Development of an Abrasive-assisted Cleaning Process for Milk Storage Vessels Using Size-fractionated Sand and Fragmented Coconut Coir

Abstract

Cleaning of dairy storage vessels is essential for maintaining product quality and reducing residue accumulation on food-contact surfaces. This study developed and evaluated an abrasive-assisted cleaning approach using size-fractionated sand and fragmented coconut coir in combination with a detergent solution. Sand and coir were cleaned, dried, graded by size and screened in preliminary trials using detergent solution at contact times of 60, 120 and 180 s. Cleaning performance was assessed from total dissolved solids (TDS), electrical conductivity (EC) and CIELAB colour values of the recovered detergent solution. A conceptual cleaning model comprising a water reservoir, pump, delivery hose, dosing arrangement and test vessel was then used to evaluate selected sand and coir fractions for cleaning milk-soiled aluminium cans. The cans were soiled with a milk-dye mixture and cleaned at flow velocities of 0.5, 0.7 and 1 m/s for contact times of 5, 10 and 15 s. Detergent solution alone served as the control. The results showed significant differences (P<0.05) in TDS, EC and colour parameters among the cleaning treatments and operating conditions. In general, detergent combined with sand or coir produced higher soil-removal indicators than detergent alone, suggesting that the added abrasive materials improved the mechanical action of the cleaning solution. Sand with detergent showed the highest response in several treatment combinations, while coir with detergent also improved cleaning performance compared with the control. The findings indicate that locally available sand and coconut coir may support an economical abrasive-assisted cleaning process for milk storage vessels under the tested laboratory conditions. Further validation is required before industrial application.