rinsing 744.966 mg/100g.Under such condition,bacterial count and mould number of surface of rinsed raisin rinsed by ethanol-ultrasonic were 93.86%and 93.41%respectively.Ultrasonic rinse worked good on the cleaning effect of dry agent.The content of anionic surfactant was 0.100mg/100g,and the content of ethanol-ultrasonic cleaning was 0.060 mg/100g.Ethanol-ultrasonic cleaning had the same effect as that of ultrasonic rinse,and there was less intrinsic loss and higher sterilization rate of the raisins,but the removal efficiency of the drying agent was not good as that of ultrasonic rinse.(3)Under different conditions,handling stress and handling temperature had big effect on sterilization effect when high density CO₂rinsing raisins.Above 28 Mpa and 30?respectively the sterilization effect was good.Drying agent removal between 20?to 30?removal effect was good,processing time had no obvious influence on sterilization effect and cleaning result.The best condition of high density CO₂were:28 Mpa,30?,5 min.Under such condition,sterilization rates of bacterial count and mould number were respectively:95.12%and 95.42%,which were slightly higher than that of ultrasonic rinse,with the cleanliness of drying agent reached 21.47%.(4)Unwashed,ethanol-ultrasonic rinsed,high density CO₂rinsed and ultrasonic rinsed green raisins were stored up for 29 days.L^*value of green raisins decreased during storage,a^*value,b^*value and?E value were increased,L^*value of high density CO₂rinsed raisins was the highest,while by ultrasonic rinse was the lowest.The Browning index increased with the increase of the storage time,and the Browning index of the ultrasonic rinsed raisins was significantly higher than other treatments.During storage,the quality change of green raisins with high density CO₂rinsed was the most slowly,while with ultrasonic rinse was the fastest.Angle of repose was not changed over the storage time,but extended with the storage time,angle of repose had no obvious change,angle of repose of ultrasonic rinse was as much as 40.491�.Angle of repose of raisins with two kinds of waterless cleaning method had no differences with unwashed green raisins.