rus
Issue #3/2015
K.Guryeva, S.Beletsky
Application of the ОXITEST device for assessment of sunflower oil oxidation stability
Application of the ОXITEST device for assessment of sunflower oil oxidation stability
FSBI R&DISP of FSRA uses modern innovative device OXITEST in scientific researches of food quality during storage. This article describes practical application of the new laboratory device for characterization of sunflower oil oxidation stability at different temperatures.
Теги: auto-oxidation reaction oxidation stability автоокислительная реакция окислительная стабильность
During long-term food products storage their quality is deteriorating due to unstable components oxidation by atmospheric oxygen. Primarily, it applies to unsaturated acids and lipid complexes. Rancidity or auto-oxidation of lipids – is one of the most important factors that affect the shelf life of products. Rancidity is characteristic for all products even containing just traces of fat, for example flour and grits, that’s why control of the oxidation process – is so important applied problem [1].
OXITEST (Fig.1) – is the device that provides the most convenient and accurate determination of samples oxidation stability of primary and finished products without any pre-treatment (fat separation). The device can be used to analyze a wide range of samples, it is suitable both for the development of formulations and for final quality control in the food processing, cosmetic and chemical industries. Using this device, it is also possible to determine the quality and selection of packages (comparison of different types of packages), to assess various antioxidant and preservative additives [2].
OXITEST provides quick and accurate analysis of oxidation stability of a sample. Acceleration of the oxidation reaction is achieved by increasing the temperature (up to 110°С) in controlled atmosphere of pure oxygen under pressure. Since oxygen is consumed at the auto-oxidation reaction, the resulting dependence of the oxygen pressure to exposure time provides useful information on the sample behavior during long storage [2].
The device is equipped with two separate titanium oxidizing chambers. They are intended for accelerated oxidation stability testing of two identical samples of products or of two different products in the same conditions (Fig.2).
The whole process of analysis is controlled by specially developed software OXISoft [2]. The program allows not only to process and store results, but also compare results of different tests, export data in the processing software (Excel), quickly and easily sort results using filters.
OXITEST is versatile solution for a wide range of tasks, including:
analysis of products stability in the process of their storage, storage timing, products characterization after expiry of time slots with composition of experimental curves;
analysis and selection of storage conditions;
analysis and selection of the most suitable products’ packaging;
comparison of products oxidation stability of different formulation;
oxidation stability study of vegetable oil samples of different origin;
study of the effectiveness of various antioxidants;
obtaining information on the process of products oxidation that slightly change their properties during storage, especially with low (4–5% or less) fat content. In addition to OXITEST, chromatographic methods of analysis may be used;
obtaining information on stability of incoming materials and finished products [2].
Scope of application of the device: food processing industry, oil and fat industry and research centers. Fields of application: oxidation stability of oils and fats in samples of the food processing industry and feeds; quick comparison of different forms of product or test of different batches of the same raw materials, packaging studies, assessment of the effectiveness of various antioxidants, oxidation stability of fuels better known as biodiesel.
Basic specifications of ОXITEST device
Number of oxidizing chambers........................... 2
Capacity of a single chamber................ up to 100 ml
Interface................................................. USB
Power................................................. 900 W
Power supply............................. 230 V / 50–60 Hz
Temperature range................ from ambient to 110°С
Pressure range...................................... 0–8 bar
Both vegetable oils (sunflower oil of various grades and manufacturers, including high-oleic oil, corn oil, olive oil) and foods containing lipid fraction (head rice and buckwheat, condensed milk, etc.) at various temperatures: 70, 90, 110°C were tested using OXITEST device. As an example we show report on the test of vegetable oil at the temperature of 110°C and the pressure of 6 bar (Fig.3). The induction period (the time at which the rate of oxidation drastically increases) was determined at the curve knee point of pressure – time curve of the sample. And the oxidation rate can be determined by slope of the tangent drawn to the abruptly descending portion of the pressure curve.
The study of oxygen absorption by oil at different temperatures showed that with temperature increasing of the experiment, the induction period is reduced. For example at 70°С the induction period was 64 h (3840 min), at 90°C – 11 h (660 min), and at 110°C – 2.1 h (126 min). Statistically it was shown that high negative correlation with the correlation index of –0.925 exists between the period of induction and temperature. The dependency diagram of the sunflower oil induction period to temperature obtained by the OXITEST device is shown in Fig.4 [3].
