Dissertation for obtaining a scientific degree of candidate of technical sciences in the specialty 05.18.01 - Technology of bakery products, confectionery and food concentrates - National University of Food Technologies of the Ministry of Education and Science of Ukraine, Kyiv, 2020.
The dissertation is devoted to the improvement of the technology of molded potato chips of high nutritional value by using rye bran, barley, pumpkin seed cake, cryopowders of broccoli and red beet with the use of special methods of raw material preparation. The chemical composition of potato grits, rye bran, barley, pumpkin seed cake, cryopowders of broccoli and red beets was determined and their optimal fractional composition with sizes of 40 μm was selected.
Physicochemical parameters of potato grits, bran, cake and cryopowders, their water absorption and fat solubility were studied. The optimal ratio of potato grits to rye bran or barley bran, or pumpkin seed cake, or broccoli cryopowder, or red beet cryopowder, which is 4: 1, was determined. It was established that at this ratio of components the structural and mechanical parameters of potato dough improved, which was confirmed by the indicators of the penetrometer.
The process of gelatinization of starch in potato dough with bran, cake and cryopowders has been studied. It was found that the maximum viscosity of potato dough with rye bran, barley, pumpkin seed cake increased compared to the control by 33.3%, 50.0% and 27.8%. The maximum viscosity of potato dough with broccoli cryopowder increased by 94%, and with cryopowder red beets – by 79% compared to the control sample. It has been found that rye, barley, pumpkin seed cake, cryopowder of broccoli and red beets affected the time of viscosity and reduced the gelatinization temperature of potato dough by 10-11.5%.
Optimization of potato dough production for molded potato chips with bran, or cake, or cryopowders has been carried out. Using the method of complete factorial experiment, regression equations were obtained, which made it possible to calculate the baking-drying temperature (120-135ºС), baking-drying duration (4.47-4.50 min), the amount of potato grit dosing (79%). Observance of the specified conditions of dough preparation allows to receive the formed potato chips of high quality.
It was found that all studied samples of molded potato chips belong to structured systems, which gives the potato dough viscous-plastic properties. The strongest structured framework of the system is characteristic of the dough from potato grits (1050 Pa), which allows to combine it with bran or cake, or cryopowders.
The comparative analysis of data of thermogravimetric and differential-thermal researches of baking-drying of the formed potato chips was carried out by dividing the DTG dependence into peaks using the Gaussian distribution and using data calculation techniques for porous solids. It was found that the largest amount of chemically bound moisture was in molded potato chips with rye bran (91%). This suggests that molded potato chips will have a longer shelf life.
The content of acrylamide in molded potato chips produced by different technologies was studied and it was proved that one of the ways to increase their safety is to bake-dry at a decrease in temperature (130-135° C) without the use of oil. Chromatographic analysis revealed that the samples of molded potato chips with rye bran, or barley, or pumpkin seed cake, or cryopowders of broccoli or red beets, the content of acrylamide was not detected. This is obviously due to the chemical composition of the raw material, the lower mass fraction of reducing sugars and aspartic acid, as well as the softened production parameters.
Changes in moisture content in molded potato chips at different storage parameters (75% and 90%) were studied. It was found that during 7 days of storage the mass fraction of moisture increased for molded potato chips fried in oil by 9 times, for baked-dried molded potato chips – by 8 times. This suggests that the finished molded potato chips are very hygroscopic, so they need to be stored only in the package.
It was established that according to the baking-drying technology the acid number in the molded potato chips increased by (2.1-5.4%), the peroxide number - by (2.0-5.5 1/2O / kg). For molded potato chips produced by classical technology, the acid number increased by (8.1-13.5%), the peroxide number – by (3.0-15.0%). The increase in acid and peroxide numbers is due to the initial oxidation of fats due to the destruction of the carbon chain with the formation of saturated and unsaturated fatty acids. The increase in acid and peroxide number during storage of molded potato chips indicates a decrease in their shelf life.
