JPH0338827B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for treating citrus juice residue, which is produced as a by-product when extracting fruit juice from citrus fruits. [Conventional technology] Methods of squeezing citrus fruits to obtain fruit juice include squeezing the juice using an in-line juicer manufactured by FMC in the United States, and peeling the skin using a peeler and then squeezing the juice using a pulper finisher. There are various methods, but no matter which method is used, the juice extraction rate is only about 25 to 60%, and about 40 to 75% of the juice lees is produced as a by-product.
Since this squeezed lees still contains a large amount of water, it is treated with a dryer to evaporate the water and make peel. Generally, industrially, the juice lees is dried using a dryer such as a rotary dryer using a direct flame burner using heavy oil. In this drying process, in order to save thermal energy from heavy oil, it is desirable to lower the moisture content of the cake in advance and to make it easy for the moisture contained therein to be removed. In other words, in citrus fruits, the pericarp and sac make up a large proportion of the fruit, and they contain a colloid substance called pectin, so the juice lees in particular has a sticky texture, and even when it is squeezed, it loses moisture. Difficult to separate. Therefore, if it is dried in this state, it is not preferable because heat does not pass through it well, making it difficult to remove water and consuming excessive thermal energy. As a countermeasure to this problem, there is a so-called liming method in which slaked lime or slaked lime in the form of lime milk is added and then pressed. That is, 0.3 to 0.6% by weight of slaked lime is added to the squeezed lees in advance and mixed.
After reacting at room temperature for ~20 minutes, the lees is squeezed. During that time, the hydrophilic pectin in the squeezed lees reacts with slaked lime and changes to hydrophobic pectin, resulting in the so-called syneresis phenomenon, and water is removed from the lees. As a result, the soluble components contained in the squeezed lees, that is, the fruit juice mixed with sugar, minerals, amino acids, vitamins, etc., become easier to separate. The fruit juice separated here is called peel water, and is a secondary fruit juice whose acid components have been neutralized with slaked lime.
It has a Brix of 10 to 14 and is a useful resource that can be used as a raw material for fermentation or as a stock solution for molasses syrup. [Problems to be solved by the invention] In the process of liming the juice lees that is produced as a by-product when extracting fruit juice from citrus fruits, and further squeezing the juice, it is possible to increase the yield of peel water and reduce the moisture content of the lees. Reducing the amount has a large effect on saving heat energy for drying when drying the lees to make peels, and has an important industrial meaning. That is, it is desired to improve the dewatering efficiency of the lees, which leads to a reduction in the water content of the lees and an increase in the yield of peel water. [Means for Solving the Problems] The present inventors have conducted various studies with the aim of further improving the liming effect, reducing the moisture content of the lees, and increasing the yield of peel water. The present inventors investigated in more detail the actual state of the liming method commonly used in citrus juice factories, and found that an extremely simple method of heat treatment at 50 to 100°C during liming was found. Therefore, the yield of peel water is 1.2 to 1.5 compared to the conventional method.
In addition, the moisture in the pressed lees can be reduced to about 69% compared to the conventional method, where the squeezed lees has about 83% moisture and is squeezed after liming to reduce the moisture to about 75%. I learned that I can do it. The present invention is based on this knowledge, and the present invention is characterized in that in the process of adding and mixing slaked lime to the squeezed citrus juice lees and then compressing and dehydrating it, the citrus fruit juice is heated to 50 to 100°C after adding and mixing the slaked lime. This is a method for processing juice lees. Citrus fruits to which the present invention is applied include, in addition to summer mandarin oranges and unshiyu mandarin oranges, for example, lemons, Valencia oranges, navel oranges, hassaku, Iyokan, yuzu, sudachi, and kabosu. Can be used to process juice lees. In addition, among the citrus fruits that are targeted for processing, fruits that are exceptionally small, have period drop that occurs in the early stage of ripening, or have been thinned are unsuitable for extracting juice, but whole fruits are crushed and then It is sometimes limed and separated into lees and peel water or molasses and processed into products. It goes without saying that the present invention can be utilized in this case as well. In the present invention, citrus juice can be squeezed according to a conventional method. Slaked lime is added to and mixed with this squeezed lees. This addition and mixing can be carried out by any means, and slaked lime in the form of milk of lime can also be used.
The amount of slaked lime added is preferably about 0.3 to 0.6% by weight. Next, in the present invention, any suitable heating means can be used for heating the squeezed lees after adding and mixing slaked lime.
It would be good if it could be increased. Regarding the heating temperature, no effect can be expected at temperatures below 50°C, and temperatures above 100°C essentially require special equipment for heating, which is not only uneconomical but also particularly difficult to achieve even at high temperatures. does not show any special effects. The temperature is preferably 60 to 90°C, depending on the actual operation and equipment. Regarding the heating time, if the temperature is high, a short time is sufficient; therefore, about 30 seconds to 10 minutes is sufficient. Generally, in industrial equipment, a thermal crushing device using a cylindrical stirring shaft with a double jacket using steam is considered, but in order to further enhance the heating effect and improve efficiency, a closed cylindrical screw conveyor with a rotating shaft is used. It is desirable to quickly raise the temperature of the entire lees to a predetermined temperature while mixing the lees and slaked lime while injecting live steam from several locations, and then heat the lees for an appropriate amount of time. The juice lees heat-treated as described above is squeezed using a conventional method, for example, using a screw press.
Obtain peel water and press cake. [Example] Next, the present invention will be explained in more detail with reference to Examples. Example 1 3 kg of slaked lime, which meets food additive standards, was added to 1000 kg of juice lees (moisture content 83.15%) obtained by subjecting Unshiyu mandarin oranges to an in-line juice extraction machine. Using a Yuu conveyor, the temperature reached 80℃ in 2 minutes, and steam was blown in to heat it at 80℃ for 5 minutes, followed by charging and squeezing at a flow rate of 2700 kg/hour using a Shoda Press screw press. A press cake and peel water were obtained. On the other hand, as a control, 1000 kg of the same pressed lees as above was operated in exactly the same manner as above (corresponding to the conventional method) except that no steam was blown in to obtain a press cake and peel water. The results are shown in Table 1 below.

