Improvement Of Nutrient Composition Of Cereals By Solid Fermentation With Ten Medicinal Fungi

Cereal grains belong to the Poaceae family of plants and are essential foods in people’s lives.As people’s living standards improve,cereals are refined,leading to significant nutritional loss.At the same time,more and more people are seeking functional foods with medicinal properties.Studies have shown that fermentation technology can enhance the value of cereals.This study selected ten medicinal fungi,namely Sanghuangporus sanghuang,Sanghuangporus baumii,Sanghuang porus weigelae,Sanghuang poru lonicericola,Sanghuangporus quercicola,Sanghuangporus subbaumii,Sanghuangporus vaninii,Ganoderma boninense,Phylloporia pulla,and Phylloporia fontanesiae,all with high nutritional value and health care functions.No researchers have reported inoculating these ten fungi on cereals for solid-state fermentation,analyzing changes in the main nutritional components of the fermented products,such as proteins,total phenols,and crude polysaccharides.This study selected five essential cereals,wheat,rice,sorghum,corn,and buckwheat,and conducted solidstate fermentation research with the aforementioned ten fungi.The effects of the ten fungal solid-state fermentations on the soluble protein,total phenol,and crude polysaccharide content of the cereals were preliminarily analyzed,comparing the differences between the original cereals and the fermented products.The combinations of fungal strains and cereals with significant comprehensive improvements were screened and subjected to non-targeted metabolomics testing to provide a basis for enhancing the added value of cereals and the resulting fermentation metabolites.The main results of the study are as follows:(1)Extraction and determination of total phenol content in fermentation products.The results showed that under the fermentation action of medicinal fungi,the total phenol content of wheat was significantly increased.Except for buckwheat,the total phenol content in wheat,rice,corn,and sorghum was significantly increased.This might be due to the synthesis of more types of polyphenols during the fermentation process through certain metabolic pathways.In different cereals,the total phenol content was not significantly increased by the same fungus,indicating that different fungi play different roles when inoculated into different raw grains.It can be seen that medicinal fungi have a significant effect on the total phenols of most raw grains.Among them,Sanghuangporus weigelae has a significant effect on the total phenol content of most raw grains,with the highest increase of 1.62 times.The crude polysaccharide content of the products fermented by Phylloporia pulla and Phylloporia fontanesiae was significantly reduced in buckwheat,rice,and sorghum,while the improvement of crude polysaccharide content in different cereals by different species of Sanghuangporus was not consistent.For the determination of soluble protein content,Sanghuangporus weigelae also had a significant improvement effect in sorghum.Comparing the comprehensive physical and chemical indicators,the improvement was more significant.Finally,Ganoderma boninense,Phylloporia pulla,Sanghuangporus sanghuang,and Sanghuangporus weigelae were selected for rice fermentation and metabolomic analysis.(2)Sample sequencing analysis was carried out on these four metabolic products and the original grains through non-targeted metabolomics.Sequencing data was analyzed,integrated,and screened,and the samples were compared based on the KEGG database.Metabolic data of differential metabolites was analyzed.Through the comparative analysis of raw rice and fermentation products,it was found that there were significant differences between untreated rice and the other four fermentation products,with a total of 563 differential metabolites identified,divided into 72 categories.The largest category had 96 metabolites,accounting for 17.1% of the total.Based on the content ratio,the category percentage differences between the four treatment groups metabolites and the raw rice were significant.Among the numerous differential metabolites,key active metabolites were screened,including flavonoids,isoflavones,hydroxycinnamic acids and their derivatives,organic oxidation compounds,and alkaloids,for content difference analysis.Flavonoid compounds have strong antioxidant and anti-tumor effects.A total of 9 differential metabolites were screened,providing a basis for their application in the medical and food fields and effectively accelerating the potential development and utilization of flavonoid compounds.Isoflavone compounds detected in the samples include dye wood flavonoids,which showed a significant increase in the Sanghuangporus weigelae fermentation group but not in the other groups,indicating potential research value.Genistein also showed a significant increase in the Sanghuangporus weigelae group.A total of 53 organic oxidation compound differential metabolites were screened,of which 39 had upregulated differential metabolites.According to the heatmap,the number of upregulated differential metabolites in the rice fermentation products inoculated with Sanghuangporus weigelae was higher compared to the other groups.Raffinose has the ability to inhibit the accumulation of toxins and waste products in the body,accelerate blood metabolism,and protect the liver.This compound showed the most significant increase in the Sanghuangporus weigelae group.The above medicinal compounds provide a basis for further research on the functional properties of fermentation products.The research results confirm the potential value of medicinal fungi in solid-state fermentation of cereals,improve the functional research of medicinal fungi,and lay the foundation for the development and utilization of the medicinal functions of medicinal fungi in the food field.