Lists of ice cream “defects” often include some characteristics that can be positive or negative, depending on the context.

Tharp & Young

Lists of ice cream “defects” often include some characteristics that can be positive or negative, depending on the context. Such terms would be considered as defects only when they are not appropriate to the target flavor profile of a specific product. On the other hand, many descriptive terms are unequivocally defects that detract from quality whenever they are detected. Both types will be described briefly below, broadly organized as to their source. When appropriate, a brief reference to causative factors will be included.
  • Added flavorings: lacks fine flavor-flavor profile falls short of target or is not “balanced”); wrong flavor-incorrect flavoring used; excessive, deficient, unnatural, atypical of designated flavor; foreign flavor-flavor profile alien to the flavor descriptor.
  • Sweeteners: syrup-similar to Karo syrup, from high corn syrup solids levels or corn syrup solids that have deteriorated due to excessive age or exposure to high temperature; excessive, deficient, unnatural.
  • Dairy ingredients: whey flavor-like graham crackers or aroma of alfalfa hay, from high levels or poor quality of whey solids; salty-high levels of MSNF/whey solids or (rarely) added sodium chloride; lacks freshness/old ingredient-stale characteristics associated with old dairy components; rancid-like grated cheese, caused by hydrolysis of milk fat; oxidized-so-called “cardboard” flavor, produced by the oxidation of milk fat in dairy ingredients or the ice cream itself (most often due to exposure to ultraviolet light); fermented/acid (tart)-flavor profile similar to that of cultured dairy products, caused by growth of lactic acid organisms; unclean/bitter/putrid-general unpleasant flavor and/or aftertaste, caused by the growth of psychrotrophic microorganisms.
  • Processing (mix or dairy ingredients): cooked-milk custard character, caused by high heat treatment; burnt-an extreme cooked character, resulting from very high temperature exposure or multiple high heat exposures.
  • External: characteristics resulting from chemical, physical, or microbiological contamination can include, but are not limited to, contamination by cleaning/sanitizing chemicals, contamination of added flavors or flavorings themselves and the like; inclusions can contribute to flavor defects either through poor quality per se or deterioration through prolonged storage.
The direct perception of flavor involves two elements: taste (sweet, salty, sour, bitter sour, and, most recently, umami/savory), which is perceived by taste buds in the mouth; and aroma, which is detected by odor perceptors in the nasal passage. The nature of flavor can be influenced by other sensory characteristics, such as body and texture. For example, the presence of ice can anesthetize the taste buds temporarily to an extent that depends upon the amount of ice and the size of the particles. Also, the viscosity of the product after it melts can interfere with the vaporization of aroma components and slow their passage to the aroma perceptors, a phenomenon referred to as “flavor masking.” When considering flavor profiles that seem to lack a particular flavor element or show an uncharacteristic balance, it is important to understand that such situations may result from a masking of a flavor profile rather than an error in the type or level of flavoring added.

The inclusion of effective sensory evaluation in an ice cream quality assurance program-i.e., the capability to identify flavor attributes that fall short of expectation and identifying their sources-is a critical element to the retention of positive attributes and the avoidance of negative influences (true defects). Once shortcomings and their sources are known, corrective action can be applied to ensure success in the marketplace.