| Waxy corn provides a variety of nutrients, such as essential amino acids, vitamins, monosaccharide, glutathione which acted as a kind of anti-cancer factor and dietary fiber and so on. However, because its relatively rough texture, poor palatability, waxy corn has been used as industrial raw materials and feed generally, both of which have less added-value. It hasn’t come to the dinner table really. Therefore, the use of scientific methods to carry out fine, deep processing, to improve food texture is an important research direction of waxy corn processing and utilization. The use of biological engineering technology and modified processing technology will make the protein and starch in waxy corn flour modified, and organic nutrients exuded, so to improve product flavor, reduce the loss of nutrition, prevent retrogradation of the product after cooling, and waxy corn flour with excellent taste and processability, so the added value of waxy corn flour can be enhanced.Waxy corn meal was used as raw material in this study. After lactic acid fermentation, enzyme modification, chemical modification, special corn flour with higher viscosity and strong anti-aging resistance was produced. Mean research were as following:Firstly, Lactobacillus plantarum, composite bacteria (Lactobacillus bulgaricus and Streptococcus thermophilus), Lactobacillus casei, Lactobacillus acidophilus were used to ferment waxy corn meal respectively. Through the four factors of orthogonal test, best process parameters of four strains modified corn meal were identified: the addition of lactobacillus concentration, the initial pH, temperature and time for the fermentation were as follows: 4%, 6.1, 41℃, 60h; 4%, 6.0, 39℃, 48h; 4%, 6.4, 43℃, 60h; 7%, 5.9, 43℃, 48h; The viscosity was as follows: 28.7; 29.9, 13.1, 17.9 Pa?S under this best condition. Through confirmatory test and the number of t tests in both groups, we conclude that Lactobacillus plantarum and composite bacteria have a greater influence on viscosity of corn flour. For the enzyme modifying ability on corn flour, the results showed that: cellulase and glucose oxidase have a better modifying ability, and have increased the viscosity of corn meal. Using the second rotation experiment design, the best process parameters of bio-composite modified corn flour are as follows: the fermentation temperature was 41℃, the lactobacillus addition was 2%, cellulase recruitment was 250mg/kg corn flour, glucose oxidase recruitment was 83.3mg/kg maize flour, the viscosity value of corn flour reaches 34.1Pa?S. Result from scanning electron microscopy and DSC analysis shows that: after been modified, the particle surface became uneven, and small holes appeared, a ten type of holes were formed between particles, Gelatinization temperature became lower, enthalpy value became smaller. After modified by four types of lactic acid bacteria, water retention capacity, solubility, swelling and the transmittance of the modified corn meal are all higher than that of the original one, except condensate.The optimum conditions for esterification of acetic anhydride modifying corn flour were that: the concentration of acetic anhydride was 6.75%, reaction temperature was 30.4℃, reaction time was 58.44min, the acetazolamide content achieved 2.894% and the rise value achieved 43. Modified corn flour was detected by scanning electron microscopy, DSC, Brabender viscosity instrument, and so on. Results showed that: the surface of corn flour was significantly eroded, there were more honeycomb-like caves, the transparency for corn flour paste was enhanced, gelatinization temperature was lowed, the viscosity of corn meal was improved, freeze-thaw stability, the condensate and anti-oxidation ability were enhanced.Waxy corn flour after modified has a slight decline in the nutritional content, the original nutrition were remained basically. |
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