McSweeney Cheese Problems Solved

1. Auflage 2007
ISBN: 978-1-84569-353-4
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 424 Seiten

Reihe: Woodhead Publishing Series in Food Science, Technology and Nutrition

Cheese is a unique food product which requires a significant amount of scientific knowledge to be produced successfully. However, due to the many, complex and interrelated changes which occur during cheese manufacture and ripening, it is still not possible to guarantee the production of premium quality cheese. Written by an international team of renowned contributors, Cheese problems solved provides responses to over 200 of the most frequently asked questions about cheese and the cheese-making process, in a unique and practical question-and-answer format.Opening chapters concentrate on queries regarding the preparation of cheese milk, the conversion of milk to curd, the ripening process, pathogens, cheese analysis and nutritional aspects of cheese amongst other issues. The latter half of the book discusses particular types of cheeses such as Cheddar, Grana-type cheeses, Mozzarella, Dutch-type, Swiss and Blue cheeses, to name but a few.Edited by a leading expert and with contributions from specialists within the field, Cheese problems solved is an essential reference and problem solving manual for professionals and trainees in the cheese industry. - Provides responses to over 200 of the most frequently asked questions about cheese and the cheese-making process - An essential reference and problem solving manual for professionals and trainees in the cheese industry - Benefit from the knowledge of leading specialists in the field

Autoren/Hrsg.

