Insoluble sediments are contained in all the samples of evaporated milk, sweetened condensed milk, and milk made from powdered milk solids that were examined. The amount of sediment was greates in the milk :powder milk, being over 13 per cent of the original substance. With the sweetened condensed milk it averaged 6.6 per cent, and 2.2 per cent with evaporated milk. The sediments from evaporated milk were coarse and granular. The coarse material had a high per cent of calcium. Granulation occurred in the milks of the least density. The granular particles are the result of recrystallization, and this takes place more quickly in fluids of low density. The sediments are characteristic of highly heated and condensed milk products, and their presence in milk would show that condensed milk or powdered milk had been used. The protein probably forms from one-half to two-th irds of this sediment. The results of the calcium, phosphorus and magnesium determinations indicate tha.t insoluble compounds are formed with these constituents. Some of the calcium is evidently in the form of carbonates and phosphates, since efferve~nce took place on addition of an acid to the granular sediment, and phosphorus was shown to be in the sediment in greater proportion than normal. / Master of Science / Major thesis in Diary Chemistry

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Call number: LD2668 .T4 1934 A51

Call number: LD2668 .T4 1956 B37 / Master of Science

Call number: LD2668 .T4 1963 D48 / Master of Science

The purpose of this investigation was to modify the procedure of Bills, Khatri and Day for use in the development of a suitable method for determining the quantitative distribution of the free fatty acids (FFA) in normal, heated, and rancid milk and milk fractions The method consists of extracting the FFA from lyophilized milk, separating the FFA from neutral fat, converting the FFA to methyl esters, and analyzing the methyl esters by gas-liquid chromatography (GLC). The salts of FFA present in lyophilized milk or milk fractions were released by lowering the pH of the sample with H₂SO₄, and subsequently extracted with ethyl ether. The extracted FFA were simultaneously isolated from the extract and methylated by using the one-step procedure of Bills, Khatri and Day. A specially designed concentration flask was employed with a reflux system to concentrate the methyl esters. The esters were then separated by GLC. Quantitative calculations were made from the GLC peak areas using internal standards. The major esterified fatty acids of milk are n-saturated, evennumbered 4:0-18:0 and unsaturated 18:1 and 18:2 acids. The distribution of major FFA in whole milks was found to be essentially the same as that of the esterified fatty acids of milk fat. Heat treatments of milk, whether pasturization or extended holding at 100°C, effect a progressive reduction in total FFA. Decreases in long chain fatty acids are also characteristic of extended heating. Milks determined to be rancid by acid degree value and organoleptic analysis showed high levels of FFA, 1.5-3.6% of the fat content of the sample. The increases in 6:0-12:0 resulting from lipase hydrolysis approximate the amounts shown by Al-Shabibi and co-authors to produce rancid flavor when added to good quality milk. Milk triglycerides, fat globule membrane, skim milk, and buttermilk show characteristic FFA patterns which appear to be related to the solubility properties of the individual acids. Seventy-one percent of the total FFA in a given portion of 40% cream was found in the triglyceride fraction, 26% in the crudie fat globule membrane preparation and 3% in the skim milk fraction. The total concentrations of FFA were found to be: 1% of the fat in whole milk or 0.04% of the fluid milk weight; 0.16% of the total weight of 40% cream; 0.28% of centrifuged triglycerides; 1.7% of the fat globule membrane; and 0.008% of the fluid weight of skim milk. / Graduation date: 1965

No description available.

No description available.

Call number: LD2668 .T4 1957 T47 / Master of Science

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