Hot-air impingement roast drying of beef jerky: Effect of relative humidity on quality attributes

To mitigate encrustation of beef jerky and improve quality during hot-air impingement roast drying (HIRD) process, the effect of different relative humidity (RH) conditions (NO (about 2.3%), 10%, 15%, 20%) at a constant roast drying temperature of 120 °C on "encrustation" thickness, cooking yield, microstructure, tenderness, color, myoglobin, lipid oxidation, flavor and sensory quality of beef jerky were explored. Results indicate that improving RH decreased the "encrustation" thickness of beef jerky significantly (p < 0.05) as the moisture distributed more evenly shown by magnetic resonance imaging analysis. Microstructure observation showed that the number of gaps between muscle bundles decreased and muscle bundles become plumper at both cores and edges of beef jerky with an increase of RH. Meanwhile, humidification could improve the color quality of beef jerky, decline the content of malondialdehyde (MDA) as well as enhance the flavor of beef jerky. The findings in this work indicate that humidification enhances the quality of beef jerky by alleviating surface encrustation, improving color, reducing lipid oxidation, and enhancing roast drying flavor during HIRD processing.