| Barley,especially barley bran,is rich in β-glucan,phenolic substances and other active ingredients,which have a variety of physiological active functions such as regulating blood lipids and lowering blood sugar,but in the existing processing process of barley,it often causes a large loss of active ingredients due to the consideration of palatability and storage stability,etc.Reconstituted rice is made from grains and cereals as the main raw material by extruding and processing crushed rice or other starch-based raw materials and other excipients mixed in a certain ratio.Since reconstituted rice can be selectively added with nutrients and the quality characteristics can be improved by processing,it is palatable and nutritious.In this thesis,based on the use of Lactobacillus plantarum dy-1 solid fermentation of bran and back addition to obtain barley whole flour,combined with low-temperature extrusion technology to prepare barley reconstituted rice,and to study its quality and functional characteristics.The main research contents and results are as follows:1.The barley varieties were screened using the comprehensive weighting method of multiple indicators,and barley 5171 was identified as the optimal barley variety.The optimal fermentation conditions were determined by using Lactobacillus plantarum dy-1 for solid-state fermentation of barley 5171 bran,and the optimal fermentation conditions were determined by response surface methodology: inoculum level 15.7%,fermentation temperature 39℃,fermentation time 176 h,and liquid to material ratio 0.8.The β-glucan and polyphenol contents in the fermented bran were significantly increased,and the fat and phytic acid contents were significantly decreased.The effect of fermentation on the composition of small molecules in barley bran was studied by ultra performance liquid chromatography-high resolution mass spectrometry(UPLC-HRMS),and the results showed that the contents of amino acids,unsaturated fatty acids and most phenolic substances in barley bran increased significantly after fermentation,and the contents of saturated fatty acids decreased significantly.2.The whole barley flour was produced by adding back the solid fermented barley bran,and the barley reconstituted rice was obtained by low-temperature extrusion with japonica rice.The differences in quality characteristics between barley reconstituted rice,japonica rice and barley kernel were analyzed by differential scanning calorimetry(DSC),mass spectrometry and sensory evaluation,and the differences in volatile components between barley reconstituted rice,japonica rice and barley kernel were analyzed by gas chromatography-mass spectrometry(GC-MS),and the results showed that: compared with japonica rice and barley kernel,barley reconstituted rice starch had better thermal stability and aging resistance,and the hydration capacity was enhanced;the cohesiveness,elasticity and chewiness increased after cooking,the hardness and gelling decreased,and the taste was better;the brightness and yellowness decreased,the greenness increased,and the color became darker,and the sensory score was significantly higher than that of barley kernel,which was not significantly different from that of japonica rice;the content and types of aldehydes and furans,which contributed significantly to the flavor,were more abundant and the flavor was better.3.Some functional properties of barley reconstituted rice were investigated by in vitro simulated gastrointestinal digestion and colonic fermentation using japonica rice and barley kernel as controls,and the results showed that compared with japonica rice,barley reconstituted rice had lower content of rapidly digested starch,increased content of resistant starch and slowly digested starch,and significantly lower GI value than japonica rice.Total phenolic content,DPPH clearance,ABTS clearance,total antioxidant capacity and most phenolic compounds were significantly increased after in vitro simulated gastrointestinal digestion and colonic fermentation in the three groups of samples;barley reconstituted rice produced a greater degree of effect on intestinal flora structure than japonica rice and barley kernel.The relative abundance of Megasphaera,Bifidobacterium,and Ligilactobacillus in the fecal fermentation system was significantly up-regulated and the relative abundance of Parabacteroides was significantly down-regulated in the three groups of samples during in vitro colonic fermentation. |
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