Energy efficiency and physical integrity of maize grains subjected to continuous and intermittent drying

Abstract

Grain drying is a common process, due to its need for the maintenance of quality, but it is the activity with the highest energy demand among the postharvest stages. Thus, this study aimed to evaluate the effect of different tempering times on the energy efficiency of drying process and maintenance of cell membrane integrity of maize grains harvested with moisture content at 0.34 ± 0.01 d.b. The grains were dried in an experimental fixed-bed dryer with control of temperature and air flow conditions. The experiment was conducted in a completely randomized design with five tempering times (0, 4, 8, 12 and 16 hours) and four repetitions, where zero corresponds to continuous drying, while the remaining times correspond to the intermittent dryings. The grains were dried at the temperature of 100 ºC and air flow of 15.4 m3 min-1 t-1 until reaching moisture content of 0.16 ± 0.03 d.b. For intermittent drying, the process was interrupted with 0.22 ± 0.02 d.b. and restarted after the tempering time. The increase of tempering time led to reductions in effective drying time, specific energy consumption, electrical conductivity and damage and increase in the drying rate and overall energy efficiency. Intermittent drying reduced the drying time, being 30.25% more efficient than continuous drying.

Performance of industrial drying and soybean grains quality

“…During the drying process, for each 1 kg of water evaporated from the grains, an average of 8,099.50 kJ of specific energy was required (Table 1). Specific energy consumption can be defined as the amount of energy required to evaporate a unit mass of water present in the product during drying (Lima et al, 2016;Mabasso et al, 2021).…”

Mechanical properties and integrity of stored corn grains after continuous and intermittent drying

“…In addition to contributing to maintaining product quality, intermittent drying is more energy efficient (Allaf et al, 2014;Foroughi-Dahr et al, 2015;Lima et al, 2016;Mabasso et al, 2021).…”

“…Several studies have investigated the mechanical properties of agricultural products from a quality preservation standpoint, with an emphasis on different moisture contents (Abdel Maksoud, 2009;Esehaghbeygi et al, 2009;Resende et al, 2013;Tarighi et al, 2011). There has been less focus on the temperature of drying air (Abasi & Minaei, 2014) and its relationship with rest times in storage, and although several studies mention quality, their focus is primarily on the efficiency of the drying process and/or its immediate effects (Filippin et al, 2018;Franco et al, 2020;Mabasso et al, 2020;Mabasso et al, 2021;Oliveira et al, 2022;Park et al, 2018;Zhao et al, 2018).…”