Experimental Evaluation of Coffee Extraction Times: Integrating Statistical Analysis in Engineering Education

Elizabeth Puelles Bulnes M.; Espinoza V.A.A.; Atoche Puelles A.L. · Proceedings of the LACCEI international Multi-conference for Engineering, Education and Technology (2025) · DOI: 10.18687/laccei2025.1.1.2342

Resumen

The objective of this study is to analyse whether there are significant differences in coffee extraction times based on different commercial methods: filtration, evaporation, and immersion. To achieve this, a bifactorial experimental design was employed, using three types of coffee makers (Italian, French press, and drip filter) and three varieties of coffee from well-known brands in the Peruvian market. To ensure the validity of the statistical model assumptions, normality, homoscedasticity, and independence of residuals tests were conducted. The results showed a significant difference in extraction times with a 95% confidence level. Additionally, a post hoc Tukey and LSD (Least Significant Difference) analysis was applied with a significance level of ∝ = 0.05, identifying significantly different mean pairs and determining which method exhibited the longest extraction time. The findings indicate that the extraction method, particularly pressure and evaporation, is the primary factor influencing coffee preparation time, while the coffee brand has minimal impact. Among the evaluated extraction methods, evaporation, represented by the Italian coffee maker, proved to be the most efficient. In contrast, filtration, associated with the drip filter coffee maker, resulted in the longest extraction time. Meanwhile, immersion, represented by the French press, demonstrated greater stability in preparation times. From a sensory and chemical perspective, the research highlights that extraction times influence the essence, quality, body, and aroma of the final coffee. Furthermore, it was found that inadequate extraction can generate undesirable flavors, such as excessive acidity with short extraction times or pronounced bitterness with prolonged extractions. This study not only contributes to the understanding of optimal coffee preparation but also serves as a practical case study in engineering education. The implementation of experimental methodologies, statistical data analysis, and process optimization in this work provides a useful didactic approach for disciplines such as chemical engineering, food engineering, and industrial engineering. The experimental design applied in this research allows students to comprehend the importance of variable control, process modelling, and evidence-based decision-making. Moreover, it fosters critical thinking and innovation by exploring how small variations in extraction methods can significantly impact the quality of the final product. This study also offers valuable contributions to the gastronomic and commercial sectors and serves as an educational tool in teaching process optimization, statistical analysis, and the application of the scientific method in engineering.

Instituciones: Universidad Nacional Mayor de San Marcos; Universidad Ricardo Palma