ABSTRACT Beetroot juice is a source of polyphenols and betalains. Betalains serve both as colourants and bioactive compounds, and are known to be sensitive to temperature. Conventional thermal treatments can significantly affect the visual appearance and the nutritional quality of beetroot juice and, in consequence, the ultimate consumer acceptance. Our aim is therefore to evaluate the effects of an alternative high pressure processing on the physicochemical, nutritional, sensory and microbiological quality of a beetroot juice. The results showed that a high pressure-processed beetroot juice (600 MPa, RT, 3 min) retained the physicochemical and nutritional properties (bioactive compounds and antioxidant properties) of the freshly squeezed juice with no clearly differentiated sensory quality. The microbiological shelf-life of the juice was established at 21 days, under refrigerated conditions, observing only minor nutritional losses throughout storage. The promising results of high pressure processing for the preservation of betalain-rich juices therefore suggests that the technique represents a useful alternative to conventional thermal treatments.

中文翻译：

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甜菜根汁的高静水压加工：对营养、感官和微生物质量的影响

摘要甜菜根汁是多酚和甜菜碱的来源。甜菜碱可用作着色剂和生物活性化合物，并且已知对温度敏感。传统的热处理会显着影响甜菜根汁的外观和营养质量，从而影响最终的消费者接受度。因此，我们的目标是评估替代高压加工对甜菜根汁的物理化学、营养、感官和微生物质量的影响。结果表明，高压加工的甜菜根汁（600 MPa，室温，3 分钟）保留了鲜榨汁的理化和营养特性（生物活性化合物和抗氧化特性），但没有明显区分感官质量。在冷藏条件下，果汁的微生物保质期确定为 21 天，在整个储存过程中观察到的营养损失很小。因此，高压处理用于保存富含甜菜素的果汁的有希望的结果表明，该技术代表了传统热处理的有用替代方法。