Screening Of Raw Potato Flours With High Thickening Stability And The Application In Ketchup

Food thickener is a kind of commonly used food additive with huge market demand.With the improvement of people's life quality,food products using natural thickener are more favored by consumers.Raw potato flour is rich in starch,protein,dietary fiber and other components,which can improve the viscosity of products,and improve the texture and structure of food,and therefore has great potential as food thickener.In this paper,raw potato flours of different varieties were prepared by slicing,hot air-drying and grinding.Then several kinds of the flours with excellent thickening properties were screened,and the factors influencing the thickening stability were analyzed.Finally,the raw potato flour was applied to the thickening of ketchup.The main results are as following:Firstly,11 different varieties of potatoes were used to prepare raw potato flours with low gelatinization degree by hot air drying,and the samples suitable as thickener were screened.According to the gelatinization curve,the breakdown of raw potato flours prepared by helan,guinongshu 1,and heijingang only accounted 2% of the peak viscosity,and the viscosity stability was good.Furthermore,these raw potato flours showed excellent thickening stability.Specifically,the thermal stability of raw potato flours prepared by helan,guinongshu 1 and heijingang were 70.73%,71.14% and 61.76% respectively,the acid stability of helan,guinongshu 1 and heijingang were 65.99%,69.18% and 76.21% respectively,and the shear stability reached 75% ? 80%,which were significantly all higher than that of common raw potato flours in the control group.So,these raw potato flours could be used as green thickener in food.Secondly,the influences of starch properties and cell wall on the stability of raw potato flour thickeners were studied.The results showed that the particle size and content of starch,the cell wall integrity before drying,as well as the combination state of starch and cell wall components greatly affected the stability of raw potato flour thickeners.The hot air-drying step promoted the adhesion of intact cell wall to the surface of starch particles and form a tight combination,which strengthened the protection of non-starch components on starch and improved the stability of raw potato flour thickeners.When the content of starch was low,the protective of non-starch on starch was enhanced and the stability of the raw potato flour thickener was improved.Thirdly,the application characteristics of selected raw potato flour thickeners were studied.Thermodynamic analysis results showed that the gelatinization onset,peak,and completion temperatures of raw potato flour thickeners were higher than that of common raw potato flours,but the gelatinization enthalpies were relatively low.Compared with common raw potato flours,raw potato flour thickeners had higher solubility,but its amylose dissolution was lower(12.86?13.76 g/100g).After freezing and thawing,there was almost no water precipitating from the raw potato flour thickeners,which means the raw potato flour thickener had good freezethaw stability.Compared with the common raw potato flours,the raw potato flour thickeners had good application properties.Finally,the raw potato flour thickener was applied to the ketchup to verify and evaluate its feasibility in food system.Results showed that the soluble solid content of ketchup with raw potato flour thickener was between 22%?28%(w/w)with p H<4.6,which accorded with the description of medium-concentration ketchup in GB/T 14215-2008.The results of texture analysis implied that the raw potato flour thickener could significantly improve the hardness,cohesive,adhesive of ketchup.Furthermore,the water distribution and rheological properties results showed that the raw potato flour thickener and commercial modified starch had the similar application effects in ketchup.The stability test indicated that the viscosity of ketchup added with raw potato flour thickener changed little after storage under room temperature for30 days,which was significantly better than that with ordinary raw potato flour.Therefore,the raw potato flour thickeners were suitable for thickening of ketchup.