Determination of theoretical yield and process efficiency for Cottage Cheese

As more pressure is applied to reducing production costs, attention is increasingly being given to maximising the yield of high moisture cheeses including Cottage cheese. While yield is important, cheese quality must also be considered whenever attempts are being made to improve or optimise yield.

Considerable academic and commercial research has been devoted to optimising the yield of un-dressed or un-creamed Cottage cheese. There is now a significant volume of academic research freely available or available at low cost (On Line databases may require payment by credit card to access some journal articles); this is easy to access. Commercial information of varying quality, some of it surpassing what is available in the research literature, is also available but this is difficult to access.

The yield of Cottage cheese depends principally on the casein concentration of the milk used and the moisture content of the final product.

Milk quality is particularly important. Because casein is so critical to the yield of this product extended storage of milk, regardless of temperature used or whether thermisation has been used used, will result in low yields; this very simple causal factor is often ignored in commercial practice. Use of milk containing high somatic cell counts (SCCs), >100,000 cells/ml, has also been shown to result in low yields. However, this is unlikely to be a major problem in the UK and Ireland because of improvements in milk quality.

Cheesemaking technique also has a major influence on loss of solids including fines in the whey and has been well documented.

Determination of theoretical yield and calculation of process efficiency

As discussed earlier considerable research on the yield of Cottage cheese has been published. Over 45 years ago, Bender and Tuckey (1957) published three simple yield equations for determining the theoretical yield (Y) of Cottage cheese:

Equation 1. Y=5.71C-0.45 ---------where C is casein determined by precipitation with lactic acid

Equation 2. Y=6.03 CF-1.69 -------where CF is casein determined by formol titration

Equation 3. Y=4.9TS-29.72 ---------where TS is total solids.

Interestingly, variants of equations 1 and 2 are still used in some plants today!

More recently, Emmons and colleagues in Canada and researchers at Cornell University have developed more sophisticated approaches to determining the theoretical theoretical yield of this product e.g. Emmons et al. 1978; Klei et al.; 1998. These approaches are based on an understanding of the transfer of milk components between the curd and whey phases and knowledge of the retention of solids in un-creamed curd.

The calculator below uses current understanding of the conversion of milk constituents to cheese curd to calculate the theoretical yield of Cottage cheese. Ideally the casein concentration of milk should be used. Since some plants cannot determine casein directly a facility to input solids-not-fat (SNF) or protein has been provided. The conversion assumptions are given as footnotes. Use of SNF and protein will add additional errors to the calculation.

Sampling errors and errors in calculations can introduce very large errors in yield determination. Note due to the errors involved in sampling and analysis relatively large volumes of data along with some basic statistical analysis are required to make management decision using yield equations.

There are several approaches to determining process efficiency. One approach is to compare actual yield with theoretical yield as determined using a yield equation. The difference in yields can be expressed as a percentage and the closer this value is to 100% then the higher the value for process efficiency. This is shown below.

Process efficiency =

Actual yield x 100
Theoretical yield

Alternatively the percentage casein and protein retention's can be calculated and compared with benchmark values, if the actual retention's are significantly lower than bench mark values action may be required to improve process efficiency.

Go to Cottage Cheese Yield and Process Efficency Calculator.

How to cite this article

Mullan, W.M.A. (2006). [On-line]. Available from: . Accessed: 14 December, 2017.  

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