Evaluation of Sustainability of Wheat-Bread Chain Based on the Second Law of Thermodynamics: A Case Study

Abstract

Wheat flour, bread, and bakery products are an important source of macronutrients, micronutrients, dietary fibers, and antioxidants. Considering that Iran’s bread industry is the second highest bread-consuming industry in the world, this research is focused on the main operations of the bread production chain (wheat cultivation, milling, dough processing, and bread production). Investigating the sustainability and improvement strategies and farm-to-fork approach for the wheat-bread production chain was the aim of this work. Exergy analysis is a powerful tool in designing, optimizing, and evaluating the performance of energy systems to determine energy quality, compare different energy sources, and achieve maximum system performance. In this research, the cumulative degree of perfection, renewability index, and sustainability index of Iranian traditional loaves of bread (Sangak, Lavash, Barbari) and Baguette bread as a semi-industrial bread were estimated. Considering the functional unit of the weight of the produced bread, Baguette and Sangak breads had the highest and lowest sustainability, respectively. Considering the functional unit of energy of the produced bread, Baguette bread has the lowest exergy consumption per 100 cal of the embedded energy of bread. According to the obtained results, the bakery consumes the most exergy in the wheat-bread chain. Natural gas input is the most important indicator of unsustainability in bakeries. Meanwhile, in the entire wheat-bread chain, human labor and natural gas consumption were factors of unsustainability. By using renewable sources, the renewable index increased by 76–89%. Additionally, the use of renewable resources increased the sustainability index of bread production by 7.6 to 1.9 times.