Lactose content

There are a number of things to consider, but the most important is understanding the needs of the customer. Is the total sugar content of the product required or the lactose content The level of uncertainty in the result that is acceptable also helps focus on the choice of method. Once the method is chosen and validated, it is then important to ensure that all of the equipment is available and in a proper state of calibration. Then, all that remains is to have sufficient trained staff to carry out the analysis. Once the experimental results have been obtained and the data treatment is complete, the report can be written. The report also has to meet the customer requirements and should be written in an unambiguous way which is clear to the non-specialist. 

Although < 12% of the species of yeast use lactose (see Table III), this utilization is of commercial interest, as /3-D-galactosidase (EC 3.2.1.23) from yeasts may be used to lower the lactose content of dairy products, such as whey from cheese-making (for example, see Ref. 359) or milk itself.380... 

Reinart, A. and Nesbitt, J. M. 1956C. The lactose content of milk in Manitoba. 14th Int. Dairy Cong, 1, 957-964. 

A Cheddar-type cheese retains 48% of total solids of milk, 96% casein, 4% soluble proteins, 94% fat, 6% lactose, 6% H20, 62% calcium, 94% vitamin A, 15% thiamin, 26% riboflavin, and 6% vitamin C (National Dairy Council 1979). The lactose content varies in freshly prepared cheeses and decreases rapidly during ripening, completely disappearing in four to six weeks. The enzymes and ripening agents responsible for the rate and extent of fat and protein breakdown are fully discussed in Chapter 12, and vitamin variation is discussed in Chapter 7. 

Lactose is present in the milk of most mammals, as shown in Table 6.1. Exceptions to this pattern are the California sea lion and other Pacific pinnipeds, which have no lactose in their milks (Johnson et al. 1974 Pilson 1965 Pilson and Kelly 1962 Stewart etal 1983). Human milk contains one of the highest lactose contents, about 7%, of all mammalian milks (Renner 1983), whereas the average lactose content... 

Lactose content of milk is affected by inheritance, age, stage of lactation, and interquarter differences (Walsh et al 1968A). Such variations in lactose content constitute the major factor in variations observed in the SNF content of milk (Walsh et al. 1968B). 

Other systems make use of the sticking tendency of acid whey. Partially dried whey powder coats the inner wall of the drying chamber, whence it falls when the crystalline lactose content of the powder becomes high. However, sticking of the product on the hot metal surfaces can be a problem unless sufficient moisture is present so that lactose crystallization proceeds to the point where the powder no longer adheres to the equipment (Pallansch 1973). 

Walsh, J. P Rook, J. A. F. and Dodd, F. H. 1968A. A new approach to the measurement of the quantitative effects of inherent and environmental factors on the composition of the milk of individual cows and of herds, with particular reference to lactose content. J. Dairy Res. 35, 91-105. 

Cow s milk contains about 4.8% lactose, whereas human milk contains 7% (Fomon 1974). Lactose is used in the preparation of modified cow s milk formulas for infant feeding to duplicate as closely as possible the lactose content of human milk. Although a specific need for... 

Table 7.7. Lactose Content of Milk and Selected Milk Products.

Sasaki, M. and Keenan, T. W. 1978. Membranes of mammary gland XV. 5-thio-D-glucose decreases lactose content and inhibits secretory vesicle maturation in lactating rat mammary gland. Exp. Cell Res. Ill, 413-425. 

The second whey separation process uses both ultrafiltration and reverse osmosis to obtain useful protein from the whey produced in the traditional cheese manufacturing process. A flow schematic of a combined ultrafiltration-reverse osmosis process is shown in Figure 6.23. The goal is to separate the whey into three streams, the most valuable of which is the concentrated protein fraction stripped of salts and lactose. Because raw whey has a high lactose concentration, before the whey protein can be used as a concentrate, the protein concentration must be increased to at least 60-70% on a dry basis and the lactose content... 

The main applications of biocatalytic membrane reactors in the food sector include reduction of the viscosity of juices by hydrolyzing pectins, reduction of the lactose content in milk and whey by its conversion into digestible sugar, treatment of musts... 

One of the first cases of the application of membrane bioreactors in food processes was the production of milk with low lactose content. (3-galactosidase was entrapped into cellulose acetate fibers to carry out the hydrolysis of milk and whey lactose [2] recently the system was improved by the use of microfiltration and by UV irradiation of the enzyme solution to avoid growth of micro-organisms [45]. 

As it can be seen in Table 13.2, human milk composition is quite different from that of cow s milk. Casein and mineral contents are lower in human milk than in cow s milk, whilst the lactose content is higher in the former. With regards to fatty matter, both types of milk present similar contents, but the total protein is over three-fold higher in cow s milk. 

Product composition—a high lactose content gives low free fat a high protein content gives high free fat. 

Aguilar, C.A., Ziegler, G.R. 1994a. Physical and microscopic characterization of whole milk with altered lactose content. 1. Effect of lactose concentration.. / Dairy Sci. 77, 1189-1197. 

The characteristic carbohydrate of milk is lactose or milk sugar. With a few minor exceptions, lactose is the only sugar in the milk of all species and does not occur elsewhere. Lactose is the major constituent of the dry matter of cow s milk, as it represents close to 50 percent of the total solids. The lactose content of cow s milk ranges from 4.4 to 5.2 percent, with an average of 4.8... 

Size as well as inner structure of the WPP depend on the reaction conditions in terms of the temperatnre regime and the medium composition. As shown by Plock et al. (1997) and by Spiegel (1999), the lactose content in the aqueous phase is of great influence. Figure 19.11 shows the resulting aggregate size of the WPP,... 

Figure 19.12. Effect of temperature and lactose content on the degree of hydration of WPP (Spiegel 1999).

Effect of Ionic Strength Added and Type of Salt Added on the Relative Duration and Energy Consumption of Electroacidification and on Protein, Ash, and Lactose Contents of EDBM Isolates Produced... 

Aside from improved yield, the use of UF pre-cheese results in the improvement of product taste and texture compared to cheese produced by conventional methods because of the reduction of lactose content, controlled acidification rate, and increase in the water-holding capacity of the product due to the incorporation of whey, which makes for softer product [25,73,79]. Lucisano et al. [77] noted an enhanced rennet-induced clotting time of UF-concentrated irulk as pH is lowered from its natural pH level. 

With the objective of increasing calcium and lactose content of MF retentate in addition to micellar casein whUe maximizing whey protein depletion. Nelson and Barbano [114] developed a multistage MF process that removed -95% of whey protein from skim milk. They reported that the MF retentate produced from this process contained soluble minerals, NPN, and lactose similar to the original milk. This was accomplished by using the permeate from the UF of the MF permeate to diafilter the MF retentate after achieving a concentration factor of 3 in the MF. Aside from the recovery of native micellar caseins, they showed that the process enabled the production of whey protein stream (UF retentate) with protein content similar to that of commercial WPC. 

A high content results in a sandy body because the high lactose content may crystallize. The protein makes the ice more compact and smooth. MSNF have no relevant flavour effect except a salty, slightly sweet note. 

---