Tempeh is a traditional Indonesian food that is fermented soybeans with Rhizopus spp. and contains high-quality protein. In this study, tempeh and yeast were set as independent variables following the central composite design to optimize the nutritional quality and sensory characteristics of high-protein loaf bread added with tempeh. The optimal mixing ratio was calculated through the response surface methodology. The optimal mixing ratio of tempehadded loaf bread was 11.27 g of tempeh and 5.46 g of yeast. A comparative analysis of the quality characteristics between the tempeh-added loaf bread and the control group produced by the optimal recipe showed that tempehadded loaf bread contained higher protein content, lower carbohydrates and fats, and lower calories. Among amino acids, essential amino acids such as aspartic acid, threonine, glycine, alanine, lysine, and histidine were significantly higher in tempeh-added loaf bread. Among fatty acids, butyric acid, capric acid, myristic acid, palmitic acid, palmitoleic acid, and heptadecanoic acid were significantly higher in tempeh-added loaf bread, while lauric acid, linoleic acid, and linolenic acid were significantly lower. This study confirmed the suitability of tempeh as an ingredient for protein-enhanced loaf bread and the potential possibility of it being utilized in bakeries.

The purpose of this study was to determine the optimal composite recipe of rice muffins with 3 concentrations of Spergularia marina L. Griseb, sugar and grape seed oil, using central composite design. In addition, the mixing condition of rice muffins was optimized by subjecting it to sensory evaluation and mechanical and physicochemical analysis using response surface methodology (RSM). In regard to its antioxidant effects, Spergularia marina L. Griseb had a total phenol and flavonoid contents and DPPH free radical scavenging activity of 17.03 mg/g, 5.13 mg/g and 17.21%, respectively. The results of mechanical and physicochemical analysis showed significant values for lightness, redness, yellowness, hardness, springiness, chewiness, gumminess, cohesiveness, height, volume, weight, specific volume, loss rate, pH, moisture, sweetness and saltiness (p<0.05), and the results of sensory evaluation showed significant values for color, flavor, taste, softness, appearance and overall quality (p<0.05). As results, optimal sensory ratio was found to be 6.69 g of Spergularia marina L. Griseb, 41.89 g of sugar and 30.48 g of grape seed oil.