RESUMO
In this study, antioxidant, chemical, microbiological, and sensory attributes changes taking place during the production of probiotic yoghurt using pulp of soursop (Annona muricata), sweetsop (Annona squamosa), and custard apple (Annona reticulata) were evaluated. The products were stored at 4 °C for 28 d, during which time physicochemical properties and viability of probiotic bacteria and yoghurt starter cultures were evaluated weekly. Yoghurts prepared with fruit pulps displayed higher antioxidant activities on the first day of storage compared to the control. During the storage, the addition of fruit pulps influenced (p < 0.05) pH, titratable acidity, syneresis and counts of B. animalis ssp. lactis BB-12 of yoghurts, whereas counts of Streptococcus thermophiles and Lactobacillus delbrueckii ssp. bulgaricus were found to be insignificant. Sensory evaluation results showed that yoghurt containing soursop fruit pulp had better sensory scores than other treatments. Therefore, these results proved that soursop can be used to produce probiotic yoghurt with enhanced physicochemical, microbiological and sensory properties.
RESUMO
The rheological, emulsification and certain physicochemical properties of purified exopolysaccharides (EPS) of Bifidobacterium longum subsp. infantis CCUG 52486 and Bifidobacterium infantis NCIMB 702205 were studied and compared with those of guar gum and xanthan gum. The two strains were grown in skim milk supplemented with 1.5% (w/v) casein hydrolysate at 37 °C for 24h; they both produced heteropolysaccharides with different molecular mass and composition. The carbohydrate content of both polymers was more than 92% and no protein was detected. The EPS of B. longum subsp. infantis CCUG 52486 showed highly branched entangled porous structure under scanning electron microscopy. Higher intrinsic viscosity was observed for the EPS of B. longum subsp. infantis CCUG 52486 compared to the EPS of B. infantis NCIMB 702205 and guar gum. Both polymers showed pseudoplastic non-Newtonian fluid behaviour in an aqueous solution. The EPS of B. infantis NCIMB 702205 and B. longum subsp. infantis CCUG 52486 produced more stable emulsions with orange oil, sunflower seed oil, coconut oil and xylene compared to guar and xanthan gum. The EPS of B. longum subsp. infantis CCUG 52486 is the most promising one for applications in the food industry, as it had higher intrinsic viscosity, higher apparent viscosity in aqueous solution, porous dense entangled structure and good emulsification activity.
