Yeast Extracts: Nutritional and Flavoring Food Ingredients

Yeast extracts are the concentrates of the soluble fraction of yeast and more particularly Saccharomyces cerevisiae. As food ingredients, yeast extracts are described for their nutritional composition and flavoring properties. They are produced principally from autolysis, but in some cases, acid or exogenous enzyme preparations are added. The main nutritional components of yeast extracts include partly hydrolyzed protein with 35–40% of free amino acid, and they also contain B vitamins and some trace elements. As flavoring ingredients in foods, they provide diverse flavors depending on the methods used for their production. These flavors include meaty, kokumi, umami, and salty taste along with taste masking properties. Yeast extracts are a source of amino acids, including glutamic acid, with a content of about 5% and 10% w/w free and total glutamate, respectively. Yeast extracts have the capacity to induce the umami taste, the flavoring effect of monosodium glutamate (MSG), when providing glutamate at an amount below 1% in foods, i.e., below the amount required for pure MSG. The latest studies indicate that they can also be used as sources of bioactive substances in functional foodstuffs and dietary supplements.