| Sunflower seed is an important oil resource.In 2022,the global sunflower seed production exceeded 5.704 million tons,ranking third only after soybean and rapeseed in the world’s major oil production.At present,sunflower seeds are mainly used for oil production,and the by-product sunflower seed meal is mostly used as feed.Sunflower seed meal contains a large number of proteins,and the content is up to 29%-43%.Sunflower seed protein has the characteristics of balanced amino acid composition and high biological potency.It is an ideal plant protein resource for human beings.If it can be developed and utilized,it not only enriches the plant protein resources in China,but also improves the added value of sunflower seed industry.However,in the extraction process of sunflower seed protein,the use of conventional methods will lead to the oxidation of chlorogenic acid in sunflower seed protein to quinone.The extracted sunflower seed protein is dark brown,and its functional characteristics are also poor,which seriously affects its application in food.Therefore,in this study,low-temperature defatted sunflower seed cake was used as raw material to decolorize sunflower seed protein by ultrasonic-assisted macroporous resin adsorption decolorization.On this basis,the changes of its functional properties were analyzed and the relationship between functional properties and structure was further explored.At the same time,this study also preliminarily discussed the application of ultrasonic-assisted macroporous resin adsorption decolorization sunflower protein in sponge cake.The aim was to provide scientific basis for sunflower seed protein in food processing and utilization.The main research results are as follows:1.Using low temperature defatted sunflower seed cake as raw material,the sunflower seed protein was decolorized by different types of macroporous resin after ultrasonic treatment with different power.The results showed that under the condition of ultrasonic power 400 W,the sunflower seed protein was treated by ultrasonic treatment for 0 min,5min,10 min,15 min and 20 min,and then AB-8 macroporous resin was added to adsorb and decolorize it.The whiteness values(L*values)of sunflower seed protein were 72.86,83.26,79.13,77.84 and 78.01,respectively.Compared with untreated sunflower seed protein L*value,respectively,significantly increased by 17.45,27.85,23.72,22.43,22.6.The results showed that under the condition of ultrasonic power 400 W,sunflower seed protein was treated with ultrasonic for 0 min,5 min,10 min,15 min and 20 min,and then decolorized by AB-8 macroporous resin,the sunflower seed protein with high whiteness value was obtained.The whiteness value of sunflower seed protein treated with ultrasonic for 5 min and then decolorized by AB-8 macroporous resin was the highest,which was 83.26.2.The effects of ultrasonic treatment of sunflower seed protein for 0 min,5 min,10min,15 min and 20 min at 400 W ultrasonic power on the structure of sunflower seed protein were further investigated.The results of SDS-PAGE gel electrophoresis showed that the molecular weight of sunflower seed protein did not change significantly with the extension of ultrasonic treatment time.Circular dichroism analysis showed that the contents ofα-helix andβ-turn decreased significantly,and the contents ofβ-sheet and random coil increased significantly.The results of endogenous fluorescence spectrum analysis showed that the fluorescence intensity increased first and then decreased,and the maximum fluorescence absorption wavelength was red shifted,and the maximum emission fluorescence wavelength was blue shifted when the ultrasonic treatment time was further increased to 10 min,15 min and 20 min.The results of average particle size analysis showed that the average particle size decreased first and then increased,but the average particle size was significantly reduced compared with the unbleached sunflower seed protein.The surface sulfhydryl content increased first and then decreased;scanning electron microscopy(SEM)results showed that sunflower seed protein powder changed from compact large flakes to small fragments and porous structure appeared on the surface.3 The effects of ultrasonic assisted macroporous resin adsorption on functional properties of sunflower seed protein were investigated.The results showed that after ultrasonic treatment for 0 min,5 min,10 min,15 min and 20 min,the solubility,emulsifying ability,emulsifying stability and water holding capacity of the decolored sunflower seed protein adsorbed by AB-8 macroporous resin were significantly improved.Among them,after ultrasonic treatment for 5 min,the solubility,emulsifying ability,emulsifying stability and water holding capacity of the decolored sunflower seed protein adsorbed by AB-8macroporous resin were the highest.Compared with the untreated sunflower seed protein,the solubility increased by 51.34%,the emulsification and emulsifying stability increased by1.47 m~2/g and 16.22 min,respectively,and the water holding capacity increased by 1.51 g/g;the foaming ability and foaming stability of sunflower seed protein were significantly improved.The foaming ability and foaming stability of sunflower seed protein were the best after ultrasonic treatment for 5 min and AB-8 macroporous resin adsorption.Compared with untreated sunflower seed protein,the foaming ability and foaming stability were increased by 42.32%and 49.77%,respectively.The oil holding capacity of decolored sunflower seed protein decreased continuously.The gel properties were all significantly improved,among which the gel properties of decolored sunflower seed protein were the best after ultrasonic treatment for 5 min and adsorption with AB-8 macroporous resin,showing a stable gel network.Confocal electron microscopy showed that decolored sunflower seed protein was better wrapped on the surface of oil droplets than uncolored sunflower seed protein,which further confirmed that ultrasonic assisted macroporous resin adsorption decolorization improved the emulsification of sunflower seed protein.4.The above research results showed that ultrasonic assisted macroporous resin adsorption decolorization could significantly improve its foaming and emulsifying properties,which was expected to be applied to the processing and production of sponge cake.Therefore,this study explored the application of ultrasonic treatment for 5 min assisted AB-8 macroporous resin adsorption decolorization of sunflower seed protein in sponge cake.The results showed that when the addition amount was 5%and 10%,there was no significant difference in sensory score between the sponge cake and the non-added cake.At the same time,there was no significant difference in hardness,elasticity,cohesiveness,resilience and chewiness between the sponge cake and the non-added cake.The internal structure of the sponge cake was complete,the pores were evenly distributed,and the taste was soft,delicate and elastic.However,when the addition amount reached 15%and 20%,the sensory score decreased and the texture characteristics deteriorated.The above results showed that the sponge cake with better quality could be obtained by adding 10%ultrasonic treatment assisted by macroporous resin adsorption to decolorize sunflower seed protein. |
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