| Pancakes are one of the traditional staple foods in northern China.Their unique processing method leads to low starch gelatinization and slow digestion and absorption.Moreover,they are made from coarse cereals,so pancakes are considered to be staple foods suitable for diabetics.However,traditional pancakes are not popular among consumers because their taste are dry and hard and tough to chew,which hinders their promotion.Studies have shown that sourdough can improve the sensory and nutritional quality of high-moisture grain products such as steamed buns and steamed cakes,but there are few studies about the effect of sourdough on pancakes and other low-moisture grain products.Therefore,this study selected a specific functional Lactobacillus plantarum strain to ferment sourdough,and explored its effect on the sensory quality of pancakes.At the same time,its functionality was evaluated through in vitro and animal experiments,and a shelf-life prediction model was established.This study is targeted at providing a theoretical basis for the development and industrial production of functional pancakes staple food suitable for diabetics.The main contents and results are as follows:Firstly,the effect of sourdough addition on the p H,texture,sensory score,moisture content,water status and microstructure of pancakes was investigated.Compared with traditional pancakes,the addition of sourdough lowered the p H of pancakes effectively,improved the toughness and extensibility of pancakes,and thus improved the taste of pancakes.Among them,pancakes with 20% sourdough had the highest sensory scores.The improvement of sourdough on the sensory quality of pancakes was mainly attributed to the fact that it could significantly increase the moisture content of pancakes,change the water distribution state,promote the combination of water with sugar and starch.Furthermore,the addition of sourdough made the surface of pancakes form a more smooth and uniform microstructure,which directly affected the sensory quality of pancakes.The effect of sourdough addition on gelatinization degree,in vitro starch digestibility,starch composition fraction and glycemic index of pancakes was studied under the optimal 20%sourdough addition level.The results showed that the gelatinization degree of pancakes was obviously lower than other millet products prepared by different processing methods,such as millet steamed cakes and millet porridge,due to the processing method of high temperature,short time and low moisture contact.The addition of sourdough could significantly reduce the gelatinization degree of pancakes,and at the same time reduce the in vitro starch digestibility and glycemic index of pancakes,and improve the resistant starch score.This may be closely related to the metabolic reactions during the fermentation of sourdough,such as the generation of organic acids and exopolysaccharides,and the release of free phenols.Based on in vitro experiments,the effect of pancakes with sourdough on type 2 diabetic mice was studied by animal model.The results showed that the intervention of pancakes with sourdough could alleviate the symptoms of polydipsia and polyphagia,maintain the stability of body weight and fasting blood glucose,improve insulin resistance and dyslipidemia,and alleviate pancreatic damage.The results of short-chain fatty acids and gut microbiota indicated that pancakes with sourdough might improve the pathophysiological status of diabetic mice by promoting the production of acetic acid,butyric acid and valeric acid,regulating the gut microbiota of mice,up-regulating the abundance of beneficial microbiota such as Lactobacillus,Bifidobacterium and Akkermansia.Finally,storage experiments were conducted to monitor the changes in quality indexes of pancakes with sourdough at different temperatures,and the total plate count was chosen as the prediction index for shelf life.A first-order model of microbial growth kinetic was established according to the Gompertz equation,and combined with the Belehradek model to establish prediction model for shelf life of pancakes with sourdough.The average relative error between the predicted and measured shelf life was 10.95%,which indicated that the model could effectively predict the shelf life of pancakes with sourdough at the temperature from 4°C to37°C,and provided a theoretical basis for quality and safety control of pancakes with sourdough in industrial production. |
