Effect Of Laver (Porphyra Haitanensis) Powder On The Properties Of Dough And The Quality Of Chinese Steamed Bread

Porphyra haitanensis is a large red algae cultivated in large scale in south of China.The Porphyra haitanensis has a single product type,lack of intensive processing and high value products.It has long stayed in the stage of dried laver and roasted laver,and still has a great distance from Japan and Korea.Chinese steamed bread is traditional staple food in China and40%of wheat flour consumption is used to make Chinese steamed bread.With the progress of society,People's demand for the nutrition and quality of steamed bread is also increasing.Development of laver steamed bread not only provides an effective way for the processing and utilization of laver,but also better meets people's demand for healthy food.This experiment is to study the effect of laver powder on properties of dough and steamed bread quality.Main results for this study are as follows:?1?The laver powder was added to the flour by 1.5%to 2.5%,farinograph test results with the composite flour showed that water absorption rate,dough development time increased linearly as the content of laver powder increased from 1.5%to 2.5%,while dough stability decreased with the laver content increased.Textural analysis indicated that hardness,elasticity,and chewiness increased with laver content increased.Scanning electron microscope results showed that laver powder disrupt the microstructure and reduce stability of the gluten network.Infrared microscopic imaging analysis indicated that with the content of laver powder content increased the protein aggregate.X-ray diffraction results showed that laver powder decreased the crystallinity of starch,but had no influence on the crystal type of starch.?2?The water mobility of dough was investigated by the Low Field Nuclear Magnetic Resonance?LF-NMR?,the continuous distributed CPMG?Carr-Purcell-Meiboom-Gill?relaxation curves and distribution of T₂ relaxation time obtained by multi-exponential fitting of the relaxation curves for dough with different content of laver powder,the results showed that there were four different relaxation component,T_2bb is attributed to the starch,T₂₁1 is attributed to the water closely associated with starch and protein,T₂₂ may originate from water trapped within gluten network,T₂₃3 represents free water.The result of LF-NMR and MRI showed that the water mobility of dough was increased by adding laver powder.?3?The texture analysis results of steamed showed the hardness and chewiness were increased as the content of laver powder increased from 1.5%to 2.5%.Low Field NMR results of Chinese steamed bread indicated that the addition of laver powder would increase the water mobility of Chinese steamed bread.Linear regression analysis between the texture properties and NMR data indicated that the T₂₂2 had good correlations with hardness and chewiness.The color measurements of Chinese steamed bread indicated that the whiteness of Chinese steamed bread was decreased as the content of laver powder increased from 1.5%to2.5%.From sensory evaluation test for Chinese steamed bread,steamed bread containing 1.5%laver powder was similar to the control group The specific volume of Chinese steamed bread was affected by the addition of laver powder,Chinese steamed bread containing 1.5%had no significant different with control group,while increasing laver powder from 2.0%to 2.5%decreased the specific volume of Chinese steamed bread.