Study On The Properties Of Non-aqueous Foams Prepared By Diacylglycerol

Formation of foams is critical for providing special texture and mouthfeel in lipid-based products.Micron or millimeter-sized bubbles incorporated into continuous semi-solid fat phases have the function of maintaining shape and soft taste as well as reducing caloric content.The unique molecular structure of Diacylglycerol(DAG)leads to its surface activity and high melting point,which can be used as an alternative to hydrogenated and saturated lipids,thus reducing the saturated fatty acid content,improving food safety and forming a healthy lipid-based system with nutritious.In this paper,DAG based oleogels and non-aqueous foams were produced.The effects of DAG on interfacial crystallization,foamability and foam stability,rheological properties and crystal morphology were studied.Four different tempering procedures were used to prepare non-aqueous foams containing long-chain diacyglycerol(LCD).The best method was determined by testing the foamability and form of crystals.The effect of LCD(2-10 wt%)on crystal polymorphisms,bubble size and distribution,rheological properties,structure properties and thermodynamic properties of Fully hydrogenated palm oil(FHPO)based oleogel and foam were investigated.The 10 wt% LCD and 2 wt% FHPO-8 wt% LCD based oleogels have comparable foamability and foam stability to 6wt% FHPO based oleogel.LCD mainly formed small plate-crystals and spherical-crystals layer which tend to exist at the interface of air bubbles,but FHPO mainly formed large needle-like crystals that tend to occur in the continuous phase.As for the FHPO-LCD compound oleogel,the crystals are more uniform.Meanwhile,the pickering crystallization at oil–gas interface as well as the network crystallization in the continuous phase contribute to the smaller bubble size and improve the rheological properties of oleogels and foams.Oleogels and non-aqueous foams were prepared using medium and long-chain diacyglycerol(MLCD)and ?-sitosterol at the ratio of 20:0,18:2,15:5 and 12:8.The co-crystallization of MLCD and ?-sitosterol on crystal distribution,microstructure,rheological properties and thermodynamic properties of oleogels and non-aqueous foams were investigated.A new type of material named air-in-oil-in-water(A/O/W)emulsion,which was referred to the oil foam incorporated in an aqueous phase containing a thickening agent and a hydrophilic surfactant,was introduced.The effect of interaction between MLCD and ?-sitosterol on flavor compounds release was studied.The foamability was higher in the system with higher MLCD concentration,while almost no bubble was found in ?-sitosterol based non-aqueous foam.For foam stability,only 20 wt% MLCD based and 18 wt% MLCD-2 wt% ?-sitosterol based non-aqueous foams showed obvious oil drainage and foam collapse.The co-crystallization of MLCD and ?-sitosterol in 15 wt% MLCD-5 wt% ?-sitosterol and 12 wt% MLCD-8 wt% ?-sitosterol based oleogel led to Pickeringcrystallization at oil–gas interface as well as the network crystallization in the continuous phase,which caused higher foaming properties and improved rheological properties.The interaction between MLCD and ?-sitosterol was analyzed by Fourier transforms infrared spectroscopy.The shift of the hydroxyl stretching vibration peak of compound system with different concentration indicates the formation of an inclusion compound,representing the interaction between MLCD and ?-sitosterol.The self-assembly of -sitosterol with MLCD caused the capability of controlling release of flavor compounds by combined emulsions.These novel emulsions can be widely used in different fields such as food and cosmetics.Oleogels and non-aqueous foams containing 10wt% monoglyceride(GMS),10 wt% LCD and their compound systems were prepared by optimized tempering procedure.The effects of LCD on foam stability,crystal size and distribution,rheological properties and thermodynamic properties of oleogels and foams containing GMS were investigated.The 2 wt% GMS-8 wt% LCD non-aqueous foam did not show oil drainage and foam collapse,indicating that the compound system of LCD together with GMS can achieve high foam stability.The LCD mainly formed fine spherical crystals,while GMS formed large needle-like or rod-like crystals.For GMS-LCD based non-aqueous foam,small spherical and needle-like crystals were observed both in continuous phase and oil–gas interface,which led to high rigidity of oleogels and foams.