Optimizing of Formulation in Diet Luz with Replacing Sucrose and almond with Stevioside-Isomalt and Ganoderma lucidum by Response Surface Methodology

Introduction: Lifestyle changes related to modification in the eating quality and quantity along with mental stress led to the prevalence of non-communicable diseases such as obesity, diabetes and cardiovascular disease. Considering the consumer’s demand, food scientists are now focusing on developing suger free or low- carbohydrate, fat free and low calorie foods which rich in fiber, protein, minerals and vitamins. Luz is one of the iranian traditional sweets, which is very popular due to its desirable texture and sensory properties. However, due to the its high sugar content, its consumption is limited for obesity and diabetes peoples. In recent years, a number of synthetic sweeteners like saccharine, acesulfame‐K, aspartame, which are sweeter than sucrose and nontoxic, have been developed and identified to replace sugar. Stevioside is extracted from the leaves of S. rebaudiana Bertoni that has a great potential as a new agricultural crop for health promoting foods is increasing, and proximate analysis has shown that Stevia also contains substantial amounts of proteins, potassium, and other essential nutrients. It is a white, crystalline, odorless powder, which is approximately 300 times sweeter than sucrose. Steviol glycosides are noncaloric sweeteners, which makes them an attractive sugar substitute for food industry. Isomalt is a sugar alcohol, low-calorie bulking agent with properties and characteristics similar to sucrose. The sweetening power of isomalt lies between 0.45 and 0.60 as compared with that of sucrose. Ganoderma lucidum an oriental fungus, has a long history of use for promoting health and longevity in the world. Ganoderma is a rich source of protein, carbohydrate, fat, fiber, minerals and vitamins. Considering that now, no research has been done on the use of Ganoderma lucidum and substituting sucrose with stevioside-isomalt in Luz formulation, Therefore, the aim of this study was to investigate the possibility of almond substitution with Ganoderma lucidum and sucrose substitution with stevioside-isomalt. Materials and methods: Materials used in Luz formulation consisted of coconut powder, isomalt, sucrose, stevioside, almond, Ganoderma lucidum were supplied from salamatgostaran arayan Co. All chemicals were from Merck Co. The formulations of Luz include coconut powder (38.74%), sugar (25.83%), sorbitol (29.63%), almond (2.57%), vanilla (0.2%), cardamom (0.2%), cinnamon (0.26%) and chlorophyll (2.57%) were selected. To produce Luz, the mixture of sugar and sorbitol was heated to boiling temperature and complete dissolution. After the heat treatment (100°C for 2h), the mixture was cooled to 40°C and the coconut and almond powder was added and mixed. At the end, cardamom, cinnamon, vanilla and chlorophyll were added. The prepared mixture were molded and placed at 18°C for 24h. Protein, fat and sugar were determined according to AACC standard numbers, 46-12, 30-10 and 80-50. The density was also determined according to (Islam et al., 2012). High-performance liquid chromatography measurement of vitamin D was performed according to National institute of standard number 13579. Textural properties were determined using a Texture Analyzer. In this study, the effects of sucrose replacement with stevioside-isomalt (0-100%), almond replacement with Ganoderma lucidum (0-100%) and temperature (50-70°C) on qualitative characteristics (density, texture, colour) were investigated by response surface method (RSM) in the form of a central composite design with 6 central point (α=2). Optimal and control samples were examined in terms of qualitative characteristics such as protein, fat, sugar, vitamin D, calcium, phosphorus, density, peroxid value, textural (hardness, adhesiveness, springiness, cohesiveness, gumminess, chewiness) and sensory properties during 0, 15, 30 and 45 days after production. Comparison of the optimal and control samples was done in a Duncan's new multiple range test using SPSS ver: 9.1 software. Results and discussion: The results revealed that the an increase in the percentage of almond replacement with Ganoderma lucidum resulted in an increase the density and hardness. Independent variables had not a significant effect on the adhesive force and (b*) of the produced samples, and only almond substitution with Ganoderma lucidum had a significant effect on increasing adhesiveness. Springinesss, gumminess and chewiness, and also (L*) and (a*) increased with increasing sucrose substitution with stevioside-isomalt and almond with Ganoderma lucidum. The lowest density was belonged to sample contains 25% level of almond substitution with Ganoderma lucidum and 75% sucrose substitution with stevioside-isomalt. The interaction effect of sucrose substitution with stevioside-isomalt and almond with Ganoderma lucidum showed that, springiness increased with reducing substitution levels of sucrose with stevioside-isomalt and almond with Ganoderma lucidum. Treatments obtained by the model contain 68% sucrose substitution with stevioside-isomalt , 25% almond substitution with Ganoderma lucidum and 55°C temperature and 38% sucrose substitution with stevioside-isomalt , 0% almond substitution with Ganoderma lucidum and 60°C temperature, were introduced as optimal samples to maintain the quality characteristics and increase Luz nutritional value. Comparison between treatments showed that the optimal and control samples had not significantly different (P>0.05), in terms of protein content and density. During storage time, peroxid value of optimal samples were lower than the control sample (p < 0.05). Based on the results of sensory evaluation, the optimal and control samples had not significantly different (P>0.05), in terms of colour and sweetness, but the optimal samples received a lower overall acceptance score than the control sample (p < 0.05). In the microstructure evaluation of the optimal samples, due to the presence of Ganoderma lucidum, the uniformity of the structure of the samples was reduced and a gel network with larger particles and more pores was formed. Conclusion: According to the results of qualitative characteristics evaluation of the treatments, substitution a part of the sucrose with stevioside-isomalt and almond with Ganoderma lucidum in Luz formulation led to a successful reduction of total sucrose and fat, and an increment of calcium, phosphorus and vitamin D.