Optimization formulation of dietary Luz fortified with Stevia and Corchorus olitorius L. using response surface methodology

Recently, the prevalence of diseases related to diabetes, hypertension, and obesity, due to high and persistent consumption of sucrose is increasing rapidly. Concerns about the adverse effects of sugar consumptionon one hand, and manufacturers and consumers attention for natural sweeteners to replace sugar, on the other hand, reveal that innovative approaches are needed to help develop a healthy diet which prevents such diseases. Stevia can be introduced as a good replacement for sucrose. Corchorus olitorius L. is a rich source of bioactive compounds such as protein, fiber, vitamins, minerals, sterols, tocopherols, and carotenoids, which has significant antioxidant, antibacterial, antifungal, antiviral, anti-inflammatory and anti-cancer properties. This study aimed to reduce the sugar level in Luz preparation and produced a high nutritive product by using Corchorus olitorius.

Materials used in Luz formulation consisted of isomalt, sorbitol, coconut powder, pistachio powder, cardamom, cinnamon and chlorophyll, stevia, and Corchorus olitorius were supplied from Salamat-gostaran arayan Co. All chemicals were from Merck Co. The formulations of Luz include sorbitol (29.68%), sugar (25.85%), coconut powder (38.75%), cardamom (0.3%), cinnamon (0.26%) and chlorophyll (58.5%). 2) were selected, and isomalt was used as filler. To produce Luz, the mixture of sorbitol and isomalt was heated to reach boiling temperature and complete dissolution. After the heat treatment (126°C for 1h), the mixture was cooled to 40°C and the other materials were added and mixed. The prepared samples were molded and placed at 15°C for 3 h. Moisture, ash, protein, fat, and sugar were determined according to AACC standard numbers. The density was also determined according to AACC standard number 54-21. Textural properties were determined using a texture analyzer. Atomic Spectroscopic measurement of minerals was performed according to Devatkal et al. (2004). The color evaluation was performed by the Image Processing method. In this study, the effects of Stevia replacement with sugar (0-100%), Corchorus olitorius replacement with pistachio powder (0-100%) and cooking temperature (50-70°C) on physical and textural properties (density, hardness) of Luz were investigated. Formulation optimization of enriched dietary Luz was performed using Response Surface Method in the form of a central composite design with 6 central points and two replications (α=2) in other locations. In optimum condition, the results of physicochemical, textural and color properties were analyzed by SPSS software.

The linear model was suggested for density changes, and independent effect of variables (stevia replacement, Corchorus olitorius replacement, cooking temperature), interaction effect of Stevia and Corchorus olitorius replacement, interaction effect of Corchorus olitorius replacement and cooking temperature, the quadratic effect of Stevia replacement and the quadratic effect of cooking temperature were significant on density (P <0.05 or P <0.001). The density of all treatments increased with increasing the levels of Stevia and Corchorus olitorius replacement. An increase in density was observed with increasing cooking temperature. The interaction effect of Corchorus olitorius and cooking temperature caused a significant (P<0.05), decrease in hardness. A reduction in the level of stevia replacement resulted in a decrease in hardness. The optimum formulation of dietary Luz was introduced containing 25% Stevia, 25% Corchorus olitorius and cooking temperature of 65°C, and 55% Stevia, 75% Corchorus Olitorius and cooking temperature of 55°C. Overall, the nutritional value of dietary Luz containing Corchorus olitorius was improved in terms of protein, ash, magnesium and calcium content. The total sugar content of the optimum samples was significantly lower than the control. The textural characteristics of the optimum samples had not changed significantly.