Effects Of Woody Edible Oils On The Stability Of Pickering Emulsions And Its Application For Lycopene Loading

Emulsion system is one of the most common forms of food,which not only give foods unique sensory qualities,but also have important application values for nutrition delivery.Pickering emulsion avoids the toxic and side effects of traditional surfactants,and has good stability,anticoagulation and loading capacity.Studies have found that oil has an important effect on the stability of Pickering emulsions.Woody edible oils have higher nutritional value and health-promoting function than herbal edible oils.However,their applications in Pickering emulsions are rarely studied.In this study,different woody edible oils were used to prepare emulsions.The relationship between the physicochemical properties of the oils and the stability of the emulsions was analyzed.Afterwards,effects of woody edible oil on the stability of lycopene-loaded emulsions were investigated.The main research contents and results are summarized as follows:(1)Analysis of fatty acid composition and physical properties in different fats.Ten vegetable fats(including 8 woody fats and 2 herb fats)were compared in terms of fatty acid composition and oil viscosity.GC-MS analysis showed that a total of 21 fatty acid components were detected in the selected 10 types of oils.Among them,oleic acid and linoleic acid were the main unsaturated fatty acid components of oils and fats.Their contents in olive oil,pepper oil,red pine seed oil,walnuts Oil,camellia oil,almond oil,coconut oil,palm oil,peanut oil,and soybean oil accounted for 85.10%,79.13%,93.92%,93.84%,85.96%,87.40%,15.05%,67.80%,86.67% and 79.86% of the total fatty acids,respectively.By contrast,coconut oil and palm oil has more saturated fatty acids(83% and 27%),respectively.Oil viscosity analysis showed that all oils except palm oil exhibited the characteristics of typical Newtonian fluids,but there had significantly different oil viscosity.Peanut oil exhibited the highest apparent viscosity of 58.5 m Pa·s,whilst soybean oil had the lowest viscosity of 42.6 m Pa· s.(2)Construction of Zein-TA composite nanoparticles and its characteristics in different woody edible oils.Zein-TA composite nanoparticles(ZTP)were prepared using an anti-solvent method under the conditions of p H 5.0 and Zein:TA 5:1.The results of Fourier transform infrared spectroscopy(FTIR)and scanning electron microscopy(SEM)showed that the construction of ZTP was successful.Three-phase contact angle and ANS fluorescent probe assays showed that the hydrophobicity of ZTP was significantly lower than that of Zein.The three-phase contact angle of Zein in different oils was 108.7-120.8 °,while the ZTP was85.2-103.4 °.(3)Preparation and characterization of woody edible oils-based Pickering emulsions.Under the condition of 1% protein concentration and 50% volume fraction of oil phase,Pickering emulsions were prepared with different oils and fats.The stability experiment of the emulsions showed that the emulsions had different degrees of water phase precipitation.The emulsions containing peanut oil had obvious demulsification.By contrast,emulsions containing olive oil and coconut oil exhibited better stability.Meanwhile,results from centrifugal stability,emulsion particle size,oil encapsulation rate,and emulsion rheology assays showed that the emulsion gel strength increased with oil viscosity and polarity.Fats rich in unsaturated fatty acids was prone to form a stronger gel structure.Moreover,the fatty acid chain length will also affect the gel strength.(4)Preparation and characterization of lycopene-loaded Emulsion.Compared with those without lycopene,the lycopene-loaded emulsions had less water phase precipitation but significantly higher stability.Following the loading of lycopene,the particle size of the emulsion was reduced from 27.4-31.6 ?m to 20.54-27.0 ?m.The rheological dynamic oscillation data showed that the difference between emulsions became smaller,and the gel strength of the emulsion prepared from peanut oil,soybean oil,red pine seed oil,and camellia oil increased.The apparent viscosity of the steady-state rheological results was significantly lower than that of before loading,which affects the fats with lycopene viscosity,stability of oil-water interface characteristics.(5)Analysis of antioxidant ability and storage stability of lycopene-loaded Pickering emulsion.Following the loading of lycopene,the iron reducing power of the emulsion and the DPPH free radical scavenging activity were significantly enhanced,increasing by 42.13% and32.83%,respectively.Production of conjugated diene(CD)was effectively inhibited during storage.There was a positive correlation between the content of lipid hydroperoxide(LH)and malondialdehyde(MDA)and the storage time.Lycopene-loaded Pickering emulsion could effectively inhibit lipid oxidation.In terms of fatty acid profiles,unsaturated fatty acids are more easily oxidized than saturated fatty acids.(6)In vitro digestion of lycopene-loaded Pickering emulsion.Compared with oil alone,Pickering emulsion significantly improved the lycopene bioavailability and digestive stability,with the bioavailability increasing from 3.28% to 17.20%.Moreover,lycopene retention rate in the intestinal digestive juice was increased from 48.44% to 70.26% in soybean oil,47.90%to 64.40% in peanut oil,50.43% to 74.83% in olive oil,and 52.11% to 76.69% in camellia oil,respectively.