Whey syneresis on top of the sour cream in the package is considered a significant quality defect. There are three solutions available for solving the problem.
1. Change or increase the concentration of stabilizer.
2. Increase fat content. Higher fat sour creams have a better water-binding capacity.
3. Reevaluate the entire process and eliminate points of product abuse. This would primarily include all steps after fermentation.
Crème fraîche, or more correctly crème fraîche épaisse fermentée, is the European counterpart to the U.S. sour cream product. Crème fraîche has a fat content around 30-45% and has a mild, aromatic cream flavor. The differences between the two products originate in the manner of usage. The usage of sour cream is described above. Crème fraîche is used cold on desserts such as fruit or cakes, or warm as foundation in cream sauces that are commonly used in the French cuisine. This double usage creates a unique demand for specific product attributes. The dessert utilization requires a clean, not too sour (4), cultured flavor that doesn't overpower flavors from other dessert components. The cultured flavor should be refreshing so that it covers the impression of fat in the product. This emphasis on flavor has led to significant research at starter culture companies and dairy processing companies to develop starter cultures that cause optimum flavor development. The body and texture should be smooth and less firm than sour cream. Creme fraiche should be ''spoonable'', not ''pourable'', and should spread slightly on the dessert without being a sauce.
The incorporation of creme fraiche into warm sauce requires thermostability, otherwise the protein would precipitate and flocculate in the sauce. For regular creme fraiche (>30% fat) flocculation is rarely a problem. In contrast, low-fat creme fraiche (~15% fat) is less stable when heated. Addition of stabilizers such as xanthan gum can stabilize low-fat creme fraiche. However, based on European labeling legislation, a creme fraiche can not contain stabilizers and a stabilized product would therefore need to be marketed under another name.
Creme fraiche is produced by a process similar to that of sour cream, with the exception that no ingredients are added. Without stabilizers, it becomes a challenge to obtain good body and texture. Each processing step requires attention to producing and maintaining high viscosity. In this case the homogenizer becomes an essential tool for building viscosity. Only single-stage homogenization is utilized. The product is sometimes homogenized twice, either in subsequent runs before pasteurization, but more commonly both before and after pasteurization.
Homogenization after pasteurization promotes better viscosity and, equally important, better thermostability. An additional homogenization following fermentation gives a homogeneous product with a smooth mouthfeel. Homogenization downstream from the pasteurizer (i.e., after pasteurization) should raise concerns in regard to post-pasteurization contamination. Ideally, an aseptic homogenizer should be used. However, the high price of such homogenizers makes this an unsuitable alternative. Instead, great emphasis must be placed on proper cleaning and sanitizing of the downstream homogenizer. In addition, food safety issues are normally controlled because of the high content of lactic acid bacteria and the low pH.
There is some discussion as to the final pH of creme fraiche fermentee. Kosikowski et al. (25) and Kurmann et al. (32) state that the cream is fermented to pH 6.2-6.3. However, commercially it is commonly fermented to an end pH around 4.5. The mild flavor is not obtained by a higher pH but rather through selection of aroma-producing starter cultures. It is the combination of aroma compounds and the high fat content that mask the sour flavor in creme fraiche.
Creme fraiche is a new product on the U.S. market. The high fat content and small-scale processing contribute to a retail price that is at least twice as expensive as traditional sour cream. Nevertheless, sales are growing. Its increasing popularity is an indication of changing culinary habits promoted by growing population diversity and exposure to European culture. Although creme fraiche is far from being a mainstream product on the U.S. market, it is an interesting addition to the dairy case and can be found in many specialty stores.
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