Preparation Of Monascus Sorghum Sourdough And Its Effect On Bread Quality

Monascus,as a medicinal and edible fermentation fungus,has been used for thousands of years.During the fermentation process,Monascus produces various beneficial metabolites such as Monascus pigment,Monacolin K,and Gamma-aminobutyric acid(GABA),etc.,endowing Monascus fermentation products with many physiological active functions.Sorghum,as an important coarse cereals,is rich in starch and has high nutritional value.In order to enrich the application of sorghum and improve the nutritional value of bread,this study used Monascus purpureus LZSM06 to ferment sorghum,and then it was combined with sourdough technology to prepare sourdough bread.Meanwhile,the effects of Monascus sorghum sourdough on the structure of bread dough,bakery characteristics and nutritional value of bread were explored.The main research findings are as follows:(1)Monascus purpureus LZSM06 was used to ferment and prepare Monascus sorghum,and the changes in physicochemical and bioactive components of Monascus sorghum were analyzed.The results showed that after 3-5 days of fermentation,the Monascus pigment increased significantly and gradually became red(P<0.05);On the4th day,the total phenol content reached 122.05 mg/100g,with DPPH and ABTS free radical scavenging rates of 50.12%and 81.54%,respectively.The fermentation yield was 86.47%,and the contents of Monacolin K and GABA were 34.73 mg/100g and29.91 mg/100g,respectively.(2)Sorghum sourdough and Monascus sorghum sourdough were prepared respectively using Lactiplantibacillus plantarum LZSR03 as the fermentation strain,and the characteristics of the two types of sourdough were analyzed and compared.The results showed that Lactiplantibacillus plantarum LZSR03 could grow well in both sorghum and Monascus sorghum,with number of cells reacheing 10~9 CFU/g.After fermentation,the TTA and lactate content of Monascus sorghum sourdough were significantly higher than that of sorghum sourdough(P<0.05);Lactic acid bacteria fermentation enhanced the antioxidant activity of sourdough,and Monascus sorghum sourdough had higher antioxidant activity.(3)Four different types of bread dough were prepared,and their microstructure and protein secondary structure were studied.The results showed that the gluten structure of wheat sorghum bread dough(WSD)was the worst,while sorghum sourdough bread dough(SSD),Monascus sorghum bread dough(MSD),and Monascus sorghum sourdough bread dough(MSSD)all exhibited stronger and stabler gluten network structures;the relative content of stable and orderedα-helix andβ-sheet in MSSD was 16.04%～19.11%higher than the other three types of dough.(4)With sorghum wheat bread(WSB)as the control,sorghum sourdough bread(SSB),Monascus sorghum bread(MSB),and Monascus sorghum sourdough bread(MSSB)were prepared,respectively,to investigate the effect of Monascus sorghum sourdough on bread baking characteristics and nutritional value.The results showed that the specific volume of MSSB increased,the hardness decreased,the bread had a red appearance,and the overall acceptability was the highest.There were 22,27,37and 39 volatile flavor compounds detected in WSB,SSB,MSB and MSSB,respectively;and the content of volatile flavor substances in SSB,MSB and MSSB was 1.96,7.79and 9.87 times of that in WSB,respectively.Compared with WSB,the antioxidant activity,in vitro protein digestibility,and total free amino acid content of the other three types of bread were significantly increased,and MSSB had better amino acid characteristics.Monocolin K was not detected in WSB and SSB,while the content of Monocolin K in MSB and MSSB was 1.90 mg/100g and 1.94 mg/100g,respectively;In addition,compared to WSB and SSB,the GABA content in MSB and MSSB increased by 46.8%to 62.9%.The above results indicated that Monascus sorghum sourdough can significantly improve the baking characteristics and nutritional value of bread.(5)The production process parameters of Monascus sorghum sourdough bread were optimized using response surface methodology,with the addition amount of sourdough and dough proofing time as influencing factors,and the specific volume and overall sensory evaluation of the bread as response values.The results showed that the optimal process parameters were:the amount of sourdough added was 18%,the dough proofing time was 80 minutes,the specific volume of bread was 3.25 m L/g,and the overall sensory evaluation score was 8.05.