Estimation method of moisture content at the meat surface during drying process by nir spectroscopy and its application for monitoring of water activity

Monitoring of water activity at meat surface is important on controlling the quality of aging beef, because the fermentation microorganisms are grow on the meat surface. Although in previous study water activity of beef under drying process was investigated by near infrared (NIR) spectra, spectra data have been obtained from the whole beef cut. Therefore, this study aimed to estimate water activity of the surface of the sample using NIR spectra in the 700-1050 nm. Different thick samples in the 2-10 mm were prepared and the optimization of the measurement conditions was carried out for surface monitoring. Consequently, the optimal measurement condition were determined for monitoring the spectra from the surface of a beef cut. The change in moisture content and water activity about lump sample of beef were investigated for drying at 4°C. A linear decrease in water activity estimated by NIR spectra was observed, and the estimated water activity reached 0.8 after around 22~25 days. These results showed the evaluation potential of dry state at surface of beef by using NIR spectroscopy.