Analysis Of Nutritional Components And Fermentation Technology Of Northwestern Shanxi Sour Porridge

Northwestern Shanxi sour porridge is a traditional cereal-fermented food being popular with people of Western Inner Mongolia,Northwestern Shanxi,and Northwestern Shanxi for its unique flavor and full sour aroma.Taking broomcorn millet as its main raw material,this porridge is processed by microbial natural fermentation.Through analyzing and comparing the chemical compositions of Northwestern Shanxi sour porridge and broomcorn millet,this program concludes the nutrition and health value of Northwestern Shanxi sour porridge.Besides,the program also includes the isolation and identification of the yeasts existed in the sour porridge and the study of sour porridge fermentation technique using lactic acid bacteria,acetic acid bacteria and yeasts as inocula.This program is going to provide theoretical reference for the further industrial production of Northwestern Shanxi sour porridge.Specific research contents are as follows:(1)The chemical compositions of Northwestern Shanxi sour porridge and broomcorn millet were analyzed and compared.The major chemical composition of sour porridge were as follows: total water 75.5 g/100 g,crude fat 0.46 g/100 g,total protein 2.87 g/100 g,total reducing sugars 0.09 g/100 g,total sugars 20.51 g/100 g,ash 370 mg/100 g,lactic acid7.28 mg/mL,acetic acid 4.58 mg/mL,phytate(IP6)25 mg/100 g,calcium 9.83 mg/100 g,iron 2.75 mg/100 g,total phosphorous 10.34 mg/100 g,flavonoid 5.98 mg/100 g,total phenol 50.22 mg/100 g,amino acid 2.67 g/100 g,viscosity 5.75 m Pa·s and titratable acidity 100.19 oT.The major chemical composition of broomcorn millet were as follows:total water 4.86 g/100 g,crude fat 2.30 g/100 g,total protein 9.88 g/100 g,total reducing sugars 0.94 g/100 g,total sugars 76.01 g/100 g,ash 950 mg/100 g,calcium 25.08 mg/100 g,iron 5.33 mg/100 g,total phosphorous 42.05 mg/100 g,flavonoid 25.93 mg/100 g,total phenol 147.02 mg/100 g,amino acid 9.63 g/100 g.The EC50 of both the DPPH radical scavenging activity and ferrous ion chelating ability was significantly lower than that of broomcorn millet,which showed that the antioxidant activity of acid porridge more stronger than broomcorn millet.(2)Both of the sour porridge and broomcorn millet contained a wide variety of essential amino acids though the former enjoyed the higher contents of not only the aminoacids but also the essential amino acids.The content of essential amino acids in sour porridge accounted for 33.5% and that in broomcorn millet accounted for 32.5%.Among those amino acids contained in sour porridge the lysine was the first limiting amino acid and the methionine/cysfine is the second limiting amino acid.And in broomcorn millet the methionine/cysfine was the first limiting amino acids and the lysine was the second limiting amino acid.The sour porridge had higher amino acid score,chemical score and nutritional index than broomcorn millet.The results showed that the nutritional value of sour porridge was higher than that of broomcorn millet.(3)The yeasts in Northwestern Shanxi sour porridge was identified by observing the morphological characteristics,physiological and biochemical tests combined molecular biology methods.The results showed that 41 strains of yeasts were isolated during the six periods of the fermentation process of Northwestern Shanxi sour porridge.After the observation of their morphological characteristics,physiological and biochemical tests and the ITS analysis,these strains were respectively identified as: Pichia kudriavzevii,Issatchenkia orientalis and Saccharomyces cerevisiae.(4)To ferment sour porridge,Lactobacillus brevis,Acetobacter aceti and Saccharomyces cerevisiae were inoculated respectively into broomcorn millet according to a certain proportion.The effect of single strain fermentation,mixed strains fermentation,solid-liquid ratio,inoculum size,fermentation time and fermentation temperature on sour porridge were studied through the single factor experiments.The effect of solid-liquid ratio,inoculum size,fermentation time and fermentation temperature on the sensory evaluation of sour porridge were studied using response surface analysis method.The theoretical optimum fermentation condition for the Northwestern Shanxi acid porridge was the following: the solid-liquid ratio of 1 : 3(W/V),the inoculum size of 5%(V/V),the fermentation time of 30 h and the fermentation temperatureof 30?.Under the optimum fermentation condition,the sensory evaluation of the fermented product reached 8.25.The nutrient composition of fermented sour porridge was similar to that of traditional Northwestern Shanxi sour porridge and the protein nutritional value was higher than that of broomcorn millet.