| Potato is rich in starch,dietary fiber,protein,vitamins and inorganic salts.Its lysine content is higher than that of rice and wheat.It is a high-quality staple food raw material.As the water content of potato is as high as 79.5%,it is easy to germinate or rot during storage and transportation,resulting in solanine,which is harmful to human health.Therefore,in order to prolong the storage cycle of potato,expand its processing use and avoid the production of harmful substances,dehydration and drying of potato into whole powder is an effective method.Potato whole powder can preserve the nutrition and flavor of fresh potato to the greatest extent.It can be directly used as consumer goods or raw materials for potato deep processing.Potato is rich in polyphenol oxidase,which is prone to enzymatic browning in the process of preparing the whole powder,resulting in the decline of the quality of the whole powder.Therefore,chemical color protectants are widely used in the preparation of potato whole powder.However,with the improvement of consumers’ attention to food safety,the safety of color protectants has also been questioned by more and more people.Aiming at the browning problem existing in the processing of potato whole powder,this paper proposed to use safe and effective physical methods to protect the color of potato,in order to ensure the safety of the prepared potato whole powder,and studied the effects of different color protection methods on the physical and chemical properties and processing and application effects of potato whole powder.The main research is as follows:Study on color protection technology of potato.The potato was treated with cooking,microwave and microwave cooking,and then the whole potato powder was prepared.The results showed that the color protection effect was the best when the microwave power was 550 W,the temperature was 80℃ and the treatment time was 20 min.Under these conditions,the inhibition rate of polyphenol oxidase was 96.77%,the brightness of potato was L* = 92.99 and the saturation was C*=18.30.In the cooking color protection treatment,the color protection effect is the best when the cooking time is 20 min.Under this condition,the inhibition rate of PPO is 98.39%,the brightness of potato all pink L* = 93.28,and the saturation C* =23.07;In the microwave-cooking color protection treatment,the color protection effect is the best when the microwave power is 550 W,the temperature is 80℃,the treatment time is 20 min and the re-cooking time is 10 min.Under this condition,the inhibition rate of PPO is 98.81%,the brightness of potato all pink L* =93.60 and the saturation C* = 24.35.The three color protection methods can effectively inhibit the activity of polyphenol oxidase,and the color protection effect of potato whole powder is significant.The physicochemical properties of potato powder treated with color protection were studied and compared with that without color protection.The results showed that some starch and protein were lost during color protection treatment,and the content of amylose increased;Through scanning electron microscope,it can be found that the whole powder particles treated with color protection expand and cracks appear on the surface;the whole potato powder treated by microwave-cooking has higher gelatinization degree,the highest viscosity,the lowest enthalpy of gelatinization absorption,and the highest swelling power and solubility.It can be used in instant breakfast powder and other products;The whole potato powder treated by microwave has better water holding capacity,the lowest water precipitation,higher freeze-thaw stability,slow sedimentation rate and not easy to aging.It is suitable for quick-frozen products.The dough characteristics of potato whole powder and its application in toast were studied.The whole potato whole powder without color protection and three color protection treatments were added to the high gluten flour in the ratio of 3:7 to prepare the dough,and then the rheology,water distribution,thermodynamic properties and gluten microstructure of the dough were compared and analyzed,The results showed that the viscoelasticity of color protected potato dough was better than that of non-color protected potato dough,the content of non frozen water increased,and the water migrated from weak bound water to free water;Total sulfhydryl group(22.30 μmol/g)of cooking and color protecting potato dough and the content of disulfide bond(11.44 μmol/g)was the highest,the gluten structure was the most stable,and the gluten network structure was relatively complete in the SEM picture.By comparing and analyzing the color and aging characteristics of potato toast,it is found that the toast added with color protecting potato powder is superior to the toast with potato powder in terms of color and anti-aging properties. |
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