Granulation and encapsulation of N-Acetylcysteine (NAC) by internal phase separation

The encapsulation of small hydrophilic molecules offers advantages for the delivery of hydrophilic food supplements and food ingredients. These advantages include: masking off-flavors, reducing astringency, and controlling release profiles. We used an internal phase separation (IPS) method for simultaneous granulation and encapsulation of a small hydrophilic food supplement in corn oil. To prove that IPS is a suitable method for the encapsulation of small hydrophilic molecules with controllable release times, we used the nutritional supplement N-acetylcysteine (NAC) as our model molecule. NAC has a variety of health and pharmaceutical benefits however it suffers from poor organoleptic properties such as a bitter aftertaste, astringency, and a strong sulfur smell. We used IPS to produce free-flowing granules containing 56-78% NAC with diameters ranging from 100 to 1000 mu m. All the materials used in this process were either food safe or generally recognized as safe (GRAS). The granulated/encapsulated samples were characterized using FTIR, NMR, SEM, and LC-MS methods to confirm the presence of unreacted NAC in high loading concentrations. The kinetics of NAC release was then monitored using conductometry. The combination of hydrophilic carboxymethyl cellulose sodium salt (CMC) and hydroxypropyl methylcellulose (HPMC) gums with a hydrophobic coating such as ethyl cellulose (EC), provided an effective barrier to ensure a 5 min time window for NAC dispersion into water and drinks before the capsule starts to dissolve in water and loses more than 30 wt % of its total NAC loading.

Automated summary

The encapsulation of small hydrophilic molecules offers various advantages for delivering hydrophilic food supplements and ingredients, such as masking off-flavors and controlling release profiles. In this study, an internal phase separation (IPS) method was used to simultaneously granulate and encapsulate a small hydrophilic food supplement, N-acetylcysteine (NAC), in corn oil. By using hydrophilic gums and a hydrophobic coating, the NAC release time was controlled, ensuring a 5-minute window for dispersion in water and drinks.