Technology and factors influencing Greek-style yogurt a Review

Abstract

Introduction. Analytical studies of Greek-style yoghurt manufacturing methods, formation and physicochemical characteristics of acid milk gels and factors that define yogurt quality are presented. Material and methods. The review is based on all the most important scientific papers ever published on the subject. Results and discussion. Different yoghurt production methods: Traditional methods based on mechanical separators, methods based on membrane processes and methods based on direct recombination, give product with differences in properties. Two of the most important parameters: The textural attributes and the water holding capacity define yogurt quality and determine consumer acceptance. Numerous manufacturing parameters, such as severe heat treatments, excessive whey protein to casein ratios, high incubation temperatures, certain types of starter cultures and the use of excessive amounts of starter culture, are associated with textural defects of stirred yogurt like graininess (particles) or surface roughness (irregularities in the yogurt matrix). This method of direct recombination has advantages over others, because it is more environmentally friendly and increases the nutritional value of the finished product. Still, rheological properties of recombined concentrated yogurt are different from those of strained yogurt. Usually they form weaker gels than those made by traditional or UF methods. Different dry dairy ingredients (especially with elevated content of whey protein) should be used for production of concentrated yogurt. Conclusions. Future research should be focused on the production of concentrated yogurt by direct recombination.