Flavor Defects
Can be classified according to the
flavouring system (lacks flavour or too high flavour, unnatural flavour), the
sweetening system (lacks sweetness or too sweet),
processing related flavour defects (cooked),
dairy ingredient flavour defects (acid, salty, old ingredient, oxidized/metallic, rancid, or whey flavours), and
others (storage/absorbed, stabilizer/emulsifier, foreign). Some details are given below.
Flavoring System
Unnatural flavor - Caused by using flavours
that are not typical of the designated flavour i.e. wintergreen flavour on
vanilla ice cream. esp. vanillin
Egg: Caused by using too much egg in an ice cream that is
not specified as a custard ice cream - resembles French vanilla ice cream .
Processing
Cooked: Caused by using milk products heated to
too high a temperature or by using excessively high temperatures in mix
pasteurization. It can dissipate with time, the same as cooked defect in fluid
milk. Caramel-like, scalded milk, oatmeal
Dairy Ingredients
High Acid: Use of dairy products with high
acidity (usually due to bacterial spoilage) or holding mix too long and at too
high a temperature before freezing. Acid/sour flavours are more rare these days
due to the growth ofproteolytic psychrotrophs during storage at elevated
temperatures, rather than lactic acid bacteria.
Salty: Ice cream too high in milk solids-not-fat. Too much salt may
have been added to the mix. Whey powder, maybe salted butter, whey flavour
graham cracker like
Old Ingredient: Caused by the use of inferior dairy products in the
preparation of the mix. Powders made from poor milk or butter made from poor
cream will contribute to old ingredient flavour. Also poor egg. Unpleasant
aftertaste
Oxidized: Caused by oxidation of the fat or lipid material such as
phospholipid, similar to fluid milk
href="/dairyedu/grading.html#oxidation">oxidation. Induced by the presence
of copper or iron in the mix. Mono-and-di-glyceride or Polysorbate 80 can also
oxidize. Various stages - cardboardy, metallic.
Rancid: Caused by rancidity of certain fats. May be due to use of
rancid dairy products or to insufficient heat before homogenization of mix. Egg
yolk powder may also be the cause. See description of
href="/dairyedu/grading.html#rancid">Lipolysis, especially the release of
free butyric acid.
Others
Storage: Usually develops from "Lacks Freshness" and
is most pronounced on ice cream which have been held in a stale storage
atmosphere. Ice cream can also pick up absorbed volatile flavours from the
storage environment (e.g., paint, ammonia, or in dipping cabinets - volatiles
from nearby flavours.