Microwave heating is an emerging alternative direct heating method to face deposit and particle formation upon heating fouling-sensitive food products. This study successfully demonstrated the implementation of a new set-up for continuous microwave heating at pilot scale (f = 2450 MHz, P = 0.6–6 kW). Reconstituted skim milk concentrate (DM = 27, 31.5 and 36 g/100 g) was heated (110–125 °C, 5 s holding time) through microwave technology and with a tubular heat exchanger in order to examine heat-related product changes and compare both technologies.

The results showed significantly reduced whey protein denaturation (35–40% less β-lactoglobulin denaturation) and deposit formation (90% less fouling) of microwave heated reconstituted skim milk concentrate compared to tubular heating, whereas colour changes were insignificant for all experiments. Both methods resulted in comparable particle sizes at equal flow profiles, however, turbulent flow conditions were necessary in order to prevent elevated particle formation.

Industrial relevance

Microwave heating is a promising alternative heating method for fouling-sensitive dairy products. This study demonstrates that through short heat-uptake times gentle product handling is ensured, resulting in retained native product properties. Reduced fouling leads to extended running times, implying less and eventually shorter cleaning intervals. Moreover, compared to other direct heating methods like steam injection, no additional water/steam is added to the product. With its space-saving design and easy handling, continuous microwave heating is a rising technology with high industrial relevance.

中文翻译：

---

用于测试微波技术的新实验装置，可连续加热对结垢敏感的食品（如浓缩牛奶）

微波加热是新兴的替代性直接加热方法，用于在加热对结垢敏感的食品时表面沉积物和颗粒形成。这项研究成功地证明了在中试规模（f  = 2450 MHz，P = 0.6–6 kW）下连续微波加热的新装置的实施。 通过微波技术和管状换热器将重构的脱脂奶浓缩物（DM = 27、31.5和36 g / 100 g）加热（110–125°C，保持时间5 s），以检查与热相关的产品变化和比较这两种技术。

结果表明，与管状加热相比，微波加热的脱脂浓缩乳浓缩液的乳清蛋白变性（β-乳球蛋白变性降低了35-40％）和沉积物形成（结垢减少了90％），而颜色变化对于所有实验而言都是微不足道的。两种方法在相等的流速分布下均产生了可比较的粒径，但是，为了防止形成较高的颗粒，必须采用湍流条件。

行业相关性

微波加热是对结垢敏感的乳制品有希望的替代加热方法。这项研究表明，通过较短的吸热时间，可以确保温和的产品处理，从而保留天然产品的特性。减少结垢可延长运行时间，这意味着更少的清洁间隔，并最终缩短了清洁间隔。此外，与其他直接加热方法（例如蒸汽注入）相比，没有向产品中添加其他水/蒸汽。凭借其节省空间的设计和易于操作的优点，连续微波加热是一项具有高度工业实用性的新兴技术。