New technological strategies for dairy products valorization

ENG- The food industry is increasingly demanding more efficient and sustainable strategies to improve the quality of the final products, as well as to reduce energy consumption throughout food processing. The main objective of this thesis was to investigate the application of emerging technologies which can contribute to increase the quality and the sustainability of dairy products. The first part of the work was focused on the application of membrane filtration and high-pressure processing (HPP) to valorize the protein fractions from native concentrate whey and cheese whey. In the second part of the work, the use of pulse spray drying (PSD) was compared to conventional spray drying (SD), and its effects on the nutritional and technological properties of skimmed milk were evaluated. Whey is a good source of high-valuable proteins, which can be recovered after cheese production. Anyway, -Lactoglobulin (-Lg), which is the main whey protein and is absent in human milk, has been associated with infant allergies. This can limit the potential applications and the commercial value of the protein concentrates which could be obtained from cheese production side streams. Thus, HPP has been applied on native and cheese whey concentrates from different species (cow, sheep and goat) at two pH conditions (physiological and acid) for an -Lactalbumin (-La) enriched fraction obtention. In all cases, -Lg was significantly more susceptible to HPP than -La. This way, treatments for 4 min at 600 MPa (23 °C) provided high -Lg precipitation degree and a good balance between -La purity and yield in all whey concentrates, despite the decrease of total free thiol groups Index and surface hydrophobicity. Overall, processing concentrated whey provided advantages when compared to non-concentrated milk or whey. However, strong differences between species were observed; whey acidification (to pH 4.6) prior to HPP enhanced -Lg precipitation in bovine samples, while the contrary behavior was observed in the caprine and ovine ones. Besides, effects of HPP on cheese whey and native whey concentrates differed, probably due to manufacturing differences (e.g., temperature, acidification, fermentation, etc.), that mitigated HPP effect on WPs