Study On Critical Technology Of Low-Sugar Preserved Crisp Mei Processing

Based on the traditional technics of low-sugar crisp mei, a series of technologies auch as preservation and desulphurization of intermediate product, vacuum sugar infiltration, and hurdle technology were sudied, and new technics were established. New technics can improve product quality much better than the traditional technics.Adding 1.5% sodium pyrosulfiteand and 2.0% calcium chloride into steeping solution can prolong preservation period of intermediate products to 12 months, and the intermediate product can keep natural light yellow and good texture.The desulphurization was studied using the mei that added 1.5% sodium pyrosulfiteand as experimental material. The mei was steeped in water, combined firstly vacuum dynamic treatment at 0.092 MPa, 55 ℃ for 2.5 h, and then ultrasonic treatment at 80 KHz, 160 W, 55 ℃ for 2.5 h. in the end steeped in water for 3 d again. After desulphurization, SO₂ content of mei decreased to 0.05 g/kg, according to the China GB criterion. This new technics shorten treatment time half and keep better texture and color in coMParison to traditional technics.Research of sugar infiltration found that effect of concentration of sugar sulution and vacuum on the infliltration were significant (P<0.01 and P<0.05, respectively), but the effect of evacuation time was not significant. The optimum conditions were: 45% of sugar solution, vacuum of 0.09 MPa, and evacuation time of 0.5 h. After above treatment the mei was soaked for 24 h at atmosphere, the Sugar content of mei reach 18%, according to product criterion. This new technics shorten treatment time 9 days in coMParison to traditional technics.Taking the concentration of chlorine dioxide, immersing time, potassium sorbate and treatment time of 650 W microwaves as hurdle factors, their effects on the colonies of bacteria, mycete and yeast of crisp mei were studied. Results showd that the four hurdle factors all affected it significantly (P<0.01). The effect of combination of three hurdles was better than the respective application. Mei intermediate product steeped in 0.04 g/kg chlorine dioxide solution for 10 min after desulphurization, and steeped in sugar solution with 0.65 g/kg potassium sorbate, using microwave treatment at 650 W for 75 seconds after packaging.The accelerated test of at 37℃ and 28℃ suggested that hurdle technology can prolong shelf-life to 6 months.