Nano casein-pectin complex: exploring physicochemical, organoleptic properties, and LAB viability in skimmed milk and low-fat yoghurt.

Protein complexes with a nutritional value, heat stability, and gelling properties with no negative impact on culture viability have promising application prospects in the fermentation industry. The aim of the study was to investigate the possibility of applying physical modification seeking high-protein-fortified yoghurt production using the nano casein-pectin NCP complex as an active colloidal system with enhanced structural and thermal properties and monitor the quality properties of the physicochemical, heat stability, rheological, starter culture viability and sensory evaluation of fortified products comparing with the plain control throughout the cold storage. High-energy ball milling (HEBM) technique was used to produce nanoparticles of casein powder and smaller particles of pectin individually, and particle size and zeta potential was assessed. Deferent Nano casein-pectin (NCP) complex formulations were prepared, their physicochemical properties were assessed including protein quality via Amino Acid Analyzer (AAA), viscosity, thermogravimetric analysis (TGA), and then used in fortification of skimmed milk and low-fat yoghurt to monitor the fortification effects. The particle sizes showed to be ≈166 nm and 602.6 nm for nano-casein and pectin, respectively. Milk fortification with the NCP complex has significantly increased the nutritional value represented in increased protein content (7.19 g/100 g in NCP5); Ca, P, and S content (2,193.11, 481.21, and 313.77 ppm); and amino acid content with first limiting amino acids; histidine (0.89 mg/g), methionine (0.89 mg/g), and low content of hydrophobic amino acids (HAAs) may cause aggregation. NPC fortification enhanced physicochemical properties announced in enhanced viscosity (62. mP.s in NCP5) and heat stability (up to 200°C) compared with control skimmed milk (SM). NCP yoghurt fortification significantly increased protein content to 11 mg/100 g in T5, enhanced viscosity to 48.44 mP.s in T3, decreased syneresis to 16% in T5, and enhanced LAB viability which was translated in preferable sensorial properties. Applying fortification with nanoparticles of the casein-pectin (NCP) complex balanced the amino acid content and improved physicochemical, rheological, nutritional, and sensorial properties and LAB viability, which can be recommended further in functional food applications.

Functional products fortified with probiotic LAB isolated from Egyptian dairy sources showed hypolipidemic effects in Albino rats.

Biological food industry has increased economic importance of new Lactic Acid Bacteria (LAB) with functional aspects such as health promoting and enhanced sensorial traits. The objectives of the present study were the isolation and genotypic characterization (16S rRNA) of new LAB isolates from Egyptian Laban Rayeb, Zabady and mothers' breast milk as potential probiotics. Strains were in vitro and in vivo evaluated for their safety and probiotic health promoting traits in Albino rats then applied into two types of functional dairy products. Three strains Streptococcus thermophilus MH422542, Enterococcus faecium MH422543 and Lactococcus lactis subsp lactis MH422545, were selected from a pool of 82 strains. St. thermophilus showed proteolytic activity and production of Exopolysaccharides (EPS). When evaluated in animal models; the strains showed hypolipidemic effects especially E. faecium that reduced atherogenic indices up to 88%. The strains modulated the gut microbiota by reducing Staphylococcus sp. and coliforms with no adverse effects either on blood parameters, antioxidant enzymes, cancer markers or hepatocytes histological examination. Only E. faecium MH422543 showed an immune response by increased white blood cells (WBC) while lymph and platelets values were not affected. The probiotic strains approved their convenience as starter/ adjunct cultures and enhanced organoleptic properties of the fermented dairy products.

Starter culture development for improving safety and quality of Domiati cheese.

Eleven lactococci strains (sp. lactis and cremoris) were collected according to specific or selected characteristics for development of defined strain starter (DSS) to improve safety and nutritional quality of traditional and low salt Domiati cheese. Thirteen DSS; nisin-producing system or/and folate-producing strains were prepared. The behaviour of the strains in DSS was studied in milk and in two series of Domiati cheese; the first one made with 5% NaCl and salt tolerant strains, the second made with 3% NaCl and the control cheeses were made without starters. The population dynamics of strains and sensory evaluation of cheese corroborated the results in milk. All strains can grow well together and appeared to produce pleasant flavours, normal (typical) body and texture Domiati cheese. There was no apparent difference in cheese composition between cheeses in each series; the levels were within margins for composition of Domiati cheese. The levels of nisin (IU g(-1)) ranged from 204 to 324 IU g(-1) in 3-months' cheeses. Folate concentration increased in cheeses made with DSS cultures than control and the level ranged from 5.5 to 11.1 microg 100 g(-1) in cheeses after 3 months. All results revealed that selected DSS can be used for improving Domiati cheese.