Gluten-free products from rice are gaining popularity because of its hypoallergenic characteristic. The absence of gluten results in inferior bread qualities such as hard texture, reduced volume, and shorter shelf-life. Hydrolytic enzymes are activated during germination to stimulate plant growth, and germinated brown rice (GBR) has been shown to improve gluten-free bread properties. However, the changes in hydrolytic enzyme activities under different germination conditions and their relationship with the properties of germinated rice flour and bread have not been reported. Therefore, the objectives of this work were to investigate the activities of amylases and protease in GBR under aerobic and anaerobic germination for 2 and 4 days and their impacts on starch hydrolysis, flour properties, and bread qualities. Greater enzyme activities were observed in GBR germinated under aerobic condition and a longer time, and correlated with increased sugar content and foaming capacity. Breads were prepared from GBR along with brown rice (control). GBR breads showed a greater specific volume (4% to 10%), a reduced hardness (34% to 90%), and a lower starch retrogradation (66% to 90%) compared with the control. Bread prepared from 4-day aerobic GBR had the largest reduction in starch molecular size and displayed the lowest hardness and starch retrogradation. After stored for 5 days, GBR breads exhibited no change in specific volume and less hardness and retrogradation than the control bread. In conclusion, greater activities of protease and amylases in GBR significantly increased foaming capacity and reduced starch molecule size, respectively, which were responsible for the improved GBR bread qualities. PRACTICAL APPLICATION: Rice flour is widely used as the main ingredient in gluten-free breads, which however tend to have poor texture and reduced shelf-life due to the absence of gluten. The qualities of gluten-free breads are usually improved by the addition of many ingredients such as tapioca and potato starches. Germination process naturally produces bioactive compounds and activates enzymes. Germination conditions that produce greater activities of amylases and protease can be used to produce gluten-free breads with better qualities and longer shelf-life without the addition of starch.

中文翻译：

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发芽条件对长粒糙米酶活性和淀粉水解与面粉特性和面包品质的影响

来自大米的无麸质产品因其低过敏性而越来越受欢迎。缺乏麸质会导致面包质量变差，例如质地坚硬、体积减少和保质期缩短。水解酶在发芽过程中被激活以刺激植物生长，发芽糙米 (GBR) 已被证明可以改善无麸质面包的特性。但不同发芽条件下水解酶活性的变化及其与发芽米粉和面包特性的关系尚未见报道。因此，这项工作的目的是研究在好氧和厌氧发芽 2 天和 4 天下 GBR 中淀粉酶和蛋白酶的活性及其对淀粉水解、面粉特性和面包品质的影响。在有氧条件下和更长的时间发芽的 GBR 中观察到更大的酶活性，并且与增加的糖含量和发泡能力相关。面包由 GBR 和糙米（对照）制成。与对照相比，GBR 面包表现出更大的比容（4% 至 10%）、降低的硬度（34% 至 90%）和较低的淀粉凝沉（66% 至 90%）。由 4 天有氧 GBR 制备的面包淀粉分子大小的降低幅度最大，硬度和淀粉凝沉率最低。储存 5 天后，与对照面包相比，GBR 面包的比容没有变化，硬度和回生更少。总之，GBR 中蛋白酶和淀粉酶的更大活性分别显着增加了发泡能力和降低了淀粉分子大小，这是提高GBR面包质量的原因。实际应用：米粉被广泛用作无麸质面包的主要成分，但由于不含麸质，其质地较差，保质期缩短。无麸质面包的质量通常会通过添加许多成分（例如木薯淀粉和马铃薯淀粉）来改善。发芽过程自然产生生物活性化合物并激活酶。产生更大淀粉酶和蛋白酶活性的发芽条件可用于生产质量更好、保质期更长的无麸质面包，而无需添加淀粉。然而，由于不含麸质，它们往往质地较差，保质期缩短。无麸质面包的质量通常会通过添加许多成分（例如木薯淀粉和马铃薯淀粉）来改善。发芽过程自然产生生物活性化合物并激活酶。产生更大淀粉酶和蛋白酶活性的发芽条件可用于生产质量更好、保质期更长的无麸质面包，而无需添加淀粉。然而，由于不含麸质，它们往往质地较差，保质期缩短。无麸质面包的质量通常会通过添加许多成分（例如木薯淀粉和马铃薯淀粉）来改善。发芽过程自然产生生物活性化合物并激活酶。产生更大淀粉酶和蛋白酶活性的发芽条件可用于生产质量更好、保质期更长的无麸质面包，而无需添加淀粉。