Juice extraction is an important procedure in juice production line. According to different product forms, there are several extraction methods, making great difference to juice quality and production benefits. AGICO provide complete sets of juice production lines for various kinds of fruits, which adopt advanced technology and high quality material to achieve the best extraction effect. Here I’d like to introduce 5 major juice extraction method.
Juice is squeezed from fruits and vegetables by outside mechanical force. As a widely applied extracting method, juice pressing apply to fruits with high water content. Based on different temperature of raw materials, there are cold press, hot press and freeze press. Based on whether pomace needs to be pressed again, there are primary press and secondary press.
Hot press requires crushing fruits into pulps and heat them in advance. Given fruits’ biochemical property and processing technology, the biochemical reaction of raw materials is slow. But after crush, the enzyme escaping from plant cells speeds up the oxidation reaction dramatically. At the same time, external heating promotes the pressing efficiency.
Extraction is the process of transferring juice in fruits and vegetables to hot water. It applies to fruits with less water content, such as wild jujube, dark plum, red dates. With more pectin content, these fruits are hard to extract juice by squeeze.
Extraction can be classified into static extraction, counter flow extraction, one-off extraction, multiple extraction. Juice yield is influenced by extraction temperature, time, degree of crush, concentration difference and flow velocity.
Pulping is the process in which we isolate the kernel, seed and peel of fruits and vegetables so as to obtain their puree. Through strainer of different apertures, we can get puree of different fineness. Pulping applies to production of fruit purees and fruit squash, like strawberry, mango, peach and hawthorn juice.
Before pulping, we need to precook the crushed raw materials in order to inhibit the enzyme activity. Usually we adopt beaters with 3 channels, whose mesh sizes are, in order, 1.2, 0.8 and 0.5mm. Fine fruit flesh processed by pulping are more suitable for homogenization. As for single channel beater, the mesh size should not be too small, or it would easily be blocked.
Through horizontal spiral filter centrifuge, fruit juice and pulps are separated by centrifugal force. Slurries are transmitted to rotary drum filter through feed tube. Under high speed centrifugal force, the pomace is thrown to the drum wall and transmitted to the end of drum by conveying screws, while fruit juice drains out of screw gaps.
Rough filtration aims to eliminate large particles and suspended solids in fruit juice. Most extracting methods produce fruit juice containing a multitude of suspended solids like pulp fibers, peals and kernels. They affect juice quality and taste. Rough filtration can be conducted separately or during extraction process. It requires fruit juice to go through mesh aperture of 0.5mm. After rough filtration, we have to clarify and filter the juice. For cloudy juice and fruit nectars, homogenization and degassing are necessary.