Alginate Beads Containing Lactase: Stability and Microstructure

Abstract

β-galactosidase (lactase) is a widely used enzyme in food industry; however, it has low stability against thermal and mechanical treatments. Due to this, the purpose of present research was to analyze the encapsulation of lactase in alginate-Ca(II) beads in order to maintain its enzymatic activity towards freezing, freezing/thawing and storage. Also, the effect of the addition of trehalose, arabic and guar gums and its influence in the microstructure as well as in thermal properties and molecular mobility were studied. Lactase was successfully encapsulated in alginate-Ca(II) beads and the inclusion of trehalose was critical for activity preservation towards treatments, being improved in guar gum-containing systems. The gums increased the Tm' values which represents a valuable technological improvement. Finally, the presence of secondary excipients affected the microstructure, showing rods with smaller outer diameter and with lower compactness than alginate-Ca(II) beads. Also, beads composition greatly affects the size, shape and relaxations times.

Pink grapefruit lycopene encapsulated in alginate‐based beads: stability towards freezing and drying

“…In wet beads subjected to freezing, the crystallisation observed until reaching the first plateau corresponds to both water and lipids, with higher proportion of crystallised water at −20 °C (54%, with 46% corresponding to lipids) than at −30 °C (31% water, 69% lipid). Assuming the proportion of crystallised lipid is similar in all formulations, each bead system showed differences in the amount of crystallised water, in accordance to Traffano‐Schiffo et al ., , . The presence of trehalose reduced significantly the obtained values, mainly due to the formation of an amorphous matrix retaining a greater mass of water that is kinetically inhibited/delayed to crystallise (Traffano‐Schiffo et al ., ).…”

“…Furthermore, it has been described that arabic gum plays a role as stabiliser in drops of emulsions containing encapsulated agents (McClements & Jafari, 2018), which could be the mechanism for the increased lycopene stability respect to A-T beads. Besides, arabic gum also plays a role by reducing freezable water, reducing then crystallised interfaces that can destabilise lycopene (Traffano-Schiffo et al, 2017a, 2017b.…”

“…Diffusion coefficient (D) measurements were performed through the pulsed magnetic field gradient spin echo (PGSE) sequence as described in Aguirre Calvo et al ., and Traffano‐Schiffo et al ., .…”

“…In particular, the simple and mild aqueous‐based gel formation achieved by the ionotropic gelling of Ca(II)‐alginate remains a very attractive alternative for biomedical, food and pharmaceutical applications. However, some disadvantages are associated with this carrier, including high biomolecule leakage, low mechanical strength, large pore size and low cryo‐ and dehydro‐capacities (Santagapita et al ., ; Traffano‐Schiffo et al ., ), revealing the need to add other matrix components. In a previous work, it was shown that alginate beads with the addition of sugars and biopolymers were capable of enhancing the stability towards isomerisation as well as control the release of an encapsulated free‐solvent extract of lycopene (Aguirre Calvo & Santagapita, ; Aguirre Calvo et al ., ) and enzymes (Traffano‐Schiffo et al ., , , ).…”

“…Pectin (low methoxyl) can form gels with divalent cations by ionotropic gelation as alginate, forming rod‐like structure (Schuster et al ., ), and increase the loading efficiency of biomolecules (Santagapita et al ., ). The inclusion of arabic gum in beads reduced the amount of freezable water and increased the melting temperature of water, being both valuable technological improvements for frozen products (Traffano‐Schiffo et al ., ). The purpose of the present work is to study the stability of an encapsulated lycopene extract over freezing and drying treatments on Ca(II)‐alginate beads formulated with different excipients.…”