Abstract Background Almost 80% of the population in sub-Saharan Africa relies on traditional biomass for cooking, which is typically associated with negative environmental, health, economic, and social impacts. Thus, many stakeholders, including development agencies and national governments in the Global South are promoting the use of the improved cookstove in order to save cooking time, save financial assets, maximize fuel efficiency, and reduce indoor air pollution. However, little attention is paid to the heating practices among households, which can determine food safety levels. Specifically, cooked food should be kept at temperatures above the danger zone (from 5 to 57 °C) prior to its consumption to prevent its contamination by bacteria and other unhealthy contaminants. In general, many studies address food preparation and storage separately, despite being complementary. In this study, we attempt to understand whether, the use of improved cookstove combined with heat retention box would result in improvements with regard to fuel and time saving, and adequate food storage temperatures. Furthermore, we examine the acceptability of food prepared with these two systems based on consumers’ preference analysis. Involving 122 participants, the study was conducted in Gurué district, central Mozambique. Results The use of improved cookstove resulted in energy savings of 9% and 17% for cooking maize porridge and beans curry, respectively. The overall time consumption for cooking decreased by 14% (beans curry) and 24% (maize porridge). The use of heat retention boxes shows a better heat retention ability as compared to the locally used heat retention systems (leftovers, banana leaves). Conclusions The study concludes that improved cookstove is a sustainable mean for saving cooking time and fuel. Heat retention box has a potential to maintain adequate food storage temperatures. Both improved cookstove and heat retention box present a superior performance compared to traditional technologies; thus, can easily be diffused for not affecting the quality of food.