The molded one way or another has an adhesive surface marmalade, friable consistency and high humidity 29-30%. To give it a presentation, it is dried to 22-24% humidity. In the process of drying the article covered from above fine crystalline crust.
Marmalade amenable to drying is difficult, for two reasons:
In turn, the moisture diffusion rate depends on the moisture gradient, weight and temperature viscosity. The higher the moisture gradient, the more intensive drying process. Moisture travels from a central product layers to their surfaces.
With an increase in the viscosity of the mass, which depends on the content of the molasses, the quantity and quality of pectin, the moisture inside the movement speed slows marmalade, reducing the drying rate. That is why it is not recommended to enter the processing of apple sauce with a good ability to studneobrazuyuschey pectin syrup mixture of the prescription.
The rate of evaporation of moisture from marmalade will be affected by the formation of a crystal crust on the surface of the products. Therefore, in the initial drying period, it is necessary to create drying regimes that exclude the crystallization of sucrose, and crust formation should begin after most of the moisture diffuses through the surface layer of the products. Therefore, during the first 2-3 hours of drying, air is supplied to the chamber with a temperature of 60-62 ° C and an elevated relative humidity of 25-35%. In the subsequent drying period, the air temperature is increased to 65-68 ° C, and the relative humidity is reduced to 10-15%. Total drying time of the molded marmalade 7-8h.
The maximum permissible temperature of long-term drying of marmalade depends on the pH of the medium. At pH 3,3 - 3,5, marmalade can be dried at temperatures up to 65 ° С, and at pH of marmalade below 3,3 - only at temperatures not higher than 60 ° С. At higher temperatures, depolymerization of pectin molecules is possible, which is accompanied by the dilution of the jelly and its darkening. An additional inversion of sucrose occurs, which slows down the formation of a crystalline crust on the surface of marmalade and reduces the stability of products during storage.
Depending on the plant performance marmalade drying is carried out in tunnel kilns continuous, Mine or chamber dryers.
The tunnel dryer has 2-3 drying zones and one for cooling the marmalade. The sieves with molded marmalade are installed on 8 rack trolleys and transferred to the dryer. The dryer is assembled from separate sections. Each section has an independent heating and ventilation unit mounted on the upper floor.
The installation consists of two steam heaters and fan. Hot air enters the diffuser and guiding the uniform flow is fed into the chamber. Passing through the gaps between the sieves, hot air takes away moisture from the products and discharged through the opposite fan diffuser for reuse with partial addition thereto of fresh air. As we move along the trolley tunnel airflow direction is changed, which provides a more uniform drying of products.
Trolleys move along the tunnel on the railway track via 6 5 chain conveyor, make periodic motion.
After drying trolley with marmalade pass into the freezer, where the temperature air is supplied 20-30 ° C and a relative humidity of 65-70%. The duration of cooling marmalade 45-60 minutes.
If the drying chamber dryers are used, the cooling marmalade made in the workshop room for 4-8 hours depending on the ambient temperature.
Packing, packaging and storage of apple jelly
Dried apple marmalade tin standard quality contains 22-24% water, 20-28% of reducing substances and covered with fine crystalline crust.
Shaped marmalade manually placed in cardboard boxes weighing up to 100 500 g or box-trays, net weight up to 5 kg weighed for sale. To protect the marmalade from the outside air and moisture from the drying up of boxes and crates shrouded the top, bottom and sides waterproof paper. Each horizontal row of stacked and marmalade perestilayut waxed paper to prevent sticking. After marking boxes and crates, trays are packed in an outer packaging.
Formation marmalade, cut into articles weighing up to 20 g, dried up 18-20% humidity. After cooling, sprinkle it with sugar and packed in boxes or placed in boxes, trays.
Packaged fruit candy store in the room with 20 ° C air temperature and relative humidity 70-75%. Properly cooked marmalade under such conditions kept unchanged during 2-or more months. At temperatures below zero jellies can be stored indefinitely.
— the bulk of the moisture adsorption in the marmalade is related, but not free;
— marmalade drying can be carried out at low temperatures (60-65 ° C).