Monitoring of moisture contents and rehydration rates of microwave vacuum and hot air dehydrated beef slices and splits using hyperspectral imaging.

• Shorter fibres in beef slices improved hot air dehydration efficiency. • Microwave vacuum drying showed higher rehydration rates in samples than hot air. • Beef slices showed higher shrinkage rates and expansion ratios than splits. • Principal component analysis could cluster samples by fibre and processing factors. • Hyperspectral imaging could visualise differences in sample processing behaviours. Effects of food microstructure and processing methods on moisture migration in food during processing are important for improving product quality. This study evaluated the effects of fibre directions and dehydration methods on beef dehydration and rehydration behaviours using near-infrared hyperspectral imaging. Beef slices (transversal cut) and splits (longitudinal cut) were dehydrated by hot air drying (HAD) and microwave vacuum drying (MVD). Results indicated the moisture in the slices evaporated faster than that in the splits during HAD and MVD processed samples exhibited higher rehydration rates than HAD ones. Principal component analysis showed great performance in clustering samples based on fibre directions, processing methods and time. The established simplified RC-SG-PLSR and RC-2nd Der-PLSR models possessed good prediction accuracies for moisture (R2 p = 0.994) and rehydration rate (R2 p = 0.889), respectively. Chemical distribution maps also confirmed the influence of fibre directions and dehydration methods on moisture migration in samples. [ABSTRACT FROM AUTHOR]