Non-thermal processing of milk: Principles, mechanisms and effect on milk components

The conventional thermal treatment causes chemical modifications to milk constituents such as protein denaturation, loss of vitamins and flavoring compounds, depression at freezing point, and nonenzymatic browning, which may result in adverse changes to the flavor, color, and nutritional value of milk. This review looks into the emerging non-thermal processing techniques such as high-pressure processing (HPP), pulsed electric field (PEF), ultrasonication and hydrodynamic, UV-irradiation and plasma technology, cavitation, and their effects on milk components and bioactive compounds. For consumer acceptability and safety, simultaneous and crucial needs exist: microbial safety, fresh like quality and preservation of bioactive compounds. Technologies like HPP and PEF have been capable of achieving microbial reduction with moderate thermal inputs. Ultrasonication and hydrodynamic cavitation have the dual functions of deactivating microorganisms and homogenizing, and plasma and UV-C radiation could ensure minimal loss of heat-sensitive components. These processing techniques could be an alternative to pasteurization and sterilization of milk with assured microbial inactivation and maximal retention of nutrients in dairy

Enhancement of physicochemical stability and reduction in enzyme and microbial activity of apple juice by hydrodynamic cavitation processing

Conventional thermally processed apple juices are nutritionally depleted because the heat sensitivity degrades the bioactive compounds that comprise them. This study proposed a non-thermal technique, hydrodynamic cavitation (HC), to preserve the nutritional content and prevent the loss of bioactive components in apple juice. In addition, the effect of hydrodynamic cavitation on the physicochemical, nutrition, and enzyme inactivation of freshly expressed apple juice has been studied. The design expert software has been used for process optimization, while fuzzy logic was applied for sensory. Hydrodynamic cavitation has been used on freshly extracted apple juice with inlet pressure in the range of (34.47–103.421 kPa) for a treatment time of (0–30 min). The apple juice was treated thermally at 90 °C for 2.5 min to compare the cavitation results. The settling of particles in the cavitation sample was 7%, which was lower than the heat-treated sample (10%) and untreated control sample (39%) and had a noticeable effect on the cloud value and stability of the apple juice. The HC treatment reduces the particle size of fresh apple juice from 8934.09 nm to 1112 nm, resulting in a homogenizing effect, a decrease in viscosity, and improved juice stability. Hydrodynamic cavitation reduced the antioxidant activity from 0.4987 mg GAE mL−1 (control) to 0.3951 mg GAE mL−1 yet retained better activity than the heat-treated apple juice (0.3489 ± 0.34 mg GAE mL−1) with microbial log reduction of 0.9 at 103.42 kPa treated for 30 min. After 15 days of storage at 4 °C, HC-treated juice had higher quality features and nutrient retention than heat-treated apple juice