Smart release-control of microencapsulated ingredients from milk protein tablets using spray drying and heating

Abstract There have been many materials used for controlled release of ingredients, but only a few are food-grade for humans. The milk proteins, including casein (relatively insoluble) and WPI (soluble whey protein isolates), have been engineered and used as shell materials in spray-dried particles for controlled release of microencapsulated ingredients (acetaminophen, coffee and ascorbic acid) in this work. Smart and customized control of the release time from a few minutes to a few hours, and then to over two days has been achieved using milk proteins with techniques that include acid-gelation, spray drying and/or heat-gelation. The release rate can be easily controlled by varying the ratio of milk proteins, where the casein-gel tablets require 24 h to be degraded in SGF (simulated gastric fluid) at 37 °C but WPI tablets can be degraded within 1.5 h. The time required for releasing 80% of the ingredients from milk protein tablets follows the order: casein-acetaminophen > casein-coffee > casein-ascorbic acid > casein-WPI-acetaminophen > casein-WPI-coffee > casein-WPI-ascorbic acid > WPI-acetaminophen > WPI-coffee > WPI-ascorbic acid. Characteristics of the spray-dried particles have been studied by FTIR and DSC. After the heat treatment, the milk protein tablets containing acetaminophen (for pain relief) have shown slower release rates. Typically, only 80% acetaminophen has been released within 24 h from the heated casein-acetaminophen tablet, and the release period is over two days.