Fortification of ayran (drinking yoghurt) with encapsulated cocoa hull waste extract by nano-liposomal sytems, shelf life and bioaccessibility studies

In this thesis, ayran (drinking yoghurt) was fortificated (1:10 w/w) with encapsultated cocoa hull phenolics which extracted from cocoa hull waste. Nano-liposomal systems were used for encapsulation that were chitosan coated (secondary) liposomes and spray dried liposomes. The protection level of cocoa hull phenolics and their biovailability in these systems were investigated in fortificated ayran (drinking yoghurt) during shelf life period. Cocoa hull waste was a phenolic rich source and encapsulation of these bioactive compounds in nano-liposomal system was an intelligent way both to protect them negative environment conditions and to increase their bioavaibility. In these study we encapsulated cocoa hull waste extract (CHWE) by fine-disperse anionic liposomes with different concentration (0.1-1.0 %). Encapsulation efficiency of liposomes was depended on extract concentration which also effect the particle size of liposomes. The maximum encapsulation efficiency was found 73.6% in concentration 0.2% w/v and the particle size is 157 nm, the ζ –potential is – 25 mV at this concentration. To enhance the liposome structure, their surface was coated with chitosan and then were solidificated by spray dryer. Layer-by-layer deposition method was used for coated the primary anionic liposomes with cationic chitosan (0.4 w/v%) and before the spray drying they mixed with maltodextrin (MD) (20 w/v%). Change of encapsulation efficiency (EE%) of bioactive compounds in primary, chitosan coated (secondary) and spray dried liposome was investigated, the spray dried liposome had the higher EE%. The protection of cocoa hull phenolics by liposomal systems during in-vitro digestion was investigated by comparing freeze dried CHWE, spray dried CHWE, secondary liposome with CHWE and spray dried liposome with CHWE. The better protection of bioactive compounds in gastro-intestinal digestion (in-vitro) was supported by spray dried liposomes. It is showed that covering the liposomes with chitosan layer provided the liposome stability and getting them to dry powder forms enhanced both stability and bioaccessibility. The bioavailability of these compounds in spray dried liposome at least 4 times higher than freeze dried forms. The phenolic acids profile and their bioavailability of CHWE and the CHWE in nano-liposomal systems was determined by in ultra high performance liquid chromatography (UHPLC). There was detected 10 major phenolic compounds. Their stability in gastro-intestinal digestion showed differences which based on molecular structure of phenolic acids and their location in the liposome. The bioactive compounds of cocoa hull were protected better in spray dried liposomes compared with secondary liposome, spray dried CHWE and freeze dried CHWE. The cocoa hull waste contained both flavon-3-ol monomers, flavan (quercetin) and phenolic acids. The interaction of these compounds with carbohydrate and oil bases molecules was an important parameter of their degradation level and bioavailability. In addition, the content and location of them in liposome structure (interior or surface) is another factor to determine the protection degree. According to these datas, the ayran (drinking yoghurt) was enriched with both encapsulated and unencapsulated cocoa phenolics which extracted from cocoa hull waste. To determine the protection level of liposomes and their effect of bioaccessibility; freeze dried cocoa hull waste extract (CHWE), spray dried CHWE, chitosan coated liposome (secondary liposome) with CHWE and spray dried chitosan liposome with CHWE were used for fortification. Protection of bioactive compounds which were total phenolic compound (TPC), total antioxidant compound (TAC) and total flavonoid compound (TFC) in fortificated ayran (drinking yoghurt) samples was investigated before and after in-vito digestion during the shelf-life period (1st, 5th and 10th and 15th day) at 4oC storage temperature. Spray dried liposome showed the highest protection level of phenolic compounds both before and after in-vitro digestion which were at least 2 times and 5 times higher than ayran (drinking yoghurt) with freeze dried CHWE before and after in-vitro digestion, respectively. The bioavailabilty of CHWE phenolics in ayran (drinking yoghurt) were increased at least 7 folds when they are added with spay dried liposomes, instead of freeze dried CHWE. The CHWE phenolic profile of ayran samples were identified by UHPLC, and determined these compounds in ayran samples during shelf-life period. The spray dried liposomes showed the better protection of all phenolic compounds in ayran during shelf life period. In addition, liposomal systems showed the better protection level of phenolics both before and after in-vitro digestion. The surface charge of liposomes and their interaction of other food components, especially ayran proteins was an important parameter for liposome stability, as spray dried liposomal systems provided higher protection of phenolics compared with secondary liposomes during shelf life. There are several studies about fortification of yoghurt and yoghurt products with polyphenol extracts, but using the liposomal encapsulation of polyphenols is the first study for enrichment the ayran (drinking yoghurt). In additon these is the first study about fortification of ayran, which is a traditional fermented milk beverage in Turkey and contain salts, with polyphenol extracts.