Dairy products measure

Fat Content of Milk. Raw milk as well as many dairy products are routinely analyzed for their fat content. The Babcock test, or one of its modifications, has been a standard direct measure for many years and is being replaced by indirect means, particularly for production operations. The Babcock test employs a bottle with an extended and caHbrated neck, milk plus sulfuric acid [7664-93-9] to digest the protein, and a centrifuge to concentrate the fat into the caHbrated neck. The percentage of fat in the milk is read direcflv from the neck of the bottle with a divider or caHper, rea ding to... 

For completeness, we must mention that benzene also occurs naturally in foods such as fruits, fish, vegetables, nuts, meats, dairy products, eggs, and alcoholic beverages. Exposures are estimated by multiplying measured concentrations by usage of the food product. 

The same functions used in agriculture can be applied to processed foods. In baked goods, wheat gluten, various additives, starch damage, and water absorption are just some of the parameters measured [21-24]. Dairy products are also important and often analyzed by NIR. Moisture, fat, protein, lactose, lactic acid, and ash are common analytes in the dairy industry [25-28]. 

Among the antimicrobial residues giving rise to such technological problems in the manufacture of dairy products, residues of penicillin G in particular have been determined as most important. This is the reason why measures to reduce the presence of penicillin G residues in milk were originally taken to prevent economic loss and not due to public health concerns. 

The Sarcina lutea test is the official US Food and Drug Administration (FDA) test for detecting penicillin residues in milk and dairy products (41). In this test, milk samples are placed in stainless steel cylinders on an agar plate seeded with Sarcina lutea ATCC 9341. As milk diffuses into the agar, inhibitors prevent the growth of the organism, causing a zone the width of which is a measure of the antibiotic concentration. The test is sensitive to about 0.006 g/ ml penicillin G, and confirmation of positive results can be performed by the addition of penicillinase. 

Several methods have been introduced which express the degree of oxidation deterioration in terms of hydroperoxides per unit weight of fat. The modified Stamm method (Hamm et at 1965), the most sensitive of the peroxide determinations, is based on the reaction of oxidized fat and 1,5-diphenyl-carbohydrazide to yield a red color. The Lea method (American Oil Chemists Society 1971) depends on the liberation of iodine from potassium iodide, wherein the amount of iodine liberated by the hydroperoxides is used as the measure of the extent of oxidative deterioration. The colorimetric ferric thiocyanate procedure adapted to dairy products by Loftus Hills and Thiel (1946), with modifications by various workers (Pont 1955 Stine et at 1954), involves conversion of the ferrous ion to the ferric state in the presence of ammonium thiocyanate, presumably by the hydroperoxides present, to yield the red pigment ferric thiocyanate. Newstead and Headifen (1981), who reexamined this method, recommend that the extraction of the fat from whole milk powder be carried out in complete darkness to avoid elevated peroxide values. Hamm and Hammond (1967) have shown that the results of these three methods can be interrelated by the use of the proper correction factors. However, those methods based on the direct or indirect determination of hydroperoxides which do not consider previous dismutations of these primary reaction products are not necessarily indicative of the extent of the reaction, nor do they correlate well with the degree of off-flavors in the product (Kliman et at. 1962). 

Potter, F. E., Deysher, E. F. and Webb, B. H. 1949. A comparison of torsion pendulum type viscosimeters for measurement of viscosity in dairy products. J. Dairy Sci. 32, 452-457. 

Sweat, V. E. and Parmelee, C. E. 1978. Measurement of thermal conductivity of dairy products and margarines. J. Food Proc. Eng. 2 187-197. 

Standardization of the milk fat and total solids contents of milk is accomplished by blending cream or skim milk with separated milk. Modern technology has developed continuous standardization processes that use turbidity or infrared absorption measuring devices to monitor and adjust the composition of the product as it leaves the separator. It is important that milk be accurately standardized to meet governmental legal requirements and to manufacture dairy products with optimal functional and quality attributes. 

Consequently, a more objective way to measure the habitual intake of milk fat would be the fatty acid composition of adipose tissue. However, this is not routinely performed in larger cohort studies, due to cost and that the procedure is invasive and less tolerated by study participants. Analysis of plasma fatty acid composition is thus a more feasible option for examination to determine dairy intake in the study population. While some groups have separated plasma into its constituent phospholipids and cholesterol esters to analyze serum 15 0 and 17 0 as markers of dairy intake (Smedman et al., 1999), Baylin et al. (2005) found that plasma that was not separated into its constituent cholesteryl ester, phospholipids, and triacylglycerols was still able to reflect habitual dairy intakes comparably to adipose tissue. Thus, whole plasma is an acceptable alternative to fractionated plasma in the absence of adipose tissue for analysis to reflect habitual dairy intakes and may be a cost effective option for consideration when conducting future intervention studies to assess the affect of dairy products on health outcomes. 

W.A. Collier, D. Janssen and A.L. Hart, Measurement of soluble L-lactate in dairy products using screen-printed sensors in batch mode, Biosens. Bioelectron., 11 (1996) 1041-1049. 

Table 7.12 summarizes the level of POPs contamination in eight main locally consumed food groups in 2003. With the exception of DDT and HCB, POPs pesticides were not detected in most food groups. DDT was found in cereals, fruits, dairy products and seafoods, while HCB was detected in cereals only. PCBs was not detected in fruits, dairy products, meats or poultry, but found in seafood items at a mean concentration of 4.07 pg g-1 food. Measurable levels of dioxins/furans were found in cereals, dairy products, eggs, seafoods, meats and poultry, with mean dioxin/furan levels ranging from 0.001 (meats) to 0.285 (seafoods) pg TEQ g-1 food. Dioxins/furans were not analyzed in vegetable and fruit items sampled in 2003. 

CDDs are found everywhere in the environment, and most people are exposed to very small background levels of CDDs when they breath air, consume food or milk, or have skin contact with materials contaminated with CDDs. For the general population, more than 90% of the daily intake of CDDs, CDFs, and other dioxin-like compounds comes from food, primarily meat, dairy products, and fish. CDDs may be present at much lower levels in fruits and vegetables. The actual intake of CDDs from food for any one person will depend on the amount and type of food consumed and the level of contamination. Higher levels may be found in foods from areas contaminated with chemicals, such as pesticides or herbicides, containing CDDs as impurities. CDDs have been measured in human milk, cow s milk, and infant formula, so infants are known to be exposed to CDDs. 

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