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Naturalness of Citrous Juice


The Determination of Physico-Chemical Indices Defining the Naturalness of Citrous (Tangerine, Orange, Lemon, Grapefruit) Juices and the Development of Methods for their Determination

Tech Area / Field

  • CHE-OTH/Other/Chemistry

3 Approved without Funding

Registration date

Leading Institute
Shota Rustaveli State University, Georgia, Batumi


  • Universite du Quebec a Chicoutimi, Canada, QC, Chicoutimi

Project summary

The quality of citric juice still remains one of the urgent matters, as this production doesn’t completely meet the requirements raised by consumers.

The natural index is of great importance while evaluating the quality of citric juices. Breaking the natural quality of juice is very often considered as adulteration. The aim of adulteration one hand is the substitution of expensive raw materials for much cheaper ones, which is possible by adding outside juice into the given citric juice or by substituting fruit for the expressions of juice production. As a result, the technology of citric juice production breaks and causes the theft of state property and is considered as a criminal offence.

Adulteration reaches a large scale particularly during the production of juice concentrates when there is a chance of full substitution of fruits for expressions.

On the other hand adulteration of citric juices can be done by putting substances harmful for human organism. For example, the adding of tartaric acid or synthetic lemon acid, different dyes, emulsifying agents, synthetic amino acids and etc. causes the production of ecologically bad quality product. The reason of said above is the lack of objective methods for controlling citric juices properly.

It is necessary to mention that the work of foreign investigators devoted to the problem of citric juices adulteration is generally specific only for inpidual regions such as the USA, Japan, Israel etc. The proposed methods of different authors are so various that in total they are not accessible practically without appropriate long term investigations on the own experimental material.

This project allows:

  • to reveal physical and chemical indices which define natural quality of citric juices;
  • to develop methods for their definition; to improve quality control for producing products.

The aim of this project is to define scientifically substantiated criterion for determining the natural quality of above mentioned juices and developing methods for their determination. The project refers to applied investigations as a result of which:
  1. Qualitative and quantitative composition of organic acids, amino acids, sugar content substances, mineral substances of citric juices will be studied;
  2. Physical and chemical indexes, the sum total of which defines their natural quality much deeply, will be defined.
  3. The influence of different kind of naturalness disturbance and the change of citric juice will be studied;
  4. The change of naturalness indices of citric juices depending on the process of ripening, hot treatment, during juices keeping and also on the soil-climate conditions of fruits growing will be studied;
  5. The mathematical models of naturalness indices of citric juices will be developed;
  6. The results of the investigations will be generalized and on the basis of revealed indices, the technical documentation will be developed.

The sphere of application for project’s results- the developed methods for determining the naturalness of citric juices can be used in the plants producing these juices, in all laboratories controlling the quality of food and in arbitration practice.

The realization of TSTC aims- the project will give an opportunity to its executors from Georgia to use their qualification, knowledge and experience in the field of determining the quality of citric juices and to establish cooperation with scientists and specialists of the world-scientific society, collaborators, and to exchange experiences, to participate in conferences, meetings and joint publications.

Methodology: The objects of investigations are oranges, lemons, grapefruit juices both natural and with sugar. Because of possible chemical changes of citrus fruits during the process of ripening, the samples of juice will be produced during the season of treatment daily in accordance with technological instruction for citric juices.

The samples of juice will be kept in premises at a usual ware house temperature.

Thus both fresh-got juice and juice in the process of keeping will be investigated. The statistically processed data will take into account possible changes of juice chemical content which could exist in real industrial conditions without adulteration. The existing standards on citric juice stipulate the determination of a mass share of soluble dry substances and acidity that is not enough for objective quality assessment. That’s why for investigations, the method of analysis not considered by above mentioned standards as well as special methods of analysis elaborated by us partly which allow to determine the absence of adulteration will be used.

For investigations the following modern methods will be used: gas-liquid chromatography, atomic adsorption analysis, spectrophotometer analysis, solution chromatography with the use of an amino acid analyzer.

By using the method of plural correlation analysis the linear regressive models of citric juice content will be designed and the statistic test of their using will be developed which allow with the help of two or three indices to confirm the naturalness of pure juice even if of the values of controlling indices don’t exceed the limits of their natural changes.


The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.


ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.

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