Influence of superheated steam treatment with tempering on lipid oxidation and hydrolysis of highland barley during storage

Highland barley is an excellent source of dietary fiber and therefore this grain is receiving more and more popularity. The aim of this study was to improve the shelf life of highland barley by inactivating lipolytic enzyme using superheated steam (SS) with proper tempering and effects of SS processing on storage properties were compared. Results indicated that barley was stabilized by SS processing (160 degrees C) holding for 6 min with 6 h of tempering time could effectively reduce 38.85% lipase activity and 100% peroxides (POD) activity. Low-field nuclear magnetic resonance results showed tempering for 6 h provided proper water distribution of kernels meeting enzyme. Under the optimal conditions, highland barley maintained low free fatty acid (FFA) level and peroxide value (PV) after 8 weeks of storage and the storage quality in the form of flour has been improved more significantly than the kernels, lowing FFA levels of kernels by 15.00% and flour by 37.55%, respectively (P < 0.05). The changes of FFA composition was slowed down by SS processing after storage. Furthermore, color values and water hydration properties were altered by SS processing during the storage. In conclusions, these data highlighted the importance of SS processing, especially with proper tempering, and provided valuable information for the industry to improve the storage qualities of highland barley.

Automated summary

The use of superheated steam (SS) to process highland barley effectively reduces lipase and peroxides activity, improving the grain's shelf life. Proper tempering provides appropriate water distribution to meet enzyme needs. Under optimal conditions, both highland barley and flour quality are significantly improved with lower FFA levels.