Dairy products Analysis

Extraction of minced meat into buffer was used immediately prior to determination of lactate in meat by screen-printed sensors mounted in a FIA system [17]. The sensors were similar in design to those used for dairy product analysis [31] although they were constructed completely by screen-printing rather than having the outer membrane applied... 

Mariaca, R. Bosset, J.O. (1997) Instrumental analysis of volatile (flavour) compounds in milk and dairy products. Lait 77 13-40. 

Konev, S. V. and Kozlova, G. G. 1970. Application of secondary luminescence for fat analysis in milk and some dairy products. Proc. 18th Int. Dairy Congr. IE, 84. 

Foods. The determination of antioxidants and food preservatives is a very active part of the gas chromatography field. Adaptations and sample types are almost limitless for example, analysis of fruit juices, wines, beers, syrups, cheeses, beverages, food aromas, oils, dairy products, decomposition products, contaminants, and adulterants. A detailed discussion of this field may be found in Chapter 9. 

Acetonitrile precipitation has been the subject of some papers dealing with the analysis of mono- and disaccharides in milk and dairy products, oligosaccharides in soybeans, and general methods for sugars in foods (23). Aqueous ethanol has also been frequently utilized in the extraction of lipids as undesirable components along with the carbohydrates. A further treatment with chloroform will free the hydroalcoholic extract from the lipids. 

The solubility of NHDC in hot water, alcohol, aqueous alkali, acetonitrile, dimethyl sulfoxide, and alcohol/water mixture facilitates its selective extraction from food samples (20,91,94). It is extracted from jams, fruit juices, and dairy products with methanol (66,93) or acetone (95) and filtered or centrifuged. Chewing gum samples are dissolved in chloroform and extracted with water. The extract is centrifuged, and the clear supernatant is injected into the HPLC (95). If necessary, sample cleanup and concentration may be achieved by selective adsorption or desorption (20) on Sep-Pak Cl8 (96). Tomas-Barberan et al. (93) used Amberlite XAD-2 resin for purification of jam extract. Sugars, pectin, and other polar compounds were eluted with water, and NHDC was eluted with methanol. After concentration, the extract was further purified on a Sephadex LH-20 column prior to HPLC analysis. 

Protein-rich foods can also be specially treated. According to Saag (135), in order to extract colorants from fish, samples are boiled, filtered, washed, with an ammonia solution to displace proteins, and then washed through Sephadex LH-20 with water. The colored zones are collected for HPLC analysis. Dairy products (ice cream, cheese, yogurt) are first mixed with acetone or ethanol to precipitate the protein, which is ground up with sea sand and Celite, and the slurry is placed in a column from which dyes are eluted with a solution of ammoniacal methanol (135,162). 

FS Jiin, SL Ah, HJ Dalang. Analysis of food coal-tar dyes in commercial dairy product, soft drink, child food, pickle and vegetarian food. J Food Drug Anal 3(1) 65 -73, 1995. 

A simple isocratic technique was developed for the quantitative analysis of OAs in dairy products. An Aminex HPX-87 (300-mm X 7.8-mm ID) analytical column was eluted with 0.009 N H2S04 mobile phase UV detection at 220 and 275 nm was utilized. Lactic, citric, formic, acetic, propionic, and butyric acids were quantified for whole milk, skim milk powder,... 

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. 

Bintsis, T., Angelidis, A. S., and Psoni, L. (2008). Modem laboratory practices—Analysis of dairy products. In "Advanced Dairy Science and Technology", (T. J. Britz and R. K. Robinson, Eds.), pp. 183-257. Blackwell Publishing Ltd., Oxford, UK. 

M. M.F. Choi, Application of a long shelf-life biosensor for the analysis of L-lactate in dairy products and serum samples, Food Chem., 92(3) (2005) 575-581. 

N.G. Patel, A. Erlenkotter, K. Camman and G.C. Chemnitius, Fabrication and characterization of disposable type lactate oxidase sensors for dairy products and clinical analysis, Sens. Actuators B, 67 (2000) 134-141. 

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