Determination of the effect of vacuum cooking on hard candy quality characteristics and optimization of process parameters

Hard sugar is cooked with sucrose glucose syrup and water to 145°C, cooling to 105°C, mixed with acidity regulator, flavor and food coloring agent, shaped and high value in terms of carbohydrate. Hard sugar shelf life is 29 months at 28-32°C, 18 months at 41-55% humidity and 30-40% at 22-28°C. The length of the hard sugar shelf life is the most important advantage of the hard sugar industry in the commercial sense. This study will prevent the increase of HMF formation by minimizing the hard sugar cooking temperature. In this study, the effective process parameters for the production of hard sugar in the vacuum cooker were determined by Placket Burman design and optimum cooking conditions using the Response Surface Method. In the optimization study sucrose / glucose syrup ratio (10-90%), cooking temperature (125-165°C), vacuum intensity 0-760 mm-Hg and vacuum time (120-600 seconds) hardness, dissolution resistance, hygroscopicity, shelf life and HMF amount were chosen as independent variables. The cooking process was carried out by following the 4-factor "Central Composite Rotatable" design trial plan. For each argument, it was studied at 8 different levels, including center and axial points determined according to the experimental design to be applied. Optimum processing conditions; sucrose / glucose syrup ratio (50.00 %), cooking temperature of 139.50°C, vacuum intensity of -760.00 mm-Hg and duration of vacuum of 466.46 seconds by applying the desarability function approach. The amount of water-soluble dry substance at the optimum point was 96.50%, the shelf life was 12 months, the amount of HMF was 73.00 mg/kg, total sensory characteristics; Color 53.16, solubility 70.27, hygroscopicity 13.04, hardness 43.93 and taste 70.27.