Lemon slices are rich in vitamins, whiten and beautify the face, refresh the mind, prevent osteoporosis, and can also be added to food to enhance the taste. Today, I will introduce to you the steps of processing lemon slices in a fruit and vegetable freeze dryer:
1) Selection of raw materials
Select C-grade lemon fruit with an inner cut surface diameter of 50-60mm;
2) Cleaning
The selected lemons were placed in a concentration of 5% by weight, and the temperature was ultrasonically treated for 25 minutes under the condition of 10 ° C, and the ultrasonic frequency was 35KHz; then the cleaned lemons were placed in tea water, and ultrasonication was carried out under nitrogen atmosphere.
Treated for 30 minutes, the tea water is Xinyang Maojian tea, and the tea water is prepared from tea leaves and water in a weight ratio of 1:100 according to the conventional preparation process of tea water; wherein, the ultrasonic frequency during the ultrasonic treatment of the cleaning step is 30KHz;
3) One freeze drying
The cleaned fruits were placed in the freezer under sealed conditions and freeze-dried at -15°C for 8 hours; then the frozen fruits were transferred from the freezer to the working chamber of Shanghai Tuofen vacuum freeze-drying machine, at a temperature of 1°C/min. The temperature was raised to 55°C and kept for 6 hours, and the vacuum degree was 5Pa;
4) Slicing
Cut the freeze-dried fruit into slices with a thickness of 5mm; the temperature when slicing is -5°C;
5) Soak
The sliced fruit pieces were placed in a chitosan-vitamin complex solution for 3 minutes at 5°C, and the chitosan-vitamin complex solution was composed of chitosan, vitamin C and ethanol in a weight ratio of 1. : a mixed solution of 6:93, the ethanol is an ethanol solution with a volume concentration of 95%,
6) Secondary freeze drying
Put the soaked lemon slices in the freezer and freeze-dry at -20°C for 5 hours under sealed conditions; then transfer the frozen lemon slices from the freezer to the working chamber of the vacuum freeze dryer at a speed of 3°C/min.
After the temperature was raised to 45 °C, the temperature was kept for 8 hours, and the vacuum degree was 4Pa;
7) Packaging
Under aseptic conditions, the lemon freeze-dried tablets are packaged by nitrogen filling and food packaging film, and 2-3 freeze-dried tablets are used for packaging and sealing.