Wholegrain brown rice (WBR) with significantly enhanced quality attributes has been recently achieved after ultra-high pressure (UHP) processing, but the process-induced changes in physicochemical parameters following subsequent storage for UHP-treated WBR are scarcely documented. So this work was designed to investigate the effects of UHP treatments (0.1–450 MPa/10 min) on chemical composition, microstructure, and the changes in chemical reactions during storage (20 days/30 °C) as indicated by volatile profiling, color development, and antioxidant activities for WBR grains, compared to high-intensity ultrasound (HIU) and germination (GER) pretreatments. Results showed that significant variation in physicochemical properties was caused by both processing approaches and storage duration. Color changes (a*, b*, L*, and ΔE) were slightly noticeable after storage for all WBR samples, and UHP-treated grains represented clearly visible browning reactions. In addition, hierarchically clustered heatmap suggested that volatile fingerprinting could be preliminarily separated according to different pretreatments and storage duration. After immediate treatments, total antioxidant activities presented a decrease by 14–28% for all treated grains compared to the unprocessed samples. Within storage process, GER and HIU samples showed steadily declining trends for antioxidant activities whereas a fluctuation was observed in UHP-treated grains. Besides, samples treated by 350/450 MPa maintained more antioxidants (91–102%) than the control (83–87%), GER (64–76%) and HIU (76–88%) samples at the end of storage. Multivariate analysis revealed a close relationship between color changes and antioxidant activity. These results indicated the necessity of a complete evaluation for possible processing effects on physicochemical and nutritional characteristics of WBR grains within the entire process extending immediate treatments to its prolonged storage and consumption, in order to achieve better quality control using the optimized processing parameters.

Industrial relevance

The selected emerging techniques including UHP, HIU and GER allow the acquisition of WBR products with improved texture and cooking properties as well as the enrichment of bioactive components. Nevertheless, the processed WBR grains must be subjected to a storage process before consumption. A more comprehensive understanding of the effects of newly-developed techniques on quality characteristics of WBR grains contributes to better control of products quality, particularly extending from immediate effects to the prolonged storage.

中文翻译：

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上颜色超高压的影响，挥发性有机化合物和全粒糙米（抗氧化剂水稻贮存期间L.）：用高强度超声和发芽前处理的比较研究

经过超高压（UHP）处理后，近来已实现了具有明显增强的品质属性的全谷物糙米（WBR），但是几乎没有文献记录了该过程引起的理化参数变化，这些变化随后被UHP处理的WBR储存。因此，这项工作旨在研究UHP处理（0.1–450 MPa / 10分钟）对化学成分，微观结构以及在存储过程中（20天/ 30°C）化学反应的变化所产生的影响，如挥发性分析，颜色所示。与高强度超声（HIU）和发芽（GER）预处理相比，WBR谷物的发育和抗氧化活性更高。结果表明，理化性质的显着变化是由加工方法和储存时间引起的。颜色变化（一*b *，L *和ΔE）对于所有WBR样品，在储存后略显着，并且经UHP处理的谷物表现出清晰可见的褐变反应。此外，分层聚类的热图表明，可以根据不同的预处理方法和存储时间初步分离出挥发性指纹图谱。立即处理后，与未处理的样品相比，所有处理过的谷物的总抗氧化剂活性降低了14–28％。在储存过程中，GER和HIU样品的抗氧化活性呈稳定下降趋势，而UHP处理的谷物则出现波动。此外，在储存结束时，经350/450 MPa处理的样品所含的抗氧化剂（91–102％）比对照（83–87％），GER（64–76％）和HIU（76–88％）多。多变量分析显示颜色变化和抗氧化活性之间存在密切的关系。这些结果表明有必要对整个加工过程中可能对WBR谷物的理化和营养特性产生的加工效果进行完整评估，以便通过立即处理延长其储存和消耗时间，从而使用优化的加工参数实现更好的质量控制。

行业相关性

选定的新兴技术（包括UHP，HIU和GER）允许获得质地和蒸煮特性得到改善以及生物活性成分丰富的WBR产品。但是，加工后的WBR谷物必须在消费前进行储存处理。对新开发的技术对WBR晶粒质量特性的影响的更全面的了解有助于更好地控制产品质量，特别是从即时影响扩展到长期存储。