Temperature-responsive palm oil-based-oleogels for encapsulation of D-limonene: effect of fat crystallisation and melting point

D-limonene is an important flavouring ingredient with a wide range of applications. However, its high volatility and low stability have severely impacted its application in the food industry. To address these limitations, temperature-flavour release control system is expected to be established to reduce the loss of D-limonene during processing and storage, as well as to control its release by temperature. The aim of the current study is to construct an oleogel system to encapsulate D-limonene using carnauba wax as a gelling agent and palm oils (POs) as the base oil. POs with 24 degrees C, 38 degrees C, 42 degrees C, 48 degrees C, and 52 degrees C melting points were selected to systematically investigate the effects of the base oil melting point on the crystal morphology, interactions, physicochemical properties, microstructure, and D-limonene release of the oleogels. The enthalpy of melting, enthalpy of crystallisation, hardness, stickiness, and gel strength increased in oleogels prepared using POs with a higher melting point. In addition, the oil-binding capacity (OBC) (>95%) of the oleogels increased with the base oil melting point, while the fat crystal distribution became more homogeneous and denser. Based on the influence that extraction temperature has on the concentration of released D-limonene (a lower concentration of aroma was released from high-melting-point POs oleogels at low temperatures (<1.9 mg mL(-1)), whereas the control group released >2.5 mg mL(-1)), suitable POs can be selected to achieve the release or retention of the aroma. These results demonstrate that a temperature-responsive flavour delivery system can be prepared with different PO melting points. The molecular dynamics of flavour release revealed that storage temperature and fat crystalline state impact the cumulative release rate of D-limonene.