Effect Of Moderate Peeling On Nutritional Quality And Storage Stability Of Wheat Flour

The traditional milling process stripped away the cortex,aleurone layer and germ of wheat,leading to the loss of a lot of nutrients.Whole wheat flour is a safety hazard because it contains contaminated wheat skin,and lipid and lipase in the cortex and embryo make it intolerant to storage.In order to ensure the nutritional quality and safety quality of wheat flour,peeling and pulverizing process came into being,peeling rate is an important parameter in the peeling and pulverizing process.Too low peeling rate cannot remove the skin,and too high peeling rate may cause damage to nutrient-rich aleurone layer.Based on this,according to the structural characteristics of wheat grains,moderate peeling is proposed in this paper,aiming to make more wheat embryos and aleurone layers grind into flour by peeling and scraping a small amount of cortex,so that wheat flour has a more balanced nutrition,good storage stability and longer shelf life.In this paper,two durum wheat,Xinong 20 and Xinong 985,were used as raw materials.The effects of moderate peeling on nutritional quality and storage stability of wheat flour were studied,which provided theoretical basis for the development and storage of peeling wheat flour.The possibility of adding antioxidants to prolong the shelf life of peeled wheat flour was investigated.The main findings are as follows:(1)Moderate peeling rate of 3% preserved the essential nutrients and active substances in wheat better.The nutritional indexes of moderately peeled wheat flour meet the requirements of whole wheat flour industry standard.Compared with whole wheat flour,the contents of total dietary fiber and ash decreased,the contents of total starch and γ-aminobutyric acid increased,and the contents of other nutrients and active substances did not change significantly after moderate peeling.High peeling rate could decrease the contents of crude fat,crude protein,total dietary fiber and ash,the contents of alkylresorcinol,γ-aminobutyric acid,total phenol and total flavonoids,and the total antioxidant activity.(2)Moderate peeling can delay the hydrolysis and oxidation of lipid in wheat flour,improve the storage stability of wheat flour,and the effect is more significant when the peeling rate is higher.With the extension of storage time,the fatty acid value,peroxide value and malondialdehyde content of whole wheat flour and peeled wheat flour increased,and the increase of moderately peeled wheat flour was smaller than that of whole wheat flour,but larger than that of high peeled wheat flour.At the end of storage,the fatty acid value of Xinong 20 whole wheat flour increased by 77.7%,that of moderately peeled wheat flour increased by 53.3%,that of 6% and 9% peeling rate wheat flour increased by41.5% and 31.1%,respectively.The peroxide value increased by 0.44meq/kg for whole wheat flour,0.41meq/kg for moderately peeled wheat flour,0.10 and 0.06 meq/kg for 6%and 9% peeling rate wheat flour,respectively.The malondialdehyde increment of whole wheat flour was 2.96 times that of moderately peeled wheat flour.The fatty acid value of Xinong 985 whole wheat flour increased by 92.4%,that of moderately peeled wheat flour increased by 87.6%,that of 6% and 9% peeling rate wheat flour increased by 67.2% and15.3%,respectively.The peroxide value of whole wheat flour increased by 0.20meq/kg,that of moderately peeled wheat flour increased by 0.07meq/kg,that of 6% and 9% peeling rate wheat flour increased by 0.16 and 0.10 meq/kg,respectively.The increase of malondialdehyde in whole wheat flour was 1.95 times that of wheat flour with 3% peeling rate.The lipase activity and fat oxidase activity of peeled wheat flour decreased with the increase of peeling rate,and the peroxidase activity was lower than that of whole wheat flour,but there was no significant difference between wheat flour with different peeling rate.(3)Adding antioxidants can improve the storage stability of moderately peeled wheat flour and prolong its shelf life.After the addition of antioxidants,the fatty acid value,peroxide value and malondialdehyde content of moderately peeled wheat flour were significantly lower than those of the control group.Among them,BHA had the most significant inhibition effect on fat hydrolysis,which was more suitable to be added by spraying method,and adding vitamin C by dry mixing method had the best inhibition effect on fat oxidation.