Jasmal Ahmari Syamsu 1,2,3, Andi Muhammad Rusyidi 4, Sri Purwanti 1, Abdul Alim Yamin 1 and Ichlasul Amal 5
1Faculty of Animal Science, Universitas Hasanuddin, Makassar, Indonesia; 2Feed Technology and Industry Research Group, Universitas Hasanuddin, Makassar, Indonesia; 3Center of Research and Development for Livestock Resources and Tropical Animals, Universitas Hasanuddin, Makassar, Indonesia; 4South Sulawesi Provincial Livestock and Animal Health Service, Makassar, Indonesia; 5Animal Feed Technology Study Program, Faculty of Vocational Studies, Universitas Hasanuddin, Makassar, Indonesia
*Corresponding author: jasmal.syamsu@unhas.ac.id
Rice bran is widely used as a feed ingredient, but rice husk adulteration can compromise its quality. This study developed a Rice Bran Physical Adulteration Index (RBPAI) based on simple physical measurements and evaluated its potential for screening commercial rice bran. We prepared reference mixtures containing 0–100% rice husk at 2.5% intervals and obtained ten replicate measurements at each of 41 adulteration levels. We measured bulk density (BD), tapped density (TD), and angle of repose (AR), and subjected the mean values at each adulteration level to principal component analysis (PCA). We used the retained principal component to construct the RBPAI, then calibrated it against known rice husk proportions using linear regression. We then applied the index to 31 commercial rice bran samples collected from rice mills, traders, feed mills, and livestock farmers in South Sulawesi, Indonesia. Bulk density and TD increased progressively with increasing rice husk proportion, whereas AR decreased. The first principal component explained 98.433% of the total variance and yielded the equation RBPAI = 0.337ZBD + 0.337ZTD − 0.335ZAR. The RBPAI showed a strong linear relationship with rice husk proportion (R² = 0.969), with an apparent calibration mean absolute error (MAE) of 4.259 and root mean square error (RMSE) of 5.183 percentage points. Commercial samples exhibited substantial variation in RBPAI-derived adulteration estimates across supply-chain groups and sampling locations. These findings suggest that RBPAI can convert low-cost physical measurements into a practical preliminary screening tool for assessing rice bran quality. However, because rice husk content in the commercial samples was not independently verified, treat the field estimates as model-based indications and confirm them with appropriate analytical methods.