Use of a crosslinked casein micelle hydrogel as a carrier for jaboticaba (Myrciaria cauliflora) extract

Casein micelle hydrogels were developed using transglutaminase (Tgase) as a crosslink agent in order to encapsulate anthocyanins from jaboticaba fruit (Myrciaria cauliflora). Spray dried casein micelles (CMs) powder was rehydrated in ultrapure water at a concentration of 4.5% w/w, and Tgase was added at 3 units/g of casein. The suspensions were incubated at 45 °C for 1 h, followed by enzyme deactivation at 85 °C for 5 min. Jaboticaba extract (JE), obtained from jaboticaba peel, was added to the suspensions at a concentration of 2% (w/w) at 25 °C. In the suspensions, Tgase promoted a reduction in CMs size and an increase in the degree of casein polymerization. The presence of JE did not affect CMs size or charge. The hydrogel samples were produced by acidification of the suspensions using 2% w/w of glucono – δ – lactone until pH 4.5 at 30 °C. The hydrogels were analyzed using small deformation rheology and confocal laser scanning microscopy. Tgase treatment promoted the formation of a more compact protein matrix compared to the samples without the enzyme. The presence of JE decreased hydrogel elasticity and increased hydrogel pore size. The JE release profile was evaluated by immersing the hydrogels in three buffer solutions at pH 2.0, 4.5 and 7.0. The release rates for the hydrogels with Tgase were lower for all pH values. Solutions with higher pH values induced faster release rates. These findings can be applied to specific delivery systems, such as the transport of JE in an intestinal environment.