The scientific objectives of PREMIUM were fulfilled thanks to secondments (141 PM in 5.5 years) and work performed outside secondments. More than 30 samples of oligosaccharides of original composition were produced either by synthesis from sugars (sucrose and lactose) or by hydrolysis of polysaccharides from natural substrates (yacon, chickpeas, lentils). Original protocols were setup to obtain oligosaccharides from wastewater of food industry. The OS were screened according to their physical properties, ability to protect LAB during freezing and freeze-drying, and the environmental impact of their production process. Two PREMIUM’s oligosaccharides and one commercial sample were selected to perform experiments at a pilot scale, which were necessary to conduct life cycle analysis and multicriteria analysis of the LAB production system. 18 scenarios were compared, including 3 processes (freezing, freeze-drying, spray-drying), 3 oligosaccharides' mixtures and 2 LAB. Relevant indicators and methods for evaluating the stabilization alternatives and identifying the most promising strategies for the eco-friendly preservation of LAB were defined at pilot and industrial scales.
An innovative process based on layer-by-layer encapsulation was developed to improve bacterial recovery after drying. This process was setup at the laboratory scale and then optimised to be scale-up at the pilot scale.
Vibrational spectroscopic techniques were developed and applied during the project. They were used as high throughput methods to determine the oligosaccharides compositions, their ability to protect LAB during the process, and to identify the main cellular damages induced by freeze-drying, spray-drying, and storage. Cellular markers of degradation, such as nucleic acids, cell proteins and cell walls, were identified. Microscopy was applied to obtain super resolution imaging of single LAB cells. Furthermore, experimental approaches and molecular dynamics simulations were developed to investigate potential interactions between oligosaccharides and LAB membranes. The influence of the physical properties, such as the glass transition temperature, on the long-term storage stability of dehydrated LAB, was also investigated.
Methods and knowledge acquired during the project were transferred to study other LAB of commercial interest (probiotics) and other cellular models, such as mammalian cells.
Information, experience, and skills were exchanged among all partners, both internationally and across sectors (47 secondments), thus expanding and enriching knowledge on the different topics and methods covered by PREMIUM. This was possible through 85 secondments and 141 PM, 4 face-to-face meetings, supervision of PhD students (10), and collaborative dissemination of results: 21 articles, 4 book chapters, 35 conferences participations and 4 invited lectures.
PREMIUM developed a visual identity and targeted actions to communicate and create awareness on PREMIUM’s activities and results (logo, flyer, website, presence on social media (Facebook, Twitter, Instagram), YouTube channel, 4 external newsletters). PREMIUM organised: 4 workshops, 14 training sessions and 4 winter schools involving around 450 people.
