Sweetened condensed milk lactose crystallization

Sweetened condensed milk. Crystallization of lactose occurs in sweetened condensed milk (SCM) and crystal size must be controlled if a product with a desirable texture is to be produced. As it comes from the evaporators, SCM is almost saturated with lactose. When cooled to 15-20°C, 40-60% of the lactose eventually crystallizes as a-lactose hydrate. There are 40-47 parts of lactose per 100 parts of water in SCM, consisting of about 40% a-and 60% /1-lactose (ex-evaporator). To obtain a smooth texture, crystals with dimensions of less than 10 /an are desirable. The optimum temperature... 

Figure 6.4. Lactose crystal forms. (A) A variety of a-hydrate crystals from pure solution. (B) /3-Lactose crystals from pure solution. (C) a-Hydrate crystals in sweetened condensed milk. (D) a-Hydrate crystals in sandy ice cream. (E) a-Hydrate crystals in frozen condensed milk. (From Nickerson 1974.)...

The crystallization principles previously discussed are applied in processing dairy products, such as sweetened condensed milk, instant milk powder, stabilized whey powders, lactose, and ice cream. 

The control of lactose crystallization in sweetened condensed milks has been reviewed extensively (Webb 1970 Hall and Hedrick 1971 Hun-... 

Sweetened condensed milk is supersaturated with lactose, and the lactose crystals formed tend to settle and also give the product a sandy mouth feel. To prevent this, crystal size should be at most 8 pm, and one generally tries to achieve this by adding crystalline seed lactose, about 0.3 g per kg product. Calculate what the maximum size of the seed particles may be. One kg of sweetened condensed milk contains about 110 g lactose, 440 g sucrose, and 260 g water. Consult also Table 2.2. 

Even though liquid whey has been successfully commercialized in the form of alcoholic and nonalcoholic beverages, these are still a rarity in most countries. Most whey is converted to whey solids as ingredients for human food or animal feeds by traditional processes such as spray drying, roller drying, concentration to semisolid feed blocks, or production of sweetened condensed whey. Jelen (1979) reported other traditionally established processes including lactose crystallization from untreated or modified whey, production of heat-denatured whey protein concentrate, or recovery of milk fat from whey cheese in whey butter. ... 

---