StatusThe thesis was presented on the 7 September, 2012
Approved by NCAA on the 15 November, 2012
Abstract– 0.48 Mb / in romanian
The thesis was prepared in Chisinau in 2012 and is written in Romanian.
Structure of the thesis: The thesis is of 156 pages and consists of Introduction, four Chapters, Conclusions and Recommendations and preliminary outline of new lines of research, 288 References, 16 Tables and 81 Figures. The obtained results were published in 28 scientific works.
Area of research: Processes and devices in food industry.
Aim of research: Development of a novel, environmentally friendly, wasteless technique for electrophysical processing of secondary milk products, whey being among them. This technique consists in extraction of protein-mineral concentrate from whey and simultaneous isomerization of lactose into lactulose, without using chemical reagents and high temperature.
Objective of research: The analysis of an electrophysical processes of whey processing and activation of internal sources for extraction of protein fraction along with the simultaneous isomerization of lactose into lactulose; the development of an electrolyzer meant for the investigations of the processes of whey processing; the ascertainment of methods for investigation of the process of electrofractionation, for measuring electrical and thermal parameters, for detertmining physico-chemical and biochemical parameters; the investigation of electroractionation of whey; the structural and functional analyses of the results obtained during the present research; optimisation of the technological process in the electrolyzer with a diaphragm, and its operation, through elaboration of an electrolyzer with the permanent mode.
Novelty and originality of the scientific work performed: The main assets of the present thesis are the following: under detailed investigation was the phenomenon of intensification of the process of an extraction of whey protein and mineral fractions, with the simultaneous isomerization of lactose into lactulose through the following mechanisms: L-A transformation and rearrangement of Amadory when applying electric current; physical, chemical and biochemical processes were identified, namely those of complexation – coagulation of proteins, the process consisting of five separate stages; conversion of aqua-complexes into hydro-complexes was established and described, bringing out the phenomenon of electroactivation through reducing active acidity; the role of bivalent ions in complexation, the solubility of the extracted protein fractions at different current density were identified; a model was proposed to calculate thermal parameters of electrophysical processing; the results obtained have a favourable positive impact on the environment due to the simultaneous usage of important whey fractions that are abundent in run-off water, hence they are environmentally friendly; in addition, the technique proposed is economical because it is possible to use the final products in pharmatheutical and food industries.
The main solvet scientific problemis the electrophysical treatment of whey with the extraction of the protein-mineral concentrate and the simultaneous isomerization of lactose into lactulose without the direct utilization of chemical reagent with the low power consumption.
Theoretical and practical importance: The technique was elaborated to investigate electrophysical whey processing, and the methods were identified for establishing physicochemical and biochemical parameters; an experimental prototype of electrolyzer was developed for treatment of process liquids in laboratory conditions, which made it possible to study whey processing with possible modifications of construction that provide for substitution of membrane and of anodic liquid, along with the ruling out non-functional areas of the electrolyzer; optimal processing parameters were identified as follows: low temperature (35-45oC), reduction of energy consumption, quantitative and qualitative analyses of the fractions obtained. In addition, а mathematical model of the electrophysical whey processing was developed, which allows for obtaining the dependency between the quantity of the extracted protein in the protein-mineral concentrate, current density, and duration of the treatment. For the extraction to be optimal, at 70% of the protein fractions in the protein-mineral concentrate, the use should be made of an ion-selective membrane MK-40 and of 2% solution of calcium chloride in distilled water. The two-stage process of isomerization of lactose into lactulose was proposed. At the first stage, 35-40% of lactose is isomerized, and at the second stage - 65-70% , with the supplimentary extraction of proteins - at 15-25 %. A rotating electrolyzer was designed and made, with the permanent operating mode. The technological-economic calculations were caried out of the electrophysical whey treatment. The results obtained during investigations described here can be used in the extraction of major fractions from different biological environment.