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https://doi.org/10.29013/AJT-20-5.6-37-43
Ziyaeva Sitora F., postgraduate student, Department of Chemistry Samarkand State University E-mail: [email protected] Vasina Svetlana M., Ph.D., Associate Professor, Department of Chemistry,
Samarkand State University E-mail: [email protected]
PHYSICO-CHEMICAL FUNDAMENTALS TECHNOLOGY PRODUCTIONOF MULBERRY JUICE CONCENTRATE
Abstract: The chemical composition of white and black mulberries has been determined. A comparative analysis of different mulberry varieties shows that the white mulberry fruits are characterized by a higher content of pectin substances and organic acids than black varieties. It has been proposed to use the hot fermentation method to break down pectin substances. Based on the studies, the amount of enzyme necessary for the breakdown of pectin substances has been proposed. The enzymatic activity of amylase and pectinase in the wastes of apple juice after ultrafiltration. Was studied it was found the in the waste a significant amount of enzymes remains that retain their activity, which made it possible to assume their repeated use after regeneration.
Keywords: berry, white and black mulberry, pectin substances, hot fermentation, amylase, pectinase, regeneration.
Introduction mulberries common in Uzbekistan, as well as the
One of the most important areas in meeting the waste of mulberry juice after fermentation. The sub-demand of the population for high-quality food ject of the research is amylase (Amylase AG 300 L) products is the search and use oflittle-used and non- and pectinase (Pectinex Ultra AFP Pectinase) con-traditional types of local plant raw materials. From tained in the waste fruit juices after ultrafiltration. this point of view, mulberry culture, widespread in Analysis and processing of the research results Uzbekistan and practically not used in food produc- was carried out by the methods of physicochemical tion, can serve as a promising raw material for the analysis.
production ofvarious products. The purpose of this The applied method for determining the mass work is to study the physicochemical fundamentals concentration of carotene is based on photometric of the mulberry juice production technology [9]. measurements after extraction from products with Mulberry is sweet or sweet-sour juicy fruit with organic solvents and using column chromatography a delicate aroma. It is used mainly in raw form. In or- to purify the associated coloring matter. The mass der to use mulberry fruits for food production, their fraction of soluble solids was determined using a re-chemical composition was investigated. fractometer. The quantitative content of vitamin C
Objects and research methods was calculated by the results of the potentiometric
The objects of the research were the fruits of titration after extraction with a solution of hydro-white (morus albalinn) and black (morus nugralinn) chloric acid. The content of vitamins B1 and B2 was
determined by the method of acid-enzymatic hydrolysis using columns with cation exchangers and by the measurement of fluorescence intensity using a fluorometer. The fixation of organic acids in the studied samples was carried out by High Performance Liquid Chromatography.
When conducting the researches on the content of pectin substances, the conventional methods of analysis were used: the mass fraction of pectin substances was determined by the calcium-pectate method, the content of free and methoxylated car-boxyl groups by the titrimetric method; total number of carboxyl groups and degree of esterification -by calculation method [1].
The results of the pectolytic activity of enzymes were obtained on the basis of the method for determining the products of pectin hydrolysis, which is not precipitated by zinc sulfate under the action of enzymes of the pectolytic complex under standard conditions. To evaluate the activity of amylase the Volgemuta method was used [3].
Experimental part
The fruits of white (morus albalinn) and black (morus nugralinn) mulberries were taken for the investigation. The content of water, carbohydrates, organic acids, minerals and vitamins were taken as the main indicators. The obtained results are presented in (table 1).
Table 1. - The chemical composition of mulberry fruits,% in wet weight
Indicator Mulberry varieties
white Black
Carbohydrates: 10.54 8.57
Pectic substances 1.7 1.3
Organic acids 1.1 0.8
Minerals 0.45 0.38
Vitamins. mg %
Vitamins. mg %: Carotenes 0.02 0.04
B1 0.04 0.05
B2 0.02 0.04
As the studies have shown that the main components of the dry substances of all of mulberry vary in the range of8.57-10.54%. The content ofpectic substances in all samples studied is about 1%. The fruits contain a sufficient amount of minerals, vitamins.
A comparative analysis of different varieties of mulberry shows that the white fruits of mulberry are characterized by a higher content of pectic substances and organic acids compared with black
fruits. The black fruits are superior to the whites on the content of vitamins. Soluble pectin is a poly-saccharide consisting of interconnected residues of galacturonic acid, which is presented in it in the form of methyl ether.
