The effects on the cake quality characteristics and shelf life the use of sourdough powder

In this study, it is aimed to minimize the physical, chemical and microbiological deterioration that may occur as a result of prolonged shelf life by adding sourdough powder without using preservatives. For these purposes, control group cakes (KT) to which baking powder was added, sourdough powder cakes (EHT) produced using sourdough powder substituted for baking powder, sourdough powder and baking powder cakes (EHT+KT) used in sourdough powder and baking powder were produced. The production process of cakes with EHT and KT used together was optimized. In the optimization, Response Surface Method (RSM), Central Composite Design (CCD) were used. The design of the experiment was done by Design Expert® 11 software program. In EHT + KT cake optimization experiments were carried out according to the conditions proposed by the program using the parameters of fermentation time, sourdough powder and baking powder amount, determined response of the analysis results (chemical, physical, microbiology and sensory analyzes) of the variables were transferred to the Design-Expert program. In the CCD, ANOVA test was applied to model the response variable and test the suitability of the proposed model and optimum process conditions for producing high-quality cakes in minimum time were determined. As a result of optimization the formulation for the cake with EHT + KT; 11 g EHT amount, 3 h 12 min fermentation time, 3.2 g KT are determined as optimum conditions. The optimized cake (EHT + KT), the cake with EHT and the control group cake (KT) were subjected to shelf life analyzes once a week for 2 months. For exploration shelf life, cakes was packed in a modified atmosphere (0.0% O2, 26.1% CO2, 73.9% N2) and stored at room temperature. During storage TBA reagents value (μmol MDA/kg), % free fatty acid (in term of oleic acid) value, peroxide value (meq O2/kg fat), % amylose, rope count (log cfu/g), color, changes in texture (hardness) and sensory analysis were examined. As a result of the analyzes, the hardness, TBA reagents and % amylose values of the cakes increased, and the lowest hardness value was 4574.67 Newton KT group, the TBA reagents value was 127.93 μmol MDA / kg EHT group, the % amylose value of 1.13% EHT group cake samples showed. Decrease in free fatty acid value from the 4th week of storage has been observed and the lowest free fatty acid value at the end of storage 1,17 % EHT groups showed cake samples. While the peroxide value increased in the EHT and KT cakes, decrease was observed in the EHT + KT cake group, and the lowest peroxide value at the end of storage showed 0.31 meq O2/kg oil EHT+KT cake samples. The rope count showed a continuous increase in the KT group, whereas EHT+KT showed an increase after from the 6th week, but in the EHT group an increase wasn't observed at all. Due to mold growth in control group cakes, sensory analysis was not continued after from the 5th week of storage. When the results obtained are evaluated, it has been determined that the microbiological problems that may occur during storage can be largely eliminated in cakes where EHT is used. When the cake production process is examined in the literature, there is no study on sourdough powder being used in cakes which can be used instead of preservative chemical additives. As a result obtained from the studies carried out within the scope of this master's thesis can be used as a reference in subsequent studies.