| Oats are well recognized as a whole-grain cereal, which are rich in nourishment composition such as: protein, fat and vitamin, highly recommended as an important part of the daily diet. As a substrate for microbial fermentation, oats using for microbial transformation, can fully improve the added value of its products. In this paper, red mold oats were obtained by inoculating Monascus spp., the formula optimization of solid-state fermentation culture substrates and and optimization of solid-state fermentation conditions by response surface methodology were investigated. In order to research the transformation mechanism of red mold oats, the changes of the nutrients(including starch, protein, polysaccharide, flavonoids and total phenol) and especially the the new components(pigment and Monacolin K) before and after fermentation were investigated. Finally the oxidative stability of fermentation product was investigated by vitro bioactivities experiments.The main content of oats is starch(about 60%). The moisture were controlled between 40% and 60% during the solid- fermentation, the starch could be made full use by Monascus spp. under different conditions, but resulting in different Monascus metabolites.In order to obtain the red mold oats rich in nutrients, the fermentation formula was invested by single factor optimization experiment, the results showed that additive substance and its concentrations have some regularity; Monascus spp. used starch to produce proteins, polysaccharides, flavonoids, total phenol and monascus pigment, Monacolin K etc; the results indicated that the optimal carbon source and nitrogen source were 8% glycerol and 2% yeast extract respectively.Oats have better buffering capacity and water-retaining property. The p H of soak solution, initial moisture, temperature and inoculum size affect the transformation of the red mold oats nutrition ingredient. The optimal fermentation condition was as follows: natural p H, 10% inoculum size, 30 oC for 10 days.Response surface methodology was used to optimize the fermentation conditions, and the optimal fermentation condition was 8.03% glycerol, 2.14% yeast extract and 10.11% inoculum size. Under the optimal conditions of the validation experiments, the contents of red mold oats were as follows : proteins 19.30±0.55 g/100 g, polysaccharide 21.01±0.61 g/100 g, flavonoids 8.52±0.23 mg/g, total phenol 10.70±0.38 mg/g, red pigments 4646±24 U/g, Monacolin K 15007.2±143.0 mg/kg.The product yield was 34%. Contents of polysaccharide(1.58±0.05 g), flavonoids(63.90±0.02 mg), total phenol(80.25±0.03 mg), under the optimal conditions of the validation experiments, which were more than unfermented oats( polysaccharide 0.29±0.02 g, flavonoids 2.60±0.06 mg, total phenol 5.70 ±0.05mg). Meanwhile the total starch contents decreased 12.00±0.12 g along with proteins reducing 2.20±0.11 g. Besides red mold oats were rich in newly added composition(red pigments 34845±180 U, Monacolin K 112.55±1.07 mg). It showed that after fermentation with the starch totally used, Monascus spp. used carbon sources and nitrogen sources suche as starch and proteins for growth. In the process, the total proteins decreased, but with the proteins synthesised by Monascus spp., it improved the value. At the same time, newly added functional material improved antioxidant activitie and the effect of reducing weigt, which greatly enhanced the value of products.In vitro bioactivities experiments, the removal abilities of DPPH and NO2- and the reduction ability of ironincreaseed 20.16 times, 16.09 times, 20.00 times respectively, which showed that the Monascus spp. fermentation of oats promoting the transformation of starch to antioxidantive elements, such as flavonoids, polyphenols, monascus pigment and other nutrients, which was especially suitable for patients with hyperglycemia and diabetes as functional foods or additive. |
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