| Potato,also known as "yangyu",will be sliced dry,fried puffed after eating,is widely adopted by the folk cooking way.The potato slices obtained by drying can not only solve the problem of intolerant storage of fresh potatoes,but also can be fried to enrich the traditional potato food categories.The experience shows that the effect of direct drying of potato slices is poor,and the potato slices can not only protect the color,but also improve the effect of frying.In the process of blanching and drying potato slices,a series of changes occurred in cell structure,starch particle morphology and structure,which gave the material basis of potato slices to improve the extruded properties of frying.Literature research shows that the quality of hot expanded starch based food is widely affected by the starch aggregation structure in raw materials.Based on this,on the basis of traditional potato slices production,this study will systematically study the effects of pretreatment methods on its frying and puffing performance,in order to provide scientific and technological basis for promoting the industrial production of high-quality fried potato slices.The objective of this study was to reveal the influence of pretreatment blanching-aging process on potato frying puffing properties,and to explore the influence of pretreatment(blanching time,leaching conditions and aging conditions before blanching)on potato chip puffing properties.The physicochemical properties of starch in dry samples were tested and analyzed by measuring gelatinization degree and crystallinity degree,and the texture,color,oil content and swelling rate of expanded products were measured,and the oil distribution was observed by laser confocal microscope.The effects of blanching and aging treatment on physicochemical properties of dry potato slices and puffing properties of potato crisps were described,and suitable pretreatment conditions were selected.The main research results of this paper are as follows:(1)The influence of blanching treatment and blanching time on the puffing performance of potato slices was explored.Blanching treatment changed the gelatinization degree and crystallinity of dry potato slices;It is found that blanching has an important effect on the texture formation of fried potato slices.With the extension of blanching time,the hardness of fried products increases from 3.65 N to20.29 N,which is nearly 6 times of the original increase,and the brittleness increases from 1.75 to nearly 3 times(6.5).However,oil content increases with the extension of blanching time,which increases from 15.49% to 20.86%.(2)The influence of soaking conditions on the expanding performance of potato slices before scalding treatment was explored,and the influence of acid leaching on the gelatinization degree and crystallinity of dry potato slices was not significant;By analyzing and measuring the swelling characteristics of the samples after frying,it was found that the swelling characteristics of the samples after dipping for 30 min were significantly improved.After frying,the hardness of the samples after dipping for 30 min decreased from 14.74 N and 13.52 N to 11.28 N.The oil content was reduced from 19.48% and 21.32% to 18.01%,and the oil absorption of the product was also significantly improved.In conclusion,acid leaching plays an important role in improving the puffing characteristics of puffed products,which is helpful to obtain products with good taste.(3)The influence of aging process on the puffing performance of potato slices was explored.After the sample was fried and puffed by hot air drying at 100℃,many large pore bubbles were formed on its surface,which greatly increased its volume.It was the group of samples with the largest volume puffing rate among the six groups of samples.However,the linear puffing ratio(length and width)close to 1.00 indicated that the potato slices did not occur uniform and complete puffing,and the texture was not ideal,indicating the necessity of aging in the pre-processing of puffed potato slices.(4)The effect of aging time on potato chip expansibility was explored.Crystallinity of dried samples increased,and volume expansibility of fried samples decreased(expansion rate decreased from 10.43 times of non-aging,hot air drying at50℃ to 6.35 times of hot air drying at 50℃ for 24 h aging).It shows that with the increase of the degree of starch recrystallization,the gel forms a stronger structure,and the same pressure during frying puffing becomes more and more difficult to form a large pore structure in the internal water network.In addition,the samples obtained by natural drying had greater crystallinity,but the linear expansion rate and volume expansion rate of the expanded products were the largest among the six groups of samples,which may be related to the formation of a more uniform and dense gel network structure during the slow aging process of natural drying.According to the above content,the pretreatment process of raw materials before frying puffing,especially the blanching-aging process is the key step to determine its frying puffing characteristics.By changing the blanching time,leaching conditions and aging conditions to control the gelatinization degree and aging process of the sample,improve the gel structure of the dry sample and the structure and texture of the fried puffing sample,Blanching for 6 min made the dry sample gelatinized completely,and the fried puffed sample improved in all aspects.The bulking properties of the products were optimized after 30 min leaching,and the bulking products with higher bulking rate and better texture were obtained after 12 h aging.The research can provide a theoretical basis for improving the quality of starch based raw material slicing and frying extruded products and lay a foundation for the industrialization of related products. |
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