Construction Of Oleogel Loaded With Tea Polyphenols And Its Application In Bakery Products

Oleogelation is a healthy method to solidify oil,which can transform liquid oil into solid gel without chemical modification.Edible oleogel has certain plasticity and mechanical strength,and can be used as a new substitute for traditional plastic fat.However,as a lipid product with high unsaturated fatty acids,oleogels have lower oxidative stability than traditional solid fats.Tea polyphenols(TP)is an effective natural antioxidant,which can inhibit the process of lipid oxidation,but it has poor solubility in oil due to its hydrophilicity.In this study,a composite gelator(TP gelator)was prepared by embedding TP into beeswax after emulsification,and then used for the construction of oleogel.The structure characteristics and formation mechanism of TP gelator were studied;meanwhile,the physicochemical properties and loading mechanism of TP loaded oleogel(TPO)were analyzed;moreover,the TPO was used to replace shortening in cookies to investigate its application feasibility in bakery products.This paper intended to develop an oleogel system with high oxidation stability and provide a theoretical basis for its application in water-soluble nutrient carriers and bakery products.The main research contents and results are as follows:Firstly,soybean lecithin was added into molten beeswax as oil phase.TP aqueous solution was emulsified and dispersed in it to form a W/O emulsion,and TP gelator was obtained after lyophilization to remove water.The technological parameters were determined by single factor optimization experiments and the structure of TP gelator was characterized to explore its formation mechanism.The results showed that the addition content of 6%(w/w)soybean lecithin,the shear rate of 14500 r/min and the concentration of 30 mg/m L TP solution could be used to prepare the TP gelator with high embedding rate and good dispersibility.Beeswax interacted with soybean lecithin and TP through intermolecular interaction to form a stable complex.The polar group of soybean lecithin was combined with the phenolic hydroxyl groups of TP,and the hydrophobic chains were connected with the beeswax.TP was dispersed in the crystallization network of beeswax without changing its melting characteristics and crystal structure.Secondly,the TP gelator was dispersed in soybean oil to form TPO.The loading mechanism of TPO were studied by comparing with the properties of beeswax oleogels(BWO)and no-load oleogels(NLO).The physicochemical properties of TPO as plastic fat were analyzed by using shortening and margarine as reference.The results showed that with the increase of TP gelator concentration,the number of needle-like crystals inside oleogel increased,forming a denser crystalline network,which showed a stronger structure macroscopically.The emulsification process of TP gelator slightly reduced the gelation ability of beeswax.TP did not participate in the construction of the internal structure,but was distributed in the crystalline network in an amorphous form.TPO has good physical and oxidative stability.The oil binding capacity of 8%TPO remained above 99% during storage,and the peroxide value at the end of storage decreased by 60.6% and 54.7% compared with that of soybean oil and NLO.The crystal structure and melting characteristics of 8% TPO are similar to those of shortening,and it has the potential to be used as a substitute in bakery products.Finally,TPO instead of shortening was applied to bakery products.The structural characteristics of TPO and TPO/shortening blends in different proportions and their baking performance in cookies was studied.The results showed that both TPO and TPO/shortening blends remained stable viscoelastic semi-solid structure after shearing,which had similar rheological properties to shortening.TPO partially replaced shortening significantly increased the unsaturated fatty acid content in cookies,and at the same time effectively enhanced the oxidation stability of vegetable oil-based cookies.The peroxide value decreased by 33.5%compared with soybean oil cookies.The physicochemical properties(such as appearance,texture and oil migration)of TPO cookies were better than those of cookies containing soybean oil,but there were still different from shortening cookies.While the cookies prepared by the blend of oleogel replacing 50% shortening were most similar to shortening cookies and were more easily accepted by consumers.