Fruit & Vegetable (F&V) smoothies are rich in nutrients and other health related compounds. However, they have a short shelf-life and the traditional methods applied to preserve them generate losses in their natural flavor and nutrients. The aim of this study was to optimize the pressure level (35–650 MPa) and holding time (1–9 min) of High Pressure Processing (HPP), performed at an initial temperature of 20 °C and only modified by adiabatic heating of a F&V smoothie in order to achieve microbial and enzymatic inactivation while maintaining its natural attributes. Response surface methodology with a Doehlert design and Desirability function were employed to simultaneously optimize these quality attributes. Results showed that HPP enhances microbial quality and does not affect pH, total soluble solids, texture and total phenolic content. Moreover, the optimal HPP treatment (627.5 MPa/6.4 min) leads to reductions of 85%, 45% and 10% on PME, POD and PPO, increases antioxidant capacity by 75% and maintains or slightly improves the color of the smoothie.

Industrial relevance text

F&V smoothies are tasty, healthy, convenient and ready to drink, fulfilling all the current demands of consumers. This has led to an accelerated increase in their popularity. However, they have a short shelf life mainly attributed to microbial and enzymatic spoilages. HPP is proposed as a non-thermal method able to prolong shelf-life of the products by means of microbial and enzymatic inactivation, while preserving bioactive compounds and quality characteristics. An optimization assay was carried out in order to find optimal process conditions for the F&V smoothie's preservation. The promising results obtained can help to promote the use of HPP as an alternative technology for the preservation of this kind of products.

中文翻译：

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优化高压加工参数以保留水果和蔬菜混合果汁的品质属性

水果和蔬菜（F＆V）果汁富含营养成分和其他与健康有关的化合物。但是，它们的保质期短，并且采用传统方法保存它们会损失其天然风味和营养成分。这项研究的目的是优化高压工艺（HPP）的压力水平（35–650 MPa）和保持时间（1–9 min），该工艺在初始温度20°C下进行，并且仅通过绝热加热进行F＆V奶昔，以实现微生物和酶的灭活，同时保持其自然属性。采用具有Doehlert设计和Desirability函数的响应面方法来同时优化这些质量属性。结果表明，HPP可提高微生物质量，并且不影响pH值，总可溶性固形物，质地和总酚含量。

行业相关文字

F＆V冰沙美味，健康，方便并且可以即饮，满足了消费者当前的所有需求。这导致它们的受欢迎程度加速增加。但是，它们的保质期短主要归因于微生物和酶的腐败变质。HPP被提议作为一种非热方法，能够通过微生物和酶的灭活来延长产品的货架期，同时保留生物活性化合物和质量特征。进行了优化试验，以找到F＆V奶昔保存的最佳工艺条件。获得的有希望的结果可以帮助促进HPP作为保存此类产品的替代技术的使用。