If properly incorporated, hydrocolloid stabilizers can provide excellent functional attributes to cultured dairy products. Stabilizers are high molecular-weight hydrophilic (water-loving) hydrocolloids that are added to food products to control water. Many stabilizing compounds are polysaccharides, often derived from plant sources. Examples include seed gums (guar gum, locust bean gum), those isolated from seaweeds (carrageenan, agar), microbially-derived polysaccharides (xanthan gum), as well as pectins, food starch and modified-food starch. In addition, protein-based stabilizer gelatin may be used in certain cultured dairy product applications. Each individual hydrocolloid molecule controls and interacts with water, other stabilizer molecules and various mix components through specific mechanisms. Control of water, in most cases, is accomplished by hydrating the polymer, that is, molecules of stabilizer associate with a large quantity of water. However, in some cases, the polymer may actually form a network or gel within the product, such as in the case of gelatin.
While sometimes possible to stabilize a cultured product using only a single type of stabilizing molecule, more common tactics take advantage of synergies between various gums and use blends of stabilizers that provide finished product with the desired sensory and quality attributes. In fact, many suppliers offer complete packages to achieve specific product attributes.
Why Add Stabilizers?Stabilizers are employed throughout a range of cultured products, including buttermilk, cream cheese, sour cream, yogurt and cottage cheese (in the dressing). The main reasons for adding stabilizers to cultured products are to build appropriate body and texture, increase product viscosity, provide reset viscosity, and to prevent syneresis.
Stabilizers-with the possible exception of starch-are added to mix for cultured product manufacture at low levels, often 0.5% or less. Because these molecules are so hydrophilic (bind water so well) they require care in dispersing. The primary concern in stabilizer incorporation is to assure dispersion of the stabilizer into the mix without forming "fish eyes"-globules of hydrated stabilizer surrounding a dry unhydrated core of stabilizing material. Partially hydrated stabilizer in this form is not functional and can lead to understabilized products, processing problems and lost revenue.
Three general methods are used to incorporate stabilizer into dairy mixes. The first is the "over-the-top" method. Here, the stabilizer is added over the side of the make-up vat. If this method is employed, the stabilizer should be added slowly with the contents of the vat under agitation. Where possible, predisperse the stabilizer with enough sugar or salt to prevent particles of stabilizer from coming into contact with each other during the initial hydration phase. This method is the most labor intensive and is most likely to result in poor batch stabilization.
In the powder-funnel method, a funnel is attached to the inlet side of a pump (either positive or centrifugal) and the powder is slowly drawn into the flowing liquid by the low pressure region created by the flowing fluid. The physical action of the pump rotor provides some additional mixing of the dry ingredients into the mix. Powder funnels should be equipped with a valve to prevent drawing air into the mix after all the powder has been incorporated.
The most efficient-and third-method for incorporating stabilizer is to use specialized high-shear blending equipment. This equipment results in rapid incorporation and dispersion of the material into the mix. Care must be taken, however, to avoid incorporating air into the mix. The advantage of high-shear blending allows for rapid incorporation of the stabilizing ingredient without excessive and prolonged agitation.