Research On Preservation And Quality Control Of Wet Raw Noodles

As the classic food with a long history, wet raw noodles have been much public recognition. High moisture wet raw noodles possess good taste and eating value, but high moisture conversely results in deterioration highly vulnerable to microbial infestation during storage period. The present study used multiple preservation methods in wet raw noodles pretreatment, in order to prolong the shelf life of wet raw noodles, and studied the variation in the quality of the preservation technique under constant temperature storage of wet raw noodles. The main contents and results are divided into the following four parts:Separate and purify, extract the main advantage spoilage bacteria of wet raw noodles, and then obtain four dominant spoilage moulds and three dominant spoilage bacteriaa by microscopic examination and preliminary qualitative identification, which are gram-negative bacteria, gram-positive bacillus, gram-positive bacillus, penicillium, aspergillus flavus, yeast, aspergillus niger. They provide the basis for the later targeted preservation.Effects of evaluating different microwave power, different sterilization time and different flour weight on the spoilage microorganisms, shelf-life and texture characteristics of noodles. And the studies by orthogonal test have shown that the best microwave heating process in flours:microwave power 800 W, sterilization time 30 s, flour weight 100 g. The sterilization rate of bacteria count and mold count were both more than 90%, moreover the noodles could be stored for 17 days at 4℃. In addition, sensory quality, cooking quality and texture characteristics of noodles had both been improved.The fumigation inhibitory effect of ten kinds of essential oils and isolate spices on seven kinds of specific spoilage organisms from wet raw noodles was compared in the study, which including cubeba oil, rosemary oil, oregano oil, clove oil, orange oil, ginger oil, thymol, cinnamic aldehyde, anethole and citral. Results indicated that thymol was better to inhibit bacterial,cinnamic aldehyde was better to inhibit mold,and then they were recombined in the experiment. The composite spices showed a notably synergistic interaction when the optimum proportion of thymol and cinnamic aldehyde was 2:3. Seven kinds of tested spoilage microorganism were completely inhibited by the composite spices of 93.25μL/L. The composite spices also had a significant inhibition effect on the bacteria and mould in wet raw noodles. When the spatial concentration was 100 μL/L, mold count in the noodles was 50 CFU/g after 5 days at 28℃, colony count was 6.5×104CFU/g after 12 h at 37℃, which was still in the guarantee period.Effect of pretreatment of wheat flour and essential oil fumigation on sensory quality, moisture, acidity, color and protein secondary structure of wet raw noodles during storage period. The α-helix and β-folding content of gluten protein secondary structure were both increased,and the content of β-corner and random coil were reduced by microwave treatment of wheat flour on wet raw noodles, which is beneficial to the formation of gluten network structure. In the complex essential oil vapor fumigation, wet raw noodles was stored at room temperature 25℃ and refrigeration temperature 4℃. Its quality changed as follows. (1)The sensory quality of wet raw noodles fell by a big margin in the first half of storage period.fell by a small margin in the latter half.But it decreased more smoothly than the blank group,and the overall sensory score was higher than the blank group. (2)Moisture content of wet raw noodles was higher than the blank group,and it declined slow down. So essential oils fumigation was beneficial to the moisturizing of wet raw noodles. (3)The acidity of wet raw noodles increased slower than the blank group and was inhibited effectively. (4)The whiteness value of wet raw noodles was biger and delined slower than the blank group.So it could maintain the color of wet raw noodles better.