McSweeney, P L H

Leseproben

Milk
1 Introduction P.L.H. McSweeney Milk is a fluid secreted by the female of all mammals, the primary function of which is the complete nutrition of the neonate of the species. Since the nutritional requirements of the young of the different mammalian species differ greatly, it is unsurprising that the compositions of milks of different species vary considerably. Typical compositions of the milks of the principal dairy species are shown in Table 1. In addition to interspecies differences, milk from a particular species will also vary with the individuality of the animal, breed, nutritional status, stage of lactation, age, interval between milkings, health (mastitis and other diseases) and stage of lactation [2, 3] The principal components of milk are water, lactose, protein (caseins and whey proteins), fat and minerals. Table 1 Typical compositions (%) of milks from the major dairying species Cow 12.7 3.7 3.4 4.8 0.7 Goat 12.3 4.5 2.9 4.1 0.8 Sheep 19.3 7.4 4.5 4.8 1.0 Buffalo 16.0 3.7 6.9 5.2 0.8 Milk is the principal starting material for cheesemaking. Its caseins form the structural matrix of cheese and the fat entrapped contributes to cheese texture and flavour. The minerals of milk (particularly the colloidal calcium phosphate associated with the caseins [4] are factors that affect cheese texture and lactose is the essential fermentation substrate for lactic acid bacteria. Further reading
Fox PF, Mcsweeney PLH. Dairy Chemistry and Biochemistry. London: Blackie Academic and Professional; 1998. 2 What is the typical composition of cow’s milk and what milk constituents favour cheesemaking? A.L. Kelly The principal constituents of milk of any species are water, fat, protein (caseins and whey proteins), sugar (lactose) and minerals (salts such as calcium and phosphate; see 4), with trace quantities of vitamins and enzymes. Milk is a complex system, being both an emulsion (of milk fat in globules protected by the milk fat globule membrane), a colloidal suspension (75–80% of the protein is casein, which is found in aggregates called casein micelles) and a solution containing many dissolved components. The typical range of composition of cow’s milk is as follows: Lactose Range 4.0–5.0% Average 4.8% Protein Range 3.0–3.5% Average 3.3%  Casein Range 2.2–2.8% Average 2.6%  Whey protein Range 0.5–0.8% Average 0.65% Fat Range 3.0–5.0% Average 3.5% Salts Range 0.6–0.9% Average 0.7% The levels of fat in milk are much more inherently variable than those of other constituents. Milk composition can vary according to diet of the cows, stage of lactation (e.g. reduced casein and lactose contents in late lactation), mastitis and seasonality; the latter two will be discussed in [3] For the cheesemaker, the most important constituents, with the reason for their importance, are shown in Table 1. The pH of milk is an important characteristic of milk for cheesemaking that depends on its composition, particularly the levels of salts and whether they are ionised. High milk pH (as sometimes occurs in mastitis or late lactation milk) renders conditions less favourable for the action of chymosin, which has an acidic pH optimum. Table 1 The most important constituents of cow’s milk for cheesemaking Casein Forms the rennet gel which is primary structural element of cheese; influences texture and flavour through proteolysis during ripening Fat Contributes to cheese texture and to flavour, via lipolysis, to an extent dependent on variety Lactose Fermentation substrate for starter lactic acid bacteria; products of lactose fermentation also contribute to flavour during ripening Calcium Essential for formation of a rennet gel in the initial stages of cheesemaking; level in curd influences texture Whey proteins are normally lost in the whey and are not important unless steps are taken to force their incorporation into curd (e.g. heat treatment to recover denatured whey proteins [12] or ultrafiltration [16] to recover native whey proteins). Much of the lactose and salts are also lost in the whey. Casein and fat have the highest proportional recovery from milk into cheese (ideally > 90% for both). The composition of milk for cheesemaking can be manipulated by the cheesemaker by: • standardisation of fat:protein ratio (see [9] • addition of protein (e.g. sodium caseinate) although rarely practised; • addition of calcium chloride (see [33] Further reading
Harding F, ed. Milk Quality. London: Blackie Academic and Professional; 1995. Jensen RG, ed. Handbook of Milk Composition. San Diego: Academic Press; 1995. 3 How do seasonal variations in milk composition affect cheese quality? A.L. Kelly The composition of milk produced by mammals changes from the commencement of lactation (i.e. colostrum) to the end of lactation and drying-off. Levels of almost all milk constituents change during lactation, and thus the suitability of milk for cheesemaking can vary throughout the lactation period. A plot of changing milk composition throughout a typical lactation cycle is shown in Fig. 1. For many countries, year-round calving is practised, and the milk received by cheese factories is generally a mixture of mid-lactation milk, with smaller amounts of early- and late-lactation milk; hence, variations in composition are diluted and quality remains at an average throughout the year. Fig. 1 Schematic diagram illustrating changes in fat (?), protein (?), lactose (?) and calcium (?) contents of milk during lactation, relative to average composition (dotted line). Values are illustrative only to show typical trends (redrawn from Walstra, P., Guerts, T.J., Noomen, A., Jellema, A. and Van Boekel, M.A.J.S. (1999) Dairy Technology, Marcel Dekker, New York). However, in certain regions (e.g. Ireland, New Zealand and parts of Australia) there are pronounced seasonal calving patterns, with calving being concentrated at certain times of the year. In the case of Ireland, historical preference for economical production of milk from cows fed on summer grass has resulted in a national summer:winter milk volume ratio of around 10:1. As a result, there is only a small amount of milk available in winter, and this is generally utilised for liquid milk products; conversely, during the summer, the relatively large volumes of milk available are used intensively for the production of long shelf-life products, such as milk powder, casein, butter and Cheddar cheese. In Ireland, many cheese factories are closed during winter months due to insufficient availability and poor quality of milk. In addition, in countries with seasonal milk production, the changes in composition during an lactation cycle of individual cows confound changes in the overall quality of milk collected at different times of the year. For instance, milk collected in Ireland in late autumn/early winter comprises a high proportion of late-lactation milk, which can cause a reduction in the quality of cheese made therefrom. Alternatively, cheesemakers must adapt their cheesemaking protocols and schedules to compensate for any changes in composition (e.g. by addition of calcium chloride [33] or changes in standardisation ratio [9] Further reading
Auldist MJ, Coats S, Sutherland BJ, Mayes JJ, Mcdowell GH. Effects of somatic cell count and stage of lactation on raw milk composition and the yield and quality of Cheddar cheese. J. Dairy Res. 1996;63:269–280. Auldist MJ, Walsh BJ, Thomson NA. Seasonal and lactational influences on bovine milk composition in New Zealand. J. Dairy Res. 1998;65:401–411. 4 What are milk salts and how do they affect the properties of cheese? A.L. Kelly A minor but highly significant fraction of milk is a mixture of salts, at approximate levels shown in Table 1. Some minerals are present in different phases in milk; of most relevance to cheesemaking, calcium is partitioned between the colloidal phase (i.e. deposited as nanocrystals of calcium phosphate within the...