June 1, 2018 — No food ingredient may be more influential than flavors. “We make selections about taste and preference of food based on these small sets of molecules that are barely perceptible and measurable,” said Robert McGorrin, Ph.D., CFS, Department Head and Jacobs-Root Professor, Food Science & Technology, Oregon State University, in his presentation “Protein + Flavor = A Formulation Challenge.” Creating the right balance of flavors is especially demanding when developing high-protein foods. The addition of protein may alter the flavor by either adding off-flavor notes, such as beany or bitter types often associated with soy protein, or by causing astringency, which falls into the category of chemesthesis, producing a chemical sensation. Proteins may also change the flavor profile through flavor interactions, flavor binding or flavor release, McGorrin noted. He delved into helpful insights on proteins and flavors.
The type of protein can pose a challenge. “Soy, whey, casein, pea, rice, depending on how they are heated—high temperature- short time or ultra-high temperature—can bring in notes we describe as burnt, caramelized, nutty, beany, sulfuric or bitter. Amino acids also provide their own bitterness and metallic off- flavors,” said McGorrin.
Because proteins are good at binding and absorbing flavor, any sensory evaluation done on a new formulation should be delayed for at least a week to give the flavor a chance to equilibrate. It is important to “bucketload” the formulation with flavor at perhaps four to 10 times the initial quantity needed to basically titrate the active sites on the proteins until that equilibrium point is reached, cost permitting, noted McGorrin. “You have to compensate for flavor loss.” Flavor in clear beverages may be affected by incorporating hydrolyzed protein. These systems require less flavor, because less binding occurs with these proteins, but McGorrin cautioned that more off-flavor defects may be present.
Factors, such as pH, can also influence the protein’s contribution to flavor. Beverages at a pH of 3.5 can accentuate more off-flavor defects (e.g., bitterness, astringency, chalkiness). The optimum pH to avoid a gritty texture or astringent taste is pH 6-7. However, “pH 3.5 is best with citrus beverages to make orange and lemon flavors pop,” explained McGorrin.
Flavor requirements are also dependent on the food product. For example, water activity (aw) is very influential. Protein bars have low moisture (aw= 0.2), undergo non-thermal processing and are stored at room temperature. Conversely, protein beverages are high moisture (aw = 1), are thermally processed and are stored in refrigeration. However, their flavors are unstable, because they are more reactive in solution—finding mobile sites to bind to on the protein; and flavor scalping, or muting, can also occur as protein absorbs the flavor, McGorrin noted.
Flavor masking is a technique used to minimize inherent protein off-flavors. Sweetener modifiers/enhancers or bitter blockers can often help mask off-flavors, as well. Sodium chloride, monosodium glutamate and adenosine monophosphate are examples of bitter taste receptor blockers. Vanilla or peach flavor may help mask beany notes from soy protein. Using a complementary flavor is another method used to mask off- flavors. For example, pea protein contains earthy notes. Soy has beany notes. These flavor notes are also common in peanuts, so adding peanut or nut flavors complements and helps mask these off-notes by creating flavor synergy.
Instead of masking undesirable notes, flavor completion or insertion allows these notes to become part of the flavor system. McGorrin gave the example of undesirable green notes in soy protein. By adding a “jammy-style” strawberry flavor that lacks green notes to the flavor system, the green notes inherent in soy protein complete the perception of the strawberry flavor profile.
McGorrin stressed the importance of involving the flavor supplier to reduce development time. Formulation secrets need not be revealed; but, process method, storage environment, moisture content, pH, added vitamins, presence of high-potency sweeteners and percent protein will help identify an appropriate flavor choice early on, he added.
“Protein + Flavor = A Formulation Challenge,” Robert J. McGorrin, Ph.D., CFS, Department Head and Jacobs-Root Professor, Food Science & Technology, Oregon State University. This presentation was given at the 2018 Protein Trends & Technologies Seminar and delved into helpful insights on proteins and flavors. To download free presentations and the Post-conference summary of this event, go to https://foodproteins.globalfoodforums.com/food-protein-rd-academy/protein-and-flavor-a-formulation-challenge-presentation/
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