产中性蛋白酶菌种的选育及其在玉米淀粉生产浸泡工艺中的应用

从玉米淀粉生产企业的玉米浸泡水中筛选出可在中性pH值条件下降解蛋白质的菌种;经对该菌种进行原生质体紫外诱变处理,其蛋白酶活性提高了198%;将不同浓度的发酵液添加到玉米淀粉生产的浸泡水中,替代SO2。方差分析表明,菌液的作用时间和SO2含量对淀粉得率的影响显著。得到的优化组合为:玉米先在添加0.1%SO2的浸泡液中浸泡18h,然后在pH值7.0条件下加入20%的蛋白酶发酵液,继续浸泡10h。改进方法后获得的淀粉得率为67.71%,总的浸泡时间缩短至28h。     

响应面法优化玉米两步浸泡工艺

以玉米为原料,采用两步浸泡工艺提取淀粉,通过单因素试验考察第2步浸泡工艺中浸泡时间、浸泡温度和酸性蛋白酶添加量对淀粉得率的影响,并通过响应面法建立淀粉得率与浸泡时间、浸泡温度及蛋白酶添加量之间的关系。玉米浸泡的最优工艺条件：第1步浸泡温度52℃、浸泡时间3h;第2步浸泡温度51℃、浸泡时间2.25h、加酶量700U/g。拟合得到的模型较好的符合实际。该方法浸泡时间2.25h,淀粉得率64.9%。     

纤维素酶对玉米淀粉生产中浸泡效果的影响

本研究通过使用纤维素粗酶制剂对湿法生产玉米淀粉的浸泡工艺的影响进行了研究,结果表明,纤维素粗酶制剂能够显著地缩短玉米淀粉生产的浸泡时间,降低了二氧化硫的使用浓度,在0.1%的二氧化硫浓度的浸泡液中添加0.3%纤维素粗酶制剂,作用时间为12h,其淀粉得率为57.0%,而使用传统的逆流法工艺(实验室模拟)浸泡48h的淀粉得率仅为54.1%。     

产酸性蛋白酶微生物的筛选及其在玉米淀粉生产中的应用

分别从土壤和泡菜中筛选到适合玉米淀粉湿法加工浸泡条件(50℃,pH值3.5～5)的微生物,经形态学及分子生物学鉴定,初步确定该菌株为烟曲霉(Aspergillas fumigates);提取发酵液中的酸性蛋白酶粗酶进行酶学性质研究,发现该酶在50℃,pH值3.5～5下仍保持较高的稳定性;将发酵液应用于玉米淀粉湿法浸泡工艺中,优化的玉米浸泡条件为:浸泡温度50℃、乳酸含量0.5%、SO2含量0.08%,初次浸泡12 h,然后添加12%发酵液浸泡10 h。新工艺减少了环境污染,浸泡时间缩短了26 h,更有利于生产。     

乳酸与酸性蛋白酶协同浸泡在玉米浸泡工艺中的应用

为解决传统玉米浸泡工艺耗时长、污染环境等问题,以玉米为原料,采用乳酸与酸性蛋白酶协同浸泡提取玉米淀粉,并对该工艺进行优化。通过单因素试验研究了初始乳酸浓度、乳酸浸泡时间、加酶量和酶作用时间对玉米淀粉得率的影响,然后通过正交试验优化组合得到最佳工艺条件:初始乳酸浓度0.6%、乳酸浸泡时间16 h、加酶量1000 U/g玉米、酶作用时间20 h。在最优条件下,淀粉得率由传统工艺的56.02%提高到69.76%,浸泡时间缩短了大约20 h。此浸泡工艺取缔了亚硫酸的使用,又大大缩短了浸泡时间,能够减少能源消耗及环境污染、降低生产成本。     

嗜热乳酸菌与酸性蛋白酶协同提取玉米淀粉

在玉米浸泡的过程中,采用嗜热乳酸菌与酸性蛋白酶协同浸泡的方法提取玉米淀粉,并优化该工艺。通过单因素试验研究初始嗜热乳酸菌菌液浓度、嗜热乳酸菌浸泡时间、加酶量和酶作用时间对玉米淀粉得率的影响,通过正交试验优化组合得到最佳工艺条件:初始嗜热乳酸菌浓度16%、嗜热乳酸菌浸泡时间26 h、加酶量1 100 U/g、酶作用时间24 h。在最优条件下,淀粉得率由传统工艺的56.02%提高到64.26%。此浸泡工艺取缔了亚硫酸的使用,在较低酶添量的情况下,利用嗜热乳酸菌与酸性蛋白酶协同作用,能有效减少能源消耗及环境污染、提高玉米淀粉及其副产物的利用率。     

国外科技简讯

在湿法提取玉米粉工艺中直接浸泡玉米渣的新工艺 在传统玉米湿法加工工艺中,将整粒玉米用SO_2浸泡。但是,在这种工艺中,浸泡时间长,淀粉得率也很不理想。本工艺先将玉米加工成玉米楂,结果浸泡时间可以缩短6小时,浸泡液中SO_2浓度可以降低10％。该工艺优点为:①淀粉得率高。玉米楂浸泡10小时后,淀粉得率也只有87.4％;②淀粉中蛋白残留量量低。其残留量可以低列0.5％;③淀粉质量高。该工艺提取淀粉的表观粘度为377～462波氏单位,而用整粒玉米浸泡时所得淀粉的表观粘度则高达490波氏单位。(摘自《谷物化学》)     

