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The 'flavor' of texture
Texture influences the taste of a product. As formulations are modified, texture changes, and flavor release does, too.
“How the product dissolves in the mouth at the moment of consumption impacts the flavor release and therefore the flavor perception,” Mr. Gonzales said. “If we think about yogurt and we are looking at addressing clean label and sugar-reduction trends, there are numbers of parameters to take into account. These include ingredients to remove and those to add to achieve these labeling goals. You need to define the target sugar content and evaluate the impact on texture as sugar is reduced. You also need to evaluate sweetness perception.”
Formulation modifications may impact processing parameters. This is particularly true for cultured dairy products where the fermentation process impacts texture.
“This is because the product is alive and constantly changing,” Mr. Hopkinson said. “The texture is also largely due to the gel formation through the acidification of the milk base, and this is a very complex operation.
“Further, the acidification and resulting gel formation is augmented by the formation of exopolysaccharides by the cultures involved. Very small changes during processing can result in big changes in texture.”
For these reasons, cups of yogurt seldom have the same texture on the day of manufacturing and after about 45 days of shelf life. Cultures, enzymes and hydrocolloids may assist with minimizing this variation.
“Yogurt, sour cream and buttermilk are fermented in production to a pH of 4.5 to 4.6, but by the end of the shelf life the pH is 4.0 or less,” said Brian Surratt, senior scientist — dairy applications, Cargill Texturizing Solutions, Minneapolis. “Because the isoelectric point of milk proteins is 4.6, their interactions change as the pH shifts, resulting in textural changes that we often see as water that has ‘wheyed off,’ also known as syneresis. In these applications, hydrocolloids are used to provide a consistent texture for a longer time.”
Different ingredients work best in the varied styles of yogurt. For example, there are specific cultures for drinkable yogurts that provide smoothness and stability.
“The yogurt category provides consumers with a wide range of options with different texture experiences,” said Judy Whaley, vice-president of new product development, Tate & Lyle, Hoffman Estates, Ill. “There’s everything from foam products with whipped or mousse-like qualities to stirred products with a creamy mouthfeel to high-density products with a ‘cuttable’ texture. In order to achieve these novel textures, formulators must have a deep understanding of how to manipulate texture.”
Mirjana Curic-Bawden, principal scientist, application manager for fermented milk and probiotics, cultures and enzymes, Chr. Hansen, Milwaukee, said, “Visual texture is the first thing that consumers see when they open the yogurt cup. Cup-set yogurt has to be carefully developed to ensure high gel firmness and no syneresis over shelf life. Stirred yogurt is more challenging since it goes through the mechanical stress after the fermentation. This can easily destroy the texture and result in drinking instead of stirred yogurt.
“Cultures for stirred yogurt should have low-process post-acidification in order to fill the cups before developing acidity. It is ideal to fill the cups at incubation temperature.”
Culture selection also varies by yogurt flavor and sweetness. For example, cultures that develop mild yogurt flavor with low acidity may allow for a reduction in added sugars.