Browsing by Author "Holdaway, Charles W."
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- A bacteriological survey of the practices used by a local creamery in handling and manufacturing dairy productsAlphin, Horace E. (Virginia Tech, 1935-05-15)Introduction: Modern dairy practice is subject to many regulations designed to prevent a product being delivered to the consumer in an unsanitary condition. Large numbers of bacteria do not necessarily condemn food products, but usually an excessive number of bacteria is associated with inferior materials and unsanitary practices. Definite legal limits of the number of bacteria permissible in the milk supply have been established by the health authorities, and the burden rests primarily upon the retailer to observe them. If the distributor is to maintain the highest standards of keeping quality it is essential for him to have some knowledge of the bacterial action going on in the pasteurizing, cooling, and bottling processes. The main factor in protecting the keeping quality of milk becomes one of preventing the entrance of bacteria, of destroying them after they enter, or of keeping them at a low temperature to check their growth. The first interest of the distributor should be to restrict the number of bacteria getting into the milk, so long as is practical with the expense involved. The problem of plant contamination can be most economically approached by making an extensive survey of the product from the time it enters the creamery until it is ready for delivery. The survey was made to show the influence that the various manufacturing operations exert on the bacterial content of fluid milk, butter, and ice cream. It is reasonable to suppose that some parts of the processing equipment are greater bacterial contributors than others. If the plant operator had some knowledge of the most abundant sources of contamination, he could make an effort to keep the number of bacteria to a minimum, by exercising greater care in cleaning and sterilizing the utensils.
- The detection, chemically, of condensed milk in ice creamHoldaway, Charles W. (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1916)This study was taken up at the suggestion of the Pure Food Department of Virginia, and a preliminary report containing a suggestion of the method most likely to give results was submitted by one of the chemists of that Departent. The proposed method was based on the theory that the process of condensing milk causes a portion of the fat to resist all methods of extraction in general use; that not only to the usual methods of ether extraction fail to recover all the fat from condensed milk, but that results are the same with the Babcock Test and all its modifications. Using this theory as a basis, a method of procedure was submitted for the complete recovery of the fat, and it was concluded that the difference in results obtained by it and by one of the old methods would be evidence of the presence of condensed milk.
- An investigation as to the inconsistencies of the methylene blue reduction test and means of controlling sameAlphin, Horace E. (Virginia Tech, 1935-09-05)The dissolved oxygen content of market milk fluctuates enough to cause a variation in the test.
- Statistical weighting for age of advanced registry cowsHoldaway, Charles W. (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1916)A Biometrical Study of Advanced Registry data with a view of determining the correct age weighting for comparison of different animals for milk and fat production.
- A study of milk made from condensed and powdered milksHoldaway, Charles W. (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1916)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.