酶法提取玉米淀粉工艺研究

以玉米为原料,对酶法提取玉米淀粉工艺进行了研究。通过单因素试验,研究蛋白酶添加量、浸泡液pH值、浸泡时间、浸泡温度对淀粉得率的影响,通过四因素三水平正交试验确定酶法提取玉米淀粉工艺的最佳参数为：蛋白酶添加量1．5mL,浸泡液pH值3．4,浸泡时间14h,浸泡温度50℃。     

利用电解水替代SO2改进玉米淀粉生产浸泡新工艺研究

采用电解水代替SO_2以改进玉米淀粉生产工艺。以传统工艺(0.2%SO_2)作为对照,通过酸性电解水(Ac EW)与碱性电解水(Al EW)二次浸泡来提取玉米淀粉。结果表明,最佳提取工艺为Ac EW浸泡43 h后再使用Al EW浸泡5 h,此工艺下淀粉收率最高,达到(67.2±1.6)%,并与传统的湿法工艺(SO2浸泡48 h)的淀粉收率(67.4±1.0)%比较,无显著性差异(P0.05)。     

酶法与碱法提取糜子淀粉的最佳工艺条件研究

采用酸性蛋白酶浸泡法和碱液浸泡法从糜子籽粒中提取淀粉。通过单因素试验确定酶法最佳提取工艺条件为:pH4.0,酸性蛋白酶体积分数2%,浸泡时间10h,浸泡温度50℃,此条件下淀粉提取率为70.12%。碱法最佳提取工艺条件为:pH11.0,料液比1∶5,浸泡时间8h,浸泡温度25℃,此条件下淀粉提取率为81.59%。     

L -半胱氨酸与发酵酸浆协同作用优化玉米湿磨工艺

为了改进玉米湿磨工艺,采用L-半胱氨酸替代传统浸泡工艺中的SO2,降低传统玉米淀粉生产过程中由SO2浸泡引起的环境污染。在具有絮凝活性的副干酪乳杆菌副干酪亚种L1发酵液制成的玉米酸浆中加入L-半胱氨酸,浸泡玉米碎粒,浸泡一定时间后加水磨浆,过筛除去纤维等杂质,淀粉在具有絮凝活性的副干酪乳杆菌副干酪亚种L1的作用下迅速沉降。通过改变酸浆的用量、L-半胱氨酸用量、浸泡温度、浸泡pH值、浸泡时间和菌种接入量,考察各因素对浸泡液中可溶性蛋白质的增量和淀粉提取率的影响,并采用响应面法确定最佳湿磨工艺。结果表明：最佳工艺参数为浸泡时间48 h、L-半胱氨酸质量浓度1.5 g/100 mL、浸泡pH 7、自然发酵酸浆用量比（m（玉米粒质量）∶V（酸浆体积））1∶4、浸泡温度30 ℃,此条件下淀粉提取率的最大值为93.21%。     

Steeping of Wheat at Various Temperatures – Effects on Physicochemical Characteristics of the Starch

Wheat prior to isolation of starch by wet-milling and a commercial starch sample were steeped at various temperatures (10° to 50°C.) in water. An extended steeping (72 h) increased the gelatinization temperature. In starches steeped for a limited period (24 h) a slight loss of amylose and decrease in solubility occurred as steeping temperatures increased. Water-binding capacities, however, remained virtually identical, decreased somewhat with higher steeping temperatures. The data show that time rather than temperature of steeping is critical in preserving native properties of wheat starch granules.     

玉米淀粉实验室提取方法研究

以普通黄马齿玉米为原料,采用湿法提取淀粉工艺,制得淀粉得率高、优质纯净玉米淀粉;通过大量实验设计筛选出最佳提取方案:浸泡温度50℃,乳酸和NaHSO3浓度均为0．5％,浸泡时间36 h,流槽倾斜度为0．015 cm／cm。     

Factors Improving the Steeping Process of Corn Grains. Part II. Effect of Enzyme Addition

The effect of addition of proteolytic enzymes to the steeping liquor of corn grains was studied to reduce the steeping period and to obtain starch of low protein content. For this purpose the intact, scratched and broken corn grains were steeped in presence of Alcalase and Neutrase enzymes. It was found that the steeping period decreased by about 50% in case of broken grains, while steeping intact or scratched corn grains in presence of the enzymes gave no effect.     

THE INFLUENCE OF THE GRAIN MICROFLORA ON THE GERMINATIVE PHYSIOLOGY OF BARLEY

Barley samples, which varied in maturity, were either steeped with calcium hypochlorite and then with a mixture of antibiotics, or in water, for twenty or sixty hours. The steeped grains were placed on agar and were scored for germination, growth of rootlets and α-amylase production at intervals up to ninety six hours after draining. The rates and final percentages of germination, rootlet growth per germinated corn and α-amylase per germinated corn were all greater where grain had been steeped with antimicrobial agents compared to water-steeped control samples of grain. It was confirmed that the antimicrobial agents reduced the extent of inhibition of germination which followed extended steeping. Thus controlling microbes increased grain germinability and the vigour of the grains which germinated. However, the vigour of more water sensitive grain was not increased enough to be equal to that of mature grain by reducing microbial activity . Experiments in which grain was reinfected with a suspension of microbes, following steeping with antibiotics, supported the theory that the observed effects were due to reductions in microbial activity and not any secondary effects of the antimicrobial agents.