Under the influence of soluble pectin with the diluted alkaline enzyme pectase, methoxyl groups can be easily split off- methyl alcohol and free pectic acid, which is a polygalacturonic acid, are formed.
Table 2. - Physico - chemical indicators of pectic substances of mulberry fruits,% of dry matter
Indicator Mulberry Variety
White Black
Galacturonic acid content 70.3 69.8
Degree of methoxylation 64.8 63.9
Molecular mass 22000 16000
To determine the possibility of using mulberry fruits, their pectic substances were investigated. The obtained data are presented in (table 2).
The analyses showed that the pectic substances of mulberry fruits are characterized by low molecular weight, with a not very high degree of methoxylation and with a sufficiently high degree of purity (the content of galacturonic acid is 70.3-69.8%).
The results of chemical analysis of mulberry fruits allow us to conclude that it can be used in the production of juices.
Enzymes are used to produce high-quality and persistent juice concentrates[3-5]. As enzymes,
it is possible to use amylase and pectinase brands Amylase AG 300 LK.F. and Pectinex Ultra AFP contains KF.
It is known [6] that the protein of nature provides enzymes with the ability of proteins to change activity depending on various factors. The degree of activity change from various factors can be determined from the rate of the enzymatic reaction. We studied the effect of temperature and pH on the rate of enzymatic reactions of the enzymes used. When studying the influence of any factor on the rate of the enzymatic reaction, all other factors remained unchanged and had optimal values.
Table 3. - The effect of temperature on the amylase activity of K.F.
Incubation temperature, °C Coloring with Iodine Name of the products detected on the basis of color
0 blue No decomposition detected
22-30 Orange Incomplete decomposition
45-50 yellow Complete decomposition
85 blue Enzyme inactivation
To determine the effect of temperature on the To determine the effect of temperature on pec-activity of amylase, a known method was used [7]. tinase activity, ethanol test for pectin was used [8]. The obtained results are presented in (Table 3). Table 4 presents the experimental data on the effect
of temperature on pectinase activity.
Table 4 - The effect of temperature on the activity of pectinase K.F.
Temperature incubation, °C Detection index Name of products detected on the basis of color
0 gelformation No decomposition detected
22-30 Heavy precipitation Incomplete decomposition
45-50 Homogeneous system Complete decomposition
85 gelation Enzyme inactivation
Based on the obtained data, it was found that the optimum temperature value at which the reaction proceeds at maximum speed is above 50 °C. Increasing above the optimum temperature leads to a decrease and then stopping of the enzyme action, which is associated with denaturation. During the transition from optimal to low temperatures, the rate of the enzymatic reaction drops and stops at 00C. The reason is a decrease in the speed of movement of
the molecules of the substrates and enzymes, which slows down the formation of the enzyme-substrate complex and the reaction. As the temperature rises from negative values, the effect of the enzymes is restored, and the rate of the catalyzed reactions increases.
The effect of pH on the activity of enzymes was studied. The obtained results are presented in (tables 5 and 6).
Table 5. - The effect of pH on amylase activity
Indicators Test tube numbers
1 2 3 4 5
pH 2.87 4.10 5.33 6.59 7.96
Coloring with iodine brown orange yellow orange brown
It is established that the most optimal is the pH value of 5.33, at which the reaction proceeds at maximum rate.
Table 6. - The effect of pH on pectinase activity KF
Indicators Test tube numbers
1 2 3 4 5
pH 2.87 4.10 5.33 6.59 7.96
detection Gelation Large precipitation Homogenous system Flake-like precipitation Gel plug
Taking into account that the properties of pectin have studied the effect of the quantitative content of to form jelly adversely affect the yield of the juice, we the enzyme on the yield of the juice.
Table 7. - The effect of enzyme concentration on the physico - chemical
indicators of mulberry
Indicator The content of the enzyme% wet weight
0.005 0.01 0.03 0.05
Content of pectic substances.% 1.04 1.1 1.30 1.30
Decomposition degree.% 800 86 100.0 100
-f-1—
0,01 0,02 0,03
Figure 1. The dependence of the yield of black mulberry juice on the amount of enzyme injected and temperature
It is known from the literature data that for carry- depending on the amount of pectin substances. The ing out the fermentation process, the amount of en- effect of the quantitative content of the enzyme on zyme injected varies in the range from 0.01 to 0.05%, the processing process of black mulberry at room
temperature was studied. Pectinase was used as a pectolytic enzyme.
