Investigation of degradation characteristics and kinetics of Kastamonu halvah depending storage

Kastamonu Halva is a traditional food produced in accordance with its technique by adding white sugar, wheat flour, butter, citric acid, and water, and seasonings if necessary. The most significant distinguishing characteristic of Kastamonu Halva, which received the geographical indication as of 2018, is the use of butter in the production of halva. However, producers of halva have abandoned the use of butter and started using hydrogenated vegetable fat because of the high cost of butter and the loss of textural and sensory qualities during its shelf life. Geographical indication application has been made as "butter and/or vegetable margarine". Recently, different basis weights and packaging techniques have been applied by manufacturers in the process of halva production. However, there is no study investigating their effects of them on the quality of Kastamonu halva during storage. The aim of the thesis was to examine the deterioration characteristics and to determine the kinetic parameters of Kastamonu halva produced with 3 independent variables (fat, packaging, and weight types). For this purpose, the change in quality parameters of Kastamonu halvah produced as 8 types (2 types of fat x 2 packaging techniques x 2 different weights) were examined for 12 months. It has been determined that the humidity values were variable within themselves, the packaging technique was more effective in this change (p<0.05), and the types of fats and package weights have less effect. It was determined that the vacuum packaged samples did not exceed the maximum 6% level specified in TSE (Turkish Standards Institution) 13028 Pulled Halva Standard during 12 months of storage. It was determined that the packaging technique was more effective (p<0.05) than the types of fat and weight on the change in peroxide number. The highest peroxide number determined in TSE 13028 Pulled Halva Standard is 10 meq O2/kg, and as of the 9th month, it has been observed that all products exceed the limit value specified in the standard. It has been determined that the color qualities was not affected by the difference in fat and weight during the storage, and the vacuum packaging technique is more effective than shrink packaging in preserving the color qualities. Two peak formations were observed in the DSC thermograms. This showed that the changes in halvah were based on the presence of carbohydrates and sugar, while at the same time its shelf-life qualities depended on sugar and non-sugar carbohydrates. It has been determined that the use of vegetable margarine was effective in its thermogravimetric qualities, delays retrogradation and slows down moisture loss. It was observed that the increase in humidity of confectionery products was effective on the glass transition temperature, as well in the shrink halva samples in this study, and it was determined that less moisture intake affected the glass transition temperature less. It has been determined that there was less decrease in the glass transition temperatures of the vacuum-packed samples, especially in the second endothermic peak area. This change was also observed in the results of the texture profile analysis, and it was determined that there was a statistically significant (p<0,05) change in the values of hardness and chewing ability of the shrink-wrapped samples compared to the vacuum-packed samples after the 6th month. It was determined that the vacuum-packaged samples with butter and vacuum packed samples with 280 grams of vegetable margarine had the best combination in terms of preserving their textural qualities. It was determined that all the changes were also perceived by the panelists in the sensory evaluation. At the same time, it was determined that while the flavor of roasted flavour was dominant in the beginning, the taste of sugar came to the fore over time. According to the evaluations of the panelists, 280 grams of buttered vacuum packaged sample was the most popular during the storage period. According to the evaluations of the panelists, the most popular combination at the end of the storage period was the 280 gram buttered vacuum packaged sample. In this study, it was determined that the acceptability of buttered halva with vacuum packaging technique continued during the storage period.It has been determined that humidity and oxygen are effective on the changes in the quality parameters of the halva samples during storage. Reaction kinetics on moisture and moisture-based textural properties could not be calculated. It was determined that only the hardness value of the BS2 sample matched the 2nd order reaction kinetics. L* value was found to be suitable for 0th order in TS2 and BS2 samples, and 2nd order reaction kinetics in vacuum packed TV1 and BV1 products. The b* value of the BS1 sample was found to be suitable for the 2nd order reaction kinetics. It was determined that the peroxide number, which increased during storage, conformed to the 1st order reaction kinetics in the TV2 sample and the 2nd order reaction kinetics in the other samples, depending on the oxygen permeability of the packaging technique. İn this study, it was concluded that the recommended maximum shelf life is 8 months for vacuum and shrink-wrapped samples, depending on the increase in peroxide, when stored at 30% relative humidity and 20 ºC storage conditions. However, it was determined that the shelf life of shrink-wrapped products decreased to 6 months due to textural and sensory losses.