The effect of microwave on the extraction of inulin from jerusalem artichoke and investigating the cryoprotective role of powdered inulin in frozen fermented bread dough

The aim of the thesis study is to produce inulin powder from Jerusalem artichoke by employing conventional and microwave-assisted extraction methods. It was also aimed to carry out powder product characterizations and to determine the effects on the quality properties of fermented bread dough by considering different freezing methods and storage time. Conventional and microwave-assisted extraction methods were used in the production of inulin powder from Jerusalem artichoke. The effects of the extraction process parameters (temperature, time and solvent ratio) on the inulin yield were investigated with two different optimization methods: response surface method (RSM) and genetic algorithm (GA). The physicochemical and powder product properties of inulin powders produced under optimum processing conditions were determined. Inulin powder produced under optimum method and processing conditions was added to the fermented bread dough formulation. Doughs were frozen using three different freezing methods (static, airflow and individual quick freezing; IQF) and their quality characteristics were examined during six months of storage. It has been determined that the model created with GA can provide higher inulin yield compared to RSM. GA optimum processing conditions were found as 80 ℃, 25 min and 19 mL/g for conventional extraction; 80 ℃, 60 min and 32 mL/g for microwave-assisted extraction, respectively, as temperature, time and solvent ratio. Under these conditions, inulin yields for conventional and microwave-assisted extraction were found to be 85.6% and 91.8%, respectively. The results indicated that the microwave-assisted extraction method significantly improve the powder product properties such as water holding capacity, volumetric gel index, Carr index, wettability, viscosity, dispersibility and solubility. Freezing of inulin powder added fermented bread dough by rapid freezing methods (air blast/IQF) was effective in maintaining quality parameters such as water activity, ion leakage, enzyme activity, texture properties, specific bread volume and bread value number during storage. On the other hand, the addition of inulin powder did not provide a protective effect on the drip loss value during storage. The microwave-assisted extraction method has promising potential for the production of inulin powder to be used as functional ingredient in food, pharmaceutical and chemical industries. Inulin powder has the potential to eliminate quality problems in frozen fermented bread dough, therefore the use of inulin powder can be a guide for the frozen food industry.