[Table] As clearly shown in Table 1, when the heat treatment according to the present invention is performed, the water content of the press cake decreases, the extraction rate of the peel water increases, and at the same time, the soluble solid content in the peel water also increases. It can be seen that the dehydration efficiency of the squeezed lees has further improved. Example 2 6 kg of slaked lime, which meets food additive standards, was added to 1000 kg of squeezed lees (moisture 81.02%) obtained by subjecting summer mandarin oranges to an in-line juice extraction machine. , in 3 minutes
When the temperature reached 70℃, steam was blown in to heat it at 70℃ for 5 minutes, and then it was charged and squeezed using a screw press manufactured by Shoda Press at a flow rate of 2700 kg/hour to obtain a press cake and peel water. . On the other hand, as a control, 1000 kg of the same squeezed lees as above was operated in exactly the same manner as above except that no steam was blown in to obtain a press cake and peeled water. The results are shown in Table 2.

【table】

〔Effect of the invention〕

In the industry of extracting fruit juice from citrus fruits, the problem is how to dispose of the juice residue, and saving heat energy for drying it into peels has become an economically important factor. According to the present invention, by applying a simple method of heating in the liming process, the dehydration efficiency of the squeezed lees is increased, the water content of the lees is reduced, and the yield of peel water is increased, which is extremely economical. You can get valuable results.

Claims (1)

[Claims] 1. A method for treating citrus juice lees, which comprises heating the citrus juice lees to 50 to 100°C after adding and mixing slaked lime in the step of compressing and dehydrating the citrus juice lees.