| Combining with the distribution and growth of microorganisms on sprouts, we discussed the microbial impact on preservation and security, and methods of controling microbe and effectiveness evaluations. It designed to provide the technical support to produce highly quality safe sprouts. The results are as follows:1. This research studyed the effect of different packaging material and modified atmosphere packaging on sensory score, pH, total volatile basic nitrogen during mungbean sprouts preservation, and the distribution of microbial population of part and whole mungbean sprouts. It turned out that microbes play an important role in the process of corruption on sprouts.So we can effectively extend preservation by reducing total number of microbes on mungbean sprouts.2. This study discusses the structure characteristics and bacterial distribution of mungbean, effectiveness evaluation and mechanism of convention and vacuum treatment of sodium hypochlorite. It turns out that the total bacterial number of seed, epidermis and inward of mung bean is 8.41×106, 6.70×103 and 8.30×106 cfu/g, respectively. Colony counts of seed, epidermis and inward of mung bean, soaked in sodium hypochlorite(2000-10000 ppm, 1 h), were reduced by 0.98-2.11, 0.99-1.33 and 0.90-2.08 log cfu/g, respectively. Colony counts of seed, epidermis and inward of mung bean, soaked in sodium hypochlorite(2000-10000 ppm, 0.05 MPa, 1 h), were reduced by 3.65-3.77, 1.11-1.56 and 3.58-3.72 log cfu/g, respectively. By the analysis, vacuum treatment can force sodium hypochlorite overcome the influence of wax layer of epidermis and inner cavity structure of mungbean, contact bacteria effectively and improve the effect of sterilization.This research investigated the optimization of the disinfection technology of mung bean soaking with sodium hypochlorite by using disinfection ability as index, and available chlorine concentration, soaking time and absolute pressure as factors in three levels. Results analyzed by response surface method showed that the optimization was available chlorine concentration of 5066.95 ppm, time at 2.26 h, absolute pressure on 0.02 MPa, and on this conditions, the total number of microbes of 4.55 log cfu/g, germination rate of 97%.3. This research got the optimized conditions and the impaction on germination and growth of seeds of leaching water including ozone water, sodium hypochlorite, acidic water and tap-water to inhibit microbe on sprouts, The results showed that, total plate count reduced 1.95 log cfu/g with acidic water(pH=6), and roots rotted rate reduces from 10.02% to 3.54%, but unaffected germination and growth.4. We observated cotyledon, hypocotyl and root on mungbean sprouts by SEM and CLSM. The results showed that a large number of bacteria, linked with the cell walls by a certain form, mainly made up of different size of rod-shaped bacteria, were adhered on the surface and interior of mungbean sprouts. The bacteria can been cleared with sterile water, ultrasonic wave, sodium hypochlorite and so on unless damaging mungbean sprouts. The results confirmed that the natural bacteria biofilm on mungbean sprouts can protect bacteria. It is the effective way to break bacteria biofilm to eliminate microorganism on sprouts.5. By breaking bacteria biofilm with Panzea BG, Pentopan Mono BG, Viscozyme L, Celluclast 1.5L, Ultraflo Max, Hemicellulase and Xylanase, we confirmed that the biofilm contain β-D-xylan-1,4-glycosidic, but not β-D-glucan-1,3- or-1,4-glycosidic.The results by treating with Xylanase showed concentration of 2%(w/w), pH 5.5, temperature at 35℃, time at 2 h. The total number of microbe on mungbean sprouts reduced from 7.66×106 to 6.53×104 cfu/g, without affecting quality, and preservation can extend 2 days. |
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