Properties of set-style skim milk yoghurt as affected by an enzymatic or Maillard reaction induced milk protein oligomerisation

Protein oligomers (2.9 × 104–3.0 × 105 g/mol) were introduced into yoghurt in amounts of 15–37% of the total protein by an enzymatic modification of proteins in yoghurt milk by lactoperoxidase, laccase or glucose oxidase as well as by a dry matter increase of yoghurt milk with sodium caseinate/lactose, sodium caseinate/pectin and total milk protein/lactose Maillard products. Yoghurt from enzymatically treated milk was characterised by an up to 10% lower acidity, up to 47% diminished gel strength and up to 18% decreased whey drainage than yoghurt from untreated milk. Yoghurt from protein/saccharide Maillard product enriched milk exhibited up to 4% reduced acidity, up to 27% increased acetic aldehyde content as well as up to 58% decreased whey drainage in relation to yoghurt from untreated protein/saccharide mixture enriched milk. Sensorically, yoghurt from enzymatically treated milk as well as from protein/saccharide Maillard product enriched milk was described by an even and whey-draining appearance, by a soft, homogeneous and creamy consistency as well as by a mild, less yoghurt characteristic taste and smell.This study for the first time presents an overview over the impact of novel protein oligomerisation techniques on physicochemical and sensory properties of yoghurt in regard to possible practical applications of an enzymatic as well as Maillard reaction induced oligomerisation in complex food systems.