Tests findings showed that using OXITEST device it is possible to perform comparative assessment of different products oxidation stability, as well as computation of storage period and useful life. Experimental data obtained at three temperatures will be used by us to justify the possibility of extrapolation of accelerated oxidation parameters in relation to the real conditions of sunflower oil storage in reservoirs and in bottles at warehouses.
OXITEST (Fig.1) – is the device that provides the most convenient and accurate determination of samples oxidation stability of primary and finished products without any pre-treatment (fat separation). The device can be used to analyze a wide range of samples, it is suitable both for the development of formulations and for final quality control in the food processing, cosmetic and chemical industries. Using this device, it is also possible to determine the quality and selection of packages (comparison of different types of packages), to assess various antioxidant and preservative additives [2].
OXITEST provides quick and accurate analysis of oxidation stability of a sample. Acceleration of the oxidation reaction is achieved by increasing the temperature (up to 110°С) in controlled atmosphere of pure oxygen under pressure. Since oxygen is consumed at the auto-oxidation reaction, the resulting dependence of the oxygen pressure to exposure time provides useful information on the sample behavior during long storage [2].
The device is equipped with two separate titanium oxidizing chambers. They are intended for accelerated oxidation stability testing of two identical samples of products or of two different products in the same conditions (Fig.2).
The whole process of analysis is controlled by specially developed software OXISoft [2]. The program allows not only to process and store results, but also compare results of different tests, export data in the processing software (Excel), quickly and easily sort results using filters.
OXITEST is versatile solution for a wide range of tasks, including:
analysis of products stability in the process of their storage, storage timing, products characterization after expiry of time slots with composition of experimental curves;
analysis and selection of storage conditions;
analysis and selection of the most suitable products’ packaging;
comparison of products oxidation stability of different formulation;
oxidation stability study of vegetable oil samples of different origin;
study of the effectiveness of various antioxidants;
obtaining information on the process of products oxidation that slightly change their properties during storage, especially with low (4–5% or less) fat content. In addition to OXITEST, chromatographic methods of analysis may be used;
obtaining information on stability of incoming materials and finished products [2].
Scope of application of the device: food processing industry, oil and fat industry and research centers. Fields of application: oxidation stability of oils and fats in samples of the food processing industry and feeds; quick comparison of different forms of product or test of different batches of the same raw materials, packaging studies, assessment of the effectiveness of various antioxidants, oxidation stability of fuels better known as biodiesel.
Basic specifications of ОXITEST device
Number of oxidizing chambers........................... 2
Capacity of a single chamber................ up to 100 ml
Interface................................................. USB
Power................................................. 900 W
Power supply............................. 230 V / 50–60 Hz
Temperature range................ from ambient to 110°С
Pressure range...................................... 0–8 bar
Both vegetable oils (sunflower oil of various grades and manufacturers, including high-oleic oil, corn oil, olive oil) and foods containing lipid fraction (head rice and buckwheat, condensed milk, etc.) at various temperatures: 70, 90, 110°C were tested using OXITEST device. As an example we show report on the test of vegetable oil at the temperature of 110°C and the pressure of 6 bar (Fig.3). The induction period (the time at which the rate of oxidation drastically increases) was determined at the curve knee point of pressure – time curve of the sample. And the oxidation rate can be determined by slope of the tangent drawn to the abruptly descending portion of the pressure curve.
The study of oxygen absorption by oil at different temperatures showed that with temperature increasing of the experiment, the induction period is reduced. For example at 70°С the induction period was 64 h (3840 min), at 90°C – 11 h (660 min), and at 110°C – 2.1 h (126 min). Statistically it was shown that high negative correlation with the correlation index of –0.925 exists between the period of induction and temperature. The dependency diagram of the sunflower oil induction period to temperature obtained by the OXITEST device is shown in Fig.4 [3].
Tests findings showed that using OXITEST device it is possible to perform comparative assessment of different products oxidation stability, as well as computation of storage period and useful life. Experimental data obtained at three temperatures will be used by us to justify the possibility of extrapolation of accelerated oxidation parameters in relation to the real conditions of sunflower oil storage in reservoirs and in bottles at warehouses.
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