| With the improvement of nutrition and health concept,people pay more attention to diet and health,and the demand for low-fat products is increasing day by day.Cookies are a very popular baked product,occupying an important consumption position.High fat content is a major feature of cookies,and high fat intake will increase the risk of cardiovascular diseases and obesity.Therefore,it is of great significance to look for green and safe fat substitutes and increase high fat intake to ensure the food safety and health of Chinese residents.Starch,as the main component in food,has been widely used in the food industry because of its rich source and low cost.In this paper,natural starch from different sources was used as raw material to prepare modified starch-based fat replacers by enzymolysis combined after high hydrostatic pressure and energy gather ultrasonic pretreatment technology,and its physical and chemical characteristics were comprehensively compared to screen out the best raw material source and pretreatment method.Then,the preparation technology was systematically optimized,and the influence of modification on the physicochemical properties and structural characterization of starch was analyzed.Finally,the modified starch-based fat replacers obtained under the optimal process was applied to the development of low-fat cookies,aiming at providing theoretical basis and specific methods for the development and utilization of fat substitutes.The specific research results are as follows:(1)Five kinds of natural starches were pretreated with high hydrostatic pressure(300 MPa,10 min)and energy-gathering ultrasonic(0.75 W/cm~3,10 min),respectively.Then the starch-based fat replacers was prepared by high temperature resistantα-amylase controlled degradation method(95°C,15 min),and the physicochemical properties were compared.Compared with natural starch,modification can improve the water-holding capacity and oil-holding capacity,low-temperature solubility and swelling capacity(25°C and50°C)of five kinds of starch.Among all starch-based fat replacers,the sweet potato starch-based fat replacers(EGUSPS)prepared by energy-gathering ultrasonic combined with enzymolysis have the highest water-holding capacity(560.39%),emulsifying stability(276.4×10-2),good oil-holding capacity(183.35%)and solubility(41.89%,25°C;42.53%,50°C;50.66%,75°C),swelling power(11.21%,25°C;11.7%,50°C;15.29%,75°C),emulsifying activity index(17.01 m~2/g)and thermal stability.Compared with other sources of starch-based fat replacers,it has the best potential to replace the fat used in baked goods.(2)Fromultrasonic energy density,ultrasonic time,enzyme dosage,enzymatic hydrolysis time four conditions system optimized the optimal production process of sweet potato modified starch-based fat replacer as follows:ultrasonic energy density 0.75 W/cm~3,ultrasonic treatment time 15 min,enzyme dosage10 U/g,enzymatic hydrolysis time 5 min;The structural characterization analysis of the optimized sweet potato modified starch-based fat replacer showed that the modification changed the morphological characteristics of sweet potato starch granules,which resulted in a large number of crumbs and surface pores,and destroyed the crystalline area of the starch,resulting in the improvement of water and oil holding capacity,solubility and swelling capacity,glucose equivalent(DE value),emulsifying activity,emulsifying stability,emulsion particle size and thermal stability.FTIR results showed that ultrasonic-assisted enzymatic modification did not introduce new groups.(3)The sweet potato starch-based fat simulant prepared by the optimal production process can replace10%-70%of the oil in cookies.The results show that the linear viscoelastic range LVR of the dough increases,the structural stability and the dough plasticity increase significantly after the sweet potato starch-based fat simulant replaces the oil.Compared with full-fat cookie(FF),reduced-fat cookie has better appearance morphology,color,finer structure,and is equivalent to it in odor and taste Grey theory weighted analysis shows that the quality characteristics of sweet potato starch-based fat simulant are close to the"ideal sample"when the ratio of fat substitute is 50%(FR50)and 70%(FR70). |
