Optimization Of Baking Process Conditions Of Pumpkin Seeds And Its Effect On Microstructure And Storage Characteristics

Pumpkin seeds are rich in nutrients and contain amino acids,fatty acids,vitamins and other substances required by the human body,which have the effects of alleviating high blood pressure,anthelmintic and anti-inflammatory.After the pumpkin seeds are roasted,the microstructure and storage characteristics will change to some extent,and they will easily deteriorate and fail during the storage process.In this study,pumpkin seeds were used as raw materials,and salt was used as a heat transfer medium to optimize the roasting process of pumpkin seeds and analyze the effect of the roasting process on the microstructure and storage characteristics of pumpkin seeds.The main findings are as follows:1.Through single factor experiment and orthogonal experiment,the pumpkin seeds roasting process is optimized.The results show that the order of factors affecting the sensory evaluation of pumpkin seeds is heating time>heating temperature>NaCl and pumpkin seed mass ratio,and the best process condition is heating.At a temperature of 140? and a heating time of 15 min,the mass ratio of NaCl to pumpkin seeds was 4:1.Under this condition,the sensory evaluation score of pumpkin seeds was 94 and the chewability was 16.2 mJ.2.By comparing the XRD patterns of pumpkin seeds before and after baking,it can be found that the peak angle of pumpkin seeds before and after baking is close to the XRD pattern,and only the peak value has changed,indicating that the baking process has not changed the crystal structure of pumpkin seeds;The infrared spectrum of pumpkin seeds found that after roasting,pumpkin seeds may appear to decompose long-chain unsaturated fatty acids into aldehydes or ketones.Both pumpkin seeds before and after baking at 750 cm-1 and 1600 cm-1 Similar absorption peaks indicate that the double bond structure of pumpkin seeds' unsaturated fatty acids was not destroyed by roasting;by comparing the scanning electron micrographs of pumpkin seeds before and after roasting,it was found that the microstructure of pumpkin seeds after roasting had changed to a certain extent.There are more obvious pores between the tissues,the cells are arranged in disorder,the distribution is irregular,and there are dry wrinkles,atrophy and ruptures.It shows that the baking treatment will cause some damage to the surface morphology of pumpkin seeds.By comparing the specific surface area of pumpkin seeds before and after baking,it is found that the specific surface area of pumpkin seeds before baking is 1.454 m2/g,and the specific surface area of pumpkin seeds after baking is 9.040 m2/g,indicating that the evaporation and evaporation of water during roasting will increase the specific surface area of pumpkin seeds.By comparing the texture characteristics of pumpkin seeds before and after roasting,it is found that after roasting,the hardness,chewability.Both the breaking strength and the shear strength decreased,which indicated that the water loss of pumpkin seeds due to roasting treatment would cause some changes in the texture characteristics of pumpkin seeds.3.Roasted pumpkin seeds with tert-butyl hydroquinone(TBHQ),roasted pumpkin seeds with D-isoascorbic acid(VC),roasted pumpkin seeds without antioxidant and untreated pumpkin seeds The sealed package was placed in an oven at 37? and named as TBHQ group,VC group,roasted group and unbaked group.On the 42nd day,the acid value and peroxide value of TBHQ group were the lowest of the four groups..The volatile components of pumpkin seeds in TBHQ group and roasted group on day 42 were analyzed by head space solid phase microextraction combined with GC/MS.The results showed that the aldehydes in pumpkin seeds in TBHQ group were 5 species less than roasted group.The content decreased by 3.84%;the volatile matter content of ketones was one less,and the relative content decreased by 1.24%;the volatile matter content of two acids was less,and the relative content increased by 2.3%,which shows that the addition of antioxidants can delay the oxidation and rancidity of pumpkin seed oil.Using TBHQ as an antioxidant additive for pumpkin seeds is beneficial to the storage and preservation of pumpkin seeds.