A study of the visible characteristics of cheese

Al-Dahhan, Amir H (1977) A study of the visible characteristics of cheese. PhD thesis, University of Glasgow.

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These studies have shown that seaminess is a visible characteristic present in a significant proportion of Cheddar cheese made in Scotland. Earlier work suggested that this characteristic could be eliminated by washing the curd with warm water prior to addition of the salt. This practice is not acceptable to the dairy industry in the United Kingdom. Studies were conducted to investigate the factors which may encourage the occurrence of-seaminess and also to find acceptable remedies to overcome its formation. Seaminess was found to appear as white lines in the curd particle junctions and was evenly distributed in the interior of cheese. Seams were easily recognised by sight, havig a varying width and were more evident in coloured than in uncoloured Cheddar cheese. They were found in the cheese directly after pressing and became more noticeable with the time of curing up to 8 weeks. Seams were present in both salted and unsalted cheese, Slit openness tended to form easily along the seams which form weak points in the cheese. The seams were found to contain higher levels of calcium and phosphate than the rest of the cheese. The levels of calcium and phosphate found in experimental and commercial cheese supported the view of other workers that the seams consist of calcium orthophosphate. The seam-producing compound tended to concentrate on the surface of pressed and un-pressed salted and unsalted milled cheddared curd. The calcium levels of material from curd particle junctions increased with the curing time to reach a maximum in 8 weeks and thereafter decreased. Compared with the rest of the cheese the seams were found to contain low levels of sodium chloride, fat and protein and had a higher pH. Electrophoretic studies showed that there was no difference in the type of protein present in the seams compared with that present in the remainder of the cheese substance. A higher than normal level of added size of both coarse and fine particle size increased the formation of seams but did not produce in experimental cheese a distinctive seamy condition as judged by a grading panel. Seaminess increased when the salt was added to curd of high titratable acidity. The presence of additives in commercial grade salt, the temperature of the curd at the time of salt addition and -the mellowing time did not influence the degree of seaminess present in experimental cheese but these factors affected salt retention, moisture content and other characteristics of cheese. The type of mill used in milling the curd significantly affected the formation of seams and other characteristics of cheese, Cheddar cheese produced from curd milled with the Bell-Siro Cheese- Maker 3 equipment tended to be more seamy than that produced under experimental and commercial conditions from curd prepared with Berry, Damrow and peg mills. The application of high pressure for pressing commercially produced cheese increased the degree of seaminess but the use of lower than normal pressure reduced but did not eliminate the condition. Information was obtained on the rate of cooling of cheese during pressing under different ambient conditions. The temperature of cheese during pressing did not affect the development of seaminess but influenced other characteristics of cheese. Under experimental market conditions consumers did not object to seaminess in good quality commercial Cheddar cheese. In the course of investigations on the development of seaminess, information was obtained on a range of characteristics and composition concerning Cheddar cheese made on an experimental scale and in large mechanised factories in Scotland.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: R JM Crawford
Keywords: Food science
Date of Award: 1977
Depositing User: Enlighten Team
Unique ID: glathesis:1977-72277
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 24 May 2019 15:12
Last Modified: 24 May 2019 15:12
URI: http://theses.gla.ac.uk/id/eprint/72277

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