Effect of Tempeh Processing on the Nutritional Composition and Immunoreactivity of Grobogan Soybeans

Soybeans are a valuable source of essential nutrients but can trigger allergic reactions in susceptible individuals. This study investigates the effects of tempeh processing, including boiling, fermentation, and frying, on the nutritional composition and immunoreactivity properties of Grobogan soybeans. The research evaluated four processing stages: raw soybeans, boiled soybeans, soy tempeh, and fried tempeh. Nutritional composition, protein profiles, and immunoreactive protein concentration were assessed at each stage to determine the changes that occurred. The results revealed significant differences in nutritional content across the processing stages. Boiling increased moisture content and decreased ash content, while fermentation enhanced protein levels. Frying reduced moisture but increased fat content. SDS‐PAGE analysis confirmed substantial protein degradation, including key immunoreactivity proteins Gly m 5 and Gly m 6. Immunoreactivity was reduced by 84.42% after boiling, 91.82% after fermentation, and 96.86% after frying. This study confirms that thermal treatment (boiling and frying) combined with microbial fermentation effectively causes protein denaturation, aggregation, and potential insolubilization, which degrades immunoreactive protein concentrations. Tempeh processing enhances the nutritional profile of soybeans and significantly reduces their immunoreactivity properties. Boiling, fermenting, and frying tempeh are effective methods for reducing immunoreactivity and increasing protein digestibility and fat content. The combination of processing steps is effective in reducing allergenicity; however, the definitive safety for individuals with soy allergies requires clinical validation. Further research is needed to investigate allergen reduction mechanisms during each processing stage and to assess the loss of bioactive compounds to optimize soy processing for safety.