Temperature‐Sensitive Microcapsules Containing Lactoferrin and Their Action Against Carnobacterium viridans on Bologna

  Lactoferrin (LF) was encapsulated in 2 types of emulsion to protect it from contact with agents like divalent cations, which interfere with its antimicrobial activity. First, paste‐like microcapsules were prepared as water‐in‐oil (W 1 /O) emulsions from mixtures of 20% w/v LF in distilled water, 20% w/v LF in 3% w/v sodium lactate or in 20 mM sodium bicarbonate, which were emulsified with an oil mixture of 22% butter fat plus 78% corn oil and 0.1% polyglycerol polyricinoleate. Second, freeze‐dried double emulsion (W 1 /O/W 2 ), powdered microcapsules were produced following emulsification of paste‐like microcapsules in an external aqueous phase (W 2 ) consisting of a denatured whey protein isolate (WPI) solution. The release of LF from the W 1 /O microcapsules was dependent on temperature and NaCl concentration. LF was not released from the W 1 /O emulsion at <5.5 °C. Its release was greater from W 1 /O microcapsules when suspended in 5% aqueous NaCl than in water at ≥10 °C, whereas LF release from freeze‐dried microcapsules was not controlled by temperature change. Paste‐like microcapsules were incorporated in edible WPI packaging film to test the antimicrobial activity of LF against a meat spoilage organism Carnobacterium viridans . The film was applied to the surface of bologna after its inoculation with the organism and stored under vacuum at 4 or 10 °C for 28 d. The growth of C. viridans was delayed at both temperatures and microencapsulated LF had greater antimicrobial activity than when unencapsulated. The temperature‐sensitive property of the W 1 /O microcapsules was reduced when they were incorporated into a WPI film.