On the basis of the obtained data, it was established that an increase in the amount of the enzyme does not affect the juice yield, it is only the temperature that affects. In this connection, it is recommended to use the method of hot fermen-
tation for the decomposition of pectic substances. For this method, it is necessary to heat up to the temperature of 50 °C and treat the enzyme at the same temperature for 30 minutes. Then the juice should be separated by pressing. The effect of pressure and speed of pressing on the juice output was investigated.
Figure 2. The dependence of the juice yield on the pressure and speed of pressing
The obtained results showed that the pressing process should be carried out slowly, which leads to a better result. Pressing should be carried out at a pressure of 6 bar and a speed of 2.7 m/min for 3 minutes. A further increase in the duration of pressing does not affect the juice yield. The influence of the pressing speed becomes more noticeable in the area of the maximum values of the juice yield. And the result of pressing does not depend on pressure.
The juice obtained after pressing was cooled and clarified in order to remove fine suspensions and colloidal substances to obtain a transparent product. For that, gelatin from 0.005 to 0.02% was added in the form of a 1% solution to the juice, mixed thoroughly and aged for 2 hours. The optimum temperature for processing the juice is 20 °C. When this occurs, additional decomposition of the remaining pectin substances due to the neutralization of negatively charged particles of pectic substances by positively
charged particles of gelatin. Then the juice was filtered through a filter. After filtration, the juice was clear. The resulting semi-manufactured juice is sent to further technological operations.
Based on the research conducted, a technology for producing semi -manufactured juice of black mulberry was proposed.
The physicochemical parameters obtained using the proposed mulberry juice technology were determined on state standard methods.
Table 8. - Organoleptic characteristics of semi-manufactured mulberry juice
Name of indicators Characteristics of clarified juice Characteristics of aromatic substances
Appearance Liquid, syrupy like with dark burgundy shade Clear liquid
Taste and smell Well pronounced, peculiar to the fruits of which the juice is made, without foreign smell and taste Well pronounced, peculiar to the fruits of which the juice is made, without foreign smell and taste
Water solubility Full, without repeated sedimentation Full, without repeated sedimentation
In the production of the juice after ultrafiltration, a waste is formed, which is a mixture of carbon adsorbent of enzymes and residues of the juice. We have extracted the sorbent, which is formed as a result of ultrafiltration, from the production line and studied the enzymatic activity of pectinase, adsorbed in it.
Pectolytic activity in the juice waste was determined using the interferometric method. For per unit of pectolytic activity was taken the amount of enzyme that catalyzes the hydrolysis of 1 gram of pectin to products, which is not precipitated by zinc sulfate when carrying out hydrolysis under strictly defined conditions: the temperature 50 °C, the hydrolysis time 1 hour, the pH value of the reaction medium 4. The pectolytie activity was expressed by number unit in 1 gram of the preparation tested (table 9).
Table 9. - The activity of pectinase KF in the waste after ultrafiltration
№ of test- Pectinase activity
tubes PKC, u/g %
1 77. 5 98. 7
2 77. 3 98. 5
3 77. 6 98. 9
Thus, it was established that after the ultrafiltration process, the fermentative activity of the enzyme
in the waste of juice production is preserved, which allows to propose using it again after regeneration. The method of regeneration of the enzyme used has been developed. The application of the developed technology allows to increase the efficiency of juice production by precipitate ting and regenerating enzymes from sorbents.
Conclusions
A comparative analysis of different varieties of mulberry shows that white mulberries are characterized by a higher content of pectic substances and organic acids compared to black varieties. Based on the obtained data, the application of the method of hot fermentation for decomposition of pectic substances has been suggested. It is established, that the process of pressing should be carried out at pressure of 6 bar and at a speed of 2.7 cm/min. It is shown that the enzymatic activity of pectinase after filtration in the waste of juice production is preserved and it is possible to reuse it after regeneration.
On the basis of the conducted research, a technological scheme for producing black mulberry semimanufactured juice is proposed. The main technical indicators of the semi-finished juice produced by the proposed technology have